BBC Research & Development exists to givedownloads.bbc.co.uk/rd/pubs/annual-review/bbc_rd_annual_review_2000-2001.pdfBBCR&D delivers competitive advantage to the BBC through technologyinnovation

BBC R&D ANNUAL REVIEW 1

BBC Research &Development exists to givecompetitive advantage to theBBC through technology.

APRIL 2000 – MARCH 20012

Over six million homes now havedigital satellite, terrestrial or cabletelevision. Digital radio is anestablished standard set for rapidtake-off. And the UK use of streamedmedia across the Internet is thehighest in Europe. Britain is wellahead of the rest of the world inimplementing these digital platformsfor broadcasting, and BBC R&D hasconsistently led progress in thesefields. Prestigious awards in the pastyear for our Digital TerrestrialTelevision team and for John Sykes andJustin Mitchell, pioneers in digitalbroadcasting, reflect the contributionthat BBC R&D has made andcontinues to make.

There is still much work to bedone to consolidate, improve andextend our digital broadcastingplatforms, and BBC R&D continues toplay a major part. The service strategyunveiled by Greg Dyke in September2000 requires significant developmentof our underlying technicalinfrastructure. New coding andmultiplexing arrangements for digitaltelevision are needed to accommodateour planned new channels. Theschedule information needed tosupport onscreen programme guidesand other navigation systems needsfurther development as the range ofour services becomes more complexand the devices our audience usesbecome more sophisticated. Furtherdevelopment of the enhanced andinteractive capabilities of digitaltelevision are needed to deliver theexciting new media services beingdesigned by the BBC. Andbroadcasters’ obligations to provideaudio description and signing servicesto our audiences need innovativetechnical solutions. BBC R&D’s workremains central to our achievingthese aims.

BBC R&D delivers competitive advantage to the BBC throughtechnology innovation.

As digital broadcasting platforms mature, BBC R&D faces a newchallenge – to create joined-up solutions which bring the benefitsof digital technology to the whole of the BBC’s production anddistribution chain.

Peter BuryHead ofResearch & Development


Alongside the deployment ofservices on the digital platforms, a keyobjective for the BBC is modernisingprogramme production. Now tools arebecoming available which offerintegrated production solutions. Wecan improve efficiency in programmemaking, and we can also create newways for audiences to enjoy BBCcontent. Production modernisationgives the BBC R&D team a range ofnew challenges and new fields towork in.

• Low-cost computers andnetworks allow us for the firsttime to handle large parts of theproduction process, fromcapture through editing andarchiving through to playout, onstandard IT platforms.BBC R&D’s ORBIT project isleading the world in building thetools to make this possible.

• We are making use of ourexpertise in digital televisiontransmission to develop theworld’s first digital radio camera.The prototype radio cameraoffers creative flexibility as wellas reliability, in the studio, aswell as in outside broadcasts.Our operational colleagues arevery keen to get it intoregular use.

• Our work on virtual realityproduction has made majorprogress, offering furtherflexibility for programme-makersand enabling whole new types ofprogramme to be made. We areworking very closely with theBBC’s Imagineering group to

make technical innovationsavailable to support newprogramme concepts.

• New plasma panels are comingto market, with direct digitalinterfaces designed by BBC R&Dand showing to their full valuethe high definition BBCprogrammes that BBC R&D ishelping to create.

• Our work applying speechrecognition to subtitling is nowfully operational within the BBC,delivering significant efficiencyimprovements in the SubtitlingUnit. The work of the BBC R&Dteam and our commercialpartners was rewarded withthe RTS prize forInnovative Applications.

We have been working at the leadingedge of the development of personalvideo recorders. BBC R&D has been aleader in the international effort tocreate standards for such services; andhas been closely involved in the launchof the first commercial personal videorecorder in the UK.

A further priority for BBC R&D isin planning for the eventual switch-overfrom analogue to digital televisionbroadcasting. We are modelling thescenarios for the transition, to ensurethat the BBC continues to deliverservice to all our licence fee payers.This has involved a major collaborationbetween our spectrum planning team,and our system engineers, as well aswith the other broadcasters in the UK,extending coverage for digital terrestrialtelevision and digital radio andmanaging the knock-ons for existing

analogue services. As our Europeanneighbours begin to deploy digitaltelevision and radio services of theirown, our work is a vital protectionagainst interference from abroad.

At the same time, our SystemDesign Group has been heavily involvedin planning the implementation of theBBC’s second digital phase; the new‘MacTaggart’ services.

The year has also seen majorprogress in the design and developmentof Digital Radio Mondiale, abroadcasting system for digital radio inthe AM bands which is needed byWorld Service to modernise thedelivery of their services around theworld for the coming century.

The technology environment ischanging fast, giving the BBC newopportunities to exploit our technicalskills in the commercial sphere. BBCTechnology, the new commercial arm ofthe BBC’s technical resources, has beenlaunched. BBC R&D is working closelywith BBC Technology: it helps us bringthe benefits of technical innovationfaster to the BBC and gives us a routeto exploit our intellectual propertymore profitably in the market.

We have an outstanding team ofengineers, scientists and mathematiciansin BBC R&D. The quality of their work,and the energy and commitment of allthe BBC R&D staff, is the reason whydemand for our work is booming. Thepast year has seen some remarkableachievements, and we look forward toeven more in the coming year.

DAB – digital radio 43

FM radio 47

digital radio mondiale 48

protection of AM services 51

ORBIT project 11

radio cameras 17

virtual production 21

high definition television 25

archives 28

speech recognition 31

watermarking 35

multichannel sound 37

communications 38

production 9 audio distribution 41


plasma displays 86

home platform 89

licensing 95

switch-over 55

improving the coverage 59

capacity planning 61

the evolving architecture of television 65

monitoring 69

resilience 71

scheduling the digital channels 73

audio description 77

new data services 79

signing 82

foreword 2

awards 6

digital television distribution 53 in the home 85


YOUNG TECHNOLOGISTOF THE YEARBBC R&D’s Justin Mitchell was named‘young technologist of the year’ bythe London branch of the RoyalTelevision Society, for his pioneeringwork on the development of digitalterrestrial television. He led our teamthat worked with LSI Logic to designthe prototype receiver chips fordigital terrestrial television set-topboxes. Launched in April 1998, thechips set the industry standard,becoming the market leader forconsumer and professional use.

We are always delighted when our work is recognised by our peers.This year’s awards are especially pleasing as they are the result of longterm commitments to public service broadcasting.

ENGINEER OF THEYEARJohn Sykes was named ‘engineerof the year’ in the ProductionSolutions Awards at the InternationalBroadcasting Conventionin Amsterdam.

The award recognised John’soutstanding contribution to thedevelopment of digital broadcasting inBritain and around the world. As Headof Transmission Systems Group, Johnhas been at the forefront of thedevelopment of digital television andradio since their beginnings in the1980s, working with internationalbodies on standards for both analogueand digital technology.

More recently John has beenworking as part of the Digital RadioMondiale consortium helping todevelop a standard for digitalbroadcasting in the AM bandsbelow 30 MHz.

Although awarded to him,John Sykes recognised that ‘The awardreflects the tremendous creativity,imagination and energy of the manyengineers and support staff inBBC R&D who have contributed tothe continuing success of digitalbroadcasting in both Britain andaround the world.’

RTS JUDGES AWARDFOR TECHNICALINNOVATIONThis year the RTS Judges’ Award fortechnical innovation was given to theBBC DTT technical team for theircontribution to the development ofdigital terrestrial television.

The BBC took the lead indeveloping the technology for digitaltelevision to guarantee that it coulddeliver public service programmes tothe widest possible audience. The workwas carried out by a team workingmainly at BBC R&D, but whichincluded others in many BBCDepartments. The BBC team not onlyestablished a technical lead, but bypublishing its results and by workingwith other organisations it hasencouraged others to follow. The workwe did was crucial to the timelydelivery of working technology forboth the broadcast network and theconsumers’ set-top boxes.

This award recognised the vitalcontribution which the BBC has madeand continues to make to thedeployment of digital television in theUnited Kingdom.

RTS INNOVATIVEAPPLICATIONS AWARDWe were particularly pleased whenAssisted Subtitling won the RTS Awardfor Innovative Applications. We werejoint recipients along withBBC Subtitling, 20/20 Speech Ltd., andSoftel Ltd. This work was an exampleof research which might never havehappened if it were not for the BBCand our public service obligations.Work on subtitling, originallyconceived for the hard of hearing, hasbrought benefits for many peoplewatching television.

The project embraced fundamentalresearch and showed how it could beapplied to real problems and lead toreal products in the market. Both20/20 Speech Ltd, and Softel Ltd wereinvolved in the project, developing asystem which combines together textanalysis, speech recognition, shotchange detection and other techniquesto help in the preparation of subtitles.Together with BBC Subtitling we wereable to create a product which reallyworks, giving significant savings in timewithout compromising quality inany way.



ORBIT project

radio cameras

virtual production

high definition television

archives

speech recognition

watermarking

multichannel sound

communications



We can make significant savings if we usemass-market IT hardware to replacespecialised broadcasting equipment. Bit-ratereduction would be necessary to make apractical implementation, with theconsequent need to decode signals touncompressed form and recode again atvarious places in the broadcasting chain.The ATLANTIC project provided the meansof doing this without the progressivedeterioration in quality normally experiencedwith repeated decoding and recoding.

The BBC makes extensive use of ITequipment for business applications and hasextensive IT networks linking its premises.If television programme-handling and office-based systems can be linked to each other ina common system, many production taskscan be readily effected via personalcomputers on the office desktop and theBBC’s media assets can be managedmore efficiently.

The ORBIT pilot demonstrates the waythis concept can be implemented.

We are already seeing many applicationsfor the technology as the BBC re-engineersits production facilities. The new Pacific Quayfacility in Glasgow, the proposed Mailbox inBirmingham and the new Broadcast CentreProject in London are all likely to benefitfrom these ideas.

THE CONCEPTORBIT starts from the premise that nearlyall of the various processes in a broadcastcentre can be performed in equipmentinterconnected via a network. Of course, thisis only possible if the material is in digitalform. Programme material is acquired andstored on file servers which are connectedto the production, playout and archive areasby way of IT networks. Many of the editorialdecisions are made whilst using standarddesk-top PC terminals. The technology canbe implemented more rapidly if the video iscompressed – to reduce the bandwidthrequired on the network and the storagerequired on the servers. The challenge forORBIT is to recommend and demonstrate

The ORBIT project is a pilot to show how inexpensive IT equipment can performmost of the broadcast processes currently requiring expensive specialisedproduction equipment. A major benefit of an IT-based system is that the storageand manipulation of metadata and programme essence (i.e. the audio and thevideo) can be tightly linked to give greatly improved efficiency in the managementof media assets.


the best practices for a high quality,flexible implementation at a low cost.

ORBIT is working with severalother projects within the BBC toensure that early use can be made ofthe results. There are links with SMEF,BBAMS, Jupiter and Pacific Quay(which are BBC initiatives whichrepresent different elements of thewhole broadcast chain, from sourceto playout and archiving).

BACKGROUNDORBIT was planned to incorporatethe requirements of television’soperational areas. For playout, materialcan be either recorded or live.Recorded material is stored in fileservers and played to air via thepresentation desk in the playout area.Programmes for live transmission,from local studios or outsidebroadcasts, will be passed directly tothe presentation desk. The materialstored on the servers comprises bothvideo and audio programme material

(known as essence) and thedescriptive data describing theprogramme, known as metadata. Someof the metadata might be broadcast –for example as teletext. However,much of it will relate to the businessside of broadcasting and bekept confidential.

The use of metadata is expectedto grow rapidly once the facilitiesbecome available and formats arestandardised.

In the future, production officeswill be created in which a number ofeditors work together on the sameprogramme or series of programmesusing desktop terminals. They will havenetworked access to servers whichhold all the material captured in thestudio, or acquired by conventionalmeans. The suggestion is thatpreliminary selection, editing and finalassembly of the material will be doneusing IT technology and infrastructure.The finished programme will be puttogether in a separate edit area, to


provide better listening and viewingconditions. Edit decision lists from theproduction office will be exported tothe edit area for refinement prior tothe final conforming of edits.

Many of the cost and efficiencysavings are obtained because the initialsearching of material can be carried outusing existing, inexpensive office ITfacilities. A high degree of datacompression will enhance thisefficiency. A reduced-quality version ofthe programme will be producedspecifically for browsing via onlineaccess, and suitable for fast, slow andreverse replay (i.e. shuttling).

The production area needs to beable to read, contribute, add to ormodify the existing metadata if the fullefficiencies are to be achieved.

The archive is an area which couldreap a huge benefit from ORBIT. Theability to browse archive material easily,with more rapid and convenient accessthan by using distribution on VHS tape(which is currently the normal methodof delivery) and supported by fullmetadata facilities, will encourage

producers to make better use of thematerial in the archives.

THE PROPOSEDIMPLEMENTATIONFor the full benefit of an IT-basedsystem to be realised in an operationthe size of the BBC’s, a very largenumber of IT devices need to beinterconnected. Any implementation ofsuch a system needs to be resilient,re-configurable and scalable. Differentconfigurations are needed to fulfildifferent business needs, and the systemhas to be capable of expansion to fulfilfuture needs. The system needs to beable to contract too, and adaptappropriately to accommodate partialfailures (e.g. the loss of one or more ofthe servers) when these occur.

The IT devices will often beclustered together in areas providingcapture, production, archiving orplayout facilities, but there will also bethe need for connections over greaterdistances, such as betweenregional centres.

Ethernet is proposed as the mainnetwork system. It is relativelyinexpensive, and is already implementedon a large scale throughout the BBC. Itwould seem to be very suitable for

applications which do not depend uponthe real-time exchange of signals.

There will be extensive use ofCORBA middleware, to facilitate theinterconnection of the various ITdevices with each other. Themiddleware is effectively a commonstandardised layer of software whichlooks after the networkinterconnections, and scalability, buthides them from the users so that theirperception of the system is simplified.All of the devices connected into thesystem are capable of communicatingwith other workstations file serversand processing equipment through thismiddleware. Each manufacturer has toprovide a single interface to thenetwork using middleware rather thana host of different interfaces to each ofthe separate systems in turn.

In order to make a practicalIT-based system capable of handlingand storing digital television signals, it isnecessary to use a substantial degree ofbit-rate reduction. A full-quality videosignal needs typically about 270 Mbit/s.Using video compression, the bit ratecan be reduced to 10 to 20 Mbit/swhilst still preserving very good imagequality, adequate for the majority ofstudio and post-production operations.


Repeated coding and decodingbetween 270 MBit/s and thecompressed signal could severelyreduce quality. We propose to useMole technology to maintain qualitythroughout the distribution chain.Mole technology was developed in theformer EC-funded ACTS ATLANTICproject, and standardised by theSMPTE. ‘Mole’ as a registered trademark of one of the partners of theATLANTIC consortium.

ATLANTIC also provides thetechnology for transcoding video

signals from studio bit-rates to thelower bit-rates required fordistribution at the best possiblequality.

HANDLING PROGRAMMEMATERIALWe have demonstrated the feasibilityof using IT facilities in an ORBIT-typesystem. The functions demonstratedinclude source signal intake, codingand storing of full-quality and browseversions of the programme, metadata-assisted searching, browsing ofmaterial and browse editing.New functions are being added as thesystem develops, and as consultationwith users progresses.

To handle the essence in digitalform, high-performance videocoding, decoding and transcodingsoftware, based on technology fromthe earlier ATLANTIC project, isunder development.

With any networked productionfacility, one of the vital issues is theefficient exchange of programme


content via the network and betweenadjoining networks. To assess this, theexisting demonstrator is beingexpanded, with the connection of afurther network of servers and clients.

ANCILLARY DATA ABOUTTHE PRODUCTION:THE METADATAProgramme metadata is to be used tohelp streamline the overall programmeproduction process. This is achieveddirectly with such commonplacefunctions as edit decision lists (EDLs)and clip names, but it also assists lessdirectly, but no less importantly, byhandling copyright and otherprogramme related information.Our intention is to provide fullmetadata functionality.

The BBC’s requirements formetadata have been studied extensivelyby the BBC’s Media Data Group whichhas proposed a set of data definitionsfor the type of data used in theproduction, development, use andmanagement of media assets, otherwiseknown as the standard media exchangeframework (SMEF). ORBIT aims tocarry out metadata functions inconformity with the SMEF data models.Based on our ‘user’ consultations, adetailed data model for the metadata inthe Phase 2 ORBIT pilot has beendeveloped, and this is being

transformed into appropriate softwaresystems by our contractors, INESC.

