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Claims  |
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What is claimed is:
1. A method for conveying a plurality of audio/video programs, and a
program guide signal including data related to scheduling times and
descriptive information of the respective audio/video programs,
comprising:
providing a plurality of respective audio/video packet signals
corresponding to said plurality of audio/video programs;
preparing scheduling data to produce programming information related to
scheduling times and descriptive information of respective said
audio/video programs;
creating a master program guide by selecting data from said programming
information according to a predetermined criterion, and including
conditional access codewords, associated with at least some of said
programming information included in the master program guide, which
conditional access codewords may be used by respective receivers for
permitting or precluding display of corresponding programming information;
forming a master program guide packet signal from said master program
guide; and
forming a multiplexed signal for transmission or storage, by multiplexing
said master program guide packet signal with said audio/video packet
signals.
2. The method set forth in claim 1 further including the steps:
creating special program guides by selecting data from said programming
information according to further respective predetermined criteria;
forming respective special program guide packet signals from said special
program guides;
associating respective conditional access codewords with programming
information related to at least one of respective said special program
guides, which conditional access codewords may be used by respective
receivers for permitting or precluding display of said at least one of
respective said special program guides;
including programming information related to said special program guides in
said master program guide; and
multiplexing said master guide packet signal, said special guide packet
signals and said audio/video packet signals.
3. The method set forth in claim 1 wherein the step of associating a
conditional access codeword, with at least some of said programming
information included in the master program guide includes associating a
universal conditional access codeword with all programming information
allocated for unconditional display in a program guide.
4. The method of claim 1 further including:
generating a user specific conditional access codeword;
forming a conditional access packet signal including said user specific
conditional access codeword; and
multiplexing said conditional access packet signal with said master guide
packet signal and said audio/video packet signals.
5. The method set forth in claim 2 further comprising:
detecting said multiplexed signal and selecting said master program guide
packet signal and said special program guide packet signals;
extracting master program guide information from said master program guide
packet signal, and storing master program guide information in memory;
extracting special program guide information from said special program
guide packet signal, and storing special program guide information in
memory;
providing a user specific conditional access codeword;
processing master program guide information for the display of special
program guide information, including comparing conditional access
codewords associated with respective special program guides with said user
specific conditional access codeword, and precluding the display of
special guide information for which the corresponding conditional access
codewords and the user specific conditional access codeword have
predetermined dissimilarities.
6. The method set forth in claim 1 further comprising:
detecting said multiplexed signal and selecting said master program guide
packet signal;
extracting master program guide information from said master program guide
packet signal, and storing master program guide information in memory;
providing a user specific conditional access codeword;
processing master program guide information for the display of program
guide information, including comparing conditional access codewords
associated with respective audio/video programs with said user specific
conditional access codeword, and precluding the display of program guide
information of an audio/video program for which the corresponding
conditional access codewords and the user specific conditional access
codeword have predetermined dissimilarities.
7. Apparatus for receiving a packet audio/video signal including a master
program guide packet signal having information related to programs
available in said packet audio/video signal, said information related to
programs including respective conditional access codes, said apparatus
comprising:
means for detecting said packet audio/video signal;
memory means;
a transport processor for selecting said master program guide packet
signal, and storing master program guide information in said memory means;
a source of a user specific conditional access code;
a display processor for displaying program guide information, said display
processor including means for accessing said conditional access codes of
respective program information and said user specific conditional access
code and responsive to similarities/dissimilarities between said
conditional access codes and user specific conditional access code
displaying/not displaying the corresponding program guide information in a
program guide display.
8. The apparatus set forth in claim 7 wherein said packet audio/video
signal further includes a plurality of special program guide packet
signals and said master program guide packet signal includes information
related to special program guide packet signals including respective
special program guide conditional access codes, and said display processor
further comprises means responsive to similarities/dissimilarities between
said conditional access codes and said user specific conditional access
code, for displaying/not displaying the corresponding special program
guide.
