U.S. patent application number 10/740929 was filed with the patent office on 2004-07-08 for system and method for providing a plurality of programming services in a television system.
Invention is credited to Jerding, Dean F., Rodriguez, Arturo A., Schlarb, John M..
Application Number | 20040133928 10/740929 |
Document ID | / |
Family ID | 22102052 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040133928 |
Kind Code |
A1 |
Jerding, Dean F. ; et
al. |
July 8, 2004 |
System and method for providing a plurality of programming services
in a television system
Abstract
A system and method of providing for displaying a full service
cable television system. The cable television system is adapted to
provide a plurality of different user services. Accordingly, the
system and method are designed to allow a user to access services
in an efficient memory conserving fashion. Using a plurality of
data tables, a cable television system is able to access a
plurality of different services including cable channels,
interactive program guides, pay per view activation, video on
demand and interactive online services such as world wide web
browsing and E-mail via their home television set.
Inventors: |
Jerding, Dean F.; (Roswell,
GA) ; Schlarb, John M.; (Duluth, GA) ;
Rodriguez, Arturo A.; (Norcross, GA) |
Correspondence
Address: |
SCIENTIFIC-ATLANTA, INC.
INTELLECTUAL PROPERTY DEPARTMENT
5030 SUGARLOAF PARKWAY
LAWRENCEVILLE
GA
30044
US
|
Family ID: |
22102052 |
Appl. No.: |
10/740929 |
Filed: |
December 19, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10740929 |
Dec 19, 2003 |
|
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09071550 |
May 1, 1998 |
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Current U.S.
Class: |
725/152 ;
348/461; 348/E7.063; 348/E7.071; 725/132; 725/140 |
Current CPC
Class: |
H04N 21/4782 20130101;
H04N 21/4622 20130101; H04N 7/165 20130101; H04N 21/8586 20130101;
H04N 7/17318 20130101 |
Class at
Publication: |
725/152 ;
725/140; 725/132; 348/461 |
International
Class: |
H04N 007/16; H04N
007/173; H04N 011/00; H04N 007/00 |
Claims
1. In a cable television system having a headend and a set-top, a
method of activating a service provided by the headend to the
set-top, wherein the service is one service of a plurality of
services provided by the headend to the set-top, the method
comprising the steps of: receiving from the headend a plurality of
tables, wherein a first table of the plurality of tables includes
multiple sets of service attributes, wherein each set of service
attributes is associated with a particular service; storing the
plurality of tables in a memory of the set-top; receiving at the
set-top a signal associated with a specific service of the
plurality of services provided by the headend, wherein the specific
service has a set of one of the multiple sets of service attributes
associated therewith; retrieving and reading the set of service
attributes associated with the specific service; and launching the
specific service responsive to the set of service attributes
associated with the specific service including a launch attribute
permitting non-subscriber launch.
2. The method of claim 1, wherein the plurality of tables includes
a second table that associates channel numbers with service
identifiers and associates service identifiers with channel
numbers, and wherein a third table associates service identifiers
with applications and sets of parameters, wherein each service of
the plurality of services provided by the headend is associated
with a unique service identifier and defined by a particular
application and particular set of parameters.
3. The method of claim 2, wherein the second table includes a
bitmap for indicating whether a channel number is valid.
4. The method of claim 2, wherein the second table further includes
a plurality of blocks of data, each block of data associating a
service identifier with a valid channel number.
5. The method of claim 4, wherein each block of data has a service
identifier field and a channel number field, and the blocks of data
are arranged such that the service identifiers in the service
identifier fields are increasing in magnitude and
non-contiguous.
6. The method of claim 3, wherein the bitmap represents a
contiguous range of channel numbers, each bit of the bitmap
representing a particular channel number, and each bit that
represents a valid channel number is set to a predetermined
value.
7. The method of claim 6, further including the steps of: accessing
a specific block of data of the plurality of data blocks, whereby
the specific block of data contains the unique service identifier
of the specific service; and retrieving the channel number
associated with the service identifier.
8. The method of claim 7, wherein the step of accessing a specific
block of data further includes the step of: searching on the
plurality of data blocks to find the specific block of data that
contains the unique service identifier of the specific service.
9. The method of claim 7, wherein each block of data of the
plurality of blocks of data further includes an attribute
specifying that the channel associated with that block of data is
reachable by incrementing or decrementing channel numbers with an
input device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 09/071,550 entitled "System and Method for
Providing a Plurality of Programming Services in a Television
System" filed on May 1, 1998.