THE ESSENTIALSTANDARDISATIONA concept such as that proposed byORBIT can only really succeed if otherorganisations accept and adopt theproposal. This requires effort to be setaside for standardisation. We arehighlighting issues in MPEG andPro-MPEG, as well as on the newMetadata working group of the AESStandards Committee, and in theSMPTE groups concerned with systemsand metadata/wrappers.

The BBC are founder members ofthe Advanced Authoring FormatAssociation. The AAF have created astandard, MXF, that enables contentcreators to easily exchange digitalcontent and metadata. It can workacross different platforms, and betweendifferent systems and applications.This standard is a vital component inmultimedia broadcasting, delivering anopen standard which will avoid thesoaring costs which might have beenthe case if we had proprietarystandards and file formats. MXF is theIT equivalent of Rec. 601, the standardused for connecting digital videoaround studios.

BBC R&D is a leading contributorof ideas and user requirements in these

fora, which are setting the policy forour industry.

PROMOTING THECONCEPTThe Phase I demonstration,incorporating software from thePortuguese Instituto de Engenharia deSistemas e Computadores, INESC, wascompleted in April 2000. Since then,demonstrations of the availablefunctionality (see above) have beengiven to representatives of major BBCprojects. These have included BCP,POMS, Pacific Quay and BBAMS, andexternal organisations.

With the creation of BBCTechnology Ltd., we now have anopportunity to implement ORBITtechnology rapidly in the BBC andexternal projects.


Producers and directors have theopportunity to use cable-free cameras in awider variety of productions, indoors instudios as well as outdoors. The new digitaltechnology gives freedom and flexibility –enabling the camera to go to places thatwere not possible before.

BENEFITSCable-free cameras, or radio cameras,provide complete freedom of movement forthe camera operator to obtain interestingshots or to follow fast action. Radiocameras are commonly used at locationbroadcasts, particularly sports events. Nowwith the new digital technology, directorscan use these cameras for indoorproductions too.

Production benefits• Complete freedom of movement.• Flexibility in use.• Minimises need for extra cameras.• Improvement to safety – no

trailing cables.• Eases set design.

• Reduced set up time.

THE NEW TECHNOLOGYThe underlying technology for the digitalcable-free camera is DVB-T. This usesCOFDM – the proven system used fordigital terrestrial television in Europe.It is rugged and provides special immunityto echoes – the main problem forcable-free cameras.

Recent advances in Large ScaleIntegration have made a portable transmitterfeasible. This is small enough and light enoughto be carried in a back pack on the camera.

We use MPEG-2 or DV videocompression to minimise the amount ofdata that needs to be transmitted, and tomaximise the ruggedness of the system.The applications of current prototypesystem are limited by the long 18-framevideo coding and decoding delay in theMPEG-2 video encoder. It is difficult to cutfrom the radio camera to a fixed camerawith any programmes containing a largeamount of music or speech.

We are working on two approaches fora low-delay video coder, but it is too earlyto report on these in detail.

We are also working with a microwavemanufacturer on a new version of theprototype that is more suited to everydayoperational use: it is more rugged andbetter integrated with the video camera.


Cable-free cameras have been used for years in sports, news and outsidebroadcasts. Unfortunately, with analogue transmission the pictures often breakup. Now, with new digital technology, we can offer a more reliable link.


TRIALS,DEMONSTRATIONS ANDBROADCASTSOur digital radio camera prototypeshave been used in trials and broadcastsat a number of locations to gainoperational experience.

Our trials have included typicaloutdoor events such as Match of theDay and horse racing at Ascot, andsome extreme indoor events such asthe International BroadcastingConvention and trials in the BarbicanCentre, a complex of concert halls andtheatre areas in London.

Experience outdoors was that thesystem is much easier to set up andoperate than an analogue system. Oneexpected benefit, non-line-of-sightoperation, was not always possible atlocations where suitable reflectivepaths for the signal were not available.

We found that rugged reception isobtained indoors, even non-line of

sight, due to the ability of the system tomake constructive use of any reflectedsignal. Both the Barbican and the IBCexhibition halls showed this effectclearly, turning, what would normally bea radio camera nightmare requiringlarge steerable dishes, into somethingthat is easy to set up using a simplereceive antenna.

When the digital radio camera hasbeen used on broadcasts, for exampleat the London Mayoral Election in theQueen Elizabeth Hall, London, for theGreat North Run in Newcastle where acamera on a motorbike followed therunners over a 13-mile course onpublic roads, and at a cross-country runin Durham using the camera on a four-wheeled buggy following the runners, itwas found that obtaining goodreception was much simpler than withthe equivalent analogue system.Especially outdoors, it was essential tomaintain light-of-sight reception atthe power level available from


COFDM MODULATORLICENSINGIf radio cameras were widely availableat reasonable cost then this couldresult in cost reductions in productionand outside broadcasts by enabling a‘cable-free’ environment.

In order to stimulate the industryand hasten the cable-free era, BBC R&Dis making available, under licence,designs for a compact COFDMmodulator board. A licence has beentaken by several companies withinthe industry.

HISTORYOf course, we already have analogueradio cameras – so why is digitalso important?

Cable-free cameras, or radiocameras, whether analogue or digital,provide complete freedom ofmovement for the camera operator toobtain interesting shots or to followfast action.

Analogue radio cameras arecommonly used at outside broadcasts,particularly sports events, but there isthe problem that the picture is oftendisturbed due to poor radio frequencytransmission conditions. The problemis that the signal bounces off walls,vehicles, trees and people, and distortsthe received signal. This leads tocolour flutter and, in extremecircumstances, break-up, and this hashindered the wider acceptance ofradio cameras in general programmeproduction, particularly in studios.

In addition to the camera operator,many broadcasters employ a secondperson to point a directional antenna.This is an expensive option, and oftenleads to comic errors if the twopeople cannot co-ordinate theiractions properly.

The problem of picture breakup was partly solved by betterantennas, and it is this route whichhas provided the BBC withcompetitive advantage in the past.We have used carefully craftedantennas offering pure circularpolarisation – a known method ofavoiding simple reflections. We havealso used intelligentdirectional antennas.

But this was only a partial solution– it is not possible to completelyeliminate the characteristicimperfections ofanalogue transmission.



Virtual production is a relatively newtelevision technique in which all or part ofthe scenery is inserted into the imageelectronically, rather than being physicallypresent. This can save time and money, byeliminating the need to build, transport, rig,break down and store physical sets.

Virtual Studios also provide new artisticfreedom, since we can create backgroundsthat are physically impossible to build in areal studio. However, virtual studiotechniques must fit in well with currentstudio practices, and must not placesignificant limitations on what is possible.They must also be capable of producing ahigh degree of realism.

CAMERA TRACKING SYSTEMIn virtual production, it is vital that we knowthe precise position of the camera to ensurethat the virtual background image is correctlyinserted. We have developed a system thatmeasures the position and orientation ofeach camera using markers placed on thestudio ceiling. A small auxiliary cameramounted on the main camera and aprocessing unit to analyse the image allowsus to compute the camera position from theknown marker positions. The system islicensed to Radamec Broadcast Systems whomarket it under the name free-dTM .

2D VIRTUALPRODUCTION SYSTEMIf the camera is restricted to pan, tilt andzoom, with no lateral movements, then thereis no need to use an expensive graphicscomputer to render a new view of the three-dimensional world every frame. The virtualbackground can be represented as a flatimage which is transformed to simulate theeffects of camera panning, tilting andzooming. We have developed a specialiseddigital video effects unit for performing suchtransformations, on either a still or a movingimage. The system is licensed to RadamecBroadcast Systems who market it under thename Virtual Scenario.

TRUMATTEConventional chroma-key techniques requirethe use of a brightly-lit background of auniform colour, usually blue. It can be a time-consuming task to light such a background,and difficult or impossible to use subtlelighting effects on the actors. Our solution tothis is a method using a retro-reflectivecyclorama cloth and a ring of coloured lightsaround the camera lens. This ensures that thebackground always appears brightly-lit to thecamera, regardless of the setting of thestudio lights, which can instead be set for thedesired dramatic effect.

We are promoting the use of the current Virtual Production technologies, and areinvestigating the use of virtual studios to originate content for new media such asthree-dimensional television, interactive or immersive television and video games.


INTRODUCTION OF THETECHNOLOGYINTO STUDIOSVirtual production techniques have notyet gained widespread acceptance inthe BBC, although there is growinginterest among programme-makersinterested in creating innovative kindsof programmes. We have been workingwith production staff to identify thebest ways of applying virtualproduction technology to particularprogrammes. We have also helped BBCResources in applying the technologyto non-BBC productions, including alarge-budget feature film. 2D virtualproduction is the most widely-usedmethod within the BBC at present; arecent example of this was the 2000Olympics coverage, which used severalVirtual Scenario systems to generatevirtual windows behind the presentersoverlooking Sydney Harbour.

One factor that is holding back thewidespread adoption of virtualproduction technology is cost. We

have been studying recentdevelopments in PC graphics cards todetermine whether consumer-typecards may be suitable for use inprofessional applications. Theperformance of some modern cards isapproaching that of high-end three-dimensional graphics computers, at asmall fraction of the cost, althoughfeatures such as broadcast-standardvideo output and genlocking areusually not available. With the price ofimage rendering systems dropping, theprice of other system elements canbecome significant. We are looking atthe possibility of implementing asimplified camera tracking systemusing a PC to measure cameramovement by real-time image analysis.This is based on work we carried outsome years ago, but until recently ithas not been feasible to implementthis on a cheap general-purposecomputer.

THE NEXT GENERATIONOF VIRTUALPRODUCTION

PrometheusThe PROMETHEUS collaborativeproject is now into its second year.The project will demonstrate an end-to-end three-dimensional programmechain, using virtual studio techniquesand incorporating high-quality virtualactors. The scene will be encoded as acollection of three-dimensional modelsusing the new MPEG-4 codingstandard, and the decoded scene will


be displayed on a three-dimensionaldisplay. The technology being developedwill be of use both in conventionalvirtual production, as well asdemonstrating what might be possiblefor new kinds of media, includinginteractive TV and three-dimensionalTV.

Within the project, we havedeveloped a system for tracking thepositions of actors in a virtual studio.This can be used to automaticallygenerate the mask signals required toallow actors to walk around a virtualobject, as well as to allow the simplerepresentation of actors as animatedthree-dimensional objects in a three-dimensional world. The actor trackingsystem is based on the hardwaredeveloped for free-dTM , and works byanalysing the silhouettes of actorsagainst a Truematte floor.

We are looking at several methodsof representing actors, using the videosignal from a studio camera mappedonto a simple three-dimensionalrepresentation of a person. Otherpartners in the project are developing amarker-free motion capture system andreal-time clothing animation softwarethat will allow fully-virtual actor modelsto be used.

We have been working with oneproject partner to assess the feasibilityof a glasses-free three-dimensionaldisplay, based on the principle ofintegral imaging. This is a goodcontender as a future domestic three-dimensional display, although we havefound that the system needs to be

based on a very high resolution flatdisplay in order to produce images witha good depth range. Such displays arenot yet readily available. We have alsobeen assessing more conventionalthree-dimensional display systems,based on dual projectors andpolarised glasses.

MetavisionThis year has seen the start of theMETAVISION collaborative project. Thisproject is developing a camera systemthat will capture images in such a wayas to make conversion to high-definition film and video easily possible.It will also gather a lot of informationabout the scene, including depth. Weare evaluating several methods ofmeasuring depth in images and lookingat the kinds of application that canbenefit from such information. Relevantapplications include three dimensionaltelevision and model creation, andspecial effects in post-production.

MPEG-4 MPEG-4 is the next generation ofdigital video (and audio) compression. Itextends the coding capabilities ofMPEG-2 by allowing a scene to becomposed of several individually-codedobjects, rather than coding the image asa single entity. The visual coding toolsprovided include tools designedespecially for moving video (similar toMPEG -2), still pictures, text, two- andthree-dimensional graphics, as well asanimated human face and body models.MPEG-4 provides audio coding tools

specially adapted for speech, music,text-to-speech, synthetic (orstructured) audio and acousticrendering. MPEG-4 is now anInternational Standard, with furtherenhancements due to be added shortly.

We are examining the potential forusing MPEG-4 in several applications.One application is the encoding ofanimated three-dimensional scenesproduced using virtual productiontechniques, which we are investigatingin the Prometheus project describedabove. Another application is theprovision of additional multimediamaterial in association with a digitalbroadcast. This is a key aspect of theSAMBITS collaborative project, whichwill demonstrate a studio system foradding MPEG-4 elements to a digitaltelevision broadcast.

One example of the kind of servicethat SAMBITS could support is theprovision of sign language. Anotherexample is delivering interactive three-dimensional models associated with aprogramme. We are working with aproduction team in BBC Science toexamine how high-quality modelsoriginally produced for creatinganimated video clips can be convertedto MPEG -4 format and delivered toviewers. We are also examining otherpossible formats for sending three-dimensional models over the Internet.MPEG-4 may also find application in theprovision of low bit rate video, both fordelivery via the Internet and as a‘browse’ format for viewing video onPCs over an intranet.



ELECTRONIC CINEMA GOESHIGH DEFINITIONIn the US, cinemas are converting to highdefinition electronic projection, allowing filmsto be delivered more cheaply without theuse of film stock (e.g. Toy Story, Star Wars).The system has a resolution comparable with35 mm film and much higher than that ofnormal television. Home cinema, based ona high definition version of DVD which isexpected in 2002, could bring that into thehome, films and sport being thekiller applications.

This trend towards high definition isbecoming established as the necessary highdefinition television production and post-production equipment is now available. Alsonew computers can now generate animationsin high definition, as they have done fornormal television for the past couple ofyears.

BUT HIGH DEFINITIONNEEDS A LARGE DISPLAYThe best domestic high definition displays(up to 60 inches) are plasma displaypanels, currently costing about £10,000 fora good one. The cheapest are based on

front- or back-projection, at about £2,500.High definition can obviously also bedisplayed on conventional televisions butconverters can make set-top boxes expensiveand the high definition experience is lost.

THE MARKET FOR HIGHDEFINITION IS DEVELOPING The commencement of high definitionbroadcasting in the US is opening the marketfor matching programmes. Although somenew US digital services broadcast signalscompatible with existing analogueservices,140 US broadcasters are now on theair with true high definition transmissions.There are, however, only a few thousand highdefinition digital receivers in use in the US.

In Japan, the analogue high definitionstandard is currently being withdrawn andbeing replaced with digital high definition. TheBBC has a digital satellite slot, incollaboration with BS Asahi. This serviceopened on 1st December 2000 with anepisode from Ancient Voices (up-converted forhigh definition broadcasting).

High definition production and broadcasting are becoming a fact of life around theworld.


BROADCASTERSCOMMIT TO HIGHDEFINITION The Discovery Channel hasannounced an early start into highdefinition and that it will fund theproduction of 100 hours of highdefinition this year. Others are buildingarchives of high definitionprogrammes, converting films to highdefinition and covering some livesport events in high definition.Broadcasters in the US and Japan areassociating high definition with highvalue programmes. They are askingabout the potential of the BBC todeliver future landmark series, like Life

of Mammals, in high definition insteadof Super 16 film format.

HOW WILL HIGHDEFINITION GROW?It is predicted that there will be aslow growth of high definition in theUS. It will be slow because they needto replace both receiving and displayequipment with expensivecomponents, and at present there is alarge number of competing digital highdefinition standards. It might take fiveyears to achieve significant penetrationof high definition in the US; 1% ofhomes might equip for high definitioneach year. High definition could beintroduced in the UK through highvalue sport services (to pubs andclubs) and via the worldwidedistribution of high definitionDVD’s and the availability of cheaphigh definition DVD players installed


in computers with highresolution displays.

BBC R&D HIGHDEFINITION ACTIVITIES Although the BBC has a lot ofexperience in making standarddefinition programmes, the majority ofthe experience in making high definitionproductions at one time resided in asmall group within the Research &Development team. Much of the workthis year has been aimed at passinginformation on production experienceand high definition technology fromBBC R&D to the relevant departments.Key staff have been attached to BBCProduction and training sessions havebeen given in collaboration withTraining Department. BBC R&D and theSMART Ventures team have assistedBBC Production, Resources and

Worldwide in bidding for highdefinition commissions.

