15012013131101 Digital Theatre System

8/11/2019 15012013131101 Digital Theatre System

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SeminarsTopics.com Digital TheatreSystem

CONTENTS

-T./D0)T/-

!!! 1 23334 566T-7 T86 )8'996-76

ST6PS :/.;'.D

-T./D0)-7 S6)0.T0 @'6S"A

streams# Some cinema processors can be configured to directly accept

digital audio, and digital audio can be converted to analog for legacy

cinema processors# The server also has the ability to command Ghouse

controlsG, i#e#, lights and curtains# -o improvements were made upon

this system until the later half of 233#

STEPS FORWARD

/n July H, 233, a digital cinema milestone was crossed with the

digital premiere of Jurasic Park III in 9os 'ngeles# This particular

presentation was compressed with a version of 5P67 2, as developed

for digital cinema applications by 7rass =alley 7roup# )alled5P67I, 7=7Bs compression was based upon the 5P67 2

decompression standard, making this the first public digital cinema

presentation to use an almoststandard decompression scheme# ;ithin

weeks, a true 5P67 2 presentation was held in -ew urtonBs Planet of te Apes, this time using an 'vica digital cinema

server# Together, these presentations marked the beginning of a new

phase for digital cinema by bringing new components to the scene#

' third server company, 6=S, whose product is also based on

5P67, later $umped in with both 7rass =alley and 'vica to create

interoperable servers# ;hile a noble goal, it did not lead to true

interoperability# 7=7 dropped out of the digital cinema game, and

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6=S and 'vica were not able to demonstrate products that were fully

interoperable#

Security got a little boost during this period, though# T and 7=7

developed a link encr!ption method, called )inelink@tmA for the

protection of the @S5PT6 2!2A digital link between server and

pro$ector# ;hile promoted by the server companies, it was not

implemented in either of the 7=7 or 'vica presentation mentioned

above# 9ink encryption is pictured in the block diagram below#

)inelink@tmA link encryption was introduced by Te%as

nstruments in their 5ark = version of the D9P )inema pro$ector#

9ink encryption encrypts the image data as it is sent to the pro$ector,

offering some security to the system# :ull security, however, re&uired

encryption of the content stored on the server, which had yet to be

introduced#

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This phase began with the promise of file interoperability,

but failed to deliver# t did produce link encryption, however, which

was a step towards addressing the security issue#

INTRODUCING SECURITY

>y early 2332, digital cinema installations were numbered in the

E3Bs# They utili(ed several types of servers, including the Fu>it, 'vica,

and 6=S servers already mentioned, as well as the Technicolor Digital

)inema server designed by Fualcomm# These systems represented

three different compression schemes, and four file formats#

/n 5ay th, 2332, another digital cinema milestone was

crossed with the digital release of Star Wars" Episode II# 'lthough

they didnBt financially contribute to the digital presentation of their

movie, 9ucasfilm heavily promoted that it should be seen as such, and

the heyday increased the digital installation count to over 33# The

movie was released in all four digital formats ++ which proved to be a

challenge all of its own#

6pisode broke ground by being the first digital movie

released employing content encryption# -ot all systems were capable

of supporting content security, but those employed by

>oeing1'vica16=S and Technicolor1Fualcomm certainly was# The

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introduction of fully secure presentation systems was a ma$or step

forward#

5any thought this phase would signal a rollout of digital cinema#

>ut numerous issues remained, the least of which were the many

incompatibilities in data packaging, encryption, key manangement,

and compression# 6%hibitors now had enough e%perience to know thatthey had operational issues, too# To add to the problems, not all

cinematographers, studios, and e%hibitors thought the &uality level

was good enough to replace film# 'nd the overriding issue remained4

there wasnBt a sound business model# Studios stood to save

significantly each year by not paying for film distribution, and

e%hibitors stood to pay significantly for the new digital e&uipment#

;hile "rd parties attempted to intermediate as system and service

providers, none were successful# The business partners needed to talk#

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Talking, however, wasnBt a simple task# ' studio collective was

