Digital CCTV Guide

www.fujifilm.co.uk/cctv

1.1. What digital media should I use?What digital media should I use?

CCCTV systems have evolved in recent yearswith digital technology establishing itself as

an emerging part of future surveillance solutions.With digital technology, the very way in which itstores data allows a wider variety of recordingmedia to be employed, so which one should beused? The real deciding factor is not so muchwhat you want to do with the recordings but howmuch footage you need to store and what youintend to do with any footage which may need tobe transferred to another party.

Based predominantly around hard drive integralstorage, digital solutions will usually store theirdata in a buffer. This data, including video, audioand other information, will then either be over-written when the hard disk is filled, or removed toanother storage media and securely archived.

Digital archiving is constantly increasing in capacity, predominantly due to archiving mediabeing used and supported by the IT industry. The most basic digital archiving media is theCompact Disc. The CD has become well knownand widely used over the years, and is useful forstoring data capacities of up to 700MB. CDs comein two variants, the CD-R which is a WORM typemedia, (Write Once, Read Many) and the CD-RWwhich can be rewritten. Wherecapacities in excess of 700MB arecommon, users and installers arelikely to make use of the constantlydeveloping DVD capacities.

DVD capacities currently dwarf those achievablewith CDs, and future developments will see thesefigures rise dramatically. Indeed, the next proposed generation of DVDs will far exceed thecurrent capacities! There are other digital storageformats including various digital tapes, which offerfault-free operation and highspeed data transfers, and datastorage technology such as 4mm,DLT, and LTO Ultrium data tapes,offering higher storage capacitiesand faster data transfer speeds.

2.2. How much footage can IHow much footage can I store on thestore on themedia Imedia I use?use?

WW hilst it is fairly straightforward how muchfootage can be stored on analogue media,

digital media is more complex. Digital image sizesare governed by how much data they are made upof. One image captured off a specific cameracould vary in size when compared to anotheraccording to a number of criteria. There are nohard and fast rules when it comes to file sizes and here we will explain why size, whilst being important, is unlikely to be constant!

Digital image file sizes can vary according to the information contained. This differs from analoguewhere a VHS cassette will store 25 frames persecond for the entire 180 minutes it is recording. It matters not if the video is of a busy street, anempty car park or a white wall.

Fujifilm’s Digital CCTV and Security GuideFujifilm’s Digital CCTV and Security Guide

1. What digital media should I use?

2. How much footage can I store on the media I use?

3. How do I calculate how much data can fit onto my media?

4. How do I deal with using digital images as evidence?

5. Do I need to meet the Data Protection Act requirements?

6. How do I ensure I am compliant with the Data Protection Act?

7. The Fujifilm Digital Evidence Kit- The solution in the bag.

DigitalCCTVGuide1907HCFINAL.qxp 20/07/2004 10:33 Page 1


The image quality can be pin-sharp or so low thatit is unusable, but you still will record 25 framesper second for 180 minutes in real-time mode.

Digital images however are databased in that eachpixel in the image contains colour information. Itmight initially seem that as all images captured bya system are the same resolution, they will be thesame size, but they are not. This is becauseimage compression algorithms will convert thedata in order to eliminate as much redundant information as possible. Where there are largeareas of continual tone, some image compression algorithms will calculate the number and positionsof the pixels and store that data rather than fromeach individual pixel. Others will take an averagevalue from a group of pixels, and will rebuild theimage using grouped averages. Subsequently, animage of an empty car park with a white wall onone side might take up little space, because imagecompression can use a small amount of data tocreate certain areas of the image. However whenthe same car park is filled with cars of differentshapes and colours, and with a certain amount ofactivity, the size of each image, in relation to thedata it contains will rise significantly, and lessfootage can be archived in any given memory.

Environmental factors can also affect image filesizes. For example, a frame of video showing anexternal scene on a clear sunny day will be smaller than the same scene on a rainy day. This is simply because the rain will be constantlychanging, and will break up any continuous areasof tone, with the result that compression will beless effective.

The size of files is affected by the quality of thevideo (lower resolutions use bigger pixels, equating to less data), the image compressionalgorithm and ratio used, the image contents,noise in the picture and environmental conditions.