We have also played a major rôlein the production Last of the BlondeBombshells. This was a complexproduction, created on 35 mm, anddelivered in both standard definitionin the UK, and in high definition inthe USA. There were many technicalhurdles to be overcome, and weadvised how both the picture and thesound should be processed efficientlyto give the required product.

Our new high definition projectorand multi-standard video-tape recorderhave enabled us to give presentationswhich have helped programme makersto understand which programmes workwell on larger screens and whichprogrammes are suitable for up-conversion and delivery in highdefinition formats. This experiencehelps us to assess the new cameras,

lenses, post-production systems andranges of video-tape recorders whichare now being offered commercially.

As a result of this work, there isnow, in the BBC, the know-how and thetechnology to be able to produceprogrammes in high definition and,working together with SMARTVentures, properly to account for thecosts and benefits of high definition.The familiarity with high definitiontechnology is also being applied insupport of bids by BBC Technology Ltdfor contracts to install digitalproduction and broadcasting facilities inthe USA.


ASSAVIDASSAVID is an internationalcollaborative project aimed at theautomated generation of metadatafor sports programmes. If successful,the software developed by theproject would be able, automatically,to review sports recordings andidentify features, such as goals infootball, the end of a race, successfulsinking of a putt in golf etc, andnote the details into a searchabledatabase. The process combinesanalysis of both the sound and thepicture to identify events. Clearly,this information will make it easierfor sports producers to track down

key sports features when theyprepare new programmes fromtheir recordings.

The general problem – that ofdescribing all events, whatever theirnature – was too large to be solvedusing current technology, hence therestriction to sports events. Our partof the project was to define the typicalneeds of a broadcaster for such asystem, ensuring that the importantissues were addressed. This was helpedby the first hand involvement of aproducer on attachment toBBC R&D from BBC Sports. Practicalinput about the real process helped toprovide a detailed set of user

The BBC is now using its archives more intensively. To help improve efficiency, we are considering new techniques for

the creation and manipulation of descriptive metadata. The manualprocess used in the past is tedious and operational pressures meanthat it is often left incomplete. Automatic creation of metadata, whilstdesirable, is, as yet, an incompletely understood process.

We are also improving the quality of material recorded in a varietyof formats, which may have been corrupted by PAL coding orstandards conversion.

requirements. The project is now goingthrough a cycle of development. It hasabout ten hours of programme materialthat we have selected, together withdata on vocabulary usage and an audiotranscription. The selection and varietyof material on the tapes should helpthe partners to test the software theyare creating, giving a better chance thatthey can successfully complete the task.

PAL DECODINGThe BBC’s television archives are avaluable source of programme materialfor the new digital services. However, alot of these programmes wereoriginated in PAL colour compositeformat. These need to be decoded todigital component form before they canbe reused.

In many cases, the decoderintroduces artefacts which are visible,and sometimes compare badly withother parts of the programme whichmay have always been digital. There areseveral different PAL decoders on themarket, all of which introduce differentdesign compromises. There is noperfect design.

We have produced a novel PALdecoder. The new PAL decoder iscomplementary – the original PALsignal can be regenerated from itsoutput. This allows future proofing ofPAL archives without the need to keeporiginal archive tapes (and the machineson which to play them). If, one day, abetter PAL decoder becomes available,the original PAL signal can bereconstituted from the digital recordingand then decoded properly.

The new decoder works in theFourier transform domain. It exploitsthe spectral symmetry of themodulated chrominance signal toseparate it from the luminance signal.This technique is very effective atremoving the cross colour and crossluminance patterns that are so commonin PAL originated material.

A problem of the legacy formatssuch as PAL is ensuring that archivetapes will be useful in the future. BBC’sArchives have completed the transferof two-inch Quad tapes to modernformats, and are now transferring theirone-inch C format tapes. These arebeing transferred both to D3, a digitalPAL format, and to Digital Betacam.

A complementary decoder would allowus to transfer all the tapes to commondigital format, without fear that we areirretrievably losing some of the signal inthe process.

BBC’s Archives have shown a lot ofinterest in the new PAL decoder, andwork is now underway to turn the idea,supported by computer simulations,into some useful hardware.

REVERSE STANDARDSCONVERSIONIn the past, many TV programmetapes were wiped instead of beingstored in the archives. Luckily, someprogrammes have survived as copiessold to other broadcasters, but oftenthese are only available in the American60 Hz standard.

The standards converters used tomake these tapes were much simplerthan those used nowadays, with muchpoorer picture quality. Using a normalstandards converter to convert back tothe European 50 Hz standardcompounds the problem, making theprogrammes unbroadcastable.

Four years ago we developed amethod of converting theseprogrammes back to the European50 Hz standard, extracting the bestpossible quality by unpicking theoriginal conversion. This proved tooexpensive to implement with thetechnology of the day, but we believe itmay now be economically viable.




Although many commercially availabledictation packages may give the impressionthat speech recognition problems have beensolved, this is far from true. In the specialcircumstances of dictation, the user works ina controlled environment, trains therecognition software to his/her own voice,dictates using normal sentence constructsand probably uses a very constrainedvocabulary. Each of these makes the task ofthe recogniser that much simpler.

In the context of normal broadcastsound tracks, the environment is veryvaried (from studio, to the side of a road)and even for a single programme manyvoices will be encountered. Furthermorethe speech is often conversational (normalsentence constructs do not apply) and canbe subject to interruptions, and a widevocabulary has to be accommodated (over60,000 words, including person and placenames). The end result is that, under theseconditions, a significant number of mistakenwords may be generated by even the mostsuccessful recogniser.

BENEFITS FOR THE BBCWhat is needed is a careful analysis of whatspeech recognition can do, rather than whatit cannot do, and from this comes a numberof applications where the errors do not

cause significant problems or where they canbe avoided.

Our main area of work has been on theAssisted Subtitling project which uses speechrecognition techniques in a slightly unusualway, to help prepare subtitles for pre-recorded programmes. In addition, we havecontinued our work in archive retrieval,enhancing the experimental system developedunder the THISL project, and have also beenlooking at how speech synthesis andanimated heads might be used.

ASSISTED SUBTITLINGThe Assisted Subtitling project has beendeveloping a new approach to creatingsubtitles for pre-recorded programmes, whichoffers valuable savings in preparation time.

Earlier work with speech recognitionindicated that the technology is not yetaccurate enough to produce subtitles directlyfrom a programme soundtrack.

However, from these considerations, theidea emerged that, as many pre-recordedprogrammes are scripted, it is not necessaryto use a speech recogniser to re-create thewords that are spoken in the programme, butwe need to know when these words arespoken. We can determine these timings byusing a speech recogniser in a different way.In this case, we provide the scripted dialogueand the speech recogniser will track through

Speech recognition is an imperfect technology, but we have developedinnovative applications for broadcasting which work despite the imperfectionsof speech recognisers.


the programme matching the text tothe soundtrack and giving a time forthe start and end of each word. Fromthese timings, we can produce subtitlesthat are correctly synchronised to therecorded dialogue.

A significant difficulty encounteredearly in this work was thatprogrammes scripts can differmarkedly in their style and layout andmay also contain typing errors. Wetherefore developed software toanalyse script layouts to determinethose parts which are actor names anddialogue, whilst rejecting the text ofstage directions or other unwantedinformation. It is important for this towork well, otherwise the subtitlesproduced will require significantediting to remove the unwanted text.

Another development required inthis work was the automaticassignment of colours for the subtitletext for each actor in a programme.Colour is often used to distinguish thetext of one person from that of

another, and is essential when theirtext appears together in the samesubtitle. However, if actors appeartogether, they must not be allocatedthe same text colour otherwise thesubtitle would be very confusing forthe viewer. From the analysis of thescript, the software searches manythousands of possible colouringcombinations to work out an optimumassignment that makes the subtitlepresentation clear and unambiguous.

We have also developed softwareto format the scripted text suitably forsubtitles. As this takes place, thepresence of shot changes in the videomust also be taken into account as thepreferred BBC style avoids having asubtitle present at the instant of ashot change. The software thereforeseeks an optimum format for eachsubtitle, taking these and many otherfactors into account. Once thesubtitles have been created, they arereviewed by a subtitler who will


correct any errors or modify the stylewhere this is felt to be of benefit.

An experimental version of thiscomplete system was installed in BBCSubtitling Unit in early 1999 and during2000 an enhanced version has beendeveloped. Over this time, it hasbecome clear that the technique offersconsiderable scope for time-savings andhas the potential to achieve a 50%reduction in preparation times forpre-recorded programmes.

No invention, however, is reallyworthwhile until a means ofexploitation has been created. To thisend, we have been developing thisapproach to subtitling with the speechtechnology company 20/20 Speech Ltdand have licensed it to the subtitlingequipment manufacturer, Softel Ltd.By this means, the assisted subtitlingideas become available not only to theBBC’s own Subtitling Unit, but to theindustry as a whole.

These techniques are now inregular use in both Glasgow and theWhite City subtitling areas.

AND TWO USEFULSPIN -OFFSThe software modules developed forAssisted Subtitling have also been puttogether to provide a similar facility viaa web page on the BBC Intranet. Thispage allows the user to upload just theprogramme script and this is thenprocessed automatically by the serverto produce the dialogue text, colouringdetails and an initial subtitle file. The

user can then download these asrequired. In this simplified version, theprogramme recording is not available tothe speech recogniser and so thesubtitles will not be properlysynchronised to the programmedialogue. However, this still offers thesubtitler a useful short-cut in preparingsubtitles for some programmes.

In a similar way, a web page forre-versioning subtitles has beendeveloped, and is again available on theIntranet. In this case, bought-insubtitles, which may not be suitable asthey stand, need to be edited to a stylemore appropriate for the UK audience.The web page automates theconversion of the subtitle appearanceand removes much of the unskilledwork from this task.

ARCHIVE SEARCHINGUSING SPEECHRECOGNITIONThe second main area of work inspeech recognition continued the workstarted in EC-funded THISL project.This project developed an archivesearch system using speech recognitionof the programme sound. Although thisproject formally ended in January 1999,with the encouraging results achieved,we continued to refine its features andmade the new version available on theBBC Intranet. This now automaticallyrecords and indexes about 35 hours ofradio and TV news and otherprogrammes each week and the entiredemonstrator archive can be accessed

using a search facility, which ispresented on the THISL page on ourIntranet. This archive has now built upto over 4000 hours of programmes,covering the last three years.

Interest in this approach toindexing programmes has beenencouraging and we have been workingwith one of the original projectpartners, who is making the systemavailable commercially, to explore howan enhanced system could be used indifferent archive applications.

SPEECH SYNTHESISAlthough our work in this area is stillin its infancy, we have an interest inunderstanding how speech synthesismight be used in many differentapplications. This work started with theVirtual Interactive Presenter project.This project is exploring the use to aninteractive talking head to help a userto navigate through an electronicprogramme guide.

We have broadened our interest inthis field and are now also consideringother applications for this area ofspeech technology.

THE PROOF OFTHE PUDDING!Our work in developing the AssistedSubtitling system was recognised inNovember 2000 by the Royal TelevisionSociety. We were delighted to receivetheir Technical Innovation award in the‘Innovative Applications’ category, forthis work.



As an owner of many valuable programmes,the BBC needs to ensure that it controlstheir broadcasting and sale to legitimatebroadcasters and other customers. This hasalways been the case but is being seen asincreasingly important with the advent ofdigital broadcasts and sales on DVD, and thepotential for near-perfect digital copies beingmade. To this end, we have been continuingour work on means of identifying ownershipof content and the prevention ofunauthorised copying.

This work has included the evaluation ofcommercial video systems on behalf of theEBU, a pilot study in BBC News24 for theautomatic monitoring of the use of externalprogramme feeds and the development ofBBC R&D’s own contributions to the science.In addition, we are advising operational areasof the BBC about the potential uses ofwatermarking and evaluating commercialaudio watermarking systems.

TRIALS OF WATERMARKSBY THE EBUMembers of the European BroadcastingUnion have a strong interest in thedevelopment of watermarks for both videoand audio signals. We, as one of the EBU’smembers, participated in a test of fourwatermarking systems which were submittedfor testing by manufacturers.

Tests were carried out on the robustnessof the systems to a wide range of potentialimpairments of the watermarks by commonvideo processing operations in a productionenvironment. These included picture shiftsand scaling, geometric distortions, bothun-noticeable and visually obvious, resamplingand the addition of gaussian white noise.Several re-recording processes were also

tested, using standards ranging from the bestmodern digital recorders to Beta SP anddomestic PAL machines. The watermarksystems were tested principally for theresulting error rate in the embedded datastream. We carried out no formal subjectiveassessments. Those were done by other EBUmember organisations. After the scheduledformal robustness tests, the equipment wasused to carry out supplementary tests on theeffects of watermarking on MPEG coding.

Results of the tests are available withinthe BBC, but cannot be reported in full here.

A FIRST PILOT TEST INBBC NEWS24A BBC News24 pilot study involved thewatermarking of one programme feed as itentered the BBC News24 technical area.The studio output was monitoredcontinuously and a log of detectedwatermarks made. Overall, at a watermarklevel that was judged to be just visible oncritical, high-quality material, the detectorsucceeded with close to 100% reliability formost pictures. However, there were sometypes of picture for which reliablewatermarking was not possible, probablybecause the nature of the pictures providedvery little scope for adding a non-visiblewatermark. Those sorts of pictures failed toprovide a detectable watermark.

THE BALANCING ACTThe maximum permissible strength of anembedded watermark is limited by thevisibility of the resulting artefacts in thepicture. That in turn depends on the natureof the underlying picture. The expectedperformance of a watermarking system isalso heavily dependent on the level of the

Watermarks offer a method of identifying broadcast material, but howshould we use them?


embedded watermark. That functioncan be an extremely steep one. Aroundthe threshold of reliable detection, themargin against false positive detectionscan be changed by three orders ofmagnitude for one decibel change inthe watermark level. The allowablewatermark level is therefore crucial.Production quality pictures may wellsupport less watermark addition thandistribution quality pictures. This maylead to significant differences in thepotential for the application ofwatermarking in the twoenvironments.

Watermarking is also a balance ofperformance between the conflictingparameters of visibility, robustness andpayload. Robustness is the ability ofthe embedded watermark to survivethe processes encountered by thesignal between the embedding anddetection of the watermark. Thepotential usefulness of a watermarkingsystem will depend both on theseparameters and the objectives. In thepilot study with BBC News, it wasintended that watermarked segmentlengths should be identified with near100% reliability and with a resolutionof about one second. That implied adetection length of a little over half asecond. The balance of performanceand objectives was unfavourable. Inother situations, the identification oflonger segments and, perhaps, withlower reliabilities may be useful.

SO WHERE ARE WE?Our testing has given us a goodunderstanding of the resilience ofwatermarks. We believe that there is avery fine dividing line between addingsufficient watermark to make a systemrobust and not adding so much thatvisible artefacts are introduced. Withsome systems that separation wasnegative. Similarly, all the audiowatermarking systems testedreasonably thoroughly have been foundto introduce significantaudible artefacts.

The current state of developmentis such that it is probably not feasibleto consider watermarking in theproduction process, at least not forthe marking of individual, short ‘clips’.The pilot study with BBC Newsdemonstrated that, at present, thedetection of very short excerpts wasnot completely reliable, even atwatermark strengths that would causenoticeable impairments on somepictures (using critical test materialand moderately experienced viewers).

So far, the watermarking work hasassumed high quality pictures in thecontext of the productionenvironment. The balance of usabilitymay well be different in thedistribution environment, where thepicture quality is lower and, as a result,more watermark signal can be addedwithout impairing the picture qualitysignificantly. However, another factorthen becomes significant. The additionof noise-like signals is known toincrease the difficulty of digital codingprocesses and, hence, results in lowerquality pictures for the same bit rate.This remains to be studied in detail,but it may be a vital factor in thewatermarking of the distribution chain.


BBC R&D staff have been involved, with Radio and Televisionstaff, in the occasional surround sound recording or post-production mix. This has enabled us to pass on our findings,accumulated over a number of years, to the BBC’s programmeproduction staff. Recently our experience has been extendedthrough the MEDUSA project.