9. Apparatus for receiving a audio/video packet signal including a master
program guide packet signal and a plurality of special program guide
packet signals and wherein said master program guide packet signal
includes information related to special program guide packet signals
including respective special program guide conditional access codes, said
apparatus comprising:
means for detecting said packet audio/video signal;
a memory;
a transport processor for selecting said master program guide packet
signal, and said plurality of special program guide packet signals, and
storing master program guide information contained in said master program
guide packet signal, and special program guide information contained is
special program guide packet signals in said memory;
a source of a user specific conditional access code;
a display processor for displaying program guide information, said display
processor including means for accessing respective special program guide
conditional access codes from master program guide information stored in
said memory, and accessing said user specific conditional access code from
said source, and responsive to similarities/dissimilarities between
respective special program guide conditional access codes and said user
specific conditional access code, displaying/not displaying the
corresponding special program guide information in a program guide
display.
10. The apparatus set forth in claim 9 wherein said audio/video packet
signal further includes a conditional access packet signal including
information corresponding to said user specific conditional access
codeword CA.sub.-- CSS, and said apparatus further includes:
a smart card processor for providing said user specific conditional access
codeword CA.sub.-- CSS responsive to said information included in said
conditional access packet signal; and
said transport processor selects said conditional access packet signal from
said audio/video packet signal and provides conditional access information
contained in said conditional access packet signal to said smart card
processor.
11. A method of processing an audio/video packet signal including a master
program guide packet signal and a plurality of special program guide
packet signals and said master program guide packet signal includes
information related to special program guide packet signals including
respective special program guide conditional access codes, said method
comprising the following steps:
detecting said packet audio/video signal and selecting said master program
guide packet signal and said special program guide packet signals;
extracting master program guide information from said master program guide
packet signal, and storing master program guide information in memory;
extracting special program guide information from said special program
guide packet signal, and storing special program guide information in
memory;
providing a user specific conditional access codeword;
processing master program guide information for the display of special
program guide information, including comparing conditional access
codewords associated with respective special program guides with said user
specific conditional access codeword, and precluding the display of
special guide information for which the corresponding conditional access
codewords and the user specific conditional access codeword have
predetermined dissimilarities. |
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Claims |
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Description |
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This invention relates to the formation, transmission and processing of a
television program guide as for a broadcast television service.
BACKGROUND OF THE INVENTION
A direct broadcast satellite system has been proposed which will transmit
compressed television and other ancillary signals in compressed and
packeted form. The system has a potential of transmitting hundreds of
programs. Each program may include a number of services. A service is
defined herein as a program component, such as a video signal, or an audio
signal, or a closed caption signal, or data, etc. The data may include
executable computer files or programs for use by appropriate receivers.
Each service of each program is identified by a unique service identifier
(SCID). Thus if a program includes four service components, the program
will be assigned four SCIDs. The information for respective services will
be transmitted in packets of predetermined amounts of data (for example
130 bytes) and each packet of information will include a SCID identifier
corresponding to the service.
A plurality of programs, for example six to eight, may be transmitted in
time division multiplexed form (on a packet basis) on a single carrier
frequency. To provide, e.g. 160 programs, the system will transmit on 20
to 28 carriers.
In order to receive a particular program, a receiver must be tuned to a
particular carrier, and programmed to select or demultiplex signal packets
associated with the desired program. Information associating the service
components (SCIDs) with a particular program are contained in a program
guide, which is itself a program that is transmitted. Because of the large
number of programs and the consequential larger number of services, the
programming information associating programs with services is ever
changing, and must be continually updated.
The program guide includes information used by respective receivers to
associate transmitted time division multiplexed service packets with
programs desired to be viewed. The program guide is a program which is
assigned a particular SCID that a receiver will automatically select on
start up to load the program guide data in memory. The receiver will
include a microprocessor, which is responsive to programming commands, to
scan the stored program guide and determine the carrier on which a desired
program is transmitted and the SCIDs associated with the desired program's
service components. Thereafter the receiver tuner will be tuned to the
appropriate carrier frequency and packet selection apparatus will route
the selected service component packets to corresponding signal processing
apparatus.
The program guide information that has been discussed thus far is only
machine usable, that is, the SCID information is useful to a receiver
apparatus but not of interest to the user. Information of interest to the
respective user is the schedule of programs, the times of broadcast, the
cost of pay per view programs, what movies or sporting events will be
shown, etc. All of this data may also be included in the program guide and
arranged in a form conducive to display and perusal. The display and
perusal may be performed by conventional menu programming using the
receiver On Screen Display apparatus.
