U.S. patent application number 13/493308 was filed with the patent office on 2012-12-13 for receivers for television signals.
This patent application is currently assigned to British Sky Broadcasting Limited. Invention is credited to Robin Crossley, David Holliday, Nicholas James.
Application Number | 20120314135 13/493308 |
Document ID | / |
Family ID | 10833725 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120314135 |
Kind Code |
A1 |
Holliday; David ; et
al. |
December 13, 2012 |
RECEIVERS FOR TELEVISION SIGNALS
Abstract
A receiver is configured to receive television signals in a
plurality of channels, a channel set identity, and a channel subset
identity. Each channel defines a television program and/or other
services provided by a broadcaster for the channel. The receiver is
configured to store a reference channel set identity and one or
more reference channel subset identities, compare the channel
identity and channel subset identity for a channel in a received
signal with the reference channel and channel subset identities,
and output the received television signal for display of the
program or other services defined thereby depending on the
comparison.
Inventors: |
Holliday; David; (Middlesex,
GB) ; Crossley; Robin; (Middlesex, GB) ;
James; Nicholas; (Middlesex, GB) |
Assignee: |
British Sky Broadcasting
Limited
Middlesex
GB
|
Family ID: |
10833725 |
Appl. No.: |
13/493308 |
Filed: |
June 11, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
09719389 |
Jun 25, 2001 |
8201197 |
|
|
PCT/GB99/01873 |
Jun 14, 1999 |
|
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13493308 |
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Current U.S.
Class: |
348/570 ;
348/E5.097 |
Current CPC
Class: |
H04N 5/44543 20130101;
H04N 5/4401 20130101; H04N 21/4532 20130101; H04N 21/25883
20130101; Y10S 707/99942 20130101; H04N 21/4331 20130101; H04N
7/163 20130101; H04N 21/8166 20130101; H04N 21/6143 20130101; H04N
21/6112 20130101; H04N 21/454 20130101; H04N 21/4622 20130101; H04N
21/482 20130101; H04N 21/426 20130101; H04N 21/84 20130101; H04N
21/26283 20130101; H04N 21/47 20130101; H04N 21/47211 20130101 |
Class at
Publication: |
348/570 ;
348/E05.097 |
International
Class: |
H04N 5/50 20060101
H04N005/50 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 12, 1998 |
GB |
9812797.0 |
Claims
1. A receiver for receiving television signals in a plurality of
channels each defining a television programme and/or other services
provided by a broadcaster, and a channel set identity and a channel
subset identity for the channel, the receiver comprising means for
storing a reference channel set identity and one or more reference
channel subset identities, means for comparing the channel identity
and channel subset identity for a channel in a received signal with
the reference channel and channel subset identities and means for
outputting the received television signal for display of the
programme or other services defined thereby depending on the
comparison.
2. A receiver as claimed in claim 1, wherein the storing means is
arranged to store a common channel subset identifying programmes
and/or other services receivable independent of the receivers
location and a regional channel subset identifying programmes
and/or other services receivable depending on the location of the
receiver.
3. A receiver as claimed in claim 1, wherein each channel has
associated with it a logical channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services containing the logical
channel number.
4. A receiver as claimed in claim 1, wherein each channel has
associated with it an order channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services depending the order
channel number.
5. A receiver as claimed in claim 1, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
6. A receiver as claimed in claim 2, wherein each channel has
associated with it a logical channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services containing the logical
channel number.
7. A receiver as claimed in claim 2, wherein each channel has
associated with it an order channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services depending the order
channel number.
8. A receiver as claimed in claim 3, wherein each channel has
associated with it an order channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services depending the order
channel number.
9. A receiver as claimed in claim 6, wherein each channel has
associated with it an order channel number which varies on a
channel subset basis, the receiver comprising means for displaying
a list of programmes and/or other services depending the order
channel number.
10. A receiver as claimed in claim 2, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
11. A receiver as claimed in claim 3, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
12. A receiver as claimed in claim 4, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
13. A receiver as claimed in claim 6, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
14. A receiver as claimed in claim 7, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
15. A receiver as claimed in claim 8, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
16. A receiver as claimed in claim 9, wherein each channel has
associated with it one or more indicators, the receiver comprising
means responsive to the indicators for controlling display of
programme and/or service information.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of U.S. patent
application Ser. No. 09/719,389, filed Jun. 25, 2001, which in turn
is a national stage filing under 35 U.S.C. .sctn.371 of
International Application No. PCT/GB99/01873, filed Jun. 14, 1999,
and claims priority under 35 U.S.C. .sctn.119 to Great Britain
patent application No. 9812797.0, filed Jun. 12, 1998. Each
application is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to improvements in receivers for
television signals.