So how much data can you fit on digital mediasuch as a CD? There is no definitive answer. Despite some manufacturers quoting how manyhours will fit on a drive, there are too many variables to provide an accurate answer.

We understand this is not very useful for usersand installers alike trying to decide which media touse. By understanding image file sizes from somemarket-leading DVR recorders and consideringhow much footage specific media are able to contain, we hope to give you a greater understanding.

Issues affecting file sizes and how much footage you can store

3. 3. How do I calculate how much How do I calculate how much data can fit on my media?data can fit on my media?

BB efore we look at image file sizes, we need tounderstand how files are measured. This

information is necessary to carry out any accuratecalculations. Digital files are made up of bytes ofinformation. Where bytes are being specified theabbreviation is “B”. Where you see a “b” beingused it is referring to “bits”, often used whenmeasuring data transfer speeds.

A byte is one piece of data, and inevitably will betoo small to be of any interest with relation to calculations of video sizes. Most image file sizeswill be quoted in kilobytes (KB) which is equal to1000 bytes. A megabyte (MB) is 1000 kilobytes, or1,000,000 bytes, and a gigabyte (GB) is 1000 MB.It will not be long before DVRs appear offering terabytes (TB) of storage, a TB being 1000 GB.The common factor here is that the multiple is1000*

Busy scenes take up more space

Colourful scenes take up more space

A lot of movement such as rain or other activity takes up more space

Redundant or repeated data take up less space as they can be compressed

A low resolution and a low compression ratio can make an image much smaller

*The above numbers are shown in decimal (Base 10). In Binary (Base2), one kilobyte (1KB) is equal to 1,024 bytes and that number shouldalso be used when performing binary calculations.



Currently most archiving of footage for general-purpose CCTV solutions will be CD-Rs. There aretwo main reasons for this. Firstly the drives andmedia costs are low. Secondly, there is a requirement for evidential video to be written toWORM (Write Once, Read Many) media.Therefore it is worth considering how much videocan be archived onto CD.

Remember that evidential footage will need to be accompanied by replay software, plus other documentation, so this will use up some capacity!

Calculating how much footage a CD-R (or anydigital media) can contain is a simple task. You need to know:

Fujifilm CD-Rs have a current capacity of 700MB. To make things simpler, convert this figure to KB,as the image file sizes are quoted as such.Therefore 700MB is equivalent to 700,000 KB. To calculate this figure, simply multiply the size inMB by 1000. To calculate from GB, multiply thesize in GB by 1000 to achieve MB then again by1000 to achieve the figure in kilobytes (KB).

The following example shows how we calculated a 700MB CD-R would contain just over 1 hour 4minutes of footage. In this example, with imagequality equivalent to S-VHS performance, averageimage file sizes are 18KB. For the purposes of thisexplanation it can be assumed that the recordingrate is 10 pictures per second (PPS).

Divide the capacity in KB by the average imagesize, and this will give the number of images thatcan be supported. In this case a CD will hold38,888 pictures. If this figure is divided by 10 (therecord rate of 10pps), it gives the number of seconds that can be stored. Simply divide by 60again to get the number of minutes that can be stored.

However taking an average of 40KB as the filesize, perhaps a recording in the highest resolutionmode, and recording in real-time (25 pictures persecond) a CD would contain only 11.6 minutes.

The following calculation can be used to ascertain how much footage can be stored on any media:

It is vital that installers and users understand thepotential of archiving media when specifying asolution. It is also useful to note there is an element of specmanship, with some providersquoting figures for the lowest possible resolutionsat very slow frame rates. However most users andinstallers prefer standard or high resolution imagesand should calculate accordingly.

44. . I have chosen the media I wish to use,I have chosen the media I wish to use,now how do I deal with using digitalnow how do I deal with using digitalimages as evidence?images as evidence?

WW hen it comes to the criteria of using videoimages as evidence, the requirements can

appear to be something of a minefield. Add theuse of digital images to the equation, and questionmarks start to appear with regularity. Quite often,depending upon whom you are talking to, you willhear a different version of the so-called “digitaldilemma” when it comes to using CCTV footage for evidential purposes.

The capacity of the mediaThe average image file size of the recorded footageThe frame rate at which it is recorded.