TECHNICAL FIELD
[0002] This invention relates in general to television systems, and
more particularly to a system and architecture for providing a
plurality of different classes of video and multimedia programming
and including the logical interface method for accessing said
plurality of video and multimedia services.
BACKGROUND OF THE INVENTION
[0003] The old definition of television services included a
channel, which was essentially nothing more than an analog
broadcast video source. However, in the new world of digital
programming, the home communication terminal ("HCT"), otherwise
known as the settop box, has become a more powerful computing
device than the typical analog cable TV set-top. In addition to
supporting traditional analog broadcast video and functionality,
these devices must also support an increasing number of services
that are not just analog (but also digital), are not just broadcast
(but also two-way communication, for example, e-mail), and are not
just video (but also such as web browser). These are all in
addition to a host of other television services that are
increasingly being demanded by customers, examples of which include
audio and audio visual programming, advanced navigation controls,
interactive program guides, impulse pay-per-view captivation, video
on demand programming, advanced configuration controls, and other
online services to name but a few. In order to provide these more
powerful and complex features, the simple channel abstractions need
to be extended beyond those that have traditionally been
provided.
[0004] With the capabilities of advanced one-way digital networks,
a multiplicity of applications become feasible such as downstream
e-mail delivery, electronic magazines, electronic newspapers, and
other graphical and textual services for news, sports and financial
information, to name but a few of broadcast authorizable services.
With the capabilities of a two-way digital network other
applications such as impulse pay-per-view, video on demand,
electronic commerce, and web browsing become possible. All these
services can be offered in parallel with conventional broadcast
television and can be considered differing service categories. As
the number of services available via cable or satellite television
increases, there is a need for a model in which the television
viewer can access these services. Given that a viewer of newer
generation digital HCTs can access up to thousands of channels and
services available, there will be a large amount of service and
channel definition information that needs to be transmitted from
the headend or server location to the client or HCT. Traditional
methods of broadcast television and services in cable television
systems do not provide the necessary amounts of information to
support all these channels and services, nor are they capable of
efficiently transmitting, storing, accessing, and processing the
corresponding large amounts of information in the HCT.
[0005] Cost limitations on HCT manufacture impose limitations in
compute, memory, and internal machine bus bandwidth that in turn
limit the amount of compute resources required to implement
increasing digital video and multimedia functionality.
Consequently, it would be desirable to provide a system in which
required service related information is transmitted from the
headend to the HCT in a methodical fashion so as to minimize:
required network transmission bandwidth; time to organize the
information for storage in the HCT; memory footprint of the
information in the HCT; and the amount of time required to then
access the information in the HCT. Additionally, this information
must be updated in an efficient manner, such as when the services
and channel lineup are changed, the HCT is provided the new
information.
[0006] It would also be desirable to provide this system and method
in which a particular application for a specific service is
preloaded on the HCT and, if not, arrange for it to be acquired
from the headend and loaded. This, of course, would require the
ability to have two-way digital cable TV network for communication
between the headend and the HCT, or an advanced one-way digital
network in which system and method acquires specific broadcast
service information by accessing and retrieving data with a
predetermined file name and identification, such file retrieved
from a broadcast file system ("BFS").
[0007] Accordingly, there exists a need to provide a mechanism
whereby applications on the HCT can be activated from the server
via a signaling message received from the HCT, to provide the user
with services such as Emergency Alert Messages, e-mail, and other
messaging.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of a cable television system in
accordance with the present invention;
[0009] FIG. 2 is an electrical block diagram of a settop terminal
included in the cable television system FIG. 1, in accordance with
the present invention;
[0010] FIG. 3 is a block diagram service application manager
service table for a cable television system, in accordance with the
instant invention;
[0011] FIG. 4 is a block diagram representation of the display
channel table used in connection with the service application
manager of the instant invention;
[0012] FIG. 5 is a block diagram representation of a split channel
table used in connection with the service application manager, in
accordance with the instant invention;
[0013] FIG. 6 is a block diagram representation of a bulk table
used in connection with the service application manager in
accordance with the instant invention; and
[0014] FIG. 7 is a block diagram representative of a logo table
used in connection with the service application manager in
accordance with the instant invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] While the specification concludes with claims defining the
features of the invention that are regarded as novel, it is
believed that the invention would be better understood from a
consideration of the following description in conjunction with the
drawing figures in which like reference numerals are carried
forward.