Program guide information is segmented into a master guide which is
transmitted on substantially all carriers and special guides which are
transmitted on only one carrier. The master guide includes limited program
information related to the next several viewing hours. The special guides
may include comprehensive programming information for an extended period
such as a month.
Various program providers may rent space on the broadcast system. Access to
program material provided by the various providers may be by subscription.
For user convenience, and also to conserve system bandwidth, it is
desirable to include programming information for all providers in one
program guide. On the other hand, it may be bothersome, for users not
subscribing to particular program providers or to particular services
available from respective providers, to have to wade through program guide
information for which the user has not subscribed. Therefore, a subscriber
specific mechanism for precluding display of particular program guide
information is desirable.
SUMMARY OF THE INVENTION
The present invention includes a method of forming program guide
information conducive to selective display at respective receivers.
Program guide information is arranged in different data blocks according
to types of guide information. One such data block contains channel
information (CSSM.sub.i) describing the respective channels. Respective
CSSM.sub.i in this block include a channel information customer service
system byte (CI.sub.-- CSS) which contains conditional access information
related to a channel associated with a CSSM.sub.i.
In a receiver embodiment, a subscriber specific byte (CA.sub.-- CSS) is
stored and accessible to program guide processing apparatus. Prior to
displaying received program guide information for a particular channel,
the subscriber byte CA.sub.-- CSS is compared with the channel information
byte CI.sub.-- CSS in the program guide. Dependent upon the results of the
comparison, the guide data for that particular channel is either displayed
or not displayed in the program guide.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the attached FIGURES
wherein:
FIG. 1 is a pictorial diagram of a satellite transmission system;
FIG. 2 is a block diagram of one of the transmission elements illustrated
in FIG. 1;
FIG. 3 is a pictorial diagram describing the general format of signal
packets in which program component service data is transmitted;
FIG. 4 is a block diagram of a portion of a receiver apparatus embodying
the present invention; and
FIG. 5 is a block diagram showing the interfacing between the .mu.PC and
the video decompression apparatus of FIG. 4.
FIG. 6 is a schematic diagram of conditional access comparison circuitry.
DETAILED DESCRIPTION
The present invention will be described in the environment of a direct
broadcast satellite system, DBS; however, it will readily be appreciated
that its use is not limited to this environment. The invention is at least
applicable, in general, to a broad range of time division multiplexed
television broadcast systems such as packet cable and high definition
television systems for example.
Referring to FIG. 1, a DBS system includes a satellite containing a number
of transponders. Respective transponders relay information between an
earth bound transmitter and an earth bound receiver (e.g. in a home). Each
transponder responds to signal transmitted on an exclusive carrier
frequency.
The system may include a plurality of transmitters, (transmitters #1 to N)
one for each transponder. The transmitters respectively transmit different
program material such that the combination of transmitters provide a wide
variety of television viewing material. The system includes a scheduler to
coordinate program material amongst the respective transmitters.
FIG. 2 illustrates an exemplary transmitter of FIG. 1. In the present
exemplary system, each transmitter is in actuality a plurality of program
generating organizations and/or equipment. These organizations/equipment
are illustrated as studios, (STUDIOS 1 to K) each of which is capable of
providing a packet audio/video/data (AVD) program. (U.S. Pat. No.
5,168,356 by Acampora et al. describes apparatus for generating packet
audio/video programs.) The respective audio or video or data component of
each program is a packet signal identified with an exclusive service
channel identifier, SCID. Packets of the respective component packet
signals are time division multiplexed in a program multiplexer (not shown)
to form the respective AVD signal provided by one of the studios. The
packet programs provided by the studios are time division multiplexed in a
channel multiplexer (MUX). The output of the channel multiplexer is then
modulated on an assigned transponder carrier frequency. The program
multiplexing apparatus and/or the modulator may include forward error
correction, FEC, apparatus for generating error parity bytes and for
interleaving portions of the signal to effect a degree of error immunity
during the transmission process.
