Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR DISTRIBU'TION OF HIGH QUALITY
IMAGE AND AUDIO PROGRAMS TO R]EMOTE LOCATIONS
BACKGROUND OF THE INV'ENTION
I. Field of the Invention
The present invention relates to electronic audio/visual processing. More
specifically, the present invention relates to apparatus and method for
distribution of digitized image, of either still or motion type, and audio
information to various locations for presentation. The invention further
relates
to the coding, encryption, transmission, storage, decompression, decryption,
and
playback of high definition electronic audio/visual programming from a central
facility to multiple display projectors or presentation systems.
II. Description of the Related Art
For several decades, the motion picture industry has depended on the
duplication, distribution, and projection of celluloi+d film for delivering
creative
programming material to geographically diverse theaters around the country
and the world. To a large extent, the methods and mechanisms for this
distribution of film material have hardly changed in. several decades.
The current film duplication and distribution process is illustrated in
FIG. 1. Film duplication typically starts with an exceptional quality camera
negative. At a film studio 50, a film editor 52 produces a master film copy
after
the process for producing the original film. From this master film copy, a
film
duplication element 54 produces what is referred as a distribution negative,
from
which distribution prints (known as "positives") are produced in quantities.
Depending on the size of the release or number of copies desired for
distributing
the film, there may be more intermediate steps or multiple copies produced at
each stage. The film positives are distributed by courier and other physical
means to various theaters, as exemplified by a theater 56. At theater 56, the
movie is displayed by projecting images from the film onto a display surface
using a film projector 58. In this traditional system, a multiple track audio
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2
program is generally created by an audio editing system and printed along
with the motion picture images on the film so that this soundtrack can be
played
back on a theater sound system in time synchronization with the motion
picture in a theater projection system.
Although the distribution process shown in FIG. I works well, there are
inherent limitations. Due to the use of celluloid material for the film and
the
bandwidth limitations of the film media, there are restrictions on the ability
to
provide high fidelity multi-channel audio programming. Then, there is the high
expense of making a large number of film duplicates, which can cost several
hundreds of dollars for each feature length film. There is also the expense,
complexity, and delay associated with physically distributing large canisters
of
celluloid film to a large and growing number of theater locations. Also, a
growing trend in the motion picture theater industry is the development of so
called "multiplex" theater locations in which multiple projection auditoriums
are
located or clustered together at a single theater location. Each projection
auditorium may show a motion picture at the same time as other motion
pictures are being shown in the other projection auditoriums in the multiplex
complex.
Because of the large number of duplicates made, it becomes increasingly
difficult to prevent illegal duplication and theft of the material. It is
estimated
that revenues lost due to piracy and theft account for billions of dollar's
lost each
year by the motion picture industry. Further, duplicated material tends to
degrade over time due to dust collection, wear-and-tear, thermal variances,
and
other known factors. Finally, management cost and other expenses are involved
in the eventual destruction of the film material, which may contain regulated
hazardous material.
New and emerging technologies are making it possible to provide
alternative approaches to the ongoing film distribution problems. For example,
advances in digital technology have led to a revolutionary distribution
concept
whereby the programming to be transferred is in an electronically stored
digitized format, rather than on an optical film media. The digitized images
can
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3
be distributed on various magnetic media or compact optical discs, or
transmitted over wired, fiber optic, wireless, or satellite communication
systems.
However, the alternative distribution technologies, including the digital
methods, have not been able to offer the image quality and projection
brightness
available using celluloid film. Competing technologies typically involve
audio/visual (AV) signals recorded on various magnetic or optical media for
display on video monitors, television, or projection equipment. These
technologies do not offer the quality of film due to bandwidth limitations.
Although satellite transmission methods are now available, they are not
currently commercially viable for the distribution of high quality AV
material.
Since the distribution of film programming is essentially a special type of
broadcast to a continent-wide region, a satellite distribution method with
inherent advantages to such wide area broadcasting would seem ultimately
appropriate for film distribution. However, in order to transmit a very high
quality AV signal in "real-time," the data rate requirement (in bits per
second) is
on the order of 1.5 billion bits per second. This high data rate requires the
capacity equivalent of an entire satellite to transmit even a single program,
which is prohibitively expensive. In addition to the ability to transmit the
necessary information via satellite, the received information must be
displayed
using a high quality projector, which has not previously been available.
In order to reduce the data rate requirement for the delivery of ultra-high
quality electronic images, compression algorithms are being developed. One
digital dynamic image compression technique capable of offering significant
compression while preserving the quality of image signals utilizes adaptively
sized blocks and sub-blocks of encoded discrete cosine transform (DCT)
coefficient data. This technique will hereinafter be referred to as the
adaptive
block size discrete cosine transform (ABSDCT) method. The adaptive block sizes
are chosen to exploit redundancy that exists for information within a frame of
image data. The technique is disclosed in U.S. Pat. No. 5,021,891, entitled
"Adaptive Block Size Image Compression Method And System," assigned to the
assignee of the present invention. DCT techniques are also
disclosed in U.S. Pat. No. 5,107,345, entitled "Adaptive Block
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4
Size Image Compression Method And System," assigned to the assignee of the
present invention. Further, the use of the ABSDCT technique
in combination with a Discrete Quadtree Transform
technique is discussed in U.S. Pat No. 5,452,104, entitled "Adaptive Block
Size
Image Compression Method And System," also assigned to the assignee of the
present invention. The systems disclosed in these patents
utilize intraframe encoding, wherein each frame of an image
sequence is encoded without regard to the content of any other frame.
Using ABSDCT, the necessary data rate may be reduced from say around
1.5 billion bits per second to approximately 50 million bits per second
without
discernible quality degradation. This compressed digital data rate may be
readily transmitted using a single satellite transponder at a very reasonable
cost,
especially when considering that this single transmission can be received by
many hundreds or thousands of theater receivers throughout a given
geographical region or country.
Distribution of film information using a digital electronic format actually
increases the potential for rapid, low-cost duplication without quality
degradation. However, along with the "ease of duplication" associated with
digital technology, there exists encryption techniques to ensure that the
information is encoded in a way that prevents useful information from being
distributed to unauthorized parties.
New technologies such as the ABSDCT compression technique, advanced
projection equipment, and electronic encryption methods offer the possibility
of
a "digital cinema" system. Generally defined, digital cinema refers to the
electronic distribution and display of ultra-high quality film programming
which
has been converted to a digital electronic representation for storage,
transmission, and display purposes. A digital cinema system would overcome
many of the limitations of the current film distribution process. Using
transmission methods such as a satellite system, the expenses involved in
duplication and distribution of film would be greatly reduced. A digital
system
would not be subject to the quality degradation over time experienced by
celluloid film. Further, a digital system would virtually eliminate the theft
and
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illegal duplication of celluloid film, and further offers the possibility of
implementing security measures within the digital system itself. However, a
complete digital cinema system has not been developed by the motion picture
industry or related arts.
Several issues and problems remain to be solved. New digital cinema
systems will require improved forms of protection to prevent theft from
theaters.
Theater complexes with multiple auditoriums have grown larger in an effort to
provide a greater economic return, resulting in mlore complicated presentation
schedules, and a larger number of locations show-ing a given film. This could
require many additional electronic copies to be forwarded to theaters for
presentation using current techniques, with associated complexity and
operating
costs.
Distribution channels and mechanisms are still defined by the older
celluloid film copying and distribution techniques discussed above. New
techniques and apparatus are needed to take full advantage of proposed digital
cinema processing, to reduce copying, provide faster releases to market, and
updating products in release, while providing increased scheduling and
distribution flexibility at reasonable cost. At the sarne time, some film
producers,
studios, and theater managers would like to have increased centralized control
over releases and distribution, and to be able to expand into newer markets.
For
example it is desirable to be able to supply films and other audio visual
presentations with alternative sound tracks to address increasing markets for
multi-lingual or alternative language audiences, in a more cost effective
manner.
What is needed is the integration of certain technology into a system and
method for the delivery and management of high quality image and audio
programming for large screen viewing. A system and method is needed for the
reliable transmission of a very high quality iinage and audio signals to
designated theaters, the flexible scheduling of feature films and
advertisements,
the integration of a high quality audio signals, and built-in security
measures.
These goals are achieved by the present invention in the manner described
below.
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SUMMARY OF THE INVEIvTION
The present invention is a system and method for the electronic
distribution of high quality image and/or audio programming from one or more
central facilities to one or more presentation or theater systems. The
apparatus
and method provide for the coding and encr,yption of image and audio
information, generally in the form of programming material. at a central hub,
the
wide area distribution of that material, and the storage and large screen
display
of the program at one or more auditoriums or presentation locations. The
programming material will generally consist of motion picture images, time
synchronized audio programming, and/or other related information, such as
visual cue tracks for sight-impaired audiences, subtitling for foreign
language
and/or hearing impaired audiences, or multimedia time cue tracks. The
program material may be lengthy in duration (such as a feature length motion
picture), of a shorter duration (such as a motion picture trailer or
commercial
advertisement) or a still image (such as for an advertisement or
announcement).
The audio and other related programs need not be time synchronized with the
image information, such as the case with background audio programming.
At a central hub, the program information is processed for distribution. A
source generation system, located either at the central hub or an alternative
site,
may be utilized to generate electronic audio and image signals from an analog
or
digital input. The source generation system will generally comprise a telecine
for generating the electronic image signal, and an audio reader for generating
the electronic audio signal. Alternatively, the elect:ronic signal may be
provided
directly from an electronic camera or other electronic source such as a
computer-
based image generation system.
The electronic image and audio signals then undergo processing by a
compression/encryption system. Again, the corrtpression/encryption system
may be located either at the central hub or at the same facility as the source
generation system, for example, a production studio. A known dynamic
compression technology is used and the compressed signal readily transmitted
over wired, fiber optic, wireless, or satellite communication systems. The
audio
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signal may be compressed using a standard digital audio compression
algorithm.