[0016] Referring now to FIG. 1 there is illustrated therein a block
diagram of a cable television system 100 including a headend 105
for receiving satellite television signals, demodulating the
signals down to base band, and transmitting the signals over the
system 100. The transmitted signals can, for instance, be radio
frequency (RF) signals, although they may more preferably be
optical signals that are transmitted over a communications medium
such as a fiber optic cable 125. When optical signals are
transmitted by the headend 105, one or more nodes 110 are included
in the system 100 for converting the optical signals to RF signals
that are thereafter routed over other media such as coaxial cables
130. Taps 115 are provided within the cable system 100 for
splitting the RF signal off to subscriber equipment, such as settop
terminals 120, cable ready televisions, video cassette recorders
(VCRs), or computers.
[0017] Referring now to FIG. 2, there is illustrated therein a
block diagram of the home communication terminal 120 and other
system equipment is shown. The terminal 120 is typically situated
within the residence or business of a subscriber. It may be
integrated into a device that has a display 235, such as a
television set, or it may be a stand alone unit that couples to an
external display, such as a display included in the computer or a
television, and that processes television signals for presentation
to subscriber on the display. The terminal 120 preferably comprises
a data port 205 for receiving the RF signals, which can include
video, audio and data information, from the tap and providing any
reverse information to the tap for transmission back to the
headend. The terminal 120 further includes a processor 210 for
controlling operations of the terminal 120 and for driving the
display, a clock 215 for providing timing functions, and a tuner
134 for tuning into a particular audio, video, and/or data channel.
Additionally, the terminal 120 includes a receiver 220 for
receiving externally generated information, such as viewer inputs
or commands from other devices. Viewer inputs could, for example,
be provided via transmitter 240, such as buttons or keys located on
the exterior of the terminal 120 or a handheld remote control
device that includes user actuated buttons. Additionally, in
certain embodiments, terminals include interface connectors for
Ethernet port, Serial port, and Universal Serial Bus port.
[0018] A memory 250, such as a nonvolatile random access memory,
coupled to the processor stores operational parameters such as
commands that are recognized by the processor. The memory also
stores program and application information that can, for instance,
be downloaded over the system to the terminal. The program
information includes program guide information that is displayed
for the subscriber in the format of a program guide including a
listing of channels, programs for viewing on the channels, and
times during which the programs are shown. The program information
also includes channel information such as the channel number and
identification information, e.g., ESPN, Disney, WXIA, etc.
[0019] As noted above, in the world of digital programming,
services are no longer considered to be simply traditional analog
broadcast services, but will include advanced one-way digital
network services and a whole host of additional two-way services
such as web browsing, video on demand, and e-mail to name but a
few. In order to provide these more powerful and complex features,
the simple channel abstraction needs to be extended so as to
provide for each of these different services in both one-way and
two-way digital networks. The instant invention provides a Service
Application Manager ("SAM") system and method that implements a
model in which a viewer can access services. Each service
identification consists, for example, of an application to run and
a parameter, such as data content, specific to that service. Many
services may be defined using the same application component,
however with different parameters. For example, an application that
can tune video programming would be executed with one set of
parameters to view, for example, HBO, and a separate set of
parameters to view, for example, CNN. Each association of the
application components (in this case tune video) and one of the
parameter components (i.e., HBO or CNN) represents a particular
service that has a unique service identification. Each of the other
services described above, such as text channels, pay-per-view,
video on demand, and web browsing fit nicely within the service
model. In addition to an application and parameter, each service
also has an identity, which may include a short textual description
(such as call letters for a particular television station), a long
textual description, and a logo image.
[0020] Additional service attributes in certain embodiments include
multimedia service attributes. A service's identity is optionally
augmented with an introductory audio that is played when the
service is launched. A short "Welcome to ABC" song or voice with
musical background, where such audio is distinctively associated
with service is an example. Likewise, a service's identity is
optionally augmented with an audio for when service is terminated
or suspended.
[0021] In other embodiments, a special effect when starting a
service, including animated transition into the service, such as
morphing from an image of service logo to displayable service, or
graphics transitions such as implosion and fades, may be associated
with the service. Likewise, a special effect may be associated with
a service when it is terminated or suspended.
[0022] In another embodiment, any of a partial or full-size image,
video or video widget serving the function of a 3-D logo is
associated with a service and displayed momentarily when service is
launched. Same or different counterpart media is employed for
service termination or suspension. The specified association of
media with service may include an amount of time to display or play
the media. Additionally, media can be combined with special
effects.
[0023] Service attributes may or may not necessarily be for
identification services but for efficiency of system and method.