JPEG COMPRESSION, 10pps, STANDARD RESOLUTION700MB x 1000 = 700,000KB ÷ 18KB (file size) = 38,888(images) ÷ 10 (pps) ÷ 60 (seconds) =64.8 minutes.

JPEG COMPRESSION, 25pps, HIGH RESOLUTION700MB x 1000 = 700,000KB ÷ 40KB (file size) =175,00 (images) ÷ 25 (pps) ÷ 60 (seconds) =11.6 minutes

Media Capacity in MB x 1000 (or Media Capacity inGB x 1000 x 1000) ÷ File Size in KB = image capacity ÷ PPS rate ÷ 60 (to calculate minutes ÷ 60again to calculate hours)



However the police and courts are aware of thepotential offered by digital surveillance solutions,and do not want to curtail the use of a credibleand efficient tool in the fight against crime.

An audit trial for digital CCTV is very much thesame as one for an analogue system. However,with digital systems the audit trail must also keeprecords of which copy is designated as a MasterCopy and which is a Working Copy.

Here we outline the steps to ensuring your evidence is admissible:

STEP 1

Obtain the relevant authority to capture images CCTV systems must obtain, where necessary, therelevant authority to capture images.

They should be regularly maintained and an audittrail commenced at the earliest opportunity.

STEP 2:

Create a Master CopyBecause digital images can be replicated without degradation, and due to the fact that the firststorage medium is usually an integral part of theDVR, a Master Copy needs to be created.

It needs to be stored securely and kept in accordance with evidential procedures. It shouldbe taken directly from the original recording medium and stored onto a removable medium.

This removable medium must be a WORM typedevice. WORM (Write Once, Read Many) devicessuch as CD-R, DVD-R and DVD+R media add alevel of credibility to digital images as once theMaster Copy is written the data cannot be affectedand changes cannot be made.

STEP 3

Create a Working CopyA Working Copy, again on WORM media, can be produced simultaneously with the Master Copy or subsequent to the Master Copy from the originalfootage, or can be produced directly from theMaster Copy.

STEP 4

Make sure your Master and Workingcopies are clearly labelled and include;

The relevant image sequences

A text file stating any hardware or software requirements for replay

Metadata such as time and date information bound to the footage

License-free software to view and make copies of the footage, including editable sequences

Instructions on how to copy the footage toVHS cassette plus details of any changes that may occur if the cassette is then played alongside the digital footage.

You may also include (though this is not a requirement) a copy of the audit trail, a testsequence to ensure replay is correct, and authentication or verification software*. *The DVR manufacturer should supply this.

5. 5. Now I know how to deal with digital Now I know how to deal with digital evidence, do I also need to ensureevidence, do I also need to ensure that that I comply with the Data Protection Act?I comply with the Data Protection Act?

TT he Data Protection Act came into force on 1March 2000. While this legislation has in no

way prevented the use of CCTV in a security context, it has placed certain restrictions on its useand the way in which the evidence gathered bythis method is handled. Not all CCTV systems arecovered by the Data Protection Act. Whether yoursystem is covered by the Data Protection Actdepends upon how the system is used.

The Police and Scientific Development Branch have published guidelines for the use of digitalimages as evidence. The guidelines do not specify which compression algorithm or archiving media should be used instead taking the view that final quality and a credible audit trail are more important.



By way of an example, small retailers would notbe covered by the Act if their store contained acouple of cameras which could not be remotelycontrolled to allow individuals to be tracked aroundthe premises, and if the only data stored were theimages picked up by the cameras. Furthermore,the footage should only be used for evidential purposes, to be passed to the police if investigating an incident in the shop.

If additional data such as Point of Sale informationincluding operator details, method of payment etc.were included, the Act may well apply.

If a retailer uses the system to view members ofstaff to appraise their level of work, the situationchanges. In such a case the individual workerbecomes the focus of the information gathering,and the video footage gives the management significant information about that individual. Insuch a case the system will be covered by the Act.

There are three main considerations whenassessing whether a system will need to becompliant with the Data Protection Act.

If the answer to all three of these points is“NO” then the system may not fall within thescope of the Data Protection Act.

When considering the second point, you must becareful to fully understand what is meant by the“users own business purposes”. For example, if aretailer uses a system to watch staff behaviour toassess whether they are doing a good job, it is fortheir own business purposes.