The encryption technique involves the use of time-varying electronic key
values and/or digital control word sequence, which is only provided to
authorized receivers. In addition, a digital signaiture or "watermark" may be
added to the image and/or audio signal. The watermark, a theater and/or time
specific visual identifier, is not perceptible to the normal viewing audience,
but
may be used to identify a source of an unauthorized copy of a program when
analyzed under non-real-time or still frame playback. Decryption information
necessary to decrypt the image and/or audio information is generated at the
individual decrypter units using secret auditorium specific keys and secure
information sent to the theater. Generally, the image and audio signals are
separately encrypted. By treating the image and audio portions as separate
programs, different audio programs may be combined with image programs for
various reasons, such as varying languages.
The compressed and encrypted signals are provided to a
modulation/transmission system at a central hub or hubs. The
modulation/transmission technique typically adcis forward error correction
information and modulates the transport data stream for transmission. The
transmission will typically be over a satellite, although terrestrial cable,
optic, or
other wireless methods may also be employed. The transmission rate of the
broadcast programming may vary in such a way that the information may be
sent at rates slower, faster, or equal to the compression data rate.
Transmission
of live event programming is supported when data transmissions occur at the
same rate as the compression rate.
The central hub also comprises a network management system. The
network management system may include control processors to manage the total
operation of the system, including control of the broadcasting,
playback/display,
security, and overall monitor/control and network management functions. The
system is capable of operating under centrally or distributed fully automatic
control, semi-automatic control or with manual intervention.
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Under 'control of the network managemerit system, the programming
material and additional control information are broadcast to the theater
systems.
Although capable of receiving all transmitted programs, the theater systems
selectively store only received programming intended for that theater system.
The system includes control methods for notifying the theater systems of the
identity of each broadcast program. In addition, a control method is provided
to
control each tlleater system's selective storage of the received programming.
At a theater system, a receiver/demodulator receives the broadcast
programming. Typically, a dish antenna is used to receive satellite signals.
The
receiver/demodulator also demodulates the received signals and performs error
correction on the demodulated signals. The demodulated signal, usually in the
form of a transport packet stream, along with the results of error correction
are
provided to a theater management system.
The theater management system monitors the demodulated signals for
errors, and requests retransmission of the signal po:rtions containing errors.
The
theater management system utilizes a return link communication path (from the
theater system to the central hub(s)) to request retransmission. The return
path
may use the telephone network, a satellite channel, the Internet or other low
data
rate communication method.
Under the control of the theater management system, storage arrays in the
theater systems provide for local centralized storage of the programming
material. The storage arrays may be solid state, magnetic, or optical, and may
store several programs at a time. The central storage system is connected via
a
local area network (electronic or optical) in such a way that any program can
be
played back and presented on any authorized. presentation system (i.e.,
projector). Also, the same program may be simultaneously played back on two
or more presentation systems. Programming material is routed from the storage
arrays to the designated auditorium(s) via a local area network (LAN) which
may use various LAN architectures. For purposes of this description, this
summary assumes the use of a LAN which incorporates a central network switch
architecture. However, other types of LAN architectures are possible with this
system.
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Programming material is processed at the auditorium in real-time during
playback. This processing includes data rate decompression and security
decryption (or descrambling). The decompression and decryption algorithms
depend on the compression and encryption techniques employed at the central
hub. The decompressed/decrypted image signal is displayed via a projector in
the auditorium, while the audio signal is presented via an electronic sound
system.
The theater management system genera:lly controls all aspects of
projection operations, including storage of the received programming,
decompression and decryption of the programming signals, and display of the
programming material. Although the programming is received at the theater
system only once, the programming stored in the storage arrays may be played
back multiple times. The theater management system may control the period of
time and/or the number of play backs that are allowed for each program.
Alternatively, control of the presentation process rnay be located locally at
the
electronic projector, a remote control unit, or take place under central
control by
the hub or other centralized element. In addition, the theater management
system may be configured to integrate projection operations with other theater
operations, such as concessions, ticketing, promotions, signage, environmental
controls, lighting, sound system operation, etc. Each theater system may
include
multiple auditorium systems sharing common storage and control functions for
flexible and more cost efficient presentation options.
The use of digital encryption provides a built-in security measure for the
digital cinema system. Cryptographic techniques are employed to provided
end-to-end encrypted data transfer. That is, the image and/or audio
information
signal is encrypted at the Source Generation System (SGS) and is decrypted
right at the auditorium in the theater system during playback. In addition to
the
electronic security measures, physical security rr-easures provide additional
protection of the programming material.
Physical security measures are especially important for protecting the
decompressed/decrypted signals from a "wiretap" prior to display by the
projector in the theater system. In a preferred embodiment, the
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decryption/decompression function is housed in a secure,
self-contained chassis which is physically attached to, or
embedded inside, the projector in a manner in which it is
not removable without authorization access and which
5 physically prevents probing of the decrypted signals. In
addition, intrusion into this secured environment or chassis
could cause a process to be commenced that deletes or erases
cryptographic key information and otherwise deletes or
changes any digital data available at the project feed point
10 to prevent copying.
Accordingly, a complete digital cinema system is
provided for the compression, encryption, reliable
transmission, storage, and playback of high quality
programming material from one or more central facilities to
one or multiple auditoriums in theater complexes or other
locations, as well as necessary management functions to
monitor and control such a system.
According to one aspect of the present invention,
there is provided apparatus for distribution of image, of
either still or motion type, and audio information to a
plurality of viewing locations comprising: means for
independently receiving, at each of the plurality of viewing
locations, at least one compressed and encrypted image file,
which is associated with at least one corresponding image
program, and a plurality of compressed and encrypted audio
files, which are associated with a plurality of
corresponding audio programs, for presentation at at least
one preselected later time, wherein the at least one
compressed and encrypted image file and the plurality of
compressed and encrypted audio files are all associable
using at least one identifier for each of the at least one
compressed and encrypted image file and the plurality of
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10a
compressed and encrypted audio files; means for
independently storing in a storage system at each of the
plurality of viewing locations the compressed and encrypted
image and audio files; means for independently distributing
the compressed and encrypted image and audio files from the
storage system to at least one auditorium at each of the
plurality of viewing locations, based at least in part on
the at least one identifier; means for independently
receiving the compressed and encrypted image and audio files
in each auditorium; means for independently decrypting the
compressed and encrypted image and audio information in each
auditorium, resulting in at least one compressed image file
and a plurality of compressed audio files; means for
independently decompressing the compressed image and audio
files in each auditorium, resulting in the at least one
corresponding image program and the plurality of
corresponding audio programs; at least one projection system
in each auditorium for receiving the at least one
corresponding image program and presenting the at least one
image program at the at least one preselected later time;
and at least one sound system in each auditorium for
receiving the plurality of corresponding audio programs and
selectively playing at least one of the plurality of
corresponding audio programs with the presented at least one
corresponding image program.
According to another aspect of the present
invention, there is provided a method for distribution of
image, of either still or motion type, and audio information
to a plurality of viewing locations comprising:
independently receiving, at each of the plurality of viewing
locations, at least one compressed and encrypted image file,
which is associated with at least one image program and a
plurality of compressed and encrypted audio files, which are
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10b
associated with a plurality of corresponding audio programs
for presentation at at least one preselected later time,
wherein the at least one compressed and encrypted image file
and the plurality of compressed and encrypted audio files
are all associable using at least one identifier for each of
the at least one compressed and encrypted image file and the
plurality of compressed and encrypted audio files;
independently storing in a storage system, at each of the
plurality of viewing locations, the compressed and encrypted
image and audio files; independently distributing the
compressed and encrypted image and audio files from the
storage system to at least one auditorium at each of the
plurality of viewing locations, based at least in part on
the at least one identifier; independently receiving the
compressed and encrypted image and audio files in each
auditorium; independently decrypting the compressed and
encrypted image and audio files in each auditorium,
resulting in at least one compressed image file and a
plurality of compressed audio files; independently
decompressing the compressed image and audio files in each
auditorium, resulting in the at least one corresponding
image program and the plurality of corresponding audio
programs; receiving the at least one corresponding image
program at at least one projection system in each auditorium
and presenting the at least one corresponding image program
at at least one preselected later time; and receiving the
plurality of corresponding audio programs at at least one
sound system in each auditorium and selectively playing the
at least one of the plurality of audio programs with the
presented at least one corresponding image program.
According to still another aspect of the present
invention, there is provided apparatus for distribution of
digitized image, of either still or motion type, and audio
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lOc
information to a plurality of viewing locations comprising:
a central facility for receiving and storing the digitized
image and audio information; means for encrypting the
digitized image and audio information; means for compressing
the encrypted digitized image and audio information; means
for transferring, from said central facility, the compressed
and encrypted digitized image and audio information as one
or more programs to the plurality of viewing locations, each
including one or more remotely located auditoriums, at a
plurality of preselected later times with preselected
offsets, wherein the compressed and encrypted digitized
image and audio information are transferred along with at
least one uncompressed and unencrypted identifier used to
identify which of the compressed and encrypted digitized
image and audio information are associated with each of the
one or more programs at each of the one or more remotely
located auditoriums.
According to yet another aspect of the present
invention, there is provided a method for distribution of
digitized image, of either still or motion type, and audio
information to a plurality of viewing locations comprising:
receiving and storing in a central facility the digitized
image and audio information; encrypting the digitized image
and audio information; compressing the encrypted digitized
image and audio information; transferring, from the central
facility, the compressed and encrypted digitized image and
audio information as one or more programs to the plurality
of viewing locations, each including one or more remotely
located auditoriums, at a plurality of preselected later
times with preselected offsets, wherein the compressed and
encrypted digitized image and audio information are
transferred along with at least one uncompressed and
unencrypted identifier used to identify which of the
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10d
compressed and encrypted digitized image and audio
information are associated with each of the one or more
programs at each of the one or more remotely located
auditoriums.