Such service attributes include: cable-operator-only launchable
service messaging viewer with emergency alerts or reminders to pay
bill. A service can be classified with an attribute as both, a
cable-operator and viewer, launchable service. Alternately, a
service attribute is an installer-only or
repair-representative-only launchable service.
[0024] A service can be classified with an attribute as one that
can be launched by time, rather than immediately to responding to
viewer input or headend signaling.
[0025] Furthermore, such service activation time is designated
by:
[0026] A. a prespecified time after viewer activation or server
signaling; or
[0027] B. input by viewer or data transmitted during server
signaling, and/or possibly with:
[0028] 1. periodic pre-specified interval values; or
[0029] 2. periodic pre-specified interval values specified by
viewer or headend message.
[0030] Examples of a service that is launched periodically is a
ticker-tape that displays periodic information updates of sports
scores or stock prices. Specification of service display duration
is included appropriately in the aforementioned. A service can also
be classified with an attribute as a "service not-blockable by
viewer" that is activated by cable headend operator.
[0031] A service may have the attribute of a background-service,
not visible to viewer. In a HCT, a service that enables HCT to
route Internet Protocol data or other information received from and
to digital network and passed via one of many possible HCT
communication ports to and from one or more of many computing
devices in the viewer's premises, establishes a communication link
between the digital network and computing devices. Such computing
devices include an advanced phone, a hand-held electronic organizer
device, a personal computer, an appliance such as a stove, and
therefore the HCT acts as a cable modem.
[0032] Although a service runs in the HCT in the forementioned, the
application running on the HCT serves as an "enabler" and possibly
as a communication switch while the designated computing device and
communication port are specified as parameters of the service. HCT
communication ports include Ethernet port, serial port, Universal
Serial Bus (USB), to name a few.
[0033] In order to access this growing number of services, it is
necessary to provide a system that can meet functionality,
efficiency, and memory footprint requirements constrained by the
capabilities of the HCT. The Service Application Manager ("SAM")
architecture consists of a SAM server component, a SAM client
component, and the interface between-the server to the client. This
interface consists of the SAM information tables broadcast on the
BFS (an example of which is disclosed in commonly assigned patent
application serial no. PCT/US97/22535, the disclosure of which is
incorporated herein by reference) and the update and signaling
messages passed from server to client. In the context of the system
illustrated in FIGS. 1 and 2, the SAM server component is part of
the headend, while the SAM client component resides in the HCT. The
SAM server stores the current SAM information, which consists of a
Service Table, a Display Channel Table, a Split Channel Table, the
Bulk Table, and the Logo Table. The SAM provides an interface for a
server operator to enter and modify the information on the SAM, and
to broadcast it to SAM clients notifying them of, for example,
information changes. The SAM also allows the applications that
execute a particular service to be introduced into the system. Each
application has a server component and a client component. The
application server may execute all the time, while an application
client may be downloaded to the HCT and executed only when the
viewer requests the service be activated.
[0034] The SAM server provides an interface through which
applications are placed on the network, services registered, a
channel lineup specified, and the SAM information stored and
modified. The SAM server may also allow changes to the SAM
information table (as described herein below) to be posted to the
network together with a time specified by the cable operator.
[0035] The SAM client provides an interface through which
applications may be activated and SAM information can be accessed.
One functionality of the SAM client is the activation of an
application client on the HCT, either to provide a specified
service or because of a signaling message from the server.
[0036] As noted above SAM information includes at least five
different tables: a Service Table stores information about all
services available on the system and each service is identified by
a specific service ID; a Display Channel Table ("DCT") provides an
abstraction to match a display channel number to a service ID (and
vice versa); a Split Channel Table supplements the DCT with
information about split channels; a Bulk Table is provided for
storing actual string and parameter data as well as attributes of
each service. The data for each table may be transmitted from the
server to the client by writing it into a binary file and then
placing the file on a broadcast file system ("BFS") such as that
disclosed in the aforementioned copending PCT Patent Application,
the disclosure of which is incorporated herein by reference.
Updates to the various table increments the tables' version number.
Accordingly, the system will always access the most recent version
of a particular table. This is important as some channels, for
example the Split Channel Table, will change fairly regularly and
indeed can change on a daily basis.
[0037] When the SAM server changes the SAM files being broadcast on
BFS, the SAM client will receive a message from the SAM server via
the HCT operating system. This message contains the current version
number of each SAM table, as well as flags optionally specifying a
"forced" update of each table. For each table, the SAM client will
check the version number specified in the message versus the local
table versions and only if they are different retrieve the file
from the BFS and check the version number a second time (unless the
"force" flag is set for that table, in which case the file on BFS
is always checked). If a file version being transmitted on the BFS
is different than the local file stored in the SAM client, the SAM
client will update its tables using the new files.