However, if the cameras are used to generallyoffer security in the environment and subsequentlycatch a crime in progress, this is not for the user’sown business purposes- although stopping theft isobviously in their own interest!

When CCTV systems are more complex, thechances of a system being covered by the Actincrease, as such systems will usually have theability to focus on individuals or examine, in detail,scenes, which identify individuals by behaviouralactivity. However, where general surveillance iscaptured by such systems, that footage will not becovered by the Act.

Should the system be covered by the Act, system owners are required to formally notify the Office ofthe Information Commissioner that they are processing data.

6. 6. What are the Data Protection Act rules?What are the Data Protection Act rules?

TT he processing of that data must comply with the eight fundamental and enforceable principles of good practice, which state that data must be:

Are the cameras operated remotely to pan, tilt or zoom in and out to track or look at specific individuals?

Are the CCTV images ever used to observe someone’s behaviour for the user’s ownbusiness purposes, such as assessing the performance of staff members?

Are CCTV images ever passed to a third party other than a law enforcement agency such as the police?

If a system is not covered by the Data ProtectionAct, it is sill vital that correct evidential procedures are followed to ensure capturedfootage is admissible.

Fairly and lawfully processed

Processed for limited purposes

Adequate, relevant and not excessive

Accurate

Not kept longer than necessary

Processed in accordance with the data subject’s rights

Secure and confidential

Not transferred to countries without adequate protection.



So how do these principles relate to the way inwhich CCTV systems are used day-to-day and what should operators do..

Well, the first step is that those operating a CCTVsystem that falls under the Act must provide aclearly-stated document of the objectives for usingit and a statement of the responsibilities of thoseinvolved in operating and managing the system.

Those who are being filmed must also be madeaware that they are entering an area where CCTVis active. This warning is usually achieved by signage, which should also include details of thepurpose of the scheme, the operators and theircontact details. If correct signage is not in place,then the scheme will be considered covert. Covertrecording may only take place if: informing peoplethat recording is taking place will compromise yourobjectives; you have reasonable cause to suspectspecific criminal activity and the covert processingis only carried out for a limited and reasonableperiod of time.

Under the Data Protection Act, individuals whohave been recorded can request a copy of anyrecording that has been made of them. Accessmay only be denied where such an action wouldcompromise the detection or prevention of crime,or where it may impede the apprehension or prosecution of offenders. If the operator cannotcomply with such a request without disclosingidentifiable images of third parties, they mustdetermine whether the images of these parties are held under a duty of confidence, in which case the images should be edited to disguisethese identities.

Privacy is also a major issue to consider. Cameras should only be set to view images thatwere intended for the objectives of the scheme. If this is not possible without viewing domestic or other areas, which would reasonably be considered private, the owners of these areasmust be consulted. If there are any doubts in thisrespect, it would be prudent to obscure the viewsuch cameras have of private areas.

Confidentiality is also a major issue as far as theDPA is concerned, indeed it is one of the mostimportant, having far-reaching effects on areassuch as traceability, security and accountability. All images recorded are considered confidentialand, to ensure this confidentiality, the Act requiresthat it should be possible to trace any recordedimage to a specific date, time, recording device,recording medium and individual. Copies of evidential images are only admissible providedthat there is a clear audit trail to the original.

On removing the medium for use in legal proceedings, the operator should ensure that they have documented:

The DPA requires that information not be kept anylonger than necessary. When using digital basedsystems, the DVR can often be set to record overimages after a certain period of time.

The fact that the Act insists on the confidentialityof recorded images means that the recordingequipment and the images themselves must bekept secure. One of the best ways of ensuring this is by using secure cabinets. Should theimages on the recording medium be retained forevidential purposes, they should be kept in a placein which access is controlled. As far as possible, itshould not be possible to interfere with the recording equipment and access should berestricted to maintenance staff and operators.

The date on which the images were removed from the general system for use in legal proceedings

The reason why they were removed from the system

Any crime incident number to which the images may be relevant

The location of the images e.g. If they were handed to a police officer, the name and station of that police officer;

The signature of the collecting police officer



Also crucial to the use of data as evidence is thequality of the CCTV images themselves. To ensure that this is the case, initial checks should take place to ensure the equipment performs properly and the media produces goodquality images.

