seminar report on digital cinema

DIGITAL CINEMA Sir MVIT, Bangalore

1. Introduction

An average household today is loaded with digital technology. A well equipped

home may have some or all of the following devices:-

A personal computer

A DVD player

Several CD players

A CD burner

A digital camera

A digital camcorder

A digital gaming console

A computer scanner

A digital television set

Several digital mobile phones

A digital satellite reception system

A digital video recorder

Clearly, digital technology has already taken over much of the home

entertainment market. It seems strange, then, that the vast majority of theatrical motion

pictures are shot and distributed on Celluloid film tape just like they were more than a

century ago. Of course, the technology has improved over the years, but it's still based on

the same basic principles. The reason is simple: Up until recently, nothing could come

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close to the image quality of projected film. Firstly a video shot with a digital camcorder

does not have a sufficiently large resolution to be projected on the big screen. Also, the

colour range that each pixel can represent is very limited. A pixel must be able to take

more than a trillion colours, to come close to the quality of video recorded on

conventional film tape. As a result the video from a camcorder is unfit to be used for

movies.

But things are starting to change. George Lucas kicked off the digital cinema

charge in May of 2002 with “Star Wars: Episode II, the Attack of the Clones”, the first

big budget live action movie shot entirely on digital video. Most theatres played 35-mm

film transfers of the movie, but some played it on digital movie projectors. Film never

entered the picture. With more and more filmmakers embracing the new technology,

including big names like Steven Soderbergh and Robert Rodriguez, digital cinema is well

on its way.

2. Elements of Digital Cinema

Digital cinema is simply a new approach to making and showing movies. The

basic idea is to use Bits and Bytes (Strings of 1s and 0s) to record, transmit and replay

images, rather than using chemicals on film.

The main advantage of digital technology (such as a CD) is that it can store,

transmit and retrieve a huge amount of information exactly as it was originally recorded.

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Analog technology (such as an Audio Tape) loses information in transmission, and

generally degrades with each viewing.

Digital information is also a lot more flexible than analog information. A

computer can manipulate bytes of data very easily, but it can't do much with a streaming

analog signal. It's a completely different language.

Digital cinema affects three major areas of movie-making:

Production - how the movie is actually made

Distribution - how the movie gets from the production

company to movie theaters

Projection - how the theater presents the movie

Production

With an Rs.20,000 consumer digital camcorder, a stack of tapes, a computer and

some video-editing software, you could make a digital movie. But there are a couple of

problems with this approach. First, your image resolution won't be that great on a big

movie screen. Second, your movie will look like news footage, not a normal theatrical

film. Conventional video has a completely different look from film, and just about

anybody can tell the difference in a second.

Film and video differ a lot in image clarity, depth of focus and colour range, but

the biggest contrast is frame rate. Film cameras normally shoot at 24 frames per second,

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while most television video cameras shoot at 30 frames per second (29.97 per second, to

be exact). Most video footage is also interlaced -- each frame is split into two sets of

horizontal lines that fit together. Video is designed this way to work with the

standard television format. A television's electron beam paints every other line as it

moves down the screen (for example, every odd-numbered line). Then, the next time it

moves down the screen, it paints the even-numbered lines, alternating back and forth

between even-numbered and odd-numbered lines on each pass.

All of these factors give conventional video a completely different flavor than

film -- the image seems to move differently. In order to mimic the characteristic look of

film, movie-makers use digital camcorders that shoot like film cameras. For example,

George Lucas shot "Attack of the Clones" with Sony HDW-F900 HDCAM camcorders

outfitted with high-end Panavision lenses. These camcorders can shoot conventional 30-

frame interlaced footage, but you can also set them to shoot 24 frames per second, just

like film cameras. On this setting, the camera can shoot progressive video -- video made

up of complete frames instead of interlaced fields. The camera also has a similar light

range and depth of field to film cameras.