The scheduler of FIG. 2, which corresponds to the scheduler of FIG. 1, is
an information management system including human intervention. The
scheduler may include the system business office. Each of the transmitters
may include a subscheduler which is responsive to the scheduler and
communicates therewith. The scheduler assigns channel space and SCIDs to
the subschedulers which in turn assign SCIDs to program components and
generate corresponding program guide information. This program guide
information is communicated to the scheduler for formation of the actual
program guide. The scheduler may also assign SCIDs to program components
on particular transmitters, and generates a packet program guide for
transmission. The scheduler maintains a running data base of all system
programming for an extended period of time. The SCIDs of respective
programs are associated with program names. In addition, the respective
program names are associated with reception times and may be tagged with
"type" codes for search purposes. For example, movies may be tagged with a
movie code, sports programs with a sports code, soap operas with a soap
code, horse operas with another code, etc. In addition, the respective
program types may be categorized into subsets of the primary types such as
movies being classified as thrillers, horror, comedies, etc., and the
sports category classified into professional and amateur, for example.
An example of the types of information that may be maintained in respective
records of the scheduler data base is shown in TABLE I. The exemplary
record shown is for the 2-hour movie, Bambi, to be aired 27 Apr. 1994 at
7:30 PM. The database may also include common system messages to be
transmitted to current subscribers.
TABLE I
______________________________________
No. ITEM DESCRIPTION
______________________________________
1 year 1994
2 month 04
3 date 27 Wed.
4 times start 7:30P; end 9:30P
5 channel SHO
6 PPV yes/no
7 closed cap.
yes/no
8 provider studio xyz
9 SCIDs video-xxx..xx; audio-xxx..xx; data-xxx..xx; etc.
10 prog. name
BAMBI
11 description
Disney movie released year ... etc.
12 class (audio/video/data)
13 subclass 1
movie
14 subclass 2
(rating)
15 subclass 3
(children/western/SciFi/
romance/nature/.etc.)
16 billing info
???
______________________________________
The scheduler scans the data base periodically and generates a master
program guide. This master program guide is an arrangement of a simplified
portion of the programming information relevant to programs which will be
transmitted within the subsequent few hours. Items from the data base
which may be included in the master guide are items 4 through 15 for the
current day spanning a period of several hours and including all programs
in progress. The arrangement is in a data file format which comports with
receiver microprocessor (.mu.PC) programming to condition the data for
display as a menu programming guide, and to identify service component
packets of programs selected for viewing.
Even though the data will, in part, be displayed on the television screen,
it is not in compressed video format, because text is not particularly
conducive to MPEG compression, and text in MPEG compressed form is not
conducive to .mu.PC manipulation. The master program guide is a data file
which is packeted in a similar manner as the other program service
components and assigned a specific predetermined SCID such as
000000000001.
FIG. 3 illustrates an exemplary packet format. Each packet includes a
prefix which is of the same form for all service types. The exemplary
prefix includes a one bit priority field P; a one bit boundary field B B,
which indicates boundaries between significant signal changes; a one bit
field, CF, which indicates if the payload is scrambled; a one bit field,
CS, which indicates the one of two scramble keys that is to be used to
unscramble a payload; and a twelve bit SCID. Following the prefix is a
service header which is service specific. The service header includes a
four bit continuity count value CC. The continuity count is service
specific, with the count value in successive packets being successively
incremented by one unit, modulo 16. For a video service the count values
are followed by a four bit field, HD which indicate certain payload
options. The remainder of the packet is the signal payload. The packet may
include error code parity bits appended to the end of the payload. Such
error coding may be performed over the entire packet, or only over
portions thereof.
The master program guide is sent in packet form to each of the transmitters
wherein it is time division multiplexed with the respective program
packets by the channel multiplexer if there is sufficient bandwidth. In
scheduling the respective transponders, the scheduler attempts to reserve
space for the program guide on each transponder, so that substantially
every system transponder conveys the master program guide regularly. Since
the master program guide is transmitted on substantially all transponders,
no matter to which transponder a receiver is tuned, the user can
immediately switch to the master program guide to review available
programming.
The master program guide is repeatedly sent and is updated regularly, for
example every 30 minutes. The repetition rate is relatively frequent, the
goal being that a subscriber turning on his receiver can access a
programming menu substantially immediately. This is possible because the
amount of data contained in the master guide is relatively limited.