Cameras should be properly maintained and serviced. Also, if the system records features suchas date, time or location, this information needs tobe accurate.

7. 7. The Fujifilm Digital Evidence Kit The Fujifilm Digital Evidence Kit The solution in the bagThe solution in the bag

TT here is a lot to consider with regards to usingdigital evidence and complying with the Data

Protection Act but help is at hand, via Fujifilm’sDigital Evidence Kit.

The Digital Evidence Kit was designed to bring total peace of mind to users of CCTV and Security recording devices by helping them withtheir responsibilities in correctly auditing all recordings, and presenting digital material in a formthat is admissible as evidence in a court of law.

The Digital Evidence Kit contains everything youneed to present digital evidence to the authorities.The number of CD Master Copies and WorkingCopies or DVD format options included dependson requirements but the Standard Kit contains:

The Fujifilm Digital Evidence Kit comes in a two-disc CD set allowing for creation of a MasterCopy and a Working Copy; and a three-disc Kit that allows the creation of two Working Copiesalongside an original Master Copy. A further set isavailable for those requiring DVD-R or DVD+Rmedia.

Fujifilm media has been designed for a long-archival life, ensuring that your evidence standsthe test of time.

The 25 standard jewel cases and 25 slimline jewelcases have been developed so that the user candecide which type of cases to standardise upon,passing the other - containing a Working Copy - to the relevant authorities. Where a three-spindlekit is used, the cases are supplemented with 25 plastic sleeves. The benefit of slimline cases isthat the space required for CD storage is dramatically reduced.

Probably the two most important additions are theDigital Evidence Logbook, and the CPS approvedEvidence Bags. Fujifilm’s CPS approved EvidenceBags feature an easy to use closure seal that provides tamper-evident security against all knownmethods of attack. Once sealed, any attempts toopen the bag will result in the word STOP appearing in white on the orange background.Whilst this clearly identifies tamper attempts, independent testing showed users could not startopening the sealed bag without making it obviousthat an attempt had been made.

Once evidence is placed in the bag, anyattempts to remove it are going to be detected!

50 Fujifilm CD-Rs (two spindles)

25 standard jewel cases

25 slimline jewel cases

Logbook to keep audit trails in check with uniquely numbered sheets

CPS-approved Tamper Evident evidence bags

Procedural Guide

‘CD friendly’ marker pen (for labelling)



Each bag is marked with a unique number, ensuring traceability and enabling accurate pinpointing of breaches in security.

Each evidence bag includes a tear-off receipt atthe bottom, which has the unique number of the bag printed onto it and sufficient space to allow forthe recipient’s details to be recorded. The bag isover-printed with a log of all activity from when aCD-R is sealed in until such a time as a copy iscalled for evidence.

The Evidence Bags allow CDs to be tracked andaudited throughout the entire storage and handlingprocess ensuring the admissibility of the footage incourt. Each kit contains 25 Evidence Bags providing an audit trail (and proof no tamperinghas occurred) for each Master Copy.

As mentioned earlier, the Data Protection Actrequires that it be possible to trace any recordedimages to a specific date, time, recording device,recording medium and operator. The DigitalEvidence Logbook was developed to enable usersto comply with this requirement by creating anaudit trail, with its pages designed to fit inside astandard CD case, which are easily detachable for when copies of footage are made.

A copy of each Logbook sheet can be inserted inthe case. One with the Master Copy, one with theWorking Copy and one retained in the book formanagement purposes. Each logbook sheet iscolour-coded and designed to ensure that a recordof the CD-Rdetails; audit information and the evidence bag number are all logged. The evidencelog sheets each contain a unique number, whichremoves the need for users to manage their ownnumbering systems.

A permanent marker pen is included so CDs can be marked with a unique number from the evidence logbook. This is important as labels can affect the balance of CDs during writing and reading, adversely affecting performance and reliability.

Following research which highlighted the fact that many users are unaware of how to presentdigital footage as evidence, a leaflet has beenenclosed explaining the basic requirements of how to present digital CCTV footage as evidence along with a handy guide to CCTV.

The complete audit trail in a box, the kit makeslife a whole lot easier for installers and users alikeoffering all the tools necessary to ensure thatevery stage of the evidence gathering process isaccurately performed in the eyes of the Law.


Documents

Digital CCTV Guide