needed to negotiate with e%hibitors# :or this reason, in early 2332,

Digital )inema nitiatives 99) was created# 't first known as -ewco

Digital )inema, D) is a collaboration of the seven ma$or motion

picture studios# 6pisode created a digital cinema bubble, and D)

appeared on the scene $ust as the bubble burst# This led to much unfair

blame placed on D) for the GslowdownG of digital cinema ++ a

slowdown which was inevitable for all of the reasons mentioned

above# Today, in 233", D) is busy sorting out many of the details of

digital cinema, both technical and financial# n the meantime, letBs take

a look at some of the technical issues of digital cinema#

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SYSTEM-LEVEL INTEROPERABILITY

The technology problem imposed by digital cinema is non+trivial#

The goal is to replace a very mature film presentation system, upon

which an entire industry is based, with a not+so+mature digital one#

/bviously, if we want our ticket prices to remain low, we want the

digital system to be not+so+immature upon rollout of the technology#

The technology for pro$ecting digital images onto screens, however,

will not stand still once rollout is begun# Thus, the concept of

GinteroperabilityG is important, as it encapsulates an aspect of system

maturity that can be addressed#

nteroperability can mean different things to different parties# 9etBs

take a look at the practical need for interoperability from an e%hibitorBs

point+of+view#

Digital cinema will not be introduced in the "C,333 cinema

auditoriums that e%ist across the 0S in months, or even in a year# t

will take many years, possibly 3 or more, to build and install a digital

cinema system for every 0S auditorium, and this is not taking into

account the over 33,333 auditoriums around the world# 'n

international rollout of digital cinema could take a very long time#

The long rollout period has significant impact on the concept of

interoperability# :or e%ample, a system installed in


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This could be due to advancements in pro$ection technology, data

storage, networks, and1or the digital link @if anyA between storage and

pro$ector# n addition, we can e%pect there will be clever and

competitive ways of designing and building systems that we have not

yet seen# The progress made by these advances will likely out+pace the

on+going work of standards+making#

/bviously, it is not desirable to impede advances in storage and

pro$ection technology, particularly if they have a beneficial impact on

cost# >ut e&ually so, it is not desirable to obsolete the investment in

digital infrastructure that will be made in the e%hibition booth# To

address this problem, a model for system+level interoperability has

been introduced, originally through work produced by the -ational

'ssociation of Theatre /wners# This model is presented below#

The model reduces the interoperability problem to only three

Presentation System interfaces4 Distribution Package, Theatre

/perations, and )ontent Security# The Distribution Package re&uires a

common file interchange format# Theatre /perations suggests

common 'Ps or protocols for managing the e&uipment in a multiple%

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theatre# Security also re&uires common 'Ps or protocols for the

delivery of security keys to the Presentation System.

f the focus for interoperability is placed on these three areas of

theatre system infrastructure, then the Presentation System is free to

evolve, as it naturally will# This concept can simplify the immediate

work of standards committees, but more importantly, it can allow

differentiation in the design of the presentation system and still gain

the confidence of the system investor# t also sets the stage for

manufacturers of complete digital cinema presentation systems, much

as there are manufacturers of platter and "Cmm pro$ector presentation

systems today# >uilding from this concept of system+level

interoperability, weBll e%plore some of the issues behind each point of

interoperability4 Presentation, Theatre /perations, Security, and

Distribution Package#

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PRESENTATION SYSTEM:

THE BROADCAST SERVER MODEL

There are two models for the secure storage and play out of digital

cinema content4 the >roadcast Server model, and the Data Server

model# ;ithin the realm of the Presentation System, there is no need

find a winning model ++ the market place is very efficient for

determining winners and losers# @;hich leads us back to the

importance of interoperabilit! as described#A

The >roadcast Server model is based on broadcast+style

servers, where image content leaves the server as a decompressed,

real+time stream# The server must decrypt the content sent by the

studio, decompress it, and stream it to the pro$ector# -aturally, link

encryption is needed to make the link between server and pro$ector

secure# :ocusing on the image and audio paths, the block diagram

below depicts the >roadcast Server model#

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The player is the device that accepts digital data and produces a

synchronous stream of video and audio#

The Lpro$ector* also has its own speciali(ation, it is entirely

different from conventional pro$ector#

n the broadcast model of digital cinema, a synchroni(ed image

stream leaves the broadcast+style server and goes to the pro$ector,

while a synchroni(ed audio stream goes to the audio processor# See thefigure given below#

THE DATA SERVER MODEL

The >roadcast Server model for digital cinema systems is

realistic but does not take advantage of 5ooreBs 9aw# ' more efficient

design is possible that utili(es e%isting standards in the data industry#

'gain focusing on only image and audio paths, the Data Server model

is presented in the block diagram below#

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The Data Server model distinguishes itself from the >roadcast

Server model by using the server only for asynchronous data transfer#

n fact, the GserverG is really nothing more than storage# 's with the

>roadcast Server model, the stored content is strongly encrypted#

0nlike the >roadcast Server model, data is only served from the

storage array upon the re&uest of the pro$ector# Thus, the Data Server

model pro$ector GpullsG data from storage, a ma$or distinction from the

>roadcast Server model server, which GpushesG data to the pro$ector#

Since the storage array does not decrypt the strongly encrypted

data, it is not part of the security system, so does not re&uire physical

protection# :urther, the link between server and pro$ector also does not

re&uire protection, since the data traveling across it retains the original

strong encryption provided by the studios# Thus, link encryption is not

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needed# The system becomes simpler, while also inherently more

secure#

5ost importantly, the link between the server and the pro$ector

can now be a standard link from the S'- @Storage 'rea -etworkA

industry# The storage can also be shared among different screen

systems# n the block diagram above, :iber )hannel is shown# :iber)hannel currently supports bandwidths up to 7b1sec, but a standard

is in process that will support 37b1sec# 8owever, 7b1sec can be

sufficient, since the transported data remains both encrypted and

compressed# 2? image data, at 2Efps @frame per secondA, with a very

conservative 3M compression and +bit words per color, re&uires a

bandwidth of 2C3 5b1sec# E? image data, again with a conservative

3M compression and +bit words per color, re&uires a bandwidth of

7b1sec#

The use of shared standards+based S'- networks can be a plus

for those e%hibitors who want the ability to instantly move shows from

screen+to+screen# Since no physical movement of data is re&uired,

multiple screens can be scheduled from a single unit of shared storage,

up to the bandwidth limitations of the S'-# S'-s also offer a degree

of scalability, allowing the storage system to grow as the number of

digital screens grows#

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Shared S'- storage may not be for everyone, though# The cost

of a S'-s network must be weighed against the benefits gained#

8owever, the Data Server model is not limited to a S'-s

implementation, and some vendors are pursuing Data Server designs

that utili(e low+cost storage @but not necessarily shared storageA#

'nd, with the data model of digital system architecture, the server

does not include the player# nstead, the player is located at thereceiver end, typically in the pro$ector as given in the figure below#

The data server will produce a stream but unlike it is synchronous# '

data server in a digital cinema system will not work with an ordinary

video pro$ector# ' pro$ector with an internal or outboard player is

re&uired#

SECURITY

Security is perhaps both the most important and least

understood aspect of digital cinema# )ertainly, the encryption and

decryption of content is not a ma$or challenge# There is general

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agreement that movies will be symmetrically encrypted using a strong,

public encryption algorithm such as '6S @'dvanced 6ncryption

StandardA with very large keys# >ut there are as many ways of getting

that symmetrical key securely to the theatre as there are security

vendors# This is where things get difficult#

The simplest approach for managing keys is for the decryptiondevice inside the theatre to have a secret private key, whose public key