BRIEF DESCRIPTION OF THE DRAWINGS
The features, objects, and advantages of the
present invention will become more apparent from the
detailed description set forth below when taken in
conjunction with the drawings in which like reference
characters identify correspondingly throughout and wherein:
FIG. 1 is a block diagram of a traditional film
distribution system;
FIG. 2 is a high-level block diagram of an
exemplary embodiment of the digital cinema system of the
present invention;
FIG. 3 is a block diagram of a film-based source
generation system;
FIG. 4 is a block diagram of a
compression/encryption system;
FIG. 5 is a block diagram of a
modulation/transmission system;
FIG. 6 is a block diagram of a network management
system;
FIG. 7 is a block diagram of a collocated theater
system;
FIG. 8 is a block diagram illustrating a hub
internal network and central hub redundancy;
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10e
FIG. 9 is a block diagram of a theater
receiver/demodulator;
FIG. 10 is a block diagram of a theater management
system; and
FIG. 11 is a block diagram of a theater decoder
system.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention comprises a system and method, sometimes
referred to herein as "digital cinema", for the electronic distribution of
high
quality audio/visual programming, such as motion pictures, from one or more
central distribution points (referred to as central hubs, facilities, or
stations) to
multiple receiving stations (referred to as theater systems, theaters, theater
complexes, or presentation systems). The digital cinema system incorporates
innovation in image and audio compression, projection technology, encryption
methodology, and many other areas. A complete system is provided which can
include apparatus for the coding, encryption, transmission, storage,
decompression, decryption, and playback of audio/visual material, and control
of various functions of the system.
Digital cinema is designed to replace the current method of physical
distribution of film to each play back or projection location such as theaters
or
remote auditoriums. It eliminates the need f'or duplication of film and
transportation of film to theaters by courier. It offers the potential for
exceptional audio/visual quality as well as built-in security measures. By
transmitting the audio and image bearing signals via satellite or some other
high
speed electronic medium, digital cinema further offers the possibility for
real-
time broadcasts of "live event" programming such as sporting events and
concerts in cinema-quality. Alternatively, programs may be transmitted to
theaters and stored on storage devices such as magnetic disks for display at
later
times.
An exemplary digital cinema system of the present invention is illustrated
in FIG. 2. Digital cinema system 100, as shown in. FIG. 2, comprises two main
systems: at least one central facility or hub 102 anct at least one
presentation or
theater system 104 (104A-104N). In a preferred embodiment, a signal
transferring image information or data and audio data is broadcast or
transmitted from central facility or hub 102 to presentation or theater system
104
using at least one satellite 106. Central hub 102 supports all theater systems
104
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(104A-104N) that are within the transmission footprint of satellite 106, or
coupled to a chosen wireless, wireline, or other high speed communication
link.
Generally, a series of theaters or presentation locations, such as outdoor
amphitheaters, schools, specialty restaurants, and. so forth, form a network
of
locations that are to receive image or audio information using the present
system.
Although a single central facility or hub 102 is shown for processing
information, a backup hub facility may be desired for increased network or
distribution reliability. Furthermore, additional hubs 102 can be employed
with
the same or other satellites 106, or other types of links, to service theaters
104 or
other presentation locations within the same gecigraphical region (or
satellite
footprint). This can occur where different hubs are used by different film
suppliers or other service providers competing within a given region being
serviced, for transmitting different levels of programming, for servicing
slightly
different types of equipment, and so forth. The present invention contemplates
using multiple satellites and hubs, as desired within the industry to provide
various levels of service.
Generally, one theater or presentation syster.n 104 (104A-104N) is utilized
for each theater or presentation location in a network of presentation
locations
that is to receive image or audio information, arLd includes some centralized
equipment as well as certain equipment employed for each presentation
auditorium. Satellite 106 may, for example, be a Ku-band geosynchronous
satellite, although other frequencies and satellite orbits can be employed. A
variety of satellite systems and satellite transponders are known which can
serve
this transfer function, based on desired location, costs, average capacity
required,
and so forth.
At central hub 102, a source generation system 108 provides digitized
electronic audio and image programs to the system. Typically, source
generation system 108 receives film material ancl generates a magnetic tape
containing digitized information or data. The film is digitally scanned at a
very
high resolution to create the digitized version of the motion picture or other
program. Typically, a known "telecine" process generates the image
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information while well known digital audio conversion processing generates the
audio portion of the program. The images being processed need not be
provided from a film, but can be single picture or still frame type images, or
a
series of frames or pictures, including those showri as motion pictures of
varying
length. These images can be presented as a series or set to create what are
referred to as image programs. In addition, other material can be provided
such
as visual cue tracks for sight-impaired audiences, subtitling for foreign
language
and/or hearing impaired audiences, or multimedia time cue tracks. Similarly,
single or sets of sounds or recordings are used to form desired audio
programs.
Alternatively, a high definition digital caimera or other known digital
image generation device or method may provide the digitized image
information. The use of a digital camera, which dlirectly produces the
digitized
image information, is especially useful for live event capture for
substantially
immediate or contemporaneous distribution. Corrtputer workstations or similar
equipment can also be used to directly generate graphical images which are to
be
distributed.
The digital image information or program is presented to a
compression/encryption system 110, which compresses the digital signal using a
preselected known format or process, reducing the amount of digital
information necessary to reproduce the original im,age with very high quality.
In
a preferred embodiment, a ABSDCT technique is used to compress the image
source. The ABSDCT compression technique is disclosed in U.S. Pat.
Nos. 5,021,891, 5,107,345, and 5,452,104 mentioned above. The audio
information is also digitally compressed using standard techniques and may be
time synchronized with the compressed image iriformation. The compressed
image and audio information is then encrypted and/or scrambled using one or
more secure electronic methods.
A network management system 112 monitors the status of
compression/encryption system 110, and directs compression/encryption
system 110 to multiplex theater, security, and transmission control
information
with the compressed/encrypted data, as desired. 1'he multiplexed signal is
then
presented to a rnodulation/transmission system 114, which, under the direction
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of network management system 112, modulates and transmits a compressed
information bearing signal to theater systems, such as theater system 104A,
via
satellite 106. That is, the compressed information may be broadcast over a
wireless communication path or link to theaters or presentation locations.
In some embodiments, the compressed image and audio information are
each transferred in a non-contiguous or separate manner independent of each
other. That is, a means is provided for compressing and transferring audio
programs associated with image information or programs but segregated in
time. There is no requirement when using the present invention to process and
transfer the audio and images at the same time. A predefined identifier or
identification mechanism or scheme is used to associate corresponding audio
and image programs with each other, as appropriate. This allows linking of one
or more preselected audio programs with at least one preselected image
program, as desired, at a time of presentation, or during a presentation
event.
That is, while not initially time synchronized with the compressed image
information, the compressed audio is linked and synchronized at presentation.
As discussed below, the compressed image and audio information can be stored,
together or separately, in the central facility for trarisfer at a later
predetermined
time.
Although FIG. 2 shows that the broadcast signal is transmitted using
satellite 106, it should be understood that the broadcast signal may be
transmitted using any of a number of terrestrial wireless transmission methods
as well, such as well known terrestrial cellular, zxiicrowave, or other types
of
radio frequency relay devices. Alternatively, wired transmission methods, such
as well known multi-drop, Internet access nodes, dedicated telephone lines, or
point-to-point fiber optic networks can be used to implement the invention.
Central hub 102 may also comprise at least one collocated theater system
116 for monitoring the quality of signals received from satellite 106 as
transmitted by modulation/transmission system 114 and providing a reception
quality measurement to network management system 112. Collocated theater
system 116 need not employ all of the features or processing capabilities
found in
similar devices located at respective theaters, but could use a simpler
satellite
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signal receiver with appropriate reception, demodulation, decompression, and
other components for generating a signal useful for analysis. For example,
collocated theater system 116 obviously need not present a complete high
quality
image for projection in order to allow sufficient analysis of the signal
quality in
5 most cases, relying on certain known characteristics for the digital data
being
transferred.
When the transmitted signal is determined to be of poor quality, network
management system 112 can make adjustments to compression/encryption
system 110 and/or modulation/transmission system 114 in order to improve the
10 transmission quality. For example changes in detected error rates for the
digital
data, or losses of data frames in received signals can be used to change
compression rates, change transmission characteristics such as signal power,
automatically re-send portions of the signal, or interrupt transmission
completely in view of certain satellite transfer problems.
15 While the present invention is equally applicable to presentation of image
and audio information to a variety of presentation locations such as outdoor
amphitheaters, drive-in complexes, civic auditoriums, schools, specialty
restaurants, and so forth, an exemplary theater or theater complex is used for
purposes of clarity in the discussion below. Those skilled in the art will
readily
understand how the present invention is applied to other types of locations.
The transferred or broadcast signal is received at theater system 104
(104A-104N) by a receiver/demodulator 120. In an embodiment wherein a
satellite transponder is used for transmission of the signal,
receiver/demodulator 120 uses at least one receiver antenna Ior receiving
the signal. Receiver/demodulator 120 demodulates the received signal and
monitors the demodulated signal for errors. To aid in this process, additional
checksum information can be added to the compressed information prior to
transmission to allow detection of errors in transmitted blocks of
information.
If the error rate exceeds a predetermined level, a theater management
system 122 may request retransmission of the signal portions containing
errors.
This request for retransmission may be sent from theater management system
122 to central hub 102 using a return link 113 which may utilize a telephone
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network with a dial-up or dedicated link, a satellite channel, a packet type
data
link, the Internet, a wireless link, or other low data rate communication
method.
In some embodiments, re-transmitted signal portions or frames of data to
be transferred to a presentation location or theater can also be accomplished
using return link 113. That is, return link 113 is configured as a two-way
link for
transferring data that includes for example re-transmission requests or other
information from a theater to the central hub, or commands, general operating
information, or compressed image and audio information from the central hub
to the theater. This two-way link can also be used for transferring
cryptographic
key data, as discussed further below.
Theater system 104 (104A-104N) is constructed with at least one and
generally multiple auditoriums 128A-128M. For example, in some commercial
markets theaters are constructed as theater complexes having many auditoriums
at a single site, often referred to as cineplex or multiplex theaters. The
received
signal can be broadcast or transferred to multiple oines of the auditoriums
within
a single theater complex.
The demodulated signal is sent from receiver/demodulator 120 to a
central storage system 123 using storage arrays 124A-124N via a Theater
Interface Network (TIN) 126 for storage. The size of storage arrays 124A-124N
is
scaleable to support theater complexes with varying numbers of projection
auditoriums. The demodulated signal may instead be presented to one of
auditoriums 128A-128M via Theater Interface Netmrork 126 when a presentation
is desired while the information is being received from central hub 102 (i.e.,
for
"live event" presentations).