These professional digital camcorders work on the same basic idea as cheaper

consumer models. They use charge-coupled devices (CCDs) to convert the incoming

light from a scene into an electronic signal, and an analog-to-digital converter to turn this

signal into a stream of 1s and 0s.

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Other than frame rate, the main difference between a professional camcorder and

a consumer model is image quality. Professional camcorders use higher-resolution CCDs

to pick up more information from the scene. For example, the HDW-F900 records 1920 x

1080 pixels. They also use more CCDs than cheaper models. Inside the camera, a beam

splitter separates the light from the scene into red, green and blue light. The camera

records each colour of light with a separate CCD in order to capture the full colour range.

When you recombine these colours, you retrieve the full colour image. Cheaper

camcorders use a single CCD to capture all colours of light, which compromises image

quality a good deal.

Sony HDW-F900 camcorders record in a high-definition format called HDCAM,

which is designed to rival film in image resolution and to adapt well to a variety of other

video formats used around the world.

Experts disagree on whether digital video is up to the quality standards of film,

but it is definitely close. If a filmmaker is satisfied with the image quality, there are some

distinct advantages to using video.

Production Benefits

Apart from image quality, there are two huge differences between film and digital

video: cost and flexibility.

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Cost

Film is hundreds of times more expensive than digital video. The raw video alone is

extremely cheap, and there is virtually no processing involved before the editing stage.

Filmmakers on a real shoe-string budget can even re-use the tape multiple times. By

Hollywood standards, digital video costs nearly nothing.

The "Star Wars" crew can definitely back this up. In an interview Rick

McCallum, one of the producers on "Attack of the Clones," said they spent $16,000 on

220 hours of digital tape, and they would have spent about $1.8 million on 220 hours of

film.

Flexibility

For the filmmaker, the most exciting element of digital technology is how easy it is to

use. Most filmmakers have already switched to digital editing systems because they make

it so much simpler to put a movie together. In the current process, filmmakers actually

convert the film footage to a digital format for post-production and then back to film

again for its theatrical release. The conversion process is costly, it ends up degrading the

image quality somewhat, and it takes time.

Digital video doesn't have to go through this conversion process. As soon as they

shoot digital footage, filmmakers can immediately play it back and start editing it. With

film, they have to send the footage off for processing before they know what they have. A

director might spend all day shooting only to discover the lighting was off and the

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footage is totally unusable. On the "Attack of the Clones" set, the crew could review the

footage after every shot. They could shoot a scene in the morning and start editing it that

afternoon.

Additionally, the crew doesn't have to get extensive coverage (repeated takes) in

case something looks wrong. They know right away if there were any problems.

Distribution

For the business side of the movie industry, the most compelling aspect of digital

cinema is distribution. In today's system, production companies spend a lot of money

producing film prints of their movies. Then, working with distribution companies, they

spend even more money shipping the heavy reels of film to theaters all over the world,

only to collect them again when the movie finishes its run.

Because the distribution costs are so high, production companies have to be

extremely cautious about where they play their movies. Unless they have a sure-fire hit,

they take a pretty big risk sending a film to a lot of theaters. If it bombs, they might not

make their money back.

If you take the physical film out of the equation, things get a lot cheaper. Digital

movies are basically big computer files, and just like computer files, you can write them

to a DVD-ROM, send them through broadband cable or transmit them via satellite. There

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are virtually no shipping costs, and it doesn't cost the production company much more to

show the movie in 100 theaters than in one theater. With this distribution system,

production companies could easily open movies in theaters all over the world on the same

day.

The digital distribution system also helps out the individual theaters. If a movie

sells out, a theater could decide to show it on additional screens on the spur of the

moment. They simply connect to the digital signal. Theaters could also show live

sporting events and other digital programming.

Projection

To the audience, the most important aspect of digital cinema is the projection

system. This is the final piece of technology that controls how the movie actually looks at

the end of the line.