is held by a trusted certificate authority, sort of a Gpublic key bankG#

The content key is encrypted with the decryption deviceBs public key,

which can only be decoded using the private key held securely within

the device#

'nother method employed does not rely on a trusted certificate

authority, and instead destroys the key used to encrypt the symmetrical

movie key immediately upon encryption# The key is later

reconstructed using a proprietary method at the theatre, allowing the

movie key to be decrypted only by authori(ed devices#

;hile not absolutely re&uired, good practice generally re&uires

that a "rd party is employed to manage the keys# Thus, the technology

used by the "rd party key manager defines the security technology

used in the theatre# n a competitive environment where multiple

security vendors co+e%ist, interoperability becomes a concern#

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Solutions for interoperability have been proposed, most notably

within the S5PT6 D)2K Digital )inema )ontent Security ;orking

7roup# 'mong the solutions offered is the introduction of a Security

5anager device within the theatre environment# n one concept, the

Security 5anager employs a proprietary means uni&ue to the security

vendor for receiving and handling keys, while using a link+encryption

method for transmitting keys to the decryption device# /ther concepts

are also being considered#

>oth content owners and e%hibitors have business re&uirements to

impose on security systems# )ontent owners want to know that only

authori(ed devices have successfully retrieved keys, and thus have a

need to track key usage# 6%hibitors, in turn, re&uire the ability to freely

move e&uipment around per maintenance and business re&uirements#

They do not want the movement of a decryption device to prevent the

playing of a movie, and likewise, they do not want the movement of

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the movie to a different screen within their comple% to prevent the

playing of the movie# 0ltimately, if the movie doesnBt play, neither

studio nor e%hibitor makes money# Thus, fle%ibility in the management

of the security system is important to both studio and e%hibitor#

The challenge that lies ahead is to allow the desired fle%ibility

while maintaining the desired level of security# 0ltimately, this is both

a technology issue and a business issue, for which a satisfactory

solution has yet to be agreed upon#

THEATRE OPERATIONS

Theatre operations in the film world are fairly straight+forward# '

show is made up by $oining policy trailers, ads, movie trailers, and the

feature movie together on a single platter# This operation is called

Gmake+upG# The platter, in turn, feeds the "Cmm pro$ector with a

contiguous show# 'utomation cues, such as those needed to control

house lights, move curtains and1or screen masking are physically

tagged to the print and read by the automation system# Thus, once a

show is Gmade+upG, its platter can be physically moved to any

pro$ector in the house for presentation to an audience#

n the digital world, it is necessary to maintain the same level of

functionality as provided by modern+day film systems# /ther features

are also possible, however, which should not be overlooked# These

features can affect how the theatre of the future is operated, right down

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to the systems used for booking content# 6%hibitors have asked for

basic features of their digital theatre operations systems4

Show Scheduling

Show G5ake+0pG

'sset @)ontentA 5anagement

Show 9ogs

6&uipment 5onitoring

Software is already being discussed by at least one vendor thatwill combine the booking of ads, trailers, and movies with the ability

to create system play lists at the time the content is booked# n this

way, the creation of play lists becomes centrali(ed, and can be

downloaded by the e%hibitor to the theatre for operational use#

9ikewise, system management software can log the play of the

content, so that the e%hibitorBs central office can efficiently oversee

operations# This capability is compelling, and it is not available today#

t demonstrates the importance of defining interfaces for theatre

operations that empower the use of new business tools#

The ability to monitor the health of e&uipment, particularly from

remote locations, is an important tool for maintenance crews# ;hile

remote monitoring is not uncommon in the T world, there is nothing

like it today in the cinema# 9ike the T world, S-5P has become the

most widely discussed protocol for use in system monitoring#

DISTRIBUTION PACKAGING

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Distribution packaging is the means for enabling a common