The MEDUSA project – Multichannel Enhancement of DomesticUser Stereo Applications – has explored many of the parameters ofmultichannel sound in the domestic environment. The projectpartners pooled their resources and expertise to tackle some ofthe tangible and less tangible problems of surround soundreproduction. For us as a broadcaster, one of the key issues is howto create multichannel recordings which can be mixed down tomonophonic or stereophonic tracks for conventional broadcastpurposes, or, conversely to produce multichannel tracks fromstereophonic recordings. As well as good sound quality we need toensure that the positioning of the sound image is accurate andreliable.

For the project partners, there was interest in the properties ofloudspeaker systems, and the way they interact with the room.MEDUSA looked at different ways of equalisation to improve theperceived reproduction of the multichannel system.

The findings of the MEDUSA project have wide applications inconsumer and professional audio, as well as creating a valuable basisfor future research work in spatial audio.

High street retailers are selling an increasing number ofhome cinema systems. As well as a large display, thesesystems usually come with a multichannel surroundsound system. The BBC is increasing the availability of itsprogrammes to overseas markets and on DVD so wemust be able to create programmes which can bedelivered with a variety of different sound options. It isnot a simple task to create a multichannel soundrecording which is also suitable for stereo- and mono-phonic delivery.


WIRELESS NETWORKSThe BBC has considerable interest inemerging wireless technologies (suchas Bluetooth, Wireless LAN,HiperLAN, HomeRF and UMTS) whichmay be suitable for both professionaluse and in domestic environments.Professional applications could includedata channels for wireless cameraoperations as well as wirelessinterconnection of studio equipment.

It is clearly of great importance tothe BBC to understand how newtechnologies might be used in thehome environment for themanipulation of its content.

The two important parameters arecapacity and reliability. We have carriedout comparative propagation tests forBluetooth and Wireless LAN in thecrowded and electrically noisyenvironments that these systems willencouter in practice. Bluetooth isintended for short range (up to 10 m)and modest bit-rates (up to 1 Mbit/s),and aims to be very cheap, to allow itsmain use to be in domestic products.In practice it was found that Bluetoothwas often limited to lower values ofrange and data throughput, whichsomewhat restricts its use in theprofessional environment. The IEEE802.11 Wireless LAN standard, whilstmore expensive, can achieve a higherrange up to about 200 m and athroughput of about 2 Mbit/s (ormore with a better antenna or if therange is reduced).

Emerging wireless technologies are offering new opportunities both inproduction and domestic environments.

MOBILE WEB CAMWithin the BBC, BBC Imagineering isconsidering exciting new ways of usingour digital delivery channels. One oftheir productions Rush, is ‘an adrenalinefuelled trip around the edge of Britainand Ireland’. During production, theywould have ideally liked a mobilewebcam inside the production vehicle.This would have transmitted web campictures continuously from any locationback to the BBC web site.

Whilst this was technically feasible,the cost would have been well beyondthe programme budget. We werehowever, able to show the possibilitiesand benefits of sending a series ofhigher quality still pictures, from anystatic or mobile location in the UK, atextremely low cost. This has theadvantage that each picture can then becarefully selected based on its merit (ifrequired). With reasonable compressiona 640 × 480 pixels picture (similar to afull size TV picture) can be sent back tobase in around ten seconds using amobile phone link. A smaller picturesuitable for a web site could be sentback in perhaps three seconds. (It isnow possible to buy a PC with a built-in digital camera and plug-in GSM link,so all the equipment required is nowavailable from just one device).

ANCILLARY SERVICESThe introduction of digital televisionhas brought about a growing awarenessof the need for sufficient frequenciesfor programme making purposes.

Multichannel capability is creatingan increasing demand for programmematerial. However, a lot of equipmentused for services ancillary tobroadcasting operates in the frequencybands used for television broadcasting.These are now occupied by digitaltelevision. The CEPT has recentlyconducted a survey on spectrum usagein Europe – the shared use ofbroadcasting bands was confirmed tobe a major activity in many membercountries. There will be greaterpressures on the broadcasting spectrumfor ancillary services in future.

The use of spectrum for ancillaryservices is licensed and largely managedby JFMG Ltd. Nevertheless, we retainthe information and knowledge toassess frequency-sharing possibilitiesfor the many radio microphone,talkback and programme links that takeplace in television Bands IV and V inthe UK, and provide maps whichindicate appropriate use of thespectrum. The continuing developmentof digital television services means thatthe situation requires regular review.

A recent development that will assistthe BBC in its program makingactivities is the digital cordless camera.The primary frequency band to operatesuch devices would normally be in the2.5 GHz region, but these frequenciesare gradually becoming overcrowded orassigned to new services.

We investigated the sharingpotential in television Bands IV and V.Although any such sharing must notinterfere with the reception oftelevision services, the low powerrequired by cordless cameras (muchless than 1 watt) means that theinterference range is small compared tothat normally experienced betweenbroadcasting stations. The studyrevealed that one or more channels arepotentially available at the majority ofthe BBC studio sites and frequentlyused outside-broadcast locations. Thisled to the conclusion that it isworthwhile considering thedevelopment a UHF version of thecordless camera. Whilst by no meansproviding a complete answer to thefrequency requirements, it does offernew programme-making opportunities.


DAB – digital radio

FM radio

digital radio mondiale

protection of AM services



The BBC has broadcast terrestrial digitalradio since 1995, but it is only during thepast year that receivers have been readilyavailable in high street shops. With thisrenewed interest, it is important to providean infrastructure that can satisfy the demandfrom the many radio stations wishing to takeadvantage of this digital revolution.

SPECTRUM REQUIREMENTSSpectrum is becoming a commodity that isfiercely sought, so it is necessary for us topromote the existence of digital radio anddemonstrate the Europe-wide demand forsuch services.

This is not something that can beachieved in isolation. We need to co-ordinateactivities, preferably on a European or worldbasis. WorldDAB (the organisation whichco-ordinates and promotes digital radioworldwide) has picked up this challenge andhas promoted a study of spectrumrequirements in Europe.

Our contribution to the WorldDAB studywas a review of the future spectrum demand

for London and Southeast England, based onan assessment of service growth over thenext ten years. This revealed a high latentdemand for radio channels, and a complexvariety of different service areas which needto be considered (to provide a range of localand regional programmes to match the needsof the population). The review included thepossibility for migrating the existing servicesfrom the FM and AM domains as well as thepotential for incorporating data services, suchas travel and news information. In order toprovide a truly UK perspective on therequirements, inputs for our report weretaken from interested parties in the BBC andthe commercial radio sector, in particular theRadio Authority.

The WorldDAB study was presented atCEPT (the conference of Europeangovernments which co-ordinates radiofrequency matters). From the reactions tothe paper, it is clear that there is similardemand in many places around Europe. Theoverall trend is for an increasing demand forspectrum, particularly in the 1.5 GHz Band.


Digital radio is now a mature and established technology for delivering high qualityaudio services to all types of radio receiver, from car radios through to hi-fi tuners.Thanks to continuing research in this area, however, digital radio now offers muchmore than simply ‘better radio’. New types of service are being developed thatmake use of digital radio as a pure data channel which will take radio into themultimedia age.


In order to meet this growingdemand for spectrum for digital radioin a number of European countries,the CEPT is proposing a European1.5 GHz Band Planning Meeting. Theintention is to provide additionalfrequencies for terrestrial broadcastingin Europe. This will restrict the optionsif we ever wish to use satellites tobroadcast World Service programmes,but Digital Radio Mondiale, the digitalshort wave solution, is expected toprovide a satisfactory alternative. TheCEPT proposal is to make use ofseven channels previously reserved forsatellite services and assign them toterrestrial services. As yet, no finaldecision has been reached on a datefor the Planning Meeting; neverthelesspreparations are currently based onthe assumption that it will be held inSpring 2002. We are participating inthe CEPT preparatory meetings thathave already prepared a timetableoutlining the steps leading to a

Planning Meeting and a questionnaireto establish national requirements.We are working with theRadiocommunications Agency and theRadio Authority to form a UK strategy– the immediate goal being a fair shareof the spectrum for the UK.Consideration of the detailedassignments to broadcasters willfollow at a later date. Our work andthat within CEPT has brought out theneed to develop planning tools suitablefor introducing local stations (theoriginal plans were based on nationalcoverage).The European BroadcastingUnion is now acting as a focus for thework, pulling together planningmethods suitable for planning serviceswith a range of coverage areas. Thiswill assist broadcasters with thepreparations for the two prospectiveplanning meetings – the CEPT meeting,and a Regional RadiocommunicationsConference that is planned for 2005by the International

Telecommunications Union, coveringspectrum allocations in Bands III, IV and V.Whilst the ITU meeting is primarily fordigital television services, therequirements of digital radio in Band IIIwill also have to be accommodated.

The original digital radio networkdoes not provide coverage to thewhole country. We have been takingprudent steps to identify means ofexpanding coverage. In this respect wenow have added a plan for serving 70%of the population of Northern Ireland,to existing plans for futureconsolidation (i.e. filling the gaps) andextension of the national network inEngland, Scotland, and Wales.

In terms of real coverage extension,we have planned two new digital radiostations at Craigkelly in Scotland andHemel Hempstead in England. Theserepresent a further step beyond theoriginal 29 transmitting stations andbring the overall coverage to anestimated 63% of the UK population.We have also gained regulatoryapproval for the final antennacharacteristics at two stations that hadbeen operating on reduced power sincetheir service launch in 1998.

Antenna surveys by helicopter havebeen carried out at many of the digitalradio transmitter sites. Most of thetransmitting antennas have been foundto be satisfactory. One notableexception is Emley Moor where anantenna re-adjustment was needed tomeet the station design specificationand achieve the desired coverage.

The success of digital radio hasbeen enhanced over the past year bythe rapid rollout of coverage by theindependent national broadcasterDigital One who have plans to achievecoverage well in excess of 80% by2002. Moreover, the Radio Authorityis licensing local multiplexes and theseare coming on air at the rate of oneper month.

The proximity of frequencies usedfor these digital local radio services,where the stations for the new servicesare not co-sited with existingtransmissions, may result in small poolsof interference to BBC nationalservices. This situation can be resolvedby the addition of BBC nationalservices to the new stations, but ofcourse this requires a considerablefinancial investment. The precise extentof the interference is dependent on anumber of factors, not least being thevariation in receiver design. As a resultwe are co-operating with thetransmission providers, Radio Authorityand Radiocommunications Agency toestablish the actual effect of theinterference. Extensive measurementshave been carried out around one localradio site, Mount Vernon in NorthLondon. The results show that the levelof interference, for the most part, ismuch as we predicted. However, ourcurrent prediction tools are tending toover-estimate the interference levelclose to the mast and we will need tomake allowances for this inour assessments.

TECHNICALDEVELOPMENTS

Traffic and Travel InformationWith recent advances in navigationsystems, the provision of reliable trafficand travel information has become animportant component in thedevelopment of intelligent transportsystems. TPEG (Transport ProtocolExperts Group) is an openly specifiedprotocol for delivering traffic and traveldata. Its data can easily be carried onmost digital bearers and is particularlysuited to digital radio as it is importantto deliver traffic and travel informationto in-car systems. Because the protocolis designed to be machine-readable it iseasy for the receiver to present theinformation to the user in a number ofdifferent ways and in any language. Thesystem supports road trafficinformation with public transportinformation being added to thespecification.

We have been transmitting a pilotservice delivering traffic and travelinformation over digital radio and theInternet since 1999. In 2000, anadvanced receiver, the BBC DigitalTravel Assistant was released. Thisprovides a Windows-based receiverfeaturing a detailed digital map with liveupdates of relevant travel information.

Multimedia Digital RadioDigital radio already providesinterference-free, ‘digital quality’audio to your home hi-fi, portable andcar radios, but now it offers even more.



By using techniques developed fromthe Internet, digital radio can nowdeliver a wide range of multimediaservices. The broadcast web siteapplication for digital radio givesservice providers the opportunity tocreate new and exciting servicessimilar to web sites on the Internet,but with the benefits of abroadcast system.

Over the last year several trialshave been carried out with broadcastweb sites and radio programmes.These have included a musicdocumentary with associatedmultimedia and educational contentand a jazz concert with a speciallycommissioned animation. And withthe release of the Psion Wavefinder,a PC-based digital radio, the generalpublic now have the ability to seebroadcast web sites on theirhome PCs.

Electronic Programme GuidesElectronic Programme Guides haverecently become widespread in thetelevision world with the growingtake-up of cable, satellite and digitalservices and work is now progressingon the development of guides fordigital radio. The schedule data istransmitted in XML form (XML is awidely-used format designed to

describe the meaning of encodeddata). Because this data is in thismachine-readable form it can be usedfor many applications, from aconventional programme guide toTiVo-like recording functionalityfor radio.

The radio of the futureWithin WorldDAB, we have played animportant rôle in developing aspecification for a Java Virtual Machinesuitable for digital radios. This willallow common applications to betransmitted to, and run on, all digitalradio platforms. Where possible thespecification is based on other similarstandards for consumer electronicsdevices such as PDAs and mobilephones. This will enable integrationand convergence for all these mobileinformation devices.

We have been offering acomprehensive test facility for digitalradios at BBC R&D, and manymanufacturers have taken advantage ofthis facility during the last twelvemonths. This has contributed toincrease the number of wellimplemented receivers now availableto the public. This facility has recentlybeen upgraded to offer testing inL-Band as well as Band III. We plan totest receivers for compliance with data


FM SPECTRUM REVIEWFM Radio is becoming more popular thanever. Listening figures are going up, and thecommercial radio stations are requestingmore and more licences. The Radio -communications Agency, the Radio Authorityand the BBC jointly commissioned anindependent report into the possibility offinding space in the congested FM band formore radio stations. Following preparatoryassistance from us to the companycommissioned to undertake the work, theRadiocommunications Agency published theFM spectrum review in June 2000. Theaccompanying Press Notice acknowledges‘the effective way the FM services have beenplanned by the BBC and the Radio Authority’.By focusing on example areas of London andLeeds, it is considered possible to introduce anumber of new small-area (less than 10 kmradius) services in metropolitan areas. Newlarge-area services cannot be accommodatedwithout impacting on the coverage of existingservices. The exercise has demonstrated thatthere appears to be little room to improveupon existing planning in the UK.

Our neighbouring countries arealso exploiting the possibilities for new FMservices. In 2000 we received and dealt withan unprecedented number requests from theRadiocommunications Agency for commentson the re-planning of FM services in theNetherlands and Belgium. Potential problemsto BBC services were identified, and as aresult requests were made for theinterference levels to be reduced.

EXTENSION OFCOVERAGE IN THENATIONAL REGIONSWe have prepared an outline plan for 16 newstations to improve coverage of BBC RadioWales in the South Wales Valleys. The gain inpopulation coverage is around 270,000. Stillin Wales, a further station, covering 16,000people, has been planned to extend the RadioCymru service in the Holywell area ofNorth Wales.

For Scotland, we have prepared an outlineplan to extend the BBC Radio nan Gaidhealservice (the service for Gaelic speakers) tothe whole of Scotland, starting in the north-east. The planning has proved to beparticularly difficult with the requirement tosqueeze six national services into spectrumallotted to four national and two locals (a netspectrum shortfall of about 1.4 MHz). By theend of 2000 we had issued plans for eightstations, covering a total population of709,900 in the northeast of Scotland.

We are aware that there are some gaps inFM coverage in England. Survey work willenable us to determine the precise scale ofthe deficiencies and to makerecommendations for plugging the gaps. Planshave been prepared for a Radio Cumbriafiller station at Keswick and a Radio Derbyfiller at Buxton. We are the key source offrequency information that is signalled overthe Radio Data System (RDS). Adviceprovided this year has enabled alterations tobe made to the local radio opt-outarrangements and, most notably, to solve ananomaly where Radio Cymru was previouslyswitching RDS radios to Local Radio trafficannouncements from Wiltshire!

Although we are making a strong move towards digital broadcasting, themajority of the licence fee payers still watch and listen to analogue services. We stillstrive to ensure that they receive the benefits of our programmes.


Short Wave transmissions have neverbeen perfect – there are too manyjokes about the quality of receptionoverseas for us to be completelycomfortable with the standard.Programmes presently delivered byshort or medium wave AM do notcompare well in audio quality withcompeting services delivered by FM.We need to protect BBC WorldService’s traditional audience, asnational services overseas transfer toFM services and the audience follows.BBC World Service is using local FM

re-broadcast arrangements whereverpossible to redress this, but a re-designof AM transmissions is also required.