Pretty much everybody agrees that a good film projector loaded with a pristine

film print produces a fantastic, vibrant picture. The problem is, every time you play the

movie, the film quality drops a little. When you go to a movie that's been playing for a

few weeks, you'll probably see hundreds of scratches and bits of dirt.

Many critics hold that a projected digital movie is inferior to a pristine film print,

but they recognize that while a film print gradually degrades, a digital movie looks the

same every time you show it. Think of a CD as compared to an audio tape. Every time

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you play an audio tape, the sound gets a little warped. A CD's digital information sounds

exactly the same every time you listen to it (unless it gets scratched).

3. Advantages of Digital Cinema

Digital Cinema is advantageous to the Film Makers, Distributors, Exhibitors as

well as the audiences.

i) Directors

Immediate Preview : The scenes can be previewed immediately after they are

shot with a digital camera so the director can immediately judge if a change in

lighting conditions are required or a re-shoot is required.

Upgradeable Equipment : Digital cameras are often highly configurable and

use detachable modular components for flexibility and upgrade-ability. They

can also record high resolution images up to 4096 x 2304 pixels.

Encourages Low Budget Films : Digital cinema is advantageous for low

budget cinemas made with limited man-power as such movies have lower

budgets and alternatives are available for cheaper capturing, editing,

processing, recording and distribution of digital cinemas.

Convenient Post-Production : The post production steps like editing, re-

recording, dubbing, graphics and special effects etc can be undertaken using

computers. This requires that the film is in digital format. There is no need for

conversion of film into digital format using expensive processes like Telecine

if the film is shot using digital cameras.

ii) Distributors

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Duplication Costs Reduced : The cost of making duplicate prints of a digital

film is significantly lower than making duplicate prints of celluloid films.

Better Piracy Prevention : When conventional film tapes are used, they have to

be physically transported to the theatres. The exact process is not formalized

and it can lead to unauthorized persons having access to the film. This carries

the risk of piracy. Whereas in Digital Cinema, the signal is encrypted and

transmitted using satellites. This protects the content from piracy.

Large number of screens simultaneously : Due to ease of transport and

reduced distribution costs, the movie can be screened at larger number of

theatre simultaneously.

Reduced costs of distribution : The cost of distributing prints to theatres over

the satellite network is lesser than physical distribution of celluloid prints.

iii) Exhibitors

More flexible scheduling : If all the screens of a movie are sold out owing

unexpected sudden demand, the exhibitor can immediately arrange for an

additional screening by placing an order with the distributor for transmission

to another screen.

New entertainment ideas : New ideas of entertainment like lighting FX,

aromas, etc can be made possible due to better synchronizing which is

possible with digital cinema.

Alternate content : With satellite broadcast of content to theatres, exhibitors

can screen alternate content like live coverage of sports, events etc.

iv) Audiences

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Higher quality entertainment : Digital cinema provides for higher picture and

sound quality than conventional cinema.

Easier Access to screenings : Larger number of screens playing the movie

means easier access to audiences.

v) 3D

Digital 3D uses polarization instead of coloured glasses (used by older 3D

cinemas) to portray the 3D effect. This ensures that the colour of the finished

image is not corrupted

4. Digital Cinema Initiatives (DCI)

Digital Cinema Initiatives, LLC or DCI is a joint venture of major motion picture

studios, formed to establish a standard architecture for digital cinema systems.

The organization was formed in March 2002 by the following studios:

Metro-Goldwyn-Mayer

Paramount Pictures

Sony Pictures Entertainment

20th Century Fox

Universal Studios

The Walt Disney Company

Warner Bros.

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The primary purpose of DCI is to establish and document specifications for an open

architecture for digital cinema that ensures a uniform and high level of technical

performance, reliability and quality. By establishing a common set of content

requirements, distributors, studios, exhibitors, d-cinema manufacturers and vendors can

be assured of interoperability and compatibility. Because of the relationship of DCI to

many of Hollywood's key studios, conformance to DCI's specifications is considered a

requirement by software developers or equipment manufacturers targeting the digital

cinema market.