A much more comprehensive program guide, termed a special guide, is also
formed by the scheduler, and includes all programming information for a
period of the following thirty days, for example. This is a significant
amount of data, but the system inventor decided it would benefit
subscribers to be able to schedule their viewing over longer periods
(weeks or a month). The special program guide is a packet data program
that is applied to only one of the transmitters and thus is available on
only one of the transponders, albeit that the particular transponder may
change day to day or hour to hour in accordance with transmitter bandwidth
availability and other scheduling requirements. The SCID of the special
guide is variable and is assigned by the scheduler. The location of the
special guide is listed in the master guide along with other programming.
In a preferred embodiment, the master guide is formed as four sequential
blocks of data designated;
SEGM: APGD: CSSM1 . . . CSSMnseg: PISM1 . . . PISMnseg. The special guide
on the other hand is partitioned into a plurality of segments or portions
(from 1 to 16) with an index "nseg" indicating the current number of
segments comprising the special guide. Each segment carries program
information for one or more channels, which range from 100 to 999 and each
special guide segment includes two sequential blocks of data;
CSSM1 . . . CSSMnseg: PISM1 . . . PISMnseg.
The SEGM block contained in the master guide includes information about the
partitioning of the channel space into segments and the number of
segments. The block APGD contains a program guide map which indicates
which special guide segments are active and their location (i.e., the
particular transponder carrying the segment) as well as the SCIDs of
respective segments. The APGD contains program information relating to
ratings and theme, such as items 10-15 in the above data base record. In
addition, the APGD includes a program guide map associating special guide
segments with respective names, numbers and types. The program guide map
associates a PG.sub.-- CSS byte or code with each guide. This code is used
to permit/preclude display of respective program guide segments.
The master guide and every special guide contain a CSSM block and a PISM
block. The CSSM block is a channel to service.sub.-- id segment map. This
includes data describing channels (channel name, call letters, channel
number, type, . . . ) which are in the corresponding segment. The PISM
block contains linked lists of program information (title, start time,
duration, rating, category, . . . ) that are on each channel described in
the corresponding CSSM.
The program guide information may be apportioned amongst the different ones
of the plurality of special guides in varying formats. That is, respective
special program guides may include information from only one of a
plurality of program providers. Alternatively, information carried on
different blocks of channels may be divided amongst the plurality of
special program guides. For example, program guide information for
channels 100 to 300 may be allocated to special guide 1; channels 301 to
500 to special guide 2; channels 501 to 700 to special guide 3; etc. In
both of these special guide formats, each special guide may include
program guide viewing information for that number of days the special
guide has capacity to hold. Another alternative arrangement is the
division of viewing times. For example, the master guide may include
program guide information for the next two hour interval; special guide 1
may include program guide information for the following next 8 hours;
special guide 2 may include program guide information for the following
next 8 hours; special guide 3 may include program guide information for
the following next 8 hours; etc.
Included in every CSSM.sub.i record is a CI.sub.-- CSS byte or code. The
CI.sub.-- CSS byte is used to permit/preclude display of respective
channel/program information in the master or special program guides.
CI.sub.-- CSS and PG.sub.-- CSS bytes may be program provider specific or
arbitrarily assigned on a channel basis by the system manager. The
PG.sub.-- CSS of a special program guide which is specific to a particular
provider may be assigned a provider specific code. This provider specific
code may be utilized by respective receivers to preclude display of this
special guide to non subscribers. CI.sub.-- CSS bytes associated with
channel/program information provided in program guides may also be
provided provider specific codes such that display of channel information
which is contained in non provider specific program guides may be
precluded. (Note that the master guide may be non provider specific.) It
will be appreciated that a provider may be assigned more than one code to
allow for selective display of program guide information between different
classes of subscribers or non subscribers. In addition, the system manager
may assign a universal .sub.-- CSS codeword to permit unconditional
display of program guide information. Assume that the CI.sub.-- CSS and
PG.sub.-- CSS bytes are eight bits. The system manager may assign the byte
00000000 to connote unconditional access. Any guide or channel assigned a
CI.sub.-- CSS and PG.sub.-- CSS byte of 00000000 will be available to be
viewed by all system users, whether or not they are subscribers.
Program guide information may be divided into conditional access classes
for viewer access. In the simplest arrangement all program guide data may
be arranged in eight conditional access, CA, classes, one for each bit of
the eight bit CI.sub.-- CSS and PG.sub.-- CSS byte. These CA classes may
be assigned on a program provider basis or according to some other
criteria.