DAB, the digital radio system usedat VHF and UHF frequencies cannot beused on the long, medium and shortwave bands, hence the need for a newsystem. This will enable us to re-usethe traditional delivery means ofWorld Service, the short and mediumwaves, which reach target areas somedistance away without the unwantedintervention of gate-keepers.

Digital Radio Mondiale (or DRM for short) is a worldwide consortiumwhich aims to develop and bring to market, a digital radio standard foruse in LF/MF/HF bands (otherwise known as the ‘AM bands’ or ‘bandsbelow 30 MHz’). Their vision is to bring affordable digital quality soundservices to the world radio market. The prime BBC interest comes fromthe BBC’s World Service, although we cannot rule out that some usemight also be made of it for domestic services.

DRM THE NEWSYSTEM!DRM uses digital techniques to:

• Deliver a service which providesmuch better audio quality andreliability than existingAM services.

• Provide user-friendly assistedtuning, schedules andother information.

• Provide easy access to largecoverage areas.

The techniques used have commonalitywith those already developed for digitalterrestrial television and radio, but arespecially tailored to the specificrequirements of broadcasters and thecharacteristics of radio-wave

propagation at those frequenciesbelow 30 MHz.

THE COMMERCIALISSUESFor DRM to be of benefit to the BBC ithas to be a worldwide solution. It mustbe used by many broadcasters, bothnational and international, withreceivers from many manufacturers ataffordable prices. That’s the only waywe can be sure that we will havelisteners on a scale which is meaningfulto World Service. This is a tall requestand the DRM Consortium’s worktherefore needs careful nurturing tokeep the variously-motivated playersworking towards this goal. We hopethat they will all find something valuablein it for themselves.

The potential market is vast if thereceivers are cheap enough. We believe‘small margins, large numbers =reasonable return’.

We are therefore developing ourown expertise in order that we caninfluence the development of integratedcircuits which are cheap and consumethe little power that is acceptable inmany markets. Our previousinvolvement in the development of ademodulator chip for digital televisionstimulated and promoted competitionin that market.

TECHNICAL ISSUESDRM has successfully delivered asystem giving good quality audio(and a modicum of data to supportuser-friendliness) through the narrow

bandwidth, poor-quality AM channels.The solution involved a harmoniousmixture of source coding, modulationand error correction, multiplexing andtransmitter RF issues.

We have been assessing and testingthe audio coding proposals (includingformal listening tests) and the finedetails of the modulation system. Theseare vital in a system which offers muchlower data capacity than many digitalsystems. Listeners will only buyreceivers for the new standard if thereis a sufficient boost to sound qualityand reliability. Of special interest is theproposal to use the new Spectral BandReplication technology. This appears toadd extra bandwidth to a limitedbandwidth system. Our studies haveenabled us to make informed commentand to make our own proposalsfor improvements.

Listeners’ acceptance of the systemwill be helped by its user-friendliness.The receiver should make ‘tuning’ as weknow it a thing of the past, and removeany requirements for listeners to knowor care what frequency or wave-band isin use. A small part of the data capacityof the system is devoted to carryingthe information needed to make thispossible. To ensure this works in a waywhich meets our fairly complex needs– while remaining sensible – we havetaken a leading role in the definition ofthe data multiplex. Amongst theinformation transmitted is alternativefrequency information (many shortwave circuits are duplicated,transmitting on two, three or even four



frequencies), station identification,and schedules.

The system offers a range ofmodes designed to cope with varioustypes of propagation conditions. Partlyat our insistence, field tests arecontinuing to ensure that these modessupport all conditions likely to beencountered, even in tropical regions,as the system must be globally useful ifit is to deliver a satisfactory audienceto BBC World Service.

WHAT HAPPENS NEXT?DRM has worked hard to developa specification, to perform laboratoryand field trials, and to present all thisto the International TelecommunicationsUnion: a task in which we played asignificant part. The result is that theDRM system is now in the process ofbeing recognised formally as arecommended system. To secure globalacceptance this recommendation hasyet to be ratified by the InternationalTelecommunications Union, and thedetailed specification needs to beapproved by one or more of therecognised standardisation bodies.ETSI, the European standardisationbody, is already working on this. Finedetails of the DRM specification arestill being resolved and continue to bepolished, partly in response to fieldtrial results as they become available.

In parallel with all this necessarytechnical work, DRM must also ensurethat everything is in place to ensurethat the system is brought to marketin a timely and successful way –introduction strategies, committedmanufacturers and broadcasters,regulatory provisions etc.

SPECTRUMMANAGEMENT ISSUESNow that DRM is becoming a realitywe need to assess coverage andfrequency requirements.

The new system requires acomplex mix of existing planning toolsand new developments to reflect thedifferent parameters of the digitalsystem. To help develop these planningtools we are using a transmittingstation at Orfordness on the eastcoast of the UK as a pilot test station.AM broadcasts by BBC World Servicefrom Orfordness cover parts ofCentral Europe. Medium-wave signalscan be transmitted by either ground orsky waves and it is the latter thatprovides a means of achieving largearea coverage – although the samemechanism makes for long distanceinterference between stations on thesame frequency. Whereas the analogueAM service suffers interference overmuch of the required coverage area,the DRM system has the potential todeliver interference-free reception.We anticipate that the experiencegained from this study will place us ina good position to assess othercoverage opportunities using DRM.

The challenge is to fit a largenumber of new digital channels into aspectrum which is already crowded:there seem to be AM broadcasts onevery channel when we tune throughthe band. Our positive experience withplanning new services for digitaltelevision gives us confidence that weshould be able to demonstrate benefitsfor DRM too.


There is much interest in usingexisting wiring infrastructure, whether mainsor telephone, to convey data signals. Systemsusing telephone wiring are named DigitalSubscriber Line, and come in many varietiescollectively abbreviated as xDSL. Systemsusing the mains are called Power LineTransmission or Power LineCommunications. In addition, many uses arealso proposed for mains or telephone wiringinside the home, not only as an easy way tointerconnect home computers andperipherals, but also for other entertainmentand home automation purposes.

The opportunities that all these offer arewelcome enough (e.g. as another route forthe delivery of BBC content), but there is aserious snag: the cables are being used inways for which they were not designed andare not particularly suited. A consequence isthat some of the signal that is used to carrythe data ‘escapes’ and this unwantedemission can cause interference to broadcastradio services, particularly broadcasting inthe long- medium- and short-wave bands. Thenature and severity of the threat depends onthe system in question.

While interference between radiosystems is covered by the International RadioRegulations, and new pieces of equipmentalso have their unwanted emissionscontrolled by the EMC Directive, there isconsiderable doubt whether any existingregulations control these new uses ofexisting cable installations!

The UK Radiocommunications Agencyrecognised this difficulty and convened agroup, in which BBC R&D took part, to drawup some proposed emission limits. Followingthese studies the Government laid outproposals in support of thetelecommunications industry with anemissions limit that affords no protectionwhatsoever to broadcast reception. However,discussions continue on ways to requiretelecommunications operators to act oncomplaints of interference. Further more, wecontinue to present our case vigorously, inthe UK and in Europe, at conferences andmeetings of relevant bodies.

We are convinced that there is apractical solution which will permit telecomoperators to use xDSL without a majorimpact on our AM radio broadcasts.

We have to be aware of potential threats to our existing services

switch-over

improving the coverage

capacity planning

the evolving architecture of television

monitoring

resilience

scheduling the digital channels

audio description

new data services

signing



Given that digital terrestrial television providesunique opportunities for the future deliveryof services, it is necessary for us tounderstand what could be achieved in thefuture – particularly in an all-digitalenvironment. Our work has shown that,whilst analogue transmitters are stillbroadcasting, it will be almost impossibleto achieved near-universal digital coverage.However, this could be achieved at switch-overby using analogue conversions – the re-use ofhigh-power analogue UHF channels for digitalbroadcasting. We recognise that this processwould involve significant logistical difficultiesfor viewers, and would therefore need to becarefully managed.

Our work has also shown that thecurrent digital network delivers relativelypoor coverage to those extra sets aroundthe house which are not directly connectedto the roof-top antenna. These are oftenportable sets, or sets which make use of asmall set-top antenna. Converting analoguetransmissions to digital would mean thatcoverage to digital receivers would matchcurrent analogue portable coverage.Moreover, we can increase the coverage to

portable receivers (around 85% of thepopulation) if we can use a lower datacapacity mode than that used for currentdigital transmissions. This might providebetter indoor reception or other newservices after analogue switch-over. However,universal portable coverage would require aneven more dense transmitter network thanthe current 1200 station analogue network.One of the benefits of switching fromanalogue to all-digital broadcasting is that itshould allow some spectrum to be freed fornew broadcast uses, or possibly for otherapplications. We have been looking at thevarious possibilities for such freed spectrum,to try to understand how best use may bemade of it, and what value might be assignedto it.

The evolution of digital television isimportant for our European partners too.The Portuguese, whilst they held thepresidency of the Council of the EuropeanUnion, organised a conference which broughttogether the leading market players andregulatory bodies, in order to define theguiding principles for the introduction of


The UK is now at the forefront of digital television delivery to the home. This leadsto the question as to how we might now progress to an all-digital future. TheGovernment has announced its intention to switch over from analogue to all-digitalbroadcasting, and has indicated that this could start as early as 2006, and may becomplete by 2010. Our aim is therefore to identify scenarios that will facilitate thisswitch-over.


digital terrestrial television within thesingle market.

Within Europe it has beenrecognised that the existingarrangements for television planningare not an ideal basis for an all-digitalfuture. It is therefore proposed toconvene a Regional Radio -communications Conference in 2005for the 56 countries within theEuropean Broadcasting Area. Initialpreparations have already started andwe are actively participating in, orleading, a number of key groups.Although the main conference will beheld under the auspices of theInternational TelecommunicationsUnion, the majority of the technicaldiscussions are held within CEPT (theconference of European governmentsdealing with telecommunications).The European Broadcasting Union isco-ordinating the views of publicservice broadcasters to ensure a

consistent and strong representationcan be made. Our work within allthese European groups enables us toconsider the wider issues, to benefitfrom the exchange of expertise, andto understand how we can co-operatewith our neighbouring countries infacilitating the introduction ofnew services.

New concepts, such as the NokiaMediascreen, a portable device whichprovides both television reception andmobile connectivity through the nextgeneration of mobile telecommuni -cations technologies, show how apowerful business case can be madefor new services aimed at themobile user.

Although UK coverage planning isbased on reception by roof-topantennas, it is clear that otherapproaches to digital television, suchas mobile or portable reception areequally important, especially in other

countries in Europe. Some are alsoconsidering multimedia-basedapproaches using cellular type networkswith UHF return channels. All theseideas will have to be addressed in theEuropean digital plans.

BBC R&D has vast practicalexperience of digital terrestrialtelevision in the real world, dating backto our involvement in the world’s firstfield-trials of the new standard.

We have used our understanding ofreceivers and their performance to helpthe industry develop ideas for the bestpractice for receiver installation.Although this concentrates onreception using roof-top antennas, werecognise that people often haveseveral receivers in their home, andmost of these are likely to use set-topantennas. These are susceptible to

lower signal strength and distortedsignals.

We have carried out field-work toinvestigate reception on portablereceivers in homes. This has involvedvisiting volunteers’ houses withmeasuring equipment and gaining asmuch information about receptioninside as possible; particularly notingthe quality of reception on differentfloors and using different types ofset-top antenna. This gives us avaluable database to help with ourprediction tools.

The ruggedness of reception onportable receivers is not as good as onfixed installations. Frequently viewerssay that the picture quality may begood for much of the time, but theremight be problems if people move tooclose to the receiver, or if there aresome unusual traffic movementsoutside. This shows that the receiverhas been working close to its

threshold, and something has happenedto take it below the threshold for goodreception. Reception can be greatlyimproved if some form of diversitytechnique is used. Although receptionfrom one antenna can be variable, usingsignals from two or more antennas cangive much better reception. There areseveral different methods of combiningthe signals, with different compromisesbetween performance and cost. Anexperimental receiver is beingconstructed to evaluate the differentdiversity techniques.

Another area of potential newapplication for digital television maycome from the DRiVE project, of whichwe are a partner. DRiVE aims todevelop a spectrum-efficient highquality Internet protocol data networkfor wireless multimedia in vehicles. It isexploring the possibilities for dynamicspectrum allocation to be used tocombine different radio access networktechnologies, including digital radio andtelevision with the latest mobiletelephony standards.

As well as the technical mechanisms,there are major regulatory issues inthis project. Our understanding ofspectrum management and RFtechnology helps us to inform ourpartners in DRiVE and clarify theregulatory processes which govern theuse of spectrum within Europe.




One of the perceived inhibitors to thecontinuing take-up of digital television islinked with these different coverages of thevarious multiplexes, and, in particular, therelatively poor coverages of multiplexes Cand D in some areas (these carry programmeservices such as the BBC/Flextech joint-venture UKTV channels, MTV and theCarlton Food Network). This has long beenunderstood as a legacy of the way that thenetwork was initially planned, and is aparticular result of care being taken toprotect analogue services. Nevertheless it isimportant for ONdigital, the pay-TV operatoron this platform, to be able to sell a packageto consumers which includes the multiplexesC and D.

Under the auspices of the Joint FrequencyPlanning Project, BBC R&D and its partners –Crown Castle, ntl, and the ITC – haveworked hard to propose new transmittingarrangements which might lead to extensionof the core coverage of the digital terrestrialnetwork (that is, where all six multiplexes arereceivable from the same transmittingstation). This work, broadly termed multiplex

equalisation, has involved re-visiting some ofthe original decisions made about radiationpatterns, frequency assignments and radiatedpower. This inescapably leads to morewidespread interference to the currenttelevision reception of analogue viewers (thecliché is correct that there can be no gainwithout pain). A major tranche of theproject’s work has been to identifypossibilities for analogue reception fromalternative transmitters, where viewers areaffected. BBC R&D has contributed planningexpertise and experience, shaping the plansand investigating the impact of the newproposals on the existing analogue network.We have carried out field-work and providedadvice built upon our unique experience inrolling out the UHF analogue and digitalterrestrial networks. BBC R&D is the sourceof all the predictions from the Joint PlanningProject of population coverage in the UK.

This work has been supported by twoinitiatives: Digiplan which is a projectproviding an enhanced propagation model,and Spaghetti which is providing more user-friendly planning tools.

When digital television was launched, six multiplexes were offered fromthe majority of transmitting sites. However, the restrictions of internationalco-ordination sometimes meant that it was not possible to broadcast themultiplexes at the same power levels, and so the coverage areas wereoften different.


A cross-directorate group has beenmonitoring the use of capacity on theBBC’s multiplexes. As part of this process, wehave been responsible for maintaining anaccurate bit-budget for both digital satelliteand terrestrial services. We have alsomodelled the consequences of newprogramme propositions and demonstratedtheir practicability.

For a television service the videocomponent takes the greatest share of theservice bit-rate so efficiency savings oftenfocus on video encoding. The basic codingquality that can be achieved at particular bit-rates is of key importance. The techniquesand commercial compromises applied tovideo encoding vary between manufacturers,and with each generation of equipment.

We are monitoring technicaldevelopments in coding and multiplexing andtheir applicability to the BBC’s services andtechnical architecture. This is to ensure thatthe best use is being made of bit-rate on ourdigital television channels in terms either ofbit-rate efficiency or service quality(e.g. picture quality). This is a difficulttechnical problem. The relationship between

bit-rate and picture quality is not a simpleone, and so there is no simple way ofpredicting the likely quality of a programmefrom the bit-rate available.

STATISTICAL MULTIPLEXINGOne tool that can be used in appropriatecircumstances is statistical multiplexing inwhich a common pool of bit-rate is shareddynamically between a number of services.The bit-rate required to code video toapproximately constant quality often variessubstantially from shot-to-shot so an increasein demand for bit-rate in one video streamcould be met by borrowing bit-rate from oneor more other streams – if at that instanttheir individual requirements can be satisfiedwith less bit-rate. Where these conditionsapply, demanding pictures can be coded to abetter quality than if they were coded at aconstant bit-rate equal to the pool average.There will however be times when several orall the streams demand more than their fairshare of bit-rate – the overall picture qualitywill then be no better than if each servicehad been coded at a constant bit-rate equalto the pool average. The precise benefit of


There is increasing pressure to make most efficient use of available bit-rate onevery platform. The BBC is keen to add new programme services, to add newservice components (e.g. Audio Description), and to expand existing services(e.g. BBC Text) on its digital multiplexes. This issue is vital to the future of the BBC.


statistical multiplexing thereforedepends on the nature, number anddynamics of the services included inthe pool.