On July 20, 2005, DCI released Version 1.0 of its "Digital Cinema System

Specification", commonly referred to as the "DCI Specification". The document describes

overall system requirements and specifications for digital cinema. The specification also

establishes standards for the decoder requirements and the presentation environment

itself, such as ambient light levels, pixel aspect and shape, image luminance, white

point chromaticity, and those tolerances to be kept. Even though it specifies what kind of

information is required, the DCI Specification does not include specific information

about how data within a distribution package is to be formatted. Formatting of this

information is defined by the Society of Motion Picture and Television Engineers

(SMPTE) digital cinema standards.

Image and audio capability overview:

2D Image:

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2048x1080 (2K) at 24 frame/s or 48 frame/s, or 4096x2160 (4K) at 24 frame/s

In 2K, for Scope (2.39:1) presentation 2048x858 pixels of the

imager is used

In 2K, for Flat (1.85:1) presentation 1998x1080 pixels of the

imager is used

In 4K, for Scope (2.39:1) presentation 4096x1716 pixels of the

imager is used

In 4K, for Flat (1.85:1) presentation 3996x2160 pixels of the

imager is used

12 bits per colour component (36 bits per pixel) via dual HD-SDI (encrypted)

10 bits only permitted for 2K at 48 frame/s

CIE XYZ colour space

TIFF 6.0 container format (one file per frame)

JPEG 2000 compression

from 0 to 5 or from 1 to 6 wavelet decomposition levels for 2K

or 4K resolutions, respectively

Compression rate of 4.71 bits/pixel (2K @ 24 frame/s), 2.35

bits/pixel (2K @ 48 frame/s), 1.17 bits/pixel (4K @ 24

frame/s)

250 Mbit/s maximum image bit rate

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Stereoscopic 3D Image:

2048x1080 (2K) at 48 frame/s - 24 frame/s per eye (4096x2160 4K not supported)

In 2K, for Scope (2.39:1) presentation 2048x858 pixels of the imager is used

In 2K, for Flat (1.85:1) presentation 1998x1080 pixels of the imager is used

Optionally, in the HD-SDI link only: 10 bit colour, YCbCr 4:2:2, each eye in

separate stream

Audio:

24 bits per sample, 48 kHz or 96 kHz

Up to 16 channels

WAV container, uncompressed PCM

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5. SMPTE DC28 SYSTEM

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Working of the DC28 System:

The content owner or distributor’s data has four attributes:

Image: The image signal, along with its metadata goes through an image

compression stage after which it is encrypted if required.

Subtitle: Subtitle track and its associated metadata may be compressed if needed

and encrypted.

Audio: The audio track and its metadata are compressed and encrypted.

Auxiliary: This data comes into play in the case of new entertainment ideas such

as lighting FX or aromas.

All above data are packaged into a common multiplexed signal. This is transmitted

over the transport system which may be hard disks, DVD’s or the most common satellite

links to the theatres. At the theatre it is temporarily stored. They then go through Decryption,

and Decompression.

The image signals and subtitles track are sent to the display system to be projected on

the screen. Audio track is sent to the theatre audio system. The sync between audio, video

and other effects is achieved using the metadata.

A conditional access and key management system is in place. At the originator

(Content owner/Distributor) end as well theatre end, a password or biometric verification is

required to access the content. This ensures security. The theatre management system helps

to manage and schedule screenings.

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6. Image Capture Flow

The image capture flow in a digital cinema camera is as shown. The Light is

incident on an image sensor which in turn produces charges on a charge coupled device

(CCD). The charges are digitized using an analog to digital converter.

An image processing stage is present for processes such as DCT/IDCT, colour

space conversion, compression, adjustment of brightness, contrast, sharpness etc..