When a program is to be viewed, the program information is retrieved
from storage arrays 124A-124N and transmitted to one or more of designated
auditoriums 128A-128M using TIN 126. If the designated auditorium is
auditorium 128A, a decoder 130A decrypts the broadcast signal using secret key
information provided only to authorized theaters, and decompresses the signal
using the decompression algorithm which is inverse to the compression
algorithm used at Source Generation System 108 (SGS). Decoder 130A converts
the decompressed image information to a standard video format used by the
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projection system (which may be either an analog or digital format) and the
image is displayed through an electronic projector 132A. The audio information
is also decompressed and provided to the auditorium's sound system 134A for
playback with the image program. Once the period of time in which the
authorized presentation of a certain program is complete, the digitized
program
information is erased from designated one(s) c-r members of storage arrays
124A-124N to prevent unauthorized use of the material. Although not
specifically illustrated, auditoriums 128B-128M each comprise a decoder, a
projector, and a sound system.
When multiple viewing locations are desired, central storage system 123 is
configured to transfer compressed information of a single image program to
different auditoriums with preselected programrnable offsets or delays in time
relative to each other. These preselected programmable offsets are made
substantially equal to zero or very small when a single image program is to be
presented to selected multiple auditoriums substantially simultaneously. At
other times, these offsets can be set anywhere from a few minutes to several
hours, depending on the storage configuration and capacity, in order to
provide
very flexible presentation scheduling. This allows a theater complex to better
address market demands for presentation events such as first run films.
Presentation of real-time live-event programming is similar to that of
motion pictures, but bypasses the store-and-playback operation of storage
arrays
124A-124N, or uses such storage as a shorter term buffer to account for
potential
transient signal transfer interruptions or synchronization issues.
Optionally, one or more digital tape recorders 136 are provided in theater
system 104. Tape recorder 136 may be used when, a satellite link or some other
broadcast technology is unavailable, or when such technology is not a
preferred
method of transfer, such as for cost or availability reasons. In this case, a
magnetic tape or other portable media is used to clistribute the program from
a
central distribution point to theater 104. Tape recorder 136 transfers the
program to storage arrays 124A-124N using TIN 126. The program information
is then available for display at a later time. Image and audio programs may
also
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be recorded from disk storage arrays 124A-124N to tape recorder 136 for long
term archival storage for later reloading into the storage arrays 124A-124N.
Other means for higher density, high throughput data storage may be
used, replacing digital tape recorder 136. For example, other known storage
systems using optical disk technologies, like CD R:OM storage devices or
digital
versatile disks ("DVD"), or even certain solid state memory arrays may be used
within the invention.
Exemplary embodiments of the processing blocks of central hub 102 are
illustrated in FIGS. 3-9 and described herein. Soiurce generation system 108
is
shown in FIG. 3. In an exemplary embodiment, source generation system 108
digitizes a film image source such as a 35 mm motion picture film, and stores
the
digitized version on a magnetic tape. Source generation system 108 comprises
high definition (HD) "telecine" apparatus or process 140 for receiving film
source 142 and for generating digitized images from film 142. The telecine
processing is well known within the motion picture industry, and any one of
several commercially available services or devices may be used to implement
this process. However, in a preferred embodirrient, high resolution telecine
processing is used such as is currently available with equipment produced by
CINTEL or Philips BTS, as is known in the art. The resolution and specific
choices of equipment used are determined according to cost and other well
known factors when a service is being designed. Alternative resolutions can
also
be used depending on the target audience, projection equipment available, and
location, including a desire to reduce data rates for certain satellite
transfers.
If the original film is a standard format 35 mm source, the process is
performed on the image using a telecine process at 24 frames per second. The
digitized output of the telecine process may be stored using a high data rate
magnetic tape recorder or immediately compressed and/or encrypted and
stored using a lower data rate tape recorder, or other known image storage
system and media.
Since the telecine only processes the image, the audio portion of the input
source is processed independently of the image. If the audio source is in
analog
format, it is typically provided on a magnetic tape 1.44 to an audio reader
146 for
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digitizing. In one embodiment, up to twelve channels of digitized audio are
combined with the digitized image by a multiplexer 148, and the multiplexed
signal is stored with the image program on a higl:l definition digital video
tape
recorder (VTR) 150 or similar high capacity digital storage system.
Alternatively, as mentioned above, the audio programming may be stored and
processed separately from the image programming, but with time
synchronization information included to allow for properly time aligned
combination with the image program at the projection auditorium playback
system.
Although shown as part of central hub 102, it should be understood that
source generation system 108 may be located in a facility other than central
hub
102. Other facilities may be just as suitable for generating the digitized
signal
from a magnetic or an optical source. Alternatively, Source Generation System
108 may consist of a digital camera with a magnetic or optical storage device
built in or other digital means of image generation (such as for computer
generated graphics or special effects) which directly produces digital source
material. Source Generation System 108 may also consist of a digitization
system
for still images, such as an optical scanner or an image converter used for 35
mm
photographic slides or prints. Therefore, regular or specialized studios such
as
for special effects, or other facilities participatirig in the preparation and
presentation of an image program can generate the desired digitized material
which is then transferred to central facility or hub 102 for further
processing or
transmission.
A block diagram of compression/encryption system 110 is illustrated in
FIG. 4. Similar to source generation system 108, compression/encryption system
110 may be part of central hub 102 or located in a separate facility. For
example,
compression/encryption system compression/enciryption system 110 may be
located with source generation system 108 in a film or television production
studio. In addition, the compression process for either image or audio
information or data can be implemented as a variable rate process.
Compression/encryption system 110 receives a digital signal, which may
be provided by digital VTR 150 of source generation system 108. The digital
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image and audio information may be stored in frame buffers (not shown) before
further processing.
The digital image signal is passed to an image compressor 162. In a
preferred embodiment, image compressor 162 processes a digital image signal
using the ABSDCT technique described in U.S. Pat. Nos. 5,021,891, 5,107,345,
and
5,452,104 mentioned above.
In the ABSDCT technique, the color input signal is generally in a YIQ
format, with Y being the luminance, or brightness, component, and I and Q
being the chrominance, or color, components. Ot11er formats such as the YUV or
RGB formats may also be used. Because of the low spatial sensitivity of the
eye
to color, the ABSDCT technique sub-samples the color (I and Q) components by
a factor of two in each of the horizontal and veirtical directions.
Accordingly,
four luminance components and two chrominance components are used to
represent each spatial segment of image input.
Each of the luminance and chrominance components is passed to a block
interleaver. Generally, a 16x16 block is presented to the block interleaver,
which
orders the image samples within the 16x16 blocks to produce blocks and
composite sub-blocks of data for discrete cosine t:ransform (DCT) analysis.
The
DCT operator is one method of converting a time-sampled signal to a frequency
representation of the same signal. By converting to a frequency
representation,
the DCT techniques have been shown to allow for very high levels of
compression, as quantizers can be designed to talce advantage of the frequency
distribiition characteristics of an image. In a preferred embodiment, one
16x16
DCT is applied to a first ordering, four 8x8 DCTs are applied to a second
ordering, 16 4x4 DCTs are applied to a third ordering, and 64 2x2 DCTs are
applied to a fourth ordering.
The DCT operation reduces the spatial redundancy inherent in the image
source. After the DCT is performed, most of the innage signal energy tends to
be
concentrated in a few DC coefficients.
For the 16x16 block and each sub-block, the transformed coefficients are
analyzed to determine the number of bits required to encode the block or sub-
block. Then, the block or the combination of sub-blocks which requires the
least
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number of bits to encode is chosen to represent the image segment. For
example,
two 8x8 sub-blocks, six 4x4 sub-blocks, and eight 2x2 sub-blocks may be chosen
to represent the image segment.
The chosen block or combination of sub-blocks is then properly arranged
in order. The DCT coefficient values may then undergo further processing such
as, but not limited to, frequency weighting, quantization, and coding (such as
variable length coding) using known techniques, in preparation for
transmission.
The compressed image signal is then provided to at least one image encryptor
166.
The digital audio signal is generally passed to an audio compressor 164.
In a preferred embodiment, audio compressor 164 processes multi-channel audio
information using a standard digital audio compression algorithm. The
compressed audio signal is provided to at least one audio encryptor 168.
Alternatively, the audio information may be transferred and utilized in an
uncompressed, but still digital, format.
Image encryptor 166 and audio encryptor 168 encrypt the compressed
image and audio signals, respectively, using any of a number of known
encryption techniques. The image and audio signals may be encrypted using the
same or different techniques. In a preferred embodiment, an encryption
technique, which comprises real-time digital sequence scrambling of both image
and audio programming, is used.
At image and audio encryptors 166, 168, the programming material is
processed by a scrambler/encryptor circuit using a time-varying electronic
keying information (typically changed several times per second). The scrambled
program information can then be transmitted, such as over the air in a
wireless
link, without being decipherable to anyone who dDes not possess the associated
electronic keying information used to scramble the program material or digital
data.
Encryption generally involves digital sequence scrambling or direct
encryption of the compressed signal. The words "encryption" and "scrambling"
are used interchangeably and are understood to rriean any means of processing
digital data streams of various sources using any of a number of crvptographic
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techniques to scramble, cover, or directly encrypt said digital streams using
sequences generated using secret digital values ("keys") in such a way that it
is
very difficult to recover the original data sequerice without knowledge of the
secret key values.
Each image and audio program uses specific electronic keying
information which is provided, encrypted by pr+esentation-Iocation or theater-
specific electronic keying information, only to theaters or presentation
locations
authorized to show that specific program. The encrypted program key is needed
by the auditorium to decrypt the program data stream. The encrypted program
key is transmitted, or otherwise delivered, to the authorized theaters prior
to
playback of the program. Note that the program data stream may be
transmitted days or weeks before the authorized showing period begins and that
the encrypted program key may be transmitted just before the authorized
playback period begins. The encrypted program key can also be transferred
using a low data rate link, or a transportable storage element such as a
magnetic
or optical media disk, a Smart card, or other devices having erasable memory
elements. The encrypted program key may be provided in such a way as to
control the period of time for which a specific theater complex or auditorium
is
authorized to show the program.