interchange format for content# ;hile this can be thought of as the

GD=DG of the cinema world, it is far more comple% in nature# The

basic re&uirements of a packaging method are4

'llow any make of system to read the packaged content,

'llow defective files to be replaced by segment, without

replacing the entire movie,

Provide a fle%ible means for including additional language

sound tracks, subtitles, etc#,

Provide a means to communicate the synchroni(ation of files#

Through work in the S5PT6 D)2K Packaging ad hoc group, the

schematic of a packaging scheme has been outlined and circulated

among industry participants, n early 233", it was the recommendation

of the D)2K ad hoc group that 5N: @5aterial 6%change :ormatA be

employed as the packaging technology for digital cinema# 5N: is a

technology originally proposed by the Pro+5P67 group, and currently

in process for standardi(ation within the S5PT6 ;2C Technology

)ommittee for broadcast applications# ' digital cinema Goperational

patternG has yet to be proposed for standardi(ation at the time of this

writing#

PUTTING IT ALL TOGETHER

f youBve gotten this far, youBre either employed in the industry or

youBre a very interested person# Just to show in terms of a block

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diagram how a real system might look, the block diagram is given

below#

;e havenBt said much about audio, and it deserves a little

attention# G-IG audio channels are shown in the diagram, a simple

way of saying that - channels is never enough# f youBre familiar with

the history of film sound, -I says it all#

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0nfortunately, itBs not possible to achieve -I with '6S"#

;hile a popular serial transmission method, '6S" is pair limited, with

two audio channels per pair# 5'D @'6S3A is a standardi(ed serial

format that supports C channels of digital audio# @9etBs hope that C

are greater than -I#A :ortunately, S5PT6 D)2K has discussed

grouping audio in blocks of channels, making it easy to place on

6thernet, even when using !?h( sampling and 2E+bit audio# Several

6thernet audio methods e%ist, including 5agic and )obranet#

Some new blocks are shown in the diagram above# ' Theatre

5anagement System and a Security 5anager are included# The

Theatre 5anagement System is a central place for operations+related

software# The Security 5anager is discussed earlier#

DTS, for Digital Theatre System, was introduced by Steven

Speilberg with the release of Jurrassic Park in !!"# So far, this

standard applies more to the big screen than private home# The sound

is coded over si% channels as in Dolby Digital# There are now many

DTS+compatible systems available# So surround systems, like sound

cards, can decode the standard via software# 8owever, while the

e%cellent &uality of DTS undeniable, and even a bit higher than Dolby,

remember that there are no movies available in DTS alone, and that

Dolby is considered to be the digital sound standard and DTS is not#

The main feature of DTS is that its coding system favors sound

&uality over disc space# So a DTS sound band codes in 2E bits instead

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of the K bits with Dolby# )ompression uses a dynamic process where

the compression rate varies with the amount of sound to encode# This

rate ranges from 4 to 4E3 and generally results in better sound

&uality than Dolby Digital with an average rate of #C 5b1s# The main

draw back is obviously that the sound band takes up much more space

@about " times as muchA than Dolby# So D=Ds coded in DTS can only

have one language and a limited number of bonuses# >ecause it is

optional as a sound standard, there are not many D=Ds with DTS on

the market, through the number is growing#

The main advantages of the DTS are video piracy# That is, only

authori(ed people can get the data# There is no problem of physical

transportation because of the server system# The most attractive

advantage is that preservation of films or archival of films#

CONCLUSION

's you might e%pect, thereBs more to the digital cinema story than

we have covered here# Digital cinema is not television ++ it is much

more comple%, fle%ible, and &uality+oriented# ;hile not always visibleto the public, there are a lot of people working to move this

technology forward# n time, youBll be able to en$oy the fruits of their

laborO

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BIBILIOGRAPHY

# www#mkpe#com

2# DTS ' retrospective, by .eward :leming#

"# Theatre system architectures for Digital cinema, by Streven '# 5orely

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15012013131101 Digital Theatre System