Non-volatile storage is implemented in the form of compact FLASH, hard disks

or CD-R interface.

The system control unit has two parts:

System controller: Hardware I/O, memory decoding, synchronization,

status, interrupts etc.

Microcontroller: Scheduler, task manager, resource allocator, menu

manager etc.

The display driver stage manages timing control and frame rate control to

facilitate display on the LCD screen.

A high speed transport stage is necessary to stream the data into the next stage

which may be a computer. It comprises of USB 2.0, IEEE 1394 and Ethernet MAC’s.

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Image capture flow:

7. Transport Network

The transport network is used by the distributors to distribute the digital cinema

content to the theatres. It involves the physical transporting of content stored in a storage

medium or live transmission over high speed networks, the latter being the more popularly

implemented method.

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DIGITAL CINEMA Sir MVIT, BangaloreTransport Network:

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The transport network has the following blocks :

i) Packaging System: The packaged digital cinema content is

stored in a packaging system storage which communicates to the packaging management

conditional access ass well as the distributor gateway block via Ethernet using an attached

LAN/SAN interface.

ii) Distributor Gateway: This forms the bridge between the

distributor’s infrastructure and the transport network. Here the data can take two forms:

It can be stored in transportable physical media such as

hard disk. This is not generally preferred though.

It is stored in a buffer from which it is transmitted live.

iii) Transport service providers: If the data is stored in transportable physical media, then it is

transported to theatres physically using a courier network. Else it can be streamed live in

the following ways:

Via satellite using IP and ATM

Via high speed terrestrial networks using Ip and

ATM/SONET

Low speed telephone network using POTS

iv) Theatre Gateway: This connects the transport network to the theatre systems. Data can be

received in the following ways:

The physical media is received from courier network

The lice transmission of movie is received by

gateway I/O and buffered.

vi) Theatre Storage system: The data reaches the storage system via Ethernet using

LAN/SAN interface.

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Conditional access systems are in place at both distributor end as well as theatre end to prevent

unauthorized access to content. A theatre management system manages the theatre

infrastructure and schedules.

8. Projection Technology

Projection of the cinema on the screen is done using digital projectors. The major projection

technologies are :

(i) Digital Light Processor – Digital Micro-mirror Device (DLP-DMD)

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A DMD is a plate consisting of thousands of MEMS activated micro-sized mirrors. When

a grayscale video signal is supplied to it, each mirror (representing a pixel) turns to an ON position

and reflects the light falling on it if the corresponding pixel is bright. The mirrors flip between on

and off several times a second. The proportion of time for which it is on defines the pixel intensity.

This is how a gradient from light to dark is achieved.

The projector has three separate DMD’s for the three basic colour components red, blue

and green. The component video signals are respectively supplied to them. The white light from a

local light source is split into its fundamental red, green and blue components by using a prism,

and the respective components illuminate the corresponding DMD’s.

The reflected beams are then combined by projection optics to form a single beam and it

is projected on the screen.

ii) LCD Projection

There are three transparent LCD arrays. A grayscale video signal can cause partial

opaqueness of the array. Each pixel turns transparent if the pixel is bright. The degree of

transparency varies for creating light to dark gradient.

A high intensity white light source emits a beam of light which is passed through

wavelength selective dychoric mirrors as shown. Hence the three fundamental components are

incident on respective LCD arrays. The output beams are reflected and combined into a single

array using projection optics. This beam is then projected on screen.

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LCD Projector

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9. Problems facing D-Cinema

D-cinema is facing a number of limitations as of today which we hope will be resolved in the

near future. The major drawbacks are:

i) Different experience from theatre to theatre:

Ambient light, display/screen reflectivity, projector lamp intensity and optics etc are factors which

affect the final look of the movie on screen. The final look of the same content differs from theatre to

theatre because today there are a number of companies providing digital infrastructure like Christie,

UFO, Qube Digital, etc. All of them follow different standards.

ii) Not enough standardization

SMPTE DC28 is trying to solve this but currently there are no products that really support DC28

for real-time applications. Also, the DCI specifications have not been fully implemented yet by all

providers.

iii) Huge storage and bandwidth requirements

At post production stage, more than 200 Terabytes of memory space is required to store a movie.