Each auditorium that receives an encrypted program key decrypts this
value using its auditorium specific key, and stores this decr_ypted program
key in
a memory device or other secured memory.
When the program is to be played back, tl:ie theater or location specific
and program specific keying information is used, preferably with a symmetric
algorithm, that was used in encryption system 11.0 in preparing the encrypted
signal to now descramble/decrypt program informLation in real-time.
In addition to scrambling, image encryptor 166 may add a "watermark,"
which is usually digital in nature, to the image prcigramming. This involves
the
insertion of a location specific and/or time specific visual identifier into
the
program sequence. That is, the watermark is constructed to indicate the
authorized location and time for presentation, for more efficiently tracking
the
source of illicit copying when necessary. The watermark may be programmed to
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appear at frequent, but pseudo-random periods in the playback process and
would not be visible to the viewing audience. Tl'ie watermark is perceptually
unnoticeable during presentation of decompressect image or audio information
at what is predefined as a normal rate of transfer. However, the watermark is
detectable when the image or audio information is presented at a rate
substantially different from that normal rate, such as at a slower "non-real-
time"
or still frame playback rate. If an unauthorized copy of a program is
recovered,
the digital watermark information can be read by authorities, and the theater
from which the copy was made can be determined. Such a watermark technique
may also be applied or used to identify the audio pirograms.
The compressed and encrypted image and audio signals are both
presented to a multiplexer 170. At multiplexer 170, the image and audio
signals
are multiplexed together along with time synchronization information to allow
the image and audio streams to be played back in a time aligned manner at
theater system 104. The multiplexed signal is then processed by a program
packetizer 172, which packetizes the data to form the program stream. By
packetizing the data, or forming "data blocks," the program stream received at
theater system 104 (FIG. 2) may be monitored for errors in received blocks,
and
retransmission requests made only for those data blocks exhibiting errors
instead
of an entire program. This provides for increased reliability and efficiency
in
transmission.
In an alternate embodiment of the present invention, the image and audio
portions of a program are treated as separate and distinct programs. Thus,
instead of using multiplexer 170 to multiplex the :image and audio signals,
the
image signals are separately packetized for transport. In this embodiment, the
image signal may be transported exclusive of the audio signal, and vice versa.
The image and audio programs are assembled intc> combined programs only at
playback time. This allows for different audio programs to be combined with
image programs for various reasons, such as varying languages, providing post-
release updates or program changes, to fit within local community standards,
and so forth. This ability to flexibly assign audio different multi-track
programs
to image programs is very useful for minimizing costs in altering programs
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already in distribution, and in addressing the larger multi-cultural markets
now
available to the film industry.
Compressors 162, 164, encryptors 166, 168, inultiplexer 170, and program
packetizer 172 may be implemented in a software-controlled processor
programmed to perform the functions described herein. That is they can be
configured as generalized function hardware including a variety of
programmable electronic devices or computers that operate under software or
firmware program control. They may alternatively be implemented using some
other technology such as through an ASIC or through one or more circuit card
assemblies. That is, constructed as specialized hardware.
The image and audio program stream is sent to a storage array 174. The
program stream may additionally be sent to digital linear tape recorder 176.
A CES controller 178 is primarily responsible for controlling and
monitoring the entire compression/encryption system 116. CES controller 178
may be implemented by programming a general purpose hardware device or
computer to perform the required functions, or by using specialized hardware.
Network control is provided to CES controller 178 from network management
system 112 (FIG. 2) over a hub internal network, which will be described
later.
CES controller 178 communicates with compressors 162, 164, encryptors 166,
168,
multiplexer 170, and packetizer 172 using a known. digital interface and
controls
the operation of these elements. CES controller 178 also controls and monitors
array 174, digital linear tape recorder 176, the data transfer between these
devices, and modulation transmission system 114 (FIG. 2).
Storage array 174 is preferably constructed as a bank of hard disk drives,
which in general will be of similar design as the disk storage array 124 using
in
theater systems 104 (FIG. 2). However, those skilled in the art will recognize
that
other media such as re-writable optical disks could be used in some
applications.
The capacity of central hub disk storage array 174 may be lower than that of
all
theater systems 104 (total of all auditoriums or locations) combined because
typically only one program needs to be stored in storage array 174 at one
time.
Generally, a new program is stored after each program has been transferred and
removed from memory. However, multiple programs can be stored at one time,
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and even transferred at one time over a given link, depending on the equipment
being used to receive the transferred material. Disk storage array 174
receives
compressed and encrypted image, audio, and conitrol data from either program
packetizer 172 or digital linear tape recorder 176 during the compression
phase.
During the transmission phase, disk storage array 174 sends the stored data to
modulation transmission system 114. The operation of disk storage array 174 is
managed by CES controller 178.
A control multiplexer 180 receives the prog:ram stream from disk storage
array 174 and control information from CES controller 178. Control multiplexer
180 multiplexes these two data streams, and presents the multiplexed data
stream to a transport packetizer 182. Transport packetizer 182 packetizes the
data stream to form the transport data stream, and sends the packetized stream
to modulation transmission system 114.
Digital tape recorder 176 (DTR) is used for archiving the compressed
image and audio, and for the distribution of taped programs to theaters that
don't have an available satellite or other desirable ivireless or wireline
link. That
is, for generating tapes of digital information for distribution. Tape
recorder 176
receives compressed and encrypted image, audio, and control data from
program packetizer 172 during the compression plhase. A program may be de-
archived when tape recorder 176 transfers the tape--recorded data to disk
storage
array 174. The operation of digital linear tape recorder 176 is managed by CES
controller 178.
Modulation/transmission system 114 is illustrated in FIG. 5.
Modulation/transmission system 114 performs the modulation and transmission
of the transport data stream from compression/encryption system 110.
Modulation/transmission system 114 comprises at least one modulator 200 and
an IF upconverter 202, which are typically located i;n the same physical
facility as
compression/encryption system 110, network management system 112, and
collocated theater system 116. (FIG. 2.) Modulation/transmission system 114
further comprises an RF converter 204, a high power amplifier 206, and a
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Modulation/Transmission System controller 208, which are located within or
next to an earth station 210.
Modulator 200 is a standard subsystem that adds forward error correction
information and modulates the transport data stream for transmission over a
satellite (or other wireless transmission path) using known techniques.
Convolutional and concatenated Reed-Solomon encoding techniques known in
the art are used, in a preferred embodiment, for the forward error correction
function. A standard PSK (phase shift keying) rYiodulator may be used for the
modulation function.
IF upconverter 202 converts the output from modulator 200 to an
intermediate frequency (IF) of, for example, 140 MHz. This signal is then
provided to RF upconverter 204. Implementation of this subsystem may be
accomplished through the use of existing equipment with only minor
modifications for compatibility with the rest of the system, as would be
known.
RF upconverter 204 will generally be a staridard subsystem that converts
the IF signal to a transmit signal suitable for satellite transmission. In a
preferred
embodiment, an IF signal at 140 MHz is converted to a Ku-band signal. The Ku-
band output is tunable from about 14.0 GHz to 14.5 GHz. Two upconverters and
an automatic switch over unit (not shown) may be implemented to provide
equipment redundancy for improved system reliability. This output is provided
to high power amplifier 206 for amplification. Frequency bands other than the
Ku-band may alternatively be used for transmission of the signals by
satellite, or
as desired.
High power amplifier 206 amplifies the Ku-band (or other desirable
frequency) transmit signal for transmission up to a satellite transponder. Two
high power amplifiers and an automatic switch over unit (not shown) may be
used to provide equipment redundancy for improved system reliability.
MTS (modulation/transmission system) controller 208 may be used to
interface with, configure, and monitor the equipment in earth station 210.
Controller 208 may be implemented using well known programmable hardware,
such as a personal computer or workstation.
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Earth station 210 consists of all RF intercon.nections and an antenna. An
RF hut or structure is generally included that houses RF upconverter 204, HPA
206, MTS controller 208, and power and air conditioning equipment (not shown)
where useful. Generally, programming and control information are broadcast
from earth station 210 to the theater systems using one or more common
broadcast channels. The broadcast signal conitains control information for
notifying. the theater systems of the identity of each broadcast program.
Furthermore, control information is transmitted to the theater systems so that
a
theater selectively stores only received programmiing intended for the
particular
theater system and for other control functions associated with system
operation.
As mentioned, this information can typically be i:ransferred over either a
high
speed/rate or low data rate link, as desired.
Referring now to FIG. 6, network managenlent system 112 is illustrated.
Network management system 112 controls and manages digital cinema system
100. This includes control and monitoring of the components of central hub 102
and the network of theater systems 104. The control may be centralized, so
that
network management system 112 manages the total operation of the system,
including control of the broadcasting or transfer, pI.ayback/display,
security, and
overall network management functions. Alternatively, a distributed
management system, in which processors in the presentation or theater systems
control some of the theater functions, may be implemented.
Network management system 112 comprises at least one network
management processor 220, which is the central co:ntroller or "brain" for
digital
cinema system 100. Network management system 112 is, in general, based on a
standard platform workstation, or similar programmable data processing
hardware. Network management processor 220 manages the scheduling and
security aspects of digital cinema system 100.
Under control of network management system 112, programs may be
broadcast from central facility or hub 102 in advance of the time for display
of
the programming at theater 104. This procedure will generally be utilized
unless
a real-time live-event broadcast is desired. Thus, a separate process controls
the
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playback of the pre-stored programming material at a time later than that of
the
broadcast transmission from central hub 102.
Network management processor 220 also controls the broadcast,
transmission, or transfer rate of the programs. The transmission rate may be
fixed or varied depending on the type of program and the design of the
transfer
channel or path. For example, this may depend on the transfer rates for a
particular satellite transponder, or other data link. Parallel program
transfers
might also occur at higher rates. For programs which are stored and played
back at a later time, the transmission data rate may be greater than, less
than, or
equal to the "real-time" rate for that program. Also, the data rate of the
compression coding of the programming material may vary for different
programs, offering varying quality levels of compression. Transmission of live
event programming is supported with data transmissions at the same rate as the
compression rate.