BACKGROUND OF THE INVENTION
[0003] At present most television broadcasting, regardless of
medium over which the signal is broadcast (Terrestrial, Cable,
Satellite), is analogue based and comprises a single television
service (e. g. SKY ONE, SKY SPORTS, SKY MOVIES) transmitted on a
carrier signal or channel. However, the use of digital based
broadcast technology is imminent. Digital broadcast technology will
enable television service companies to transmit in a single channel
high definition television programmes, or plural programmes at
conventional definition or multiple customer services, or a
combination of these.
[0004] In a conventional analogue-based television broadcast system
programmes (or "services") are broadcast by separate television
service companies on a single carrier signal ("channel"). In a
digital based broadcast system it is possible to broadcast plural
services multiplexed together on a single carrier. Unless the
context requires otherwise the term "channel" will be used herein
to refer to the bandwidth used by a single service to broadcast
television programmes or other customer services. The term
"channel" therefore encompasses both an entire carrier signal (when
the signal is used entirely by a single service) and a portion of a
carrier signal (when the signal is shared by plural services).
[0005] The ability to transmit multiple channels in a single
carrier signal enables a far greater number of services to be
provided in the digital domain than is possible in the analogue
domain. Some of the channels in a carrier may be used to provide
conventional television programmes while simultaneously other
channels in the carrier are used to provide data for other customer
services such as television programme listings, on-line programme
ordering or so-called pay-per-view (PPV) services, and so on.
Customer services should not be confused with the "services"
provided by television companies as discussed hereinabove.
[0006] In our International (PCT) patent application published as
WO 96/37996, the teachings of which are incorporated herein by
reference, there is disclosed a receiver for television signals,
which receiver is arranged to receive video signals comprising
video data, information data and audio signals comprising audio
data and information data. The receiver is arranged to respond to
viewer operation of a control device. The receiver includes a
processor for processing selected information data to convert the
same into signals representative thereof for output to a television
in combination with the video signals. In one mode of operation the
decoder responds to manipulation of the control device by causing
brief scheduling information pertaining to programmes of a
plurality of different TV signals to be displayed over the received
signal. In another mode of operation the receiver is arranged to
display detailed scheduling information pertaining to plural
different television signals. The receiver is operable to receive
signals containing video data representing a plurality of video
clips. The processor is arranged to process the signals and to
cause simultaneous display of the clips on a television screen. The
processor is arranged to respond to user manipulation of the
control device by storing data for subsequent viewing of user
selected programmes. The decoder may further comprise a modem and
various types of digital storage media including Hard Disk, CD-ROM
drive, Digital Video Disk.
[0007] In addition to such television related services some of the
channels in a carrier may be used to provide on-line shopping
facilities by which a customer may purchase goods and/or services
from their own home. Such on-line shopping is, of course, only
possible if there is an element of interaction between the
goods/service provider and the customer.
[0008] The term "interactive services" will be used herein to refer
generally to on-line shopping facilities and the like made
available via one or more channels in a digital based broadcast
system.
[0009] Digital data multiplexing techniques enable a single channel
to carry simultaneously multiple interactive services. In itself
this creates a problem. Many customers will find bewildering the
large number of interactive services available to them. If
customers become confused they will not make use of the interactive
services. Clearly, this is undesirable.
[0010] Transmission bandwidth is a finite resource and will remain
at a premium even if full advantage is taken of digital data
compression techniques. This presents a problem when it comes to
providing an interactive service. On the one hand it is desirable
to present high quality pictures and graphics. However, higher
quality necessitates the use of a larger bandwidth. On the other
hand it is desirable to keep costs down because customers will not
make use of interactive services if they are significantly more
expensive than comparable high street services.
[0011] In our International (PCT) patent application published as
WO 97/23997, the teachings of which are incorporated herein by
reference, there is disclosed a receiver for television signals,
which receiver is arranged to receive video signals comprising
video data and information data. The receiver is arranged to
respond to viewer operation of a control device. The receiver
includes a processor for processing selected information data to
convert the same into signals representative thereof for output to
a television in combination with the video signals. The receiver is
arranged to respond to the information data to output for display
data derived from said image data and said information data and
representing an inter-active image. The receiver is responsive to
viewer manipulation of the control device to vary the inter-active
image and to establish a telecommunications link to a remote site
for on-line interaction via the inter-active image between the
viewer and the remote site. The interactive image may form part of
an interactive services interface comprising a broadcast entry
level and plural broadcast interactive levels. The inter-active
services interface may comprise one or more on-line interactive
levels entered from one of the broadcast interactive levels for
establishing an on-line connection with a remote site.
SUMMARY OF THE INVENTION
[0012] The present invention aims to facilitate the functionality
and limit the bandwidth used for the transmission of schedule data
in the decoder and EPG described in the aforementioned patent
applications.