The eight bits of the CI.sub.-- CSS or PG.sub.-- CSS byte represent 256
different states, and thus can accommodate a much larger number of CA
classifications. Nominally a broadcast system will have a relatively
limited number of program providers. Assuming that the number of providers
is sixteen or less, the number of possible states may be allocated thusly.
The four more significant bits of the CI.sub.-- CSS and PG.sub.-- CSS byte
may identify respective program providers, and the four least significant
bits may be assigned values at the discretion of the respective provider.
In this instance each of the sixteen or less providers may allocate his
program guide information into sixteen different CA display classes.
Conditional access to special guides and/or channel information is effected
at the receiver by comparing the respective CI.sub.-- CSS and PG.sub.--
CSS bytes in the program guides with a user CA.sub.-- CSS byte which
defines in part the viewing entitlements of the respective user. The
CA.sub.-- CSS byte is generated by a conditional access uplink system and
transmitted to the respective user. The conditional access uplink system,
which is an element of the scheduler, generates a user specific
conditional access packet when services are purchased or updated by the
user. For example, when a subscriber telephones a program provider to
request addition or deletion of premium channels to his subscription, the
conditional access uplink system is directed by the system manager to
create a new CA.sub.-- CSS byte or bytes for that subscriber reflecting
these changes. This new CA.sub.-- CSS byte is included in a data packet
which is directed specifically to his receiver, and a conditional access
smart card system therein. The user is directed to tune to a particular
channel for a particular time interval and the packet is applied to that
channel by the scheduler at some time during the interval as system
bandwidth permits.
The time span of the programming data included in the master guide is
determined by the amount of memory available for processing the guide in
the receiver. The exemplary system described allows for a master guide of
242 packets of 127 bytes each of data. Current data for all channels is
included in the master guide, and as much future programming data as will
fit within the 30K bytes of master guide space. This results in
approximately two hours of program viewing data.
Special guides are not limited by memory constraints, but rather by
bandwidth. To minimize bandwidth demands upon the system by the special
guide, the special guide segments are arbitrarily limited to 750 packets
of 127 bytes, or approximately 95K bytes per segment and a total of 1.5M
bytes for all 16 segments.
Each special guide segment is assigned a different SCID, and different ones
of the segments may be transmitted on different transponders so that
special guide data is substantially evenly distributed amongst all of the
transponders.
FIG. 4 illustrates in block form, a portion of an exemplary AVD receiver.
Transmitted AVD signal is captured by an antenna 5 and coupled to a
tuner-demodulator 6. The tuner is controlled by the .mu.PC to select a
desired transponder carrier frequency. The selected carrier is demodulated
and the modulating signal is output from the tuner-demodulator 6 in binary
form. The modulating signal is applied to a forward error correcting
circuit, FEC, 7, which corrects correctable errors and generates an error
signal for respective signal packets which contain non-correctable errors.
The FEC provides a time division multiplexed packet signal including a
plurality of programs one of which is the master program guide.
The packet stream from the FEC is applied to a transport processor 8. The
transport processor includes circuit elements for selecting ones of
packets from the multiplexed packet stream, decrypting (descrambling)
appropriate packets, and separating the service payloads from selected
packets. In the transport processor, the packet stream from the FEC is
applied to a decryptor 10 and to an SCID detector 9. At system start up
and at regularly spaced intervals, the system controller or .mu.PC 17 is
programmed to condition the SCID detector to detect occurrences of packets
containing the master guide SCID. On detection of master guide packets,
the SCID detector 9, conditions the memory DMA circuitry 11 to store the
master guide packet payloads in a predetermined block of a rate buffer
memory 15. The .mu.PC, responsive to user commands input via a user
interface 16, scans this block of memory for program data to determine the
SCIDs associated with program components of the program which the user
wishes to view. These SCIDs are applied to the SCID detector 9 to
condition it to select the desired program service components. The memory
DMA 11, in cooperation with the transport controller 13 and the .mu.PC
assigns respective blocks of the rate buffer memory 15 to respective
service components associated with the selected SCIDs. As packets which
contain the selected SCIDs are detected, the DMA 11, loads their payloads
in the corresponding memory blocks. As respective service component
processors 21-24 need data, they request it of DMA 11 through the
transport controller 13. Controller 13 arbitrates memory access contention
between read and write demands of the various elements according to a
predetermined priority to satisfy all elements. Blocks of the memory 15
that are assigned for storage of particular service components, such as
video and audio, are in effect conditioned to operate as first-in-first
out memories (FIFOS), each with a storage capacity of several packet
payloads.