A redundant network management processor may be provided as a
backup. Network management processor 220 interfaces to the other components
in the system over a hub internal network, which is typically implemented
using
a standard multi-drop network architecture, such as Ethernet. However, other
known network designs and types including opt:ical based links can be used.
Here, an Ethernet hub 224 of network management system 112 supports the hub
internal network, as discussed later with reference to FIG. 8.
Network management system 112 may also comprise a modem bank 226,
which provides the interface to the network of theaters over the PSTN and
generally consists of a set of dialup telephone modems, cable or satellite
modems, ISDN or cellular link controllers, or other known means. Modem bank
226 interfaces to network management processor 220 via a modem server
function. Modem bank 226 serves as the receiver of a return link communication
path from the theaters to central hub 102. The return path may be utilized by
the
theaters to request retransmission of program data blocks with errors from
central hub 102. Furthermore, extra presentations of programs, or changes or
updates in program material can be requested usirtg this link. The requests
for
retransmission and the retransmission themselves inay occur during or after
the
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transmission of the program material. In alternative embodiments, the return
path may be provided through a satellite chan.nel or other low data rate
communication method or via the Internet. In this case, other known means or
devices for interfacing are implemented, as appropriate, instead of modem bank
226.
Collocated theater system 116, illustrated in FIG. 7, monitors the quality of
the transmitted signal and provides a quality measurement to network
management system 112.
Collocated theater system 116 comprises at least one theater system
receiver 232, which typically will have the same design as a receiver of a
theater
system 104. Receiver 232 interfaces with at least one receiver antenna 234 for
receiving the signal transmitted from modulation transmission system 114
through satellite 106. Alternatively, a cable or optical feed interface is
used when
other types of links are employed, in order to test the quality of such links.
Collocated theater system 116 also comprises at least one management processor
236, which receives the signal from theater system receiver 232 and measures
the
quality parameters of the transmitted signal. Management processor 236 also
provides a quality report to network management system 112. In a preferred
embodiment, management processor 236 interfaces with network management
system 112 over an Ethernet or high speed data bus.
Referring now to FIG. 8, a block diagram o:f hub internal network 250 is
illustrated. Hub internal network 250 is the communication backbone for
central
hub 102. Hub internal network 250 may be extended internally as an Ethernet
Local Area Network (LAN) running an IP protocol suite. Thus, hub internal
network 250 physically interconnects compression/encryption system 110
(110A-110B), modulation/transmission system 114 (114A-114B), network
management processor 220, and collocated theater system 116 (116A-116B) in the
central hub. As appropriate to the specific functional partitioning of local
and
remote functions, an external interface may also be provided to connect
central
hub 102 to an external computer network or communication system, if desired.
In a preferred embodiment, central hub 102 provides for redundant or
backup components to meet the availability requirements in the event of a
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primary component failure. Each system within central hub 102 has a primary
system and either a parallel backup system or has built-in redundancy with
automatic switch over capability, as shown further in FIG. 8. Therefore, hub
internal network 250 is connected to compression/encryption systems 110A and
110B, modulation/transmission systems 114A anci 114B, network management
processors 220A and 220B, and collocated theater systems 116A and 116B using a
series or sets of redundant Ethernet transceivers, 254A-254E. These
transceivers
communicate through two or more Ethernet Cards, here, designated as cards A
and B or elements 252A and 252B. It will be readily understood by those
skilled
in the art how to provide the redundant systerrts and connections, and that
additional numbers of systems can be used for greater levels of redundancy as
desired, with appropriate interconnections anci interface elements. The
redundant processing capabilities are provided to assure reliable operation in
highly time sensitive and demanding presentation markets, such as for first
run
motion pictures. Some of the redundant components can be operated in a
"standby" or "warm start" mode as desired for rapid selection and switch over
when needed.
As previously discussed, the audio/visual programming is distributed
from central hub 102 to presentation or theater systems such as theater system
.20 104. Exemplary embodiments of the processing blocks of theater system 104
are
illustrated in FIGS. 9-11 and described herein.
FIG. 9 illustrates receiver/demodulator 120 of theater system 104.
Receiver/demodulator 120 comprises outdoor unit 270, which includes a low
noise block and a parabolic dish antenna pointed at or tracking satellite 106.
Outdoor unit 270 receives the signal transmitted from central hub 102,
amplifies
it, and converts it to an intermediate frequency (IF) in preparation for
further
processing. The dish antenna is generally an offset feed dish antenna. The
size
of the antenna generally ranges from 1.0 to 1.6 meters in diameter depending
on
the geographic location of the receiver and freqwencies of interest. The dish
antenna may be mounted on a pole, penetrating or non-penetrating roof mount.
Typically, the size of the dish will be designed to be small enough to avoid
restrictions under various governmental or other regulatory ordinances. The
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low noise block is typically a standard digital video broadcast low noise
block
(DVB LNB) that amplifies the received signal and downconverts it to an IF for
the demodulator to process. In one embodimeint, the output signal from the
LNB is an IF in the L-band frequency range. The LNB has a feed horn that is
installed at the focal point of the dish antenna. A standard coaxial cable
connects
the LNB to a demodulator 272 of receiver/demodulator 120.
Receiver/demodulator 120 also comprises a demodulator 272, an
automatic request for retransmission (ARQ) processor 274, and a transport
demultiplexer 276. In a preferred embodiment, these three components are
implemented as a plug-in circuit card assembly for a general purpose computer
such as a known IBM-compatible type personal computer or a workstation. The
circuit card assembly may be installed inside theater management system 122.
Recall that although a program is broadcast from central hub 102, and
although theater system 104 is capable of receiving all transmitted programs,
theater system 104 will selectively demodulate and store only received
programming intended for the particular theater system. Control information is
included in the broadcast signal to inform the theater systems of programming
intended specifically for them through multiplexing this control information
in
the transmitted program stream.
Thus, demodulator 272 recovers the data and clock of the selected
programming from the IF signal received from outdoor unit 270. Demodulator
270 may implement any of a number of demodulation techniques, such as a
QPSK demodulation technique when the prograrn signal had been modulated
using a QPSK scheme. Demodulator 270 may be a standard integrated circuit
such as typically used in set-top receiver equiprnient for direct broadcast
video
reception. Such demodulator devices generally include forward error correction
(FEC) signal processing functions. Error correction may, for example, be
performed using convolutional encoding with 'Viterbi decoding along with
concatenated Reed-Solomon encoding and decoding. In a preferred
embodiment, the convolutional code is a k=7, :r=7/8 code while the Reed-
Solomon is a (204,188) code. The error corrected output is provided to ARQ
Processor 274.
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ARQ processor 274 performs further error correction on the signals from
demodulator 270. ARQ Processor 274 computes a digital signature, using
methods such as cyclic redundancy check (CRC) codes, fixed length blocks of
sequential data of the demodulated signal. The resulting computed digital
signature for each block is compared to a digital signature value which was
computed using the same digital signature algorithm by
Modulation/Transmission System 114 at the central hub 102 and which has been
transmitted along with the data stream over the satellite channel. If the
digital
signature computed by ARQ Processor 274 is not identical to that transmitted
with the data, a block error is indicated. Each such data block is uniquely
identified by a block identification value. ARQ Processor 274 records the
block
identifier value for any block which exhibits a difference in the computed and
transmitted digital signature value for that block. Theater Management System
122 may utilize Return Link 284 to request retransmission of any or all of the
data blocks with mis-compared digital signatures. Central Hub Network
Management System 112 may then re-transmit those blocks requested by Theater
Systems 104. Theater Management System 122 may replace blocks in which the
transmitted and locally computed digital signatures are not identical with the
re-
transmitted blocks with the same block identification values. Such methods
greatly reduce the resulting error rate of the received signals. The output
data
from ARQ processor 274 will preferably have an error rate between 1x10-' and
1x10"", or less. Data is then provided to a Transport Demultiplexer 276.
Transport demultiplexer 276 depacketizes the demodulated data stream,
sends command packets to theater management system 122, and sends
compressed/encrypted image and audio packets to storage array 124.
An exemplary theater management systern 122 is illustrated in FIG. 10.
Theater management system 122 provides operational control and monitoring of
the entire presentation or theater system 104, or auditoriums within a theater
complex. The theater management system can also use a program control means
or mechanism for creating program sets from one or more received individual
image and audio programs, which are scheduled for presentation on an
auditorium system during an authorized interval.
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Theater management system 122 comprises a theater management
processor 280 and at least one modem 282, or other device that interfaces with
a
return link, for sending messages back to central hub 102 using a return link
284.
Theater management system 122 includes a visual display element such as a
monitor and a user interface device such as a keyiboard, which may reside in a
theater complex manager's office, ticket booth, or any other suitable location
that
is convenient for theater operations.
Theater management processor 280 is generally a standard commercial or
business grade computer. Referring to FIG. 10 with reference to FIG. 2,
theater
management processor 280 communicates with storage arrays 124A-124N,
decoder modules 130, and digital tape recorder 136 over Theater Interface
Network 126. Theater management processor 280 communicates with the
central hub network management system 112 via the return link 284. In a
preferred embodiment, modem 282 is used to communicate with central hub 102.
Modem 282 is generally a standard phone line imodem that resides in or is
connected to the processor, and connects to a standard two-wire telephone line
to communicate back to central hub 102. In alternative embodiments,
communications between the theater management processor 280 and central hub
102 may be sent using other low data rate comnlunications methods such as
Internet, private or public data networking, wireless, or satellite
communication
systems. For these alternatives, modem 282 is configured to provide the
appropriate interface structure.
Information communicated via return link 284 include requests for
retransmission of information received by theater system 104 from satellite
106
which are indicated as exhibiting uncorrectable bit errors, monitor and
control
information, operations reports and alarms, and possibly cryptographic keying
information. Messages communicated using return link 284 may be
cryptographically protected to provide eavesdropping tvpe security and/or
verification and authentication.