[0038] The update process works such that while the SAM client is
reading new files, the old files are still available to
applications on the HCT. Only when the SAM client has completed
reading any new tables does it actually update the current tables
to the new information. During this very brief "swap," both old and
new tables are locked such that the data cannot be accessed via the
SAM client interface.
[0039] The update process is also robust such that the SAM client
can handle the various non-deterministic aspects of the SAM
server's use of the BFS. For example, the synchronization of the
message being received at the client, the file being changed on the
BFS server, and the file being changed as seen by the BFS client
are all affected by network latency and could happen in different
orders.
[0040] After receiving an information update, the SAM client will
notify interested applications via the HCT OS that the SAM
information has changed. To allow other components to update their
service and channel related information, the SAM client must keep
the last version of the replaced data tables in memory.
[0041] The various SAM information tables are transmitted in band,
over QAM, for fast access by the SAM client during HCT boot. Copies
of the tables, with the exception of the Logo Table, are also
transmitted out-of-band, over QPSK. The out of band files are used
by the SAM client during SAM information update such that the
viewer's use of the HCT is not interrupted (access to in-band data
requires use of the HCT tuner).
[0042] Referring now to FIG. 3 there is a block diagram
representation of the Service Table used in the preferred
embodiment of the Service Application Manager, all in accordance
with the instant invention. The Service Table 300 contains the
service identification information, with each service assigned a
unique service ID. The header information at the beginning of the
Service Table includes the table version 308 and the number of sub
tables 310. This is followed by the service subtables. Each
subtable 302 includes the number of subtable entries, the length of
the service data segment, an index, and finally the service data
segment. The index includes a pairing of a service ID and the
offset into the data segment where the service data is actually
found. Accordingly, if a particular subtable provides information
relating to 25 different services, the index will include 25
blocks, each block corresponding to a single service. The service
IDs 306 across the entire Service Table are stored in increasing
order, but are not necessarily contiguous. Each service subtable
can store up to 64 Kb of service data.
[0043] To find a service ID in the Service Table, a binary search
is done first on the subtables to determine which subtable a
service ID is in, and then within the index of the subtable to
locate the offset of the service data in that subtable. The offset
is then used to access the data directly.
[0044] Each service data record includes all of the service
attributes. One such attribute is a description ID. The description
ID is an index into the Bulk Table for the string describing the
service. In one embodiment, each string is made up of three fields:
(1) an ASCII string decimal number specifying the length of the
short description in characters; (2) a short description ASCII
string; and (3) a long description ascii string. For example, the
following strings describe a service whose short description is
"WTHR," and the long description is "The Weather Channel," "4WTHR
The Weather Channel."
[0045] A second piece of data that is located in the data block 320
is a logo ID and which itself is an index into the Logo Table for
the service's logo pixel map. An application Universal Resource
Locator ("URL") ID is a third index into the Bulk Table for the URL
string identifying the application client in the broadcast file
system. The final attribute is an application dependent parameter,
which is interpreted as a number (i.e., a source ID) or an index
into the Bulk Table for a parameter string or parameter data.
[0046] In order to efficiently store service records for thousands
of services, the invention specifies a record with variable-length
fields. The idea is to use only as much memory for a field as is
needed for the particular value of that field. The field Size
attribute of the service is used to specify the size, in bytes, of
each field. The field Size byte uses 2 bits to encoding the number
of bytes minus 1 for each field. A value of "00" in a field means
it is 1 byte, "01," means 2 bytes, etc. No matter what the actual
field size, the access operations always return the field value in
32 bits. The access routines must operate at a byte level when
retrieving fields larger than a byte because the data will not be
word or half-word aligned. The format of the field Size byte is
shown below:
1 field Size: for(i = bit 0; i < 8; i++) { description ID size -
1 : 2 logoId size - 1 : 2 applicationId size - 1 : 2 parameter size
- 1 : 2 }
[0047] Thus, each record varies in length from 5 to 17 bytes.
[0048] Accordingly, and referring now to FIG. 4, there is
illustrated therein in a block diagram representation of the Bulk
Table used in connection with the Service Application Manager, all
in accordance with the instant invention. The Bulk Table 400
contains data relevant to the services, such as strings for
descriptions, application
[0049] URLs, and parameter data. As with the Service Table 300 of
FIG. 3, the Bulk Table comprises several initial entries 402, 404
as described above, followed by a plurality of bulk information
subtables 406 and 408.
