seminar report on digital cinema
DESCRIPTION
This is a project report for a seminar on digital cinema.TRANSCRIPT
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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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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