Theater management processor 280 may be configured to provide fully
automatic operation of the presentation systern, including control of the
playback/display, security, and network management functions. Theater
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management processor 280 may also provide control of peripheral theater
functions such as ticket reservations and sales, concession operations, and
environmental control. Alternatively, manual iintervention may be used to
supplement control of some of the theater operations. Theater management
processor 280 may also interface with certain existing control automation
systems in the theater complex for control or adjustment of these functions.
Still
alternatively, control of some theater operations, such as playback/display
and
security, may be provided over-the-air by centra}, hub 102. The system to be
used will depend on the available technology and the needs of the particular
theater, as would be known.
Through either control by theater managerrient system 122 or a network
management system, the present invention will generally support simultaneous
playback and display of recorded programming on multiple display projectors.
Multiple programs may be stored on a central storage system, comprising
storage arrays 124A-124N, for playback on one or more of the multiple display
projectors in theater system 104. As previously discussed, theater system 104
may also display the programming material as it is received from the broadcast
channel, thereby bypassing the storage capability of the system.
Furthermore, under control of theater management system 122 or a
network management system, authorization of a program for playback multiple
times can often be done even though theater systern 104 only needs to receive
the
programming once. Security management controls the period of time and/or
the number' of playbacks that are allowed for each program.
One can see that, through automated corttrol of theater management
system 122 by central facility network managerYtent system 112, a means is
provided for automatically distributing, storing, and presenting programs
under
programmable control from the central facility. In addition, there is the
ability to
control certain preselected network operations from a location remote from the
central facility using a control element. For example, a television or film
studio
can now automate and control the distribution of films or other presentations
from a central location, such as a studio office, and make almost immediate
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changes to presentations to account for rapid changes in market demand, or
reaction to presentations, or for other reason understood in the art.
Referring back to FIG. 2, it can be seen that theater interface network 126
physically interconnects theater management system 122, storage arrays 124A-
124N, auditoriums 128A-128M, and digital tape recorder 136. Theater interface
network 126 consists of a local area network (electric or optical) which
provides
for local routing of programming at theater systern 104. Programs received and
demodulated by receiver/demodulator 120 are routed through theater interface
network 126 to storage arrays 124A-124N for storage. Programs stored at
storage arrays 124A-124N or received for playback in real-time are routed
through theater interface network 126 to one or more of the projection
system(s)
at theater system 104. The theater interface network may be implemented using
any of a number of standard local area network architectures which exhibit
adequate data transfer rates, connectivity, and reliability such as arbitrated
loop,
switched, or hub-oriented networks.
Still referring to FIG. 2, storage arrays 124A-124N provide for local
storage of the programming material that it is authorized to playback and
display. In a preferred embodiment, the storage system is centralized at each
theater system. Storage arrays 124A-124N allow the theater system to create
presentation events in one or more auditoriums and can be shared across
several
auditoriums at one time.
Storage arrays 124A-124N, also sometimes referred to as disk storage
arrays 124A-124N, may comprise solid state, magnetic, or optical mass storage
devices, well known in the art. In preferred embodiments, magnetic disk
drives,
known as hard drives, as used in the computer irtdustry are used to create the
storage arrays. Such devices have desirable cost and performance (transfer
rate)
characteristics that make them well suited for the present invention. They
represent well known technology and are being manufactured with ever
increasing capacities. However, other devices, such as re-writable optical
storage devices and even solid state memory devices may be useful for some
applications.
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The central storage system may store several programs at a time. The
central storage system is connected via a local area network in such a way
that
any program may be played back and presented on any authorized presentation
system (i.e., projector). Also, the same program nriay be simultaneously
played
back on two or more presentation systems.
As discussed above, the storage arrays can be used to transfer compressed
information of a single image program to different auditoriums with
preselected
programmable offsets or delays in time relative to each other. When these
offsets are made substantially equal to zero a single image program is
presented
to multiple auditoriums substantially simultaneously. At other times, these
offsets are set at other values to accommodate various scheduling schemes.
Each of disk storage arrays 124A-124N is a bank of hard disk drives that
stores encrypted/compressed programs for scheduled playback periods in
designated auditoriums. Disk storage arrays 124A-124N are designed to be
scaleable to efficiently support the storage requirements of each theater.
Further,
each of disk storage arrays 124A-124N includes biuilt-in redundancy to prevent
loss of stored programming information in the event of a storage unit failure.
Each of storage arrays 124A-124N may, for example, be a rack-mounted system
which is expandable to accommodate the varying storage requirements of each
theater system. The use of disk storage arrays 124A-124N allows theater
management to dynamically route program showings to the various screens in a
theater complex, and to schedule pre-feature programming. This is
accomplished in a highly flexible manner useful to, respond quickly to
changing
needs or market demands.
In a preferred embodiment, each of storage arrays 124A-124N is designed
with a capacity for storage equal to that needed to store programs for all
auditoriums in the theater location. In addition, adequate storage is provided
so
that future programs may be stored prior to theiir showing authorization date
while still storing the currently "authorized for showing" programs. This
amount of available storage capacity allows for p:rograms to be authorized for
future showing to be transmitted hours, days or weeks prior to the
authorization
to playback and display such programs without affecting the ability to
playback
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and display the presently authorized programs. It has been estimated that in
terms of digital data storage capacity, on the order of 120 GigaBytes of
storage
capacity per auditorium is used in this type of arrangement. This capacity is
assuming the use of current compression and image technology, which may
change to allow reduced requirements in the near future.
Disk storage space is dynamically allocated for each program loaded into
disk storage arrays 124A-124N. This concept works for larger theaters with
multiple screens because the short and long progi-ams average out to a nominal
length, typically of around two hours. As a guideline for single screen
theaters,
the storage capacity should be sufficient to store the longest programs.
Disk storage arrays 124A-124N are generally configured to provide
simultaneous read/write capability. For example, multiple previously stored
programs may be presented (with multiple simultaneous, or near simultaneous,
separate read operations) while a new release is downloaded from satellite 106
(write operation). Using current technology, there is a physical limitation in
the
throughput of each array of disk storage arrays 124A-124N. Therefore, each
array can support a maximum number of simultaneous, or nearly simultaneous,
read operations screens and one simultaneous download session (one write
operation). Using this scheme, larger theaters require additional disk storage
arrays to provide for an adequate number of sir.nultaneous playbacks. It has
been estimated that on the order of one additional array per every five
auditoriums is appropriate.
However, the storage arrays should also be configured or configurable to
operate in a"striping ' mode where received information is striped across the
array. That is, received data that is to be stored is directed in part to
different
ones of the drives during storage. Part of the input data is transferred to
one
drive while a subsequent portion is transferred tc> the next drive and so
forth.
After sufficient latency time to allow a drive to write data, a given drive
can
again be scheduled to receive input data. Therefore, received data is
segregated
into smaller components or segments, each of which is stored at the maximum
(or a high) rate allowed by each drive on separate drives, taking advantage of
input buffering or memory storage available in the drive input channel. This
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allows slower transfer rate devices to essentially pull in data in parallel
and,
therefore, accomplish a very high transfer rate., This type of storage also
provides error protection redundancy.
The storage of data on drives, or other storage devices, should utilize
parity information which allows the program to be reconstituted upon
retrieval.
That is, a means is provided for linking the program portions together again
at
time of retrieval or presentation.
Each of disk storage arrays 124A-124N is scaleable in two ways. The
amount of storage space per screen is adjustable by adding or deleting disk
drives within each of disk storage arrays 124A-124N. The size of the disk
drives
determines the incremental steps gained in storage capacity as drives are
added.
Alternatively, additional disk storage arrays can be added to theater system
104
to support additional screens.
In a preferred embodiment, each of disk storage arrays 124A-124N is
based on a Redundant Array of Inexpensive Devices (RAID) array design with
recovery capability of an entire data file if a disk drive in the array fails.
Disk
storage arrays 124A-124N provide status and warning indicators to assist in
trouble shooting or fault isolation. Remote status, control, and diagnostics
is
another option available with this type of design.
Still referring to FIG. 2, theater system 104 typically comprises a digital
tape recorder (DTR) 136. DTR 136 is used to load a compressed/encrypted
program in disk storage arrays 124A-124N when a satellite link is unavailable
and a tape is used to distribute the program to the theater. DTR 136
communicates to storage arrays 124A-124N over TIN 126.
Normally, DTR 136 will not operate with sufficient transfer rates to
support direct distribution from DTR 136 to the projection equipment. Also,
the
read and write operations tend to occur in bursts . Therefore, large buffers
are
used to stream data smoothly from DTR 136 directly to the projection
equipment. For these reasons, DTR 136 is used for archiving and for transfer
when no satellite channel is available. Programs loaded from DTR 136 are
stored
in the storage arrays 124A-124N for playback at the full speed appropriate for
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real-time playback rates. Control of DTR 136 is performed by theater
management system 122.
The addition of DTR 136 to theater system 104 allows theater complexes,
without satellite links or channels available, to implement and take advantage
of
all the other benefits associated with the digital cinema system. In this
case,
digitized encrypted films require being physically delivered to the theaters
on
magnetic tape, similar to today's film distribution techniques. In addition,
DTR 136 may be used for long term archive of programs previously received and
stored on storage arrays 124A-124N. In this case, the program may be written
from storage arrays 124A-124N to DTR 136 and the resulting recorded tape may
be kept for later reloading back to storage arrays 124A-124N. In addition,
other
known magnetic, optical, or solid state storage devices or technologies may be
utilized to perform the function of DTR 136.
When a program is to be viewed, program information is transmitted
from a particular one or more of storage arrays 124A-124N to a particular one
of
auditorium system 128A-128M of theater system 104 via theater interface
network 126. A block diagram of an exemplary implementation of auditorium
system 128A-128M is illustrated in FIG. 11. Within such auditorium system
128a-128M, decoder 130a processes a compressed/encrypted program to be
visually projected onto a screen or surface and audibly presented using sound
systems 134. Auditorium system 128A-128M comprises a theater interface
network 290, at lest one depacketizer 292, an auditorium controller 294, an
image
decryption/decompression system 296, an audio decryption/decompression
system 298, a projector 132A, and a sound system 134A. All of the components,
with the exception of projector 132A and sc-und system 134A may be
implemented on one or more circuit card assemblies. The circuit card
assemblies
may be installed in a self-contained enclosure that mounts on or adjacent to
projector 132A. Additionally, a cryptographic smart card 300 may be used
which interfaces with auditorium controller 294 and/or image
decryption/decompression system 296 for transfer and storage of unit-specific
cryptographic keying information.