[0050] Each subtable includes the number of subtable entries, the
length of the bulk data segment, an index, and finally the bulk
data segment. The index includes a pairing of a bulk ID and the
offset into the data segment where the bulk data is actually found.
Accordingly, if a particular subtable provides information relating
to 25 different bulk data entries, the index will include 25
blocks, each block corresponding to a single bulk data item. The
bulk IDs across the entire Service Table are stored in increasing
order, but are not necessarily contiguous. Each bulk subtable can
store up to 64 Kb of bulk data.
[0051] To find a bulk ID in the Bulk Table, a binary search is done
first on the subtables to determine which subtable a bulk ID is in,
and then within the index of the subtable to locate the offset of
the bulk data in that subtable. The offset is then used to access
the data directly.
[0052] The size and the contents of the Bulk Table itself depend on
the size and type of information that is required to be stored
therein. Several types of BulkData are defined in the following.
The application URL is simply a NULL-terminated ASCII string. The
service description is two concatenated NULL-terminated ASCII
strings, the first being the short description and the second being
the long description. For example, "WGNX0CBS Atlanta0" is a
possible description string. A string is simply a NULL-terminated
ASCII string. Arbitrary data can be stored in the Bulk Table and a
pointer to that data handed out via an API in the SAM Client. It is
then up to the application client to interpret the content of the
data.
[0053] Referring now to FIG. 5, there is illustrated therein a
block diagram representation of the Display Channel Table used in
connection with the Service Application Manager, all in accordance
with the instant invention. The Display Channel Table 500 is used
to map service IDs to channel numbers displayed to the viewer
(Display Channel Number, or DCN). In one embodiment of a cable
system using the SAM, the Display Channel Table can be specified on
a per-hub basis. This allows different neighborhoods of subscribers
to receive different channel lineups.
[0054] The Display Channel Table is constructed to allow optimal
access time to determine the service ID for a particular service or
the service ID for a particular DCN. Both transformations are
required by applications executing in the HCT such as the channel
navigator and the program guide.
[0055] The Display Channel Table begins with a version number 502,
the number of valid channels in the channel index 504, and the
length of the valid service index 506. This is followed first by a
valid channel bitmap 508, containing a bit for each channel in the
cable system. For each channel that is valid, the corresponding bit
position is set in the valid channel bitmap. Next is a valid
channel index 510, each entry associated with a valid channel in
the bitmap, whose content is an index into the service/DCN index
that follows. The service/DCN index contains an entry for each
valid service ID and Display Channel Number pair. Within each
Display Channel Number in that pair is a channel flag (the
most-significant-bit of the DCN). This flag indicates whether or
not the DCN is surfable, i.e. can be reached by the user
incrementing or decrementing throughout the channel lineup. There
exists a service ID/DCN pair for every combination of service and
DCN, where a service can be associated with more than one
channel.
[0056] These data structures can be better understood by explaining
how the translation for service ID to DCN and vice-versa takes
place. To translate from DCN to service ID, first the bit for the
DCN in the valid channel bitmap is checked. If the bit is set, the
channel is valid, and the index for that channel must be
determined. The index is exactly Nth valid channel which the DCN
happens to be, or the number of bits set in the valid channel
bitmap up to and including the bit representing the DCN. This
lookup is made compute efficient by using a table that stores the
number of bits set in a single byte for each decimal value of that
byte. Thus, the channel index can be determined by taking the
decimal value of each byte in the valid channel bitmap, translating
the decimal value to a "number of bits set" using the lookup table,
and accumulating this count for each byte in the valid channel
bitmap up to the byte for the DCN. The remaining bits in the byte
where the DCN bit is located are added by shifting and masking.
[0057] The number of bits set is then directly the Nth valid
channel for that DCN, which is directly the offset into the channel
index for that DCN. The channel index contains the offset into the
service/DCN index for that DCN. Once this offset is known, the
service ID for that DCN is the upper two bytes of the 32-bit
service ID/DCN value. The total search time is then O(n) where n is
the number of total possible channels. This is achieved without
having to store for example an array of size total number of
channels, using only an array of size total number of channels
divided by eight (the bitmap) plus an array of size number of valid
channels.
[0058] To look up a service ID for a DCN, a binary search on the
service ID/DCN index 512 is done. This index is sorted in
increasing order, such that the search is O(log (number of valid
service/DCN entries)).