In this example, the transport processor includes a header and error code
decoder 12 which is a dual purpose matched filter. In one mode it
determines which of packets of entitlement data a particular subscriber is
entitled to accept. In a second mode, the decoder 12, is programmed to
search for particular start codes in payloads of video service data, for
example. Detection of the desired parameters in either mode condition the
memory addressing circuitry to either reset or not reset particular memory
address pointers. The transport processor also includes a smart card
interface. The smart card interface interfaces a smart card with the
receiver system. The smart card contains a entitlement data and processor
which controls access to particular programs, maintains billing
information, and in conjunction with a modem communicates with service
providers. The smart card utilizes the entitlement data mentioned above.
The decoder 12, directs user specific packet payloads containing
entitlement data to the smart card. This includes the conditional access
packet generated by the conditional access uplink system which contains
the user specific CA.sub.-- CSS byte or bytes. The CA.sub.-- CSS byte or
bytes is stored by the smart card apparatus for future use. The CA.sub.--
CSS data may be derived from transmitted conditional access packets, but
it may also may be resident in the smart card when purchased by the
subscriber.
The rate buffer memory 15, is multiplexed between operating as a compressed
video rate buffer, a compressed audio rate buffer, master guide storage,
smart card memory, .mu.PC working memory and .mu.PC storage. This is only
possible because the program guide is split between the master and special
guides. The master guide data is relatively small and hence consumes
little memory space. The entirety of the memory 15 is not large enough to
contain the special guide.
The master guide, once received is retained in the rate buffer memory,
albeit it is periodically updated. Master guide retention allows
instantaneous channel changes because the associated SCIDs are always
available. If the master guide were dropped after each channel selection,
a delay would be incurred between channel selections while the master
guide was reloaded.
During intervals that the special guide is to be processed, scanned, and/or
manipulated, no other services will be processed, hence the entire buffer
memory 15 is available for processing the special guide. Since the memory
is not large enough to contain the entire special guide at one time,
processing of parts of the special guide would either have to be done
iteratively or else the memory would have to be expanded. The former would
entail too long a process to be favorably accepted by consumers and the
latter would undesirably increase the cost of the apparatus.
Video decompression requires a relatively large dedicated memory. The
memory requirements for decompression of MPEG coded signal are one frame
of video display memory, two frames of storage for predicting
bidirectionally coded or B frames, and further working storage for
reformatting data applied to the decompressor. For decompressing 4.times.3
aspect ratio NTSC resolution images the required memory is about 16Mbits.
In FIG. 4 this memory is subsumed within the video processor 22, is large
enough to accommodate the special guide, and is not otherwise used when
the special guide is processed.
During intervals when it is desired to use the special guide, the SCID
detector is conditioned to select special guide packets and store their
payloads in the buffer memory 15 as though it were compressed video data.
The video processor is conditioned by the .mu.PC to request data from the
buffer memory block allotted the special guide SCID. This data is written
to the video processor memory as if it were compressed video data. In this
mode, the video channel is given priority, thus the special guide data is
stored as fast as it arrives and may be loaded relatively rapidly.
When the special guide is transmitted as segments multiplexed amongst all
channels, the microprocessor 17 must access the master guide in the buffer
memory 15 and scan the segment map and APGD data block to determine
channels and SCIDs of the respective segments. The microprocessor 17 is
programmed to tune to the requisite channels containing the desired
special guide segments and to condition the SCID detector to select the
corresponding packets. Preferably all segments on a channel will be
extracted before tuning another channel. It is also preferred that the
respective channels be tuned in ascending or descending order to minimize
resynchronization time between channels.
A .mu.PC interface is incorporated in the video processor 22 to permit
reading data from the video processor memory by the .mu.PC. The .mu.PC
contains programs (e.g. search routines with information filters of known
type) to permit the viewer to conveniently manipulate the special guide
data. Since all of the special guide data is concurrently available,
manipulation of the data may be accomplished as fast as the view | | |