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Theater interface network interface 290 allows each auditorium to
communicate with disk storage arrays 124A-124N or theater management
system 122 over theater interface network 126. Theater interface network
interface 290 includes a buffer memory such that information bursts can be
transferred at high data rates from disk storage arrays 124A-124N via theater
interface network 126 and processed at slower rates by other elements of the
auditorium system 128A-128M.
Control and monitoring data are passed between theater management
system 122 and auditorium controller 294 'while encrypted/compressed
programs are passed to image and audio decryption/decompression systems
296, 298 through this interface. Any information dlirected to auditorium 128A
is
received and passed to depacketizer 292. Conve;rsely, information directed to
other parts of theater system 104 is ignored by depacketizer 292.
Depacketizer 292 identifies and separates the individual control, image,
and audio packets that arrive from theater interface network interface 290.
Control packets are sent to auditorium controller 294 while image and audio
packets are sent to image and audio decryption/decompression systems 296 and
298, respectively.
Auditorium controller 294 configures, manages the security of, operates,
and monitors auditorium system 128A. This includes the external interfaces,
image and audio decryption/decompression systems 296 and 298, along with
projector 132A and sound system 134A. Control information comes from theater
management system 122, a remote control port, or a local control input, such
as a
control panel on the outside of the auditorium system 128A housing or chassis.
Auditorium controller 294 manages the electronic keys assigned to auditorium
system 128A. Preselected electronic cryptographic keys assigned to auditorium
system 128 are used in conjunction with the electronic cryptographic key
information that is embedded in the image and audio data to decrypt the image
and audio information before the decompression process. In a preferred
embodiment, auditorium controller 294 uses a standard micro-processor running
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embedded auditorium system 128A software, as a basic functional or control
element.
In addition, Auditorium controller 294 is preferably configured to work or
communicate certain information with theater management system 122 to
maintain a history of presentations occurring in each auditorium. Information
regarding this presentation history is then available for transfer to central
facility
102 using the return link, or through a transportable medium at preselected
times.
Image decryption/decompression system 296 takes the image data stream
from depacketizer 292, performs decryption, and reassembles the original image
for presentation on the screen. The output of this operation generally
provides
standard analog RGB signals to digital cinema projector 132A. Typically,
decryption and decompression are performed in real-time, allowing for real-
time
playback of the programming material.
Image decryption/decompression system 296 decrypts and decompresses
the image data stream to reverse the operation performed by image compressor
162 and image encryptor 166 of central hub 102. Each auditorium system 128
may process and display a different program from other auditorium systems 128
in the same theater system 104 or one or more auditorium systems 128 may
process and display the same program simultaneously. Optionally, the same
program may be displayed on multiple projectors delayed in time relative to
each other.
The decryption process uses previously provided unit-specific and
program-specific electronic cryptographic key information in conjunction with
the electronic keys embedded in the data stream to decrypt the image
information. (The decryption process has previously been described with
reference to FIG. 4.) Each auditorium system 128 is provided with the
necessary
cryptographic key information for all programs authorized to be shown on that
auditorium system 128.
A multi-level cryptographic key management system is used to authorize
specific presentation systems for display of specific programs. This multi-
level
key management system will typically utilize electronic key values which are
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specific to each authorized auditorium system 128, the specific image and/or
audio program, and/or a time varying cryptographic key sequence within the
image and/or audio program. An "auditorium specific" electronic key, typically
56 bits or longer, is programmed into each auditoriixrn system.
This programming can be implemented using several techniques, to
transfer and present the key information for use. For example, the return link
discussed above can be used through a satellite channel or other type of link
to
transfer the cryptographic information. Alternatively, smart card technology,
pre-programmed flash memory cards, and other known portable storage devices
can be used.
For example, a smart card may be designed so that this value, once loaded
into the card, cannot be read from the smart card memory. Physical and
electronic security measures are used to preveilt tampering with this key
information and to detect attempted tampering or compromise. The key is
stored in such a way that it can be erased in the event of detected tampering
attempts. The smart card circuitry includes a microprocessor core including a
software implementation of an encryption algorithm, typically Data Encryption
Standard (DES). The smart card can input values provided to it, encrypt (or
decrypt) these values using the on-card DES algorithm and the pre-stored
auditorium specific key, and output the result. Alternatively, the smart card
may be used simply to transfer encrypted electironic keying information to
circuitry in the auditorium system 128 which would perform the processing of
this key information for use by the image and audio decryption processes.
Image program data streams undergo dynamic image decompression
using an inverse ABSDCT algorithm or other iniage decompression process
symmetric to the image compression used in the central hub
compression/encryption system 110. If image compression is based on the
ABSDCT algorithm the decompression process includes variable length
decoding, inverse frequency weighting, inverse differential quad-tree
transformation, IDCT, and DCT block combiner deinterleaving. The processing
elements used for decompression may be implemented in dedicated specialized
hardware configured for this function such as an ASIC or one or more circuit
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card assemblies. Alternatively, the decompression processing elements may be
implemented as standard elements or generalized hardware including a variety
of digital signal processors or programmable electronic devices or computers
that operate under the control of special function software or firmware
programming. Multiple ASICs may be implentented to process the image
information in parallel to support high image data rates.
The decompressed image data goes through digital to analog conversion,
and the analog signals are output to projector 132A. Alternatively, a digital
interface may be used to convey the decompressed digital image data to the
projector 132A obviating the need for the digital-to-analog process.
Audio decryption/decompression system 298 takes the audio data stream
from depacketizer 292, performs decryption, and reassembles the original audio
for presentation on a theater's speakers or audio sound system. The output of
this operation provides standard line level audio signals to sound system
134A.
Similar to image decryption/decompression system 296, audio
decryption/decompression system 298 reverses the operation performed by
audio compressor 164 and audio encryptor 168 of central hub 102. Using
electronic keys from cryptographic smart card 304 in conjunction with the
electronic keys embedded in the data stream, decryption system 350 decrypts
the
audio information. The decrypted audio data is then decompressed.
Audio decompression is performed with an. algorithm symmetric to that
used at central hub 102 for audio compression. Multiple audio channels, if
present, are decompressed. The number of audio channels is dependent on the
multiphonic sound system design of the particular auditorium, or presentation
system. Additional audio channels may be transm:itted from the central hub 102
for enhanced audio programming for purposes such as multi-language audio
tracks and audio cues for sight impaired audiences. The system may also
provide additional data tracks synchronized to the image programs for purposes
such as multimedia special effects tracks, subtitling, and special visual cue
tracks
for hearing impaired audiences.
As discussed earlier, audio and data tracks may be time synchronized to
the image programs or may be presented asynchironously without direct time
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synchronization. Image programs may consist of single frames (i.e., still
images),
a sequence of single frame still images, or motion image sequences of short or
long duration.
If necessary, the audio channels are provided to an audio delay element,
which inserts a delay as needed to synchronize the audio with the appropriate
image frame. Each channel then goes through a digital to analog conversion to
provide what are known as "line level" outputs to sound system 134A. That is,
the appropriate analog level or format signals are generated from the digital
data
to drive the appropriate sound system. The line level audio outputs typically
use standard XLR or AES/EOU connectors found in most theater sound
systems.
Projector 132A presents the electronic representation of a program on a
screen. The high quality projector is based on advanced technology, such as
liquid crystal light valve (LCLV) methods for processing optical or image
information. Projector 132A receives an image signal from image
decryption/decompression system 296, typically in standard Red-Green-Blue
(RGB) video signal format. Information transfer for control and monitoring of
the projector 132A is typically provided over a digital serial interface from
auditorium controller 294.
Referring still to EIG.11, decoder module chassis 302 includes a fiber
channel interface 290, depacketizer 292, auditorium controller 294, image
decryption/decompression system 296, audio decryption /decompression
system 298, and cryptographic smart card 300. Decoder module chassis 302 is a
secure, self-contained chassis that also houses the encryption smartcard
interface,
internal power supply and/or regulation, coolirLg fans (as necessary), local
control panel, and external interfaces. The local control panel may use any of
various known input devices such as a membrane switch flat panel with
embedded LED indicators. The local control panel typically uses or forms part
of a hinged access door to allow entry into the chassis interior for service
or
maintenance. This door has a secure lock to prevent unauthorized entry, theft,
or tampering of the system. During installation, cryptographic smart card 300
containing the encryption keying information (the auditorium specific key) is
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WO 99/59335 45 PCT/US99/09418
installed inside decoder module chassis 302, secured behind the locked front
panel. The cryptographic smart card slot is accFSsible only inside the secured
front panel. The RGB signal output from the image decryption/decompression
system 296 to projector 132A is connected securely within decoder module
chassis 302 in such a way that the RGB signals cannot be accessed while the
decoder module chassis 302 is mounted to the projector housing. Security
interlocks may be used to prevent operation of the decoder module when it is
not correctly installed to the projector 302.
Sound system 134A presents the audio portion of a program on the
theater's speakers. In a preferred embodiment, sound system 134A receives up
to 12 channels of standard format audio signals, either in digital or analog
format, from audio decryption/decompression system 298.
Accordingly, a digital cinema system and method is provided for the
electronic distribution of very high quality audio and/or visual programming
material to theaters or other locations for viewirig. The system and method
allows for the flexible scheduling of feature films and advertisements, the
integration of high quality audio and image signals, and easy implementation
of
security measures, among other features and advantages.
The previous description of the preferred embodiments is provided to
enable any person skilled in the art to make or use the present invention. The
various modifications to these embodiments will be readily apparent to those
skilled in the art, and the generic principles defined herein may be applied
to
other embodiments without the use of the inventive faculty. Thus, the present
invention is not intended to be limited to the embcidiments shown herein but
is
to be accorded the widest scope consistent with the principles and novel
features
disclosed herein.