The BBC’s digital services arelargely mixed-genre channels,competitively scheduled, so it isparticularly important to determinethe working parameters for which astatistical multiplexing system willdeliver a suitable balance betweenquality of service and bit-rate. We arestatistically multiplexing five BBCservices on satellite and expect toapply statistical multiplexing toterrestrial television in 2001. This willprovide sufficient capacity to satisfythe BBC’s programme aspirations asset out by the Director GeneralGreg Dyke in his ‘MacTaggart’ Lecture.These proposals are still subject toagreement by the government.

We have concentrated onunderstanding the complex relationshipbetween quality of service and bit-ratein a statistically multiplexed bundle,and in particular on scoping theopportunities for adding additionaltelevision services to the existingterrestrial multiplex. Initially we usedan off-line system, fed with the outputsfrom our presentation studios. Qualitymeasurements and subjectiveevaluations made by experts or otherbroadcasting professionals have shownthat it is necessary to evaluatestatistical multiplexing systems for aconsiderable period of time using fullyrepresentative test material ifconsidered judgements are to be madeon average quality and parametersettings. By way of example we foundit quite possible to see no significantcoding artefacts visible during peaktime viewing on one evening and then

to see artefacts crises during thenext evening.

Subsequently we used our existingsatellite transmissions for an extendedlive experiment during which variousaverage bit-rates and bundle sizes wereused to model several servicepropositions for terrestrial television.Whilst quality measurements were alsomade, the emphasis was on viewerreaction to the on-air tests as judgedby monitoring relevant InternetNewsgroups, by monitoring calls toBBC Information and Reception Adviceand by commissioning specificconsumer research from a commercialopinion research company. The overallreaction demonstrated that increasingthe number of television services in theterrestrial multiplex from four to fivewould not significantly affect viewerperception of quality but that a further

increase would give rise to significantviewer dissatisfaction.

During 2001 statistical multiplexingequipment will therefore be installedin London, Cardiff, Glasgow andBelfast to allow five programmes to becarried on the terrestrial multiplexalong with BBC Parliament (audio only)and BBC Text.

OTHER SERVICESWe can also save capacity byconsidering the dynamics of servicessuch as subtitling, audio descriptionand, in the future, closed signing.

Using a tool called ‘Beagle’ speciallydeveloped by BBC R&D for accuratebit-rate analysis, we have beenmeasuring the bit-rate requirements forsubtitling. The measurementsdemonstrate that over any five secondperiod across the BBC multiplex wecan expect to find several hundred

kilobits of unused bit-rate in theallocated subtitling capacity.Other access service components willcome and go at programme boundariesthereby yielding spare capacity with alonger time constant. If suitableharvesting mechanisms can be appliedto the BBC digital architecture thisbounty may in the future be used toincrease the bit-rate allotted toservices such as BBC Text which areless time-critical.

The harvested bit-rates we areconsidering are much lower than thosefor video, so statistical multiplexing ofthese additional services will not freesufficient bit-rate to accommodate anentire new channel. Nevertheless, therewill be many possibilities for using suchopportunistic data multiplexingtechniques to make more efficient useof our available bit-rate capacity.



The technology required for broadcasting ischanging rapidly: more emphasis is beingplaced on the storage of programmes andsupporting data as files on hard disk ratherthan on tape, more and more of thebroadcast chain can be implemented usingsoftware packages running on computersrather than special purpose black-boxes. Weare being asked to deliver our programmesto a wider range of receiving devices, rangingfrom the traditional analogue television set,through set-top boxes for digital television tostreaming content via BBC Online to PCsand broadcast reception on mobile hand-helddevices. Each requires the material webroadcast to be formatted in a particular(and usually different) way.

The BBC is planning a new networkplayout centre in White City as well as a newbroadcast centre for BBC Scotland at PacificQuay in Glasgow. BBC R&D has beenworking closely with the project teamsdeveloping the specifications for the technicalinfrastructure for these new centres.

If we are to deliver our programmesefficiently then it is important that the BBCtakes informed decisions now about thenature of broadcasting in the later years ofthe decade when these buildings will be

operational. As well as advising the projectteams on appropriate systems for use in thenew buildings, we are also able to advise onfuture developments in the delivery of ourprogramme material and new ways ofgenerating those programmes.

We have also been working with theBBC's Technical Design Authority who aretrying to ensure that common technicalstandards, architectures and systems areadopted throughout the BBC to ensure bestpractice and commonality to meet the BBC’srequirements. This allows us to plan thechanges required as we meet the technicalchallenges as well as establishing a frameworkwithin which the many projects seeking toimplement those changes can work.

DELIVERY The BBC’s policy is to offer digitaltelevision services to the licence fee payerthrough any available delivery platform.These include terrestrial and satellitebroadcast systems, cable systems, and alsoemerging broadband systems.

The challenge is to offer viewers similarservice propositions with the same look andfeel, whichever platform the individual vieweruses. The constraints of the digital platforms


Over the course of the next few years, there will be changes in programmepropositions, technical infrastructure and the methods of delivery to the home. Weneed to offer an efficient, effective and flexible broadcasting system.


vary considerably, and the systemsarchitecture has to reflect this.For example:

• The capacities of terrestrial,satellite and cable multiplexesare significantly different.

• Each platform deliversDigital Text in a different way.There are also differences inthe delivery of other servicessuch as Subtitling.

• Terrestrial and cable systemsare well suited to regionalprogramming, whereas satellitetransmissions illuminate thewhole of the UK. At the timeof writing the BBC offersregional programmes forScotland, Wales and NorthernIreland on all platforms, and forthe English Regions onterrestrial transmissions andcable (but not satellite).

These differences have led toincreasing separation between thesystems we use to deliver satellite and

terrestrial services. At the time ofwriting, the only linkage is theencoding for the services in thenational centres, which remainscommon to the two platforms. Thiscommon element will be eliminatedduring 2001 with the introduction ofstatistical multiplexing on terrestrialtelevision, resulting in separateencoding for the two platforms.

The roll-out of digital cableservices remained relatively slowduring 2000 although it is expected topick up during 2001. Cable operatorsusually use analogue terrestrial andsatellite transmissions as their sourcefor analogue cable services, and tosome extent have continued to usethis model for the digital era. This hassome benefits, such as the ability toreflect regional variations of servicessuch as BBC ONE. However, due todifferences between the platforms,such as those noted above,re-broadcast from terrestrial orsatellite transmissions is not as

successful for digital television as itwas for analogue, and increasinglycable operators are moving to feedarrangements independent ofother platforms.

One of the more obviousdifferences between platforms is inthe delivery of interactive services.Cable makes use of the natural returnpath available to cable operators,whereas satellite and terrestrialbroadcasts use data carousels(effectively offering a web server atthe user’s end). Text servicesbroadcast terrestrially or by satelliteare not recognised by receivers fordigital cable. As a consequence, the BBChas developed a separatedelivery strategy for cable which usesexisting BBC servers at the LondonInternet Exchange.

DEVELOPMENTS DURING2000-2001Although the majority of BBCprogrammes are broadcast throughoutthe United Kingdom at particular times,the national centres and English regionsopt out and provide their ownprogrammes with more restrictedgeographical relevance. These facilitieswere included in the digital televisionarchitecture, but roll-out in the Englishregions has happened more recently.Following the initial implementation ofopt outs in the English regions in 1999,further English regions have been addedduring the past year as a result of thedivision of the former South-Eastregion. The area surrounding Oxford,has become part of BBC South, but hasthe ability to provide its own newsinserts. At the time of writing, Londonis set to become a region in its ownright, with the remaining South-Eastregion expanding to incorporate someareas previously covered by BBC South.

Oxford was the first of these newregions to go on-air, during October2000. Although editorially a sub-opt,which allowed some savings to be madein the provision of baseband equipment,the presence of different content onthe opting service requires both theservice and the broadcast signal to beuniquely identified. Consequences of

this include the need to carry out aco-ordinated re-configuration of BBCsystems and the systems of otherparties such as transmission providers,and the need for viewers receivingthese terrestrial broadcasts to re-scantheir receivers so that they will be ableto identify the new services.

The experience gained through thisprocess will be extremely useful to theBBC should it make further changes tothe structure of English regions infuture.

PLANNING FOR2001/2002Following the announcements by theDirector General in the ‘MacTaggart’Lecture, major changes are scheduledto the BBC’s digital television servicesduring the coming year. These will havea dramatic impact on the technicalarchitecture for digital television, withthe infrastructure in Television Centreand the national centres, and thecircuits connecting them, requiringmajor changes. BBC R&D has been anintegral part of planning the newarchitecture and will remain closelyinvolved to advise and assist inits implementation.

The first major change to servicesproposed is the introduction ofservices for children, sharing capacity



with other BBC services. The children’sservices will use capacity during theday and other BBC services will usethe same capacity during the eveningand night. Previously our digitaltelevision multiplexes existed in aconstant configuration 24 hours a day,seven days a week. With theintroduction of distinctly identifiableservices sharing capacity in this time-exclusive manner, the configuration ofthe multiplex has to change on aregular basis. In order to achieve this,changes to the coding and multiplexingat Television Centre and the nationalcentres are required, and control ofthese functions by the schedulecontrol system, SID, needs to beenhanced to effect the switch-overbetween one service and the next.SID also needs to send appropriateclosedown messages to the systemsthat control the programme guide onsatellite broadcasts. We have examinedthe different potential solutions forproviding the required behaviour. Wehave also built a test system toconfirm the correct operation of theend-to-end transmission chain andestablished the effect on a range ofreceivers, to ensure that these serviceswill operate as expected.

The second major change to ourservices is the introduction ofstatistical multiplexing on the BBC’sterrestrial multiplex. Statisticalmultiplexing requires new coding and

multiplexing architectures in TelevisionCentre and the national centres, andan expansion of circuit capacitybetween them. One of theconsequences of statistical multiplexingis that the bit-rate of services will bevariable, and may at times be greaterthan its current value. This can haveconsequences for cable operators whooften provide a fixed capacity for eachprogramme service, but who use off-air signals to feed their networks. Wehave advised the major UK operatorsof potential solutions to any problemsthat may result. At the time of writing,there are still many issues to beresolved, however.

The remaining elements of theservice line-up proposed by Greg Dykein the ‘MacTaggart’ Lecture last August,including converting BBC CHOICE toBBC THREE, and launching the secondservice for children, should not havemajor implications for thearchitecture, since the earlierdevelopments are expected to providethe required functionality.

Satellite services will be affected bytwo developments that place moredemand on the capacity of themultiplexes. The BBC has announcedfurther Radio services, which will becarried on satellite, and in additionsome allowance has to be made foraccess services on the satelliteplatform. Trading the requirements ofthese services, which require a fixed


The equipment (known as ‘Bitmon’) was delivered at the startof the autumn, and over the remainder of the year has beeninstalled nation-wide at key internal points and interfaces onthe digital programme chains for both terrestrial and satellitebroadcasts. It checks that the signals are correctly constitutedand conform to the relevant standards, by making a series oflogical tests and raising alarms on any discrepancies. Our maintechnical support centres in London and Birmingham canaccess the Bitmon probes for detailed alarms and analysis,using the BBC’s IT networks. Bitmon is now routinely used byoperational staff to help maintain continuity of service.

While this type of monitoring catches many faults, itdoesn't test the signal content itself. For example, a blankscreen, loss of sound, a frozen picture, absence of colour, oreven the wrong picture would all pass muster, just as long asthe formal structure of the signal is correct and self-consistent.We are now assessing how such faults could be detected bymatching a low bit-rate ‘signature’ of the signal at key points inthe programme chain. The signature needs to be recognisableeven if the signal has been processed, for example by bit ratecompression or adding a logo. The transfer of the signaturesthemselves is also being investigated – network delays maycause erroneous alarms, and routing errors that affect bothsignal and signature will not be detected.

When the BBC launched digital TV, very littleindependent monitoring equipment was available, andit was decided to wait until the market developedand the size of the digital audience justified aninvestment. That time has now come, and BBC R&Dhas played a major part in specifying suitableequipment, encouraging manufacturers to develop it,and selecting a supplier.


Recent problems with the weather and its affects on otherindustries, and issues such as the millennium bug last yearhave highlighted the need for resilience in our broadcastinfrastructure. There are many things that could go wrong,but perhaps one of the most important is the possibility ofservice collapse in the event of a major failure of a BBCregional centre. This could result in all the BBC’s terrestrialservices in that region being lost.

In most instances the option to re-radiate a signal receivedfrom an unaffected transmitter is not possible, because thesignal would be too weak at that distance for successfuldigital reception.

Our experiments have confirmed that it would bepossible to restore terrestrial services in an emergency byre-transmitting the statistically-multiplexed services from oursatellite transmissions using relatively simple additionalequipment. This approach would have its limitations. Only videoand audio could be restored this way due to the differencesbetween terrestrial and satellite platforms.

This idea has been successfully tested with theco-operation of our transmission contractors, CrownCastle International, at the Sutton Coldfield transmitter.The BBC is now considering protecting the terrestrialservice using this technique.


Reliability and resilience are key issues for the BBC.


SID S ROLESID helps us to create and deliver schedules,and send real-time trigger events. SID wasoriginally a quick response to get us up andrunning on digital satellite (originally SID wasSchedule Interface for D-SAT), but has sinceevolved to be a fundamental part of theBBC’s scheduling applications. It offersfacilities for:

• The creation, editing and checking ofprogramme metadata for electronicprogramme guides, web sites andpersonal video recorders.

• The management of the workflow indelivering schedule information.

• The delivery of real-time data aboutthe transitions between programmeswhen they happen. This is used todrive ‘Now and Next’ displays andensure that the current programme iscorrectly recorded.

INFORMATION SUPPORTEDThe system supplies information ranging frombasic metadata such as the times at whichprogrammes will be aired, their names,descriptions and genres to their formats(widescreen, stereo, subtitled etc.), web sites,email addresses, conditional accessparameters, and related programmes. Itprovides links to other relevant assets, suchas those stored in other parts of thebroadcast infrastructure such as thePromotions Object ManagementSystem, POMS.

A legacy of the pre-digital BBC is thatthere are numerous sources of information,none of them complete. This means thatextra content must be added to whateverdata can be gleaned from elsewhere.

A feature of the digital era, however, isthat there are an ever-increasing number ofparties who are interested in using data toadd value to their own offerings. Usually suchparties would prefer to be supplied with allthe relevant data so that their task is simply


We have designed and developed a system to enable the BBC to create anddeliver content to electronic programme guides and personal video recorders ondigital terrestrial, satellite and Online platforms. It provides a central point ofinformation for the BBC’s television and radio schedules, editorially checked, andconforming to a single BBC style – there’s One BBC, so there’s one source ofschedule information in the digital era! This system is called SID.


one of reformatting rather thanediting. Where this is in the BBC’sinterest, such as when the data willlead to an increased awareness of theBBC’s services, SID in conjunctionwith its major client, BBC Broadcastingand Presentation, aims to supply asmany types of information as possible.This helps the BBC to maintaineditorial control of its output acrossall media.

FEATURES

Up to date and accurateSID checks the scheduling systemsfrequently, so it can present changessoon to SID users. They can thenchange the schedule informationaccordingly, and make themodifications visible to the recipientsof the data, which include programmeguides, ‘Now and Next’ information,interactive text applications etc. Thisis vital, because unlike mostbroadcasters, the BBC changes its

schedules reactively at very shortnotice on a daily basis.

ReliableBy using tried and tested industry-leading technologies we have created afast, stable and reliable system that hasbeen running without major problemsand with very low downtime for overthree years. Only now that we areabout to handle around 100 channelsand send them to over five recipients(we started off sending about tenchannels solely to BSkyB!) do weneed to upgrade the server to usefaster processors.

Flexibility and expandabilityThroughout the lifetime of the system,new requirements have driven changesat a rapid rate – new data recipientsneed new kinds of data, and changesto existing data recipients meanchanges to SID. New working practicesneed to be reflected too. We manageand co-ordinate the necessarymodifications to the different elements


PICS is the scheduling system used for most of the day to day

planning of BBC TV services. It provides basic information about

London schedules, and is particularly useful for on-the-day timing

changes. Schedules from the Nations are provided separately.