Also, links of several tens of Gigabytes/s bandwidth are required to stream the movie to theatres.

iv) Risk of technological obsolescence

As any other upcoming digital field, the risk of very rapid technological obsolescence is a chief

drawback of digital cinema.

v) Burden of investment of exhibitors

The decrease in duplication and distribution costs benefits producers but however the exhibitors

need to bear exorbitant costs to renew their systems and install digital infrastructure.

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10. Digital cinema Video formats

Unlike other video formats, which are specified in terms of vertical resolution (e.g.

1080p, which is 1920x1080 pixels), digital cinema formats are usually specified in terms of

horizontal resolution. As shorthand, these resolutions are often given in "nK" notation,

where n is the multiplier of 1024 such that the horizontal resolution of a corresponding full-

aperture, digitized film frame is exactly 1024n pixels. Here the 'K' has a customary, improper

meaning: it should be the binary prefix "kibi" (ki) instead.

For instance, a 2K image is 2048 pixels wide, and a 4K image is 4096 pixels wide.

Vertical resolutions vary with aspect ratios though; so a 2K image with a HDTV (16:9) aspect

ratio is 2048x1152 pixels, while a 2K image with a SDTV or Academy ratio (4:3) is 2048x1536

pixels, and one with a Panavision ratio (2.39:1) would be 2048x856 pixels, and so on. Due to the

"nK" notation not corresponding to specific horizontal resolutions per format a 2K image

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lacking, for example, the typical 35mm film soundtrack space, is only 1828 pixels wide, with

vertical resolutions rescaling accordingly. This led to a plethora of motion-picture related video

resolutions, which is quite confusing and often redundant with respect to nowadays few

projection standards.

All formats designed for digital cinematography are progressive scan, and capture usually

occurs at the same 24 frame per second rate established as the standard for 35mm film.

The DCI standard for cinema usually relies on a 1.89:1 aspect ratio, thus defining the

maximum container size for 4K as 4096x2160 pixels and for 2K as 2048x1080 pixels (either

24fps or 48fps). When distributed in the form of a Digital Cinema Package (DCP), content

is letterboxed or pillarboxed as appropriate to fit within one of these container formats.

11. Conclusion

Digital cinema not only reduces the production and distribution costs of movies but also

fights piracy, the biggest evil to creativity. Digital cinema enhances the cinema experience for

consumers and paves way for new entertainment ideas and alternate content. The world has

embraced digital cinema, and in particular digital cinema is revolutionising the Indian Film

Industry. With more than 1,50,000 theatres across the globe waiting to switch to digital, digital

infrastructure providers are seeing theirs as one of the most potent business ideas too. Digital

cinema is certainly the future of cinema.

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12. References

http://en.wikipedia.org

http://www.mkpe.com/publications/archives.php

INS Asia Magazine

http://www.howstuffworks.com/digital-cinema1.htm

“Digital Cinema” by Michael Karagosian, Karagosian MacCalla Partners 2004

“Digital cinema in India” by Nirav Shah, Karagosian MacCalla Partners 2004

http://www.qubecinema.com/

http://www.dcinematoday.com/

http://www.digitalcinemareport.com/

http://www.digitalcinemasociety.org/

http://www.digitalcinemainfo.com/

http://www.qube.in/

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http://www.qube.in/

http://www.digitalcinemainfo.com/

http://www.digitalcinemasociety.org/

http://www.digitalcinemareport.com/

http://www.dcinematoday.com/

http://www.qubecinema.com/

http://www.howstuffworks.com/digital-cinema1.htm

http://www.mkpe.com/publications/archives.php

http://en.wikipedia.org/

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