[0059] In addition to the services described above, the SAM
supports the ability to split channels provided over the system. A
split channel is one in which there is more than one service that
is provided on that channel during a 24 hour period. One embodiment
of the SAM may support split channels; where each of which shows
two services, and which may change between those two services up to
three times in a 24 hour period. For example, if the channel is
specified as a split channel with service X and service Y, starting
at midnight the following splits are available: XY, XYX, XYXY.
Split channels are identified in the Display Channel Table in both
the channel index and the service ID/DCN index using a reserved
constant. This indicates to the SAM client to lookup the
information for the requested DCN in the Split Channel Table. There
is always a Split Channel Table for each Display Channel Table in
which a split channel is identified.
[0060] Accordingly, referring now to FIG. 6, there is illustrated
therein a block diagram representation a Split Channel Table 600
for use in connection with the Service Application Manager, all in
accordance with the instant invention. The Split Channel Table,
like the other tables, includes a number of initial entries such as
initial entry 602 and 604. Initial entry 602 is version that
specifies the most recent version of the split channel table
allowing the SAM system to know that it is working with the most
recent version of information. The second entry 604 specifies the
number of split channels in the channel lineup. Accordingly, and in
FIG. 6, the number of split channels identified would be one as
only one split channel record 606 is illustrated in split channel
table 600. It is to be understood, however, that any number of
split channels may be supported by this system, and the invention
is not so limited. The split channel record 606 includes a number
of pieces of information, including, for example, the DCN being
split 608, the identities of the services which are splitting the
channel 610 and 612, and a time flag 614 that specifies the hours
at which services are being provided on the channel. These times
are specified such that service 1 is on by default at midnight in
any given day. Each time then marks a swap to service 2 and back,
continuing according to the number of swaps. The core channel
management application in the HCT uses this information such that
service swaps take place automatically and are done by the client.
This differs from existing analog systems where split channels are
implemented by changing the content that is broadcast on a
particular analog channel. The split channel concept in this
invention also allows channels to be split between video services
and services of other media, such as text channels or web browsing
time.
[0061] The final SAM information table present in the instant
invention is the Logo Table as illustrated in FIG. 7. The Logo
Table 700 stores service logo data. The SAM server provides two
different Logo Tables on the BFS, both transmitted in band. One
table provides the default set of logos known by the SAM Server
upon deployment of the cable system, in the present embodiment the
range of default logo IDs is from 1-255 and is published including
the name of the logo. The data for the default logo images can be
stored in the nonvolatile memory of the HCT such that they can be
retrieved very quickly and rendered by applications in the HCT. The
set of default logos will never change, nor will the data in the
default Logo Table.
[0062] New logos registered with services by the SAM server are
stored in another Logo Table. The SAM client always loads this
table into memory on the HCT during initialization, and it can be
updated like any of the other SAM information tables. Accordingly,
the Logo Table initial entry 702 relates to version numbers of the
table.
[0063] All logos are encoded by the SAM Server using an encoder
that translates a single common image format such as GIF into the
particular format that the SAM is transmitting (and decoding within
the SAM Client).
[0064] Application clients can access the logo data in the SAM in
several ways. First, an application client can ask for the logo ID
that corresponds to a particular service. If the logo ID is stored
by the application client (one of the default logos), it can then
draw the appropriate logo using its own data. Otherwise, the
application client can ask the SAM client for the logo pixmap data,
width, and height in a format compatible with the HCT OS drawing
capabilities. A Logold of zero means no logo.
[0065] The structure of the Logo Table begins with a version number
702, number of logos 704 in the table, first logo ID in the table
706, and then the size of the logo data 708. Next is an index of
logo data offsets 710, such that index equals the logo ID minus the
starting logo ID of the table. The index for a logo contains the
offset into the logo data segment where the actual image data for
the logo is stored.
[0066] The primary functionality of the SAM is the activation of an
application client on the DHCT, either to provide a specified
service or because of a signaling message from the server.
Typically the user of the DHCT will access services via the Display
Channel Number (DCN). The SAM uses the Display Channel Table (DCT)
to map a DCN to a Serviceld. "Split" channels are supported, such
that one channel might provide multiple services, depending on the
time of day. Given a service ID, the SAM client first extracts the
appropriate application URL BulkDatald from the Service record in
the current Service Table, and then the actual URL string from the
Bulk Table. It then asks the HCT Operating System ("OS") if the
module with the application URL for the application is loaded in
the HCT memory. If not, it requests that the OS load the module
using the application URL. Once the application code is resident in
the HCT, the SAM client launches the application module as an OS
application (it may be that the application has already been
launched). It then asks the OS to activate the application, given
the module handle--this brings the application into focus. Finally,
the SAM client sends a kEt_Activate message to the application
client, including the service ID and the service parameter from the
Service Table.