Compass is the playout automation system used for most of the

BBC TV services. By hooking into Compass’s output and analysing it

carefully, SID predicts when the next programme is about to come

on air and sends triggers at just the right moment.

There is no simple way to get all the radio schedules from the BBC

except to go via Broadcast Data Services Ltd., who collate the data

from diverse sources. SID gets basic information for network radio

services from an interface to BDS.

PICS

Compass

BDS

BSkyB

ONdigital

central

collator

Coding and

Multiplexing

System

Navigator

Others

SID supplies the BBC schedule information to BSkyB for its

electronic programme guide, Personal Planner and ‘Now and Next’

services. The connection is made over a private network, and when

all systems are running normally it is not uncommon for schedule

changes made in SID to appear on televisions within ten minutes.

By supplying the ONdigital central collator with SID ‘Now and

Next’ information, all terrestrial digital television channels can show

the latest BBC programme information.

SID controls and supplies information to the BBC’s internal coding

and multiplexing system, which keeps the BBC’s digital television

services on air. In the event that ONdigital’s central collator should

fail, the BBC channels are able to use schedule information to

continue showing ‘Now and Next’ information at least for the BBC

channels, but not for other digital terrestrial television channels.

The BBC’s Navigator project takes schedule information and

packages it into formats that the public can read and use directly

– they currently have a web page (the BBC What’s On site),

and are developing interactive applications for the digital

television platforms.

New services that use schedule information are being developed –

SID facilitates such developments by giving them non broadcast

critical access to schedule information.

Sources ofraw data forscheduling

Destinationsof editorially authorisedSIDscheduleinterface


of the system. That this is almostalways possible on time reflects thethought and effort that we put intogood design both at the outset and atall subsequent stages.

SID is scalable too. The main set ofusers, the EPG Unit, began as a teamof around five members of staff, andto meet the requirements of the BBChas grown to around 20, all using thesame system, based on the samesolid technology.

EfficientBy gathering schedule information inone place, in a reliable system, theBBC is making the best use oflicence-fee payers’ money in promotingdigital services.

Challenges and plannedsolutions for the futureSo much work has been done on SIDthat it feels as though the end oughtto be in sight, but success tends togenerate more work! The challengesfor the future are as difficult andthought-provoking as any that we havehandled in the past. These includefinding more intelligent ways to enableprogrammes to be linked together tohelp viewers and listeners to find theirway to the programmes that they willenjoy – this technology is needed forthe launch of a Navigator service ondigital satellite television.

Viewers will soon be able topress a button on their remotecontrols to tell their recording device,e.g. a TiVo or other personal videorecorder, that they will later want towatch the programme whose trailer iscurrently on the screen – this is calledtrailer selection, and SID will allow itto work by supplying real-timeinformation about the programmebeing advertised.

The BBC’s plans for new children’stelevision channels and BBC THREEand BBC FOUR assume that we canturn services on and off dynamically.This is a major new requirement forSID to handle, and development hasalready begun.

As well as these new features, theSID web site and user interface will beupdated to include a new ‘intelligentsearching’ algorithm. The real-timesystems will be kept up to date tosupport new automation systems.

One of the biggest tasks ahead is amajor redesign of the user interface tomake schedule editing easier than ever,and to support a hierarchical model ofschedules that means that editors ofelectronic programme guides need notedit the whole of every nationalschedule independently, but need onlymark out the differences where anational service opts out of itssustaining feed. This will also enableschedules to be tailored for English (or

SID is flexible to meet the changing requirements of the BBC. New types of metadatacan be added with ease, helping us respond rapidly to editorial aspirations.

Metadata is just as important as the audio and video that traditionally are thecore output of the BBC. Our schedule interface is a key element in the metadatabroadcast chain.


During the past year the BBC has transmittedprogrammes with audio description on digitalterrestrial television on BBC ONE in theSouth East, BBC TWO and BBC CHOICE inEngland and on BBC Knowledge.

HOW DO WE DO THAT?The production team creates an audio trackwith the description, which is then broadcast.

We transmit data within the codeddescription signal, providing a means of fadingthe level of the programme sound duringdescription and also providing an optionalmeans of panning the description around thesound stage.

In the receiver, a special plug-in cardremoves the audio description from themultiplex using a module plugged into theCommon Interface connector of a digitalterrestrial receiver. A special module thencombines it with the normal sound track, andthen delivers the combined signal to thelistener’s loudspeakers.

The user has control of the volume of thedescription whilst the broadcaster hascontrol of the relative level of the

programme sound during descriptionpassages.

EXPLOITATIONThe separate mono description stream uses afrugal gross bit-rate of less than 75 kbits/sper described service. Furthermore in thefuture we will be able to harvest any bit-ratethat is unused during non-describedprogrammes.

This is in stark contrast to providingaudio description premixed with theprogramme sound which would require afixed gross allocation of 266 kbits/s perdescribed service. Although this methodwould minimise the amount of newequipment in the receiver, it is not a practicalsolution given the pressure on capacity in themultiplex.

We have taken a leading role in specifyingthe module functionality and in authoring teststreams to assist the manufacturer developingthe module. Unfortunately there have beendelays in the commercial development of themodule. These have resulted in The DigitalNetwork offering trial services to a smallgroup of people using a temporary solutionbased on two set-top boxes and a voice-activated attenuator. This interim solution hasa number of significant practical drawbacksespecially to the user, but it has allowed

There are many people in the UK who are sufficiently visually impaired that theycannot appreciate all the action on the television screen. Audio description is a newservice which helps them understand the salient points in the programme.


In an ideal world all the different networkswould use the same technologies to supportdata – in the same way that MPEG hasbecome ubiquitous for video and audio.However, this is not the case in practice. Inresponse the BBC has established separatedata service playout infrastructures for digitalterrestrial, satellite and cable networks.

We are working with network operators,receiver manufacturers and content creatorsto provide a coherent production anddelivery system.

Authoring the same content three (ormore) times for each target platform is not asustainable proposition. To enable thecreation of large numbers of services theproduction process needs to become as easyas creating any other type of televisioncontent. We need well understoodprocedures, standardised interfaces andsuitable high-level tools.

The content production system wedeveloped to support the launch of BBC Textin 1998 has been replaced by a more mature,more generic third party system. Many of therequirements for this new system wereidentified during the development of theoriginal launch system and much of thesystem control is now in the hands of the

editorial and operation staff who run theservice on a day to day basis. Crucially theresulting system – which went live in Summer2000 – is able to provide content for theBBC Text service builders for terrestrial,satellite and cable. So even though theapplications running on each platform arequite different, the same BBC content can bemade available to all.

Digital terrestrial televisionDigital terrestrial television is a truly opensystem in the UK. Content (video, audio, dataetc.) is broadcast following rules defined in anumber of open specifications developedover the past few years.

The operators of the multiplexes in theUK have created a group called the TDNwhich has adopted a baseline specificationthat defines the minimum support for dataservices on terrestrial television. This isreferred to as ‘UK Profile 1’ and is built ontwo international (ISO) standards. One, thegrandly named ‘Digital Storage Media –Command and Control’ (DSM-CC) is part ofthe MPEG-2 specifications, defines the way inwhich data is transmitted, and the other,MHEG-5, defines the way the data ispresented to the viewer. DSM-CC is an


One of the advantages of digital television is the potential of its data channels.Each platform, whether terrestrial, satellite or cable uses a different standard.

Nevertheless we have succeeded in delivering new services to them all, efficientlyand effectively.


extensive toolkit for handling thetransfer of multimedia content. Part ofthis, the Object Carousel, has beenselected to provide a broadcast filingsystem where a range of data contentis broadcast cyclically, with theopportunity to update, add, or removecontent as and when required.

MHEG-5 is one of the outputs ofthe Multimedia and HypermediaExpert Group. It provides a means ofhandling multimedia content, specifyingmechanisms for both presentation onscreen and user interaction.

Some early receivers werereleased as incompleteimplementations of the baselineMHEG-5 specification. This will hinderthe development of an open marketand lead to early legacy problems,i.e. having to support receivers thatwill never be upgraded tocomplete implementations.

As a result the BBC has madeavailable a limited amount of capacityto support over-air upgrades tofree-to-air receivers. We have helpedestablish a technical specificationand infrastructure for the playout ofsoftware upgrades.

BBC Text, the BBC’s digitalreplacement for CEEFAX, waslaunched on digital terrestrialtelevision as a stand-alone service. Itused an end-to-end chain that wecreated. This represented a pragmaticapproach to achieving launch, since itsimplified the requirements for thesupporting technical architecture.However, it has always been intendedthat BBC Text should be accessiblewhilst viewing the BBC’s lineartelevision channels, e.g. BBC ONE,BBC TWO etc., in the same way thatCEEFAX is available on analoguechannels. This linking is referred to as‘channel association’.

To make teletext accessible whilstviewing an analogue television channel,the relevant data must be included inthe delivery of the other parts of thatchannel – very specifically the videosignal. This means that for the sameteletext service to be accessible froma number of television channels, thebroadcast of the relevant data must beduplicated in each. Adopting thisapproach for digital television requiresthe inclusion of specific componentscontaining a separate copy of the BBCText service in each channel from

whichit is tobe

accessible. This has the benefit that itcleanly isolates the configuration andmanagement of channels within thetechnical infrastructure. However, this isincredibly wasteful of broadcastcapacity due to the duplication of data.In fact given the relatively limited bit-rate available it is uncertain if such anapproach is at all feasible.

Instead, a new approach usingshared components has beenimplemented. The components thatdeliver the BBC Text application areonly broadcast once within the digitalmultiplex. This means that there is noduplication of broadcast data and sothe most efficient use of valuable bit-rate. Then, to create the association,these components are referenced inthe multiplexing configuration of allchannels from which BBC Text can beaccessed, i.e. these components areeffectively shared by several channels.

Interactive Wimbledon 2000 is oneof the programmes that werecommissioned to explore newopportunities by enhancing regularlinear television programming. Theservice provided the viewer with easyaccess to live scores, stories andbackground information on the tennis

championships. Furthermore by beingable to control the selection andpresentation of video and audiocomponents it was able to act as anumbrella, pulling together the BBC’scoverage of the tournament, which wasspread across a number of channels,into an integrated viewer experience.The service was available for the two-week duration of the tournament.

Digital satellite televisionThe main satellite network in the UK isoperated by Sky, which has chosenOpenTV as a means of supporting itsdigital data services. Whilst Sky hasbeen running interactive services forsome time now, third party serviceshave only appeared on their networkduring 2000. The BBC only signed anagreement with Sky allowing us tobroadcast data services to run on theirplatform, at the start of 2001, but wasready to start test transmissions duringJanuary and launch services to thepublic by mid-March.

The ability to make this swiftturnaround from signing to launch wasdue, in technical terms, to two keythings. Firstly, considerable preparatorywork, meant that a technicalinfrastructure had been in place forsome time, waiting for contractualissues to be resolved before it could beused operationally. And secondly, thesignificant experience that the BBC, andin particular BBC R&D, has gained inthe use of OpenTV since first exposurein early 1996. This knowledge basecontinues to grow as new services aredeveloped on this platform.

Digital cable televisionRecently we have seen consolidation ofcompanies offering cable services. Mostnoticeably, CWC was taken over by ntl.This reduced the number of traditionalnetwork operators from the big threeto just ntl and Telewest. However, thebenefits of this may be short-lived as anumber of new broadband networksbegin to emerge.

A key event has been theemergence of Liberate Inc., as thepreferred provider of a commonsystem to support data services.

Liberate’s core functionality is basedon HTML and JavaScript. Coupled withthe inherent return path provided bycable networks, this gives the potentialfor displaying content sourced directlyfrom the World Wide Web. Whilst thisis possible many providers, including theBBC, have created content specificallyfor these platforms. This recognises thatthe characteristics and use of atelevision are very different from thoseof a PC.

The service launched with news,sport and weather information –effectively acting as a CEEFAXreplacement. However, the servicebuilder we have developed provides astandard framework into which allkinds of BBC content can be added.The service continues to be extendedwith re-versioned content from theBBC’s extensive web site. It alreadyprovides a lot of material aimed atteenagers and education such asTweenies, So… and Bitesize.

The challenge now is to providesystems that support content linked tolinear programming – EnhancedTV.



Since October 1999 we have beenproviding programmes with opensigning (i.e. the signer or interpreter isseen in vision by all viewers), some asovernight repeats. As the quota rampsup, an increasing proportion of signedprogrammes will need to transmittedduring peak-time viewing. So the needfor a delivery system for closed signingmay become more pressing (withclosed signing, the suitably-equippedviewer elects to see the signing image;other viewers need not see the signing– cf. closed subtitling).

To be credible any candidatemethod of closed signing must bepracticable, delivering a sensibleconsumer proposition with

user-acceptable quality of service andat the same time being simple tooriginate, distribute, receive and use.It must also be sustainable – able tocope both with increasing quotasand with linguistic changes in BritishSign Language whilst avoiding legacyproblems for broadcasters and users.Thirdly it must be affordable – forusers in terms of the cost of receivingequipment, for broadcasters in costof production and delivery and formultiplex operators in terms ofbit-rate.

At BBC R&D we have beeninvestigating the challenges ofproviding a closed signing system.We believe that it is important to

The Independent Television Commission required that at least 1%of commercial digital terrestrial programmes in the UK should besigned by May 2000 with the proportion rising to 5% after ten years.It requires that ‘All important gestures that convey meaning throughsign language must be easily and accurately recognised.’ The BBChas declared its aim of at least matching the requirements of theITC guidelines.


consider the overall requirements,including systems issues and themethod of coding to deliver areadable signing image.

The broadcast system issuesbeing addressed are extensive. Forthe business to be practical, we needto consider scheduling, imagecapture, editing, synchronisation,recording and playout, reactivity, livesigning, coding, getting the signingsignal across regional boundaries(including time-shifting in theNations) and monitoring. We havealso worked alongside the See Hearteam looking at production issuesrelated to both open and closedsigning. We have made considerableprogress in defining the end-to-endsignal chain which any candidatesystem must support.

An important constituent ofthis chain is the delivery mechanism.To read British Sign Language, userscontinually watch the eyes and faceof the signer whilst following themovement of his/her hands.

Facial detail and motion renditionare therefore very important.Any method of image coding or ofsigning representation must preservethese details sufficiently to allowunequivocal understanding of themessage to be conveyed withoutviewer fatigue.

Coding real camera images hasthe benefit that the same methodscan be used for authoring open andclosed signing signals. Presentlyavailable coding methods (MPEG-2),directly compatible with thetechnology of existing digitaltelevision receivers, may require asignificant bit-rate (between 0.5 and1 Mbit/s) to sustain an acceptablesigning image without undueconstraints on production methodsor signing image size. This is a veryhigh bit-rate for such an ancillaryservice on terrestrial television. Ourcomputer simulations show that,using new coding techniques (such asMPEG-4 video tools), quality signingimages with full-screen resolutionshould be attainable for 350 kbits/s orless. Such tools might allow a signingstream to be decoded in software ina suitably equipped decoder.

Animation techniques usingso-called ‘avatars’ offer the promiseof really low delivery bit-rate (below100 kbits/s) since they delivermotion primitives to the receiverwhere software builds and rendersthe avatar. At present the challenges

to using avatars include motioncapture of the signer (and inter aliacompatibility with open signing).Further development work is beingcarried out by the EuropeanVISICAST project and elsewhere toproduce an avatar system which canbe implemented in a crediblereceiver platform and deliverreadable signing acceptable to thewider signing community. Whilst theymay have other broadcastapplications, avatars are particularlyattractive for closed signing since thelow bit-rate should guaranteecomplete freedom to scheduleprogrammes with signingsimultaneously across the multiplexand thereby offer greater programmechoice to the deaf viewer.We areworking with VISICAST partners toensure that broad cast applications ofavatars (including signing) can beimplemented in a bit-rate frugalform which satisfies the knownsystem requirements and deliversthe appropriate service to theBBC’s audience.

Both MPEG-4 video codingand avatars will require specificprocessing capability in the decoderand the timescale for suitableconsumer equipment will becrucial to the delivery of signing insignificant volume during peak-timeviewing with relative freedom ofscheduling. Finding additionalbroadcast applications for this type

plasma displays

home platforms

licensing



Cathode ray tubes will continue formany years to be the most commonway of displaying television pictures.However plasma display panels arebecoming popular, especially for largedisplays. There are other technologiesbeing developed in researchlaboratories, but they will takemany years to mature, and soplasma technology is likely to have asignificant period during which it canmake a useful and profitablecontribution to both the televisionand the computer industries.

The technology will haveconsequences for broadcasters, andthe BBC needs to understand and beprepared for the impact that thistechnology will make.

The better quality pictures mayreveal some of the productionprocesses which are not visible on aconventional display tube. They mayalso show up some less obviousfeatures, such as in watermarkingwhere the display can cause apreviously invisible watermark tobecome visible.

We have been working with themarket leaders to determine just howgood this form of display can be,offering advice and suggestions forimprovements, and advising the BBCabout the consequences. In future, it isprobable that plasma displays will haveto be part of our monitoring process.

Plasma display panels are now making an increasing impact at the topend of the market. Originally they were of interest just for professionalapplications, but increasing numbers are being sold in the domesticmarket too. This will have an impact on our production decisions.Where is the industry going?

PLASMAS AND DVDThis year, we have seen an increasingnumber of DVD players feeding plasmadisplays directly. The quality of thepictures from DVD can be very good,and the pictures are often matched byfull surround sound, providing a majorimprovement in the viewing experiencewhich many people enjoy.

If this trend continues, plasma panelswill make up a significant proportion ofinstalled displays at home. Then perhapswe will have to allocate more capacityin the digital multiplex to premiumprogrammes, to match the quality ofthe competing products which arebeing delivered by DVD.

STANDARDSPlasma displays are manufactured tomeet a range of different television andcomputer standards. There are differentnumbers of effective lines of resolution,horizontal definition, refresh rates, andcolourimetry. Some of the mostcommon devices operate on computerstandards and so there is often astandards converter built into thedisplay. The screens themselvescomprise a large number of smallelements which are digitally driven.However the interfaces to the displaywere, in many of the older displays,often analogue rather than digital. Boththe standards conversion process andthe analogue to digital converter werepotential sources of distortion.

STANDARD DEFINITIONDISPLAYSRecently, our development of a directdigital interface for plasmas displays hasmade a tremendous impact on thegrowing market. The pictures from the42" Direct Digital Plasma, marketedunder licence by Electrograph Delphi,are without doubt the best that havebeen portrayed by a 480-line standarddefinition panel and have become anindustry reference point.

This has been achieved by botheliminating unnecessary conversionsfrom digital to analogue signals andback again, and by applying ourproprietary (and patented) knowledgeon format conversions.

HIGH DEFINITIONDISPLAYSOur relationships with themanufacturers of plasma displays havehelped us gain early access to hardwarefor high definition displays. We nowhave active co-operation on the supplyof technical information to go withHDTV panels recently acquired fromboth Pioneer and Hitachi and havedeveloped a serial digital interface forthese high-resolution displays. The newinterface design makes no compromiseson picture quality, and sets the standardfor the mass manufacturers to follow.The high definition digital interfaceachieves an impressive quality, farbetter than that achieved by themanufacturers’ own analogueinterfaces. We already have othermanufacturers interested in licensingthe new interface design for both



If the benefits of this technology are to beaccessible equally to all our viewers then weneed standards both for the broadcast signal,and for the functionality in the receivers.DVB, the group responsible for thestandardisation of the European digitaltelevision system, published their specificationfor the Multimedia Home Platform inJuly 2000. This may become the standard thatsupersedes the many different andincompatible interactive receiver platformscurrently in use. The TV-Anytime Forum isdeveloping standards for services that usestorage in the receiver. The myTVcollaborative project provides an importantforum for discussion and development ofstandards proposals and has a practical goal:to demonstrate TV-Anytime services runningon a Multimedia Home Platform.

Products exploiting enhanced processingpower and hard-disk storage are appearingon the market. We are evaluating theseproducts to make sure that BBC programmesare prominently available to people who usethe products.

Many broadcasters have launched or areplanning digital television services using theDVB system but there has not been aconvergence within the industry on acommon format for interactive applicationssuch as electronic programme guides andinformation services. On the contrary, thelaunch of digital television services across theworld has featured the deployment of avariety of non-interoperable and oftenproprietary platforms, each of which is unableto provide access to all the services availableto consumers. This situation threatens toprevent the evolution of a thriving, open


Computer technology is now being used in television reception equipment, bothset-top boxes and integrated digital televisions. It is already allowing interactiveapplications such as electronic programme guides and short-term storage of manyhours of television for time-shifting. The power of digital processing chips and thecapacity of hard-disk storage are both increasing rapidly while their price is fallingdramatically. Together these developments are already changing the way televisionprogrammes are selected for viewing and the way they are viewed; soon they maychange the way they are scheduled and even the way they are delivered.


market for digital receivers andservices. It is also likely to deterinvestment in content for interactivetelevision services since worldwidesales and distribution are impossiblewithout the expensive re-working ofthe material.

DVB MULTIMEDIA HOMEPLATFORMThe primary goal of the MultimediaHome Platform is to enable the birthof horizontal markets for digitaltelevision and multimedia services,where there is open competitionbetween content providers, networkoperators or platform manufacturersat each level in the delivery chain.A further goal is to exploit thepotential for convergence betweenbroadcasting, the Internet andconsumer electronics.

The Multimedia Home Platformuses the Java programming language, alanguage widely used on the Internet.It has developed a new version calledDVB-J that provides extensions tosupport broadcast- and TV-specificrequirements. The use of Java providescontent developers with a high degreeof control and flexibility for theirapplications. For example, we can nowtailor the behaviour of applications tosuit user preferences. It also allowsapplications to deal with many

protocols and data formats that arenot specifically supported by the basicplatform, providing an element offuture-proofing.

We are developing enhancementswhich support the recording ofprogrammes and interactiveapplications on mass storage devicesand which permit the transfer ofcontent and services between differentreceivers distributed around the home.

If the Multimedia Home Platform issuccessful and becomes widelyadopted it may eventually provide asolution to the problems created bythe current diversity of platforms.However, UK broadcasters, includingthe BBC, are already providinginteractive services using otherplatforms. A significant challenge forbroadcasters wishing to support theMultimedia Home Platform istherefore the migration from theirexisting platforms and applications.DVB has provided some help byallowing the new platform to includeoptional plug-in decoders to providesupport for legacy application formats.However, the Multimedia HomePlatform first needs to succeed in newmarkets for digital television wherethere are no legacy systems. It maythen look increasingly attractive as afuture upgrade path for broadcastersin the UK.

THE TV-ANYTIME FORUMThe TV-Anytime Forum aims todevelop open specifications which willallow consumer electronicsmanufacturers, content creators,broadcasters and service providers toexploit high volume digital storage inconsumer platforms. The TV-AnytimeForum has over 140 members.

We have contributed to theTV-Anytime specification through themyTV project. The specifications ofContent Referencing and Metadata forProgramme Description in particularhave seen a substantial input throughthis route.

Programme Description Metadata isthe data to be used as the basis for theselection of the programme for homerecording and viewing. It can be used bythe viewer or by an agent (a piece ofintelligent software) to attract theviewer to the programme. ContentReferencing is the means of discoveringwhere and when the selectedprogramme is available. This of coursemay be from a number of alternativesources and can be from a traditionaltelevision schedule or an Internet basedprogramme server. In either case, thespecifications being developed by theTV-Anytime Forum will allow theautomatic discovery of the alternativeprogramme locations and subsequentacquisition of the programme by the

personal video recorder Thesetechnologies will be the basis of anintelligent recorder that could act onbehalf of the viewer in the speculativeand selective acquisition of appropriatecontent from the diverse multitude ofsources in the digital age.

In addition to the selection andacquisition technologies outlined above,the TV-Anytime Forum is active in thearea of rights management andprotection and recognises the businessrequirements underpinning anysuccessful uptake of the digital deliveryand storage systems built around thenext generation of personal videorecorders. The TV-Anytime Forum hastherefore established a comprehensivelist of business model scenarios asbenchmarks to identify the requiredfunctionality and constraints necessarywithin its technical specifications.

The TV-Anytime Forum isconcerned with the creation of avibrant and attractive horizontalmarketplace enabling the consumer ina multi channel digital world. As suchit has been embraced by some of theleading players currently supplyingproprietary or vertical solutions asthey look forward to increasing theirown business plans within thewider industry.

myTVThe goal of myTV is to marryTV-Anytime standards, local hard diskstorage, DVB transmissions and set-topboxes containing a Multimedia HomePlatform. Its wider goal is tounderstand how the introduction ofhome storage will affect a viewer'srelationship with broadcast content,and how to provide worthwhileservices that the viewer wants.

The project is an extension of ideasdeveloped earlier in the SMASH andSTORit projects, and was set up

• To develop personalisedservices for digital television.

• To develop new servicesexploiting local storage, such asnavigational aids, and try outnew forms of content such asnon-linear news or magazineprogrammes.

• To follow emerging technicalstandards in this area andcontribute to their development.

• To demonstrate theinteroperability of openstandards by producing twocompatible set-top boxes withlocal storage that can run thesame applications developed inthe project, and use the sameprogramme description data,although perhaps in differentways and definitely withdifferent user interfaces.



Although myTV hopes to use the newMultimedia Home Platform, this doesnot yet include provision for hard diskstorage. myTV is developing theconcepts to allow storage to workwith the Multimedia Home Platformand is also developing andimplementing the interfaces necessaryfor many TV-Anytime features. Byimplementing TV-Anytime ideas on aconcrete platform myTV can test boththe platform and the ideas, andprovide feedback on both.

Some of the benefits of theproject are:

• Trailer selection – the abilityto simply click to select aprogramme or series forrecording whilst watchinga trailer (promotion) forthat programme.

• Downloadable navigator – thenew platform allows us todownload our own applications.We are developing our ownnavigator which can replace the

resident navigator in the box.Thus we can provide enhancedprogramme information andour own user interface to bothon-air programmes and what isstored on the box. Agentsacting on behalf of the userwill be an important part ofthis work.

• New forms of content – harddisk storage enables new formsof content that are not limitedby linear viewing as the viewercan move to any part of thedisk instantly. Ideas such assegmented magazineprogrammes and interactivedramas become possible andwe are exploring the viability ofthese ideas.

As TV-Anytime is intended to improveour viewers’ experiences it isimportant to bear in mind theirreactions to new services. We haveadopted a user-centred designapproach in the project, developing an

understanding of the needs andrequirements of our viewers and usingthis information as the basis ofassessing the success of the applicationsand services. This process will help usidentify which programme data isnecessary for both users and agentsand to develop an understanding ofwhich programmes viewers want ormight like.

By developing real boxes and realapplications and broadcasting them,myTV will test the ideas of TV-Anytime.This means the project can givepractical feedback on how well thestandards work, and we will be able toadvise the BBC how best to apply thesestandards to ensure viewers find ourprogrammes and enjoy the newservices made possible.

PERSONAL VIDEORECORDERS The personal video recorder is a set-top box which incorporates a hard diskfor short-term storage of TVprogrammes for time-shifting , fulfillingthe same functions as an analoguevideo recorder, but offering many newfacilities too. The hard disk can recordand replay at the same time, giving theviewer the opportunity to pause aprogramme whilst it is being broadcast,or even to go back and repeat a part of

the transmission, without having tomiss any of the action.

Devices manufactured by TiVo andReplay TV have been available in theUSA for over a year. TiVo has recentlylaunched in the UK.

We have worked with TiVo to offertechnical advice on their UK launch.The BBC is now present on TiVo’sChannel Highlights feature which offersthe broadcaster the opportunity topromote selected programmes to theTiVo viewer, who may choose to recordthem at the touch of a button. Thecontent for Channel Highlights isprepared by the Personal TV group inBBC Television/New Media; we haveworked with them to offer technicaland hardware advice to TiVo and tosupport field trials. An extension to thiswork now under discussion willdevelop methods and standards fortrailer selection, enabling a viewer toselect a programme or series to recordby clicking a button during thebroadcast of a trailer.

All personal video recordersultimately rely on the accuracy ofmetadata describing the programmes,which may be broadcast with the TVsignal or – as is the case with TiVo –downloaded during an automatic dailyphone call. For BBC programmes to beaccessible it will be important thatdescriptive data is captured as

programmes are made and is availablefor editing to support navigationservices on personal video recorders.This service could be supplied directlyby the BBC or via third parties.

We have also made contact withAxcent Media, who have developed apersonal video recorder that is now onsale in Germany.

THE FUTURE OFINTERACTIVITYTechnology is changing its nature tobecome ubiquitous, domestic, inter-connected and often mobile. As itdevelops more users will be interactingwith more technology than ever before.No longer will high technology be thepreserve of the specialist.

As technology becomes moreprevalent, the importance of design willbecome paramount. Users will requiresimple and usable methods ofinteraction. This is particularly so in thedomain of television, and the personalvideo recorder and the futurecapabilities offered by homenetworking. Already technology ischanging viewing behaviour

This is no Utopian vision. With thegreater functionality will come greaterproblems for the traditionally passivetelevision viewer. No longer will theysimply view. They will use. Users will beable to use a variety of methods to



choose programmes. Electronicprogramme guides, trailers,broadcaster recommendations, andinput from web sites and other deviceswill all compete to inform consumers.Software agents will automaticallydevelop viewing profiles and act uponthis information to speculatively findnew content of interest to a viewer.However, to access these services willrequire the design of a new generationof user interfaces that can suit thepopulation at large. They must besophisticated enough to satisfy theexpert, yet simple enough for the oldand young. In addition they must allowdisabled and other users full accessto the services.

We are investigating ways toharness these technical developmentsto produce new forms of content.Enhanced applications alreadysupplement traditional linearprogrammes. With hard-disk systems itwill be possible to exploit the storagecapabilities to offer a new generationof interactive content. The myTVproject is already exploring thepossibilities for segmented

programmes, allowing users to watchparts of a programme in any orderthey wish. This principle can beextended much further.

Non-linear programmes, such as aninteractive drama, create a host ofproblems for both producers andusers. The traditional means ofplanning, development and productionbecome difficult as non-linear dramasare characterised by users makingchoices. Story boards becomeimpossible to plot as there aremultiple narrative paths that can betaken, and thus many different possibleversions of the story. We are in theprocess of developing tools to aid theproduction of non-linear programmesand also researching the usability andhuman factors issues associated withnavigating around these non-linear programmes

Only by detailed understanding ofthe context of use for this newtechnology, the domestic environment,can the true potential of thetechnology be realised.


Licence fee evasion in Britain continues to falldue to improvements in detection methods,combined with media publicity to ensure thatevaders recognise the risk of being caught.

Evaders are tracked down with the helpof handheld detectors and a fleet of detectorvans, using a national database oflicence holders.

At BBC R&D we are working on aproject to develop new detection methods tosupplement those already in use. We haveinvestigated a wide range of methods andchosen for development those which arequickest and most accurate, with a view tominimising the time spent by a detector vanat each target site. We have added asatellite-based navigation system which helpsminimise the time spent travellingbetween sites.

The detection equipment in the van iscontrolled by a PC, which presents a veryuser-friendly interface to the operator.The detection results are recordedautomatically. The van will be in frequentcontact with TV Licensing’s database to checkwhether the viewer has a current licence.

It is possible that detection activities maybe circumscribed by the new EuropeanHuman Rights Act, so (for example) we maynot be permitted to know the channel beingviewed or the make of set being used. In thiscase, the detection equipment would informthe operator of what it had determined; thisdata (although it would not be revealed orrecorded) would still be a powerfulconfirmation of detection.

All of the equipment is containedwithin the van without exterior aerials.This offers the choice of covert operation,or alternately of high-profile operationsimply by emblazoning the van with the‘TV Licensing’ logo.

We are working with BBC Consulting andProjects to produce a fleet of vans equippedwith currently proven detection equipment,while the development of some furtherdetection methods nears completion, andthat of others is still in progress.

We are also investigating the furtherpossibilities of handheld detectors. Indeed,our first product was a handheld magneticdetector designed for use where van accessis impracticable; since then we have added ashirt-pocket equivalent for covert operation.

art work byKevin Claydon and Keren Greene, BBC R&D


www.bbc.co.uk

[email protected]

BBC Research & DevelopmentKingswood WarrenTadworthSurreyKT20 6NP

Tel: 01737 839500Fax: 01737 839501

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