[0067] Application clients can also be activated by a message sent
from the server. The SAM client must register with the HCT
operating system to receive SAM signaling messages. The content of
these messages is an application URL to activate and the data to
pass the application as a parameter. The SAM client thus provides a
mechanism whereby an application client can be activated given the
application URL and some data. If the data type is an integer
value, meaning the parameter itself, then it is passed directly to
the application identified by the URL via a kEt_Activate message.
However, if the parameter is a string or data, then it must be
stored by the SAM client locally and given a BulkDatald in the
range reserved for private client use. The SAM client will activate
the application client. The BulkDatald is passed as the parameter,
and a special id is used to signify a service activated via a
pass-thru message. The application client can then use the SAM
client API to retrieve the data given the bulk ID. Depending on the
application, the private bulk data might be a URL string, an actual
string to use directly, or data. The application client must be
given the parameter type it is expecting; this must be verified by
the SAM Server before the signaling message is sent. However, if
the application client is expecting a string it must check whether
the string is a URL or the content itself. If the application
client is executing on behalf of the kSam_SignalingService, then it
must delete the private bulk data when it suspends.
[0068] The SAM client can be asked to construct a kEt_Notify event
with supplied parameters and forward it to designated application
clients. Again, this can be done via a service ID or an application
URL. The notification event type is supplemented with event data
particular to the notification being sent (such as
kEd_SamDataUpdated), an ID (typically the service ID), and two
parameters.
[0069] The SAM client provides a facility whereby application
clients can be queried to determine whether particular services are
currently authorized. The SAM will look up the application URL for
the requested service ID in the Service Table, and send the
application client a kEt_IsAuthorized event requesting an
asynchronous reply to a queue created within the SAM client API.
The SAM client will wait on that queue until a kEt_AsyncResponse
event is delivered by the application client, and then return the
result to the caller of the SAM API. Thus, while the internals of
the authorization query are asynchronous, the SAM Client API is
synchronous. It is up to the application client to determine if the
service is authorized, using whatever means necessary.
[0070] Application clients can be suspended by Serviceld or
directly via application URL. Application clients can also be
suspended as a result of a signaling message from the SAM
Server.
[0071] Accordingly, in the system illustrated in FIGS. 1 and 2 it
may be appreciated that the channel selection function of this
system includes a plurality of channel cross reference tables as
illustrated in FIGS. 3-7. These tables cross reference settop
terminal channels with a variety of television services, or other
services, such as various types of video and audio programming, and
online services such as web casting and e-mail. Selection of a
particular channel transfers control of that specific application
program, along with one or more appropriate parameters obtained
from the cross reference tables, and activates the service
associated with that selected channel. In sum, the cross reference
tables in FIGS. 3-7 are channel selection functions that enable the
settop terminals to execute software and activate a variety of
services. When a viewer of the system of FIG. 1 selects a channel,
the HCT identifies the service associated with the selected channel
from the Display Channel Table and then executes the appropriate
application determined from the Service Table of FIG. 3.
[0072] Further, channel and service lineup can take place
transparently to the viewer based on the data kept in the SAM
client. This is important as subscribers often group together in
blocks favorite types of programming so as to make access to those
programs easier. In other words, a subscribers mapping of the
settop terminal channels to television services is maintained even
if the cable service provider reassigns the cable channels over
which those services are transmitted. Accordingly, when such
reassignment occurs, updated versions of the tables as specified
hereinabove are transmitted from the SAM server to the SAM client,
thus providing a transparent change in service channels for the SAM
server operator through to the SAM client user. As an example, once
parents configure channel settings to block particular services
deemed inappropriate for children, a reassignment of cable channels
over which those services are transmitted will not affect those
services blocked status.
[0073] The manner in which requests for services are made by
different applications within HCT are simplified by incorporating
an application URL, similar to that used on the Internet, to
uniformly identify application requested. In the context of
services described hereinabove, it has been set forth that the
service comprises an application and a parameter. The application
in fact the URL to the executable application code, found either on
the BFS or resident in HCT memory, while the parameter includes the
data strings described herein above.
[0074] While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the invention is
not so limited. Numerous modifications, changes, variations,
substitutions and equivalents will occur to those skilled in the
art without departing from the spirit and scope of the present
invention as defined by the appended claims.
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