[0013] In one aspect the invention provides a receiver for
receiving television signals in a plurality of channels each
defining a television programme and at least a signal in one of the
channels comprising or further comprising compressed data defining
broadcast events in the channels from time to time, the receiver
being arranged to produce output signals defining an image of
events in the programme schedule for displaying on a television
screen and comprising means for receiving data defining a
dictionary representing text portions means for decoding the
programme scheduling data to identify text portions in the
dictionary, and means for constructing the image of events using
the identified text portions.
[0014] In another aspect the invention provides a receiver for
receiving television signals in a plurality of channels each
defining a television programme and/or other services provided by a
broadcaster, and a bouquet identity and a sub-bouquet identity for
the channel, the receiver comprising means for storing a reference
bouquet identity and one or more reference sub-bouquet identities,
means for comparing the bouquet identity and sub-bouquet identity
for a channel in a received signal with the reference bouquet and
sub-bouquet identities and means for outputting the received
television signal for display of the programme or other services
defined thereby depending on the comparison.
[0015] The ordering of the programmes or other services defined may
also depend on the comparison.
[0016] In a further aspect the invention provides a receiver for
receiving television signals in a plurality of channels each
defining a television programme and wherein the signals further
comprise sorting data defining a sorting list and scheduling data
defining a schedule of programme events, the receiver being
arranged to filter the scheduling data depending on the sorting
data to produce output signals defining an image of selected events
in the programme schedule for display as a filtered schedule on a
television screen depending on the sorting data.
[0017] The invention also provides a receiver for receiving
television signals in a first plurality of channels broadcast in a
first broadcast network and a second plurality of channels
broadcast in a second broadcast network, the receiver comprising a
cache store for storing programme schedule data transmitted from
time to time in at least one of the channels broadcast in the first
network, means for decoding the data in the cache store for display
of a programme schedule of the first broadcast network, and means
for receiving and decoding programme schedule data transmitted
substantially continuously in at least one of the channels
broadcast in the second network.
[0018] The invention provides a receiver for receiving television
signals for a plurality of channels which together provide a
time-shifted service, the television signals comprising unique
identity data for each channel and programme schedule data for a
reference channel, the receiver comprising means for determining
from the data for the reference channel a schedule for each other
channel and means for displaying a schedule of programmes for each
independently identified channel in the time shifted service.
[0019] The invention provides a receiver for receiving television
signals in a plurality of channels each defining a television
programme and at least a signal in one of the channels further
comprising programme scheduling data including pay-per view-events,
the receiver being arranged to filter the data pertaining to the
pay-per-view events to produce output signals defining an image of
a schedule of the pay-per-view events for display on a television
screen.
[0020] The above and further features of the invention are set
forth with particularity in the appended claims and together with
advantages thereof will become clearer from consideration of the
following detailed description of an exemplary embodiment of the
invention given with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic diagram of a television receiver
system;
[0022] FIG. 2 is a functional block diagram of a satellite
decoder;
[0023] FIG. 3 is a functional diagram showing interaction between
hardware and software of the decoder of FIG. 2;
[0024] FIG. 4 is a schematic diagram representing a compressed text
string;
[0025] FIG. 5 is a schematic diagram of a bouquet and a plurality
of sub-bouquets;
[0026] FIG. 6 is a stylized example of a Box Office menu; and
[0027] FIG. 7 is a stylized example of a Box Office screen.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
[0028] System Overview
[0029] Referring now to FIG. 1 of the accompanying drawings a
television receiver system 1 comprises a television (TV) 2, a
digital integrated receiver decoder 3 (decoder) connected to
receive signals from a satellite dish antenna 4, and a video
cassette recorder 5 (VCR), and a modem 7. The system 1 optionally
further comprises a personal computer 6 (PC) and a games console 8
each connected via respective lines to the decoder 3. SCART
connectors or other standard connectors may be used as appropriate.
The decoder 3 acts as an interface between the TV 2 and the VCR 5,
PC 6, modem 7 and games console 8 and thus serves to control the
system 1.
[0030] Receiver/Decoder
[0031] FIG. 2 of the accompanying drawings shows the decoder 3 in
greater detail. The dish antenna receives signals from a satellite
(not shown). Signals from the dish antenna 4 are input to a tuner
12 and from there to a quadrature phase shift key (QPSK)
demodulator 13. Demodulated signals are error corrected by way of a
forward error corrector circuit 14. Satellite (and indeed cable)
programmes are usually scrambled to prevent unauthorised access by
non-authorised subscribers. The decoder 3 therefore comprises a
conditional access control circuit 16 which co-operates with a
smart card 16a to determine whether the viewer has subscribed to a
particular channel and is therefore authorised to access the
channel. Parental control over channel access is also provided, at
least in part, by the access control circuit 16. The decoder 3
further comprises a descrambling circuit 17 which is controlled by
the access control circuit 16 to enable the descrambling of the
signal by authorised subscribers.
[0032] The received signals comprise digitally encoded data. It is
envisaged that the data will be compressed using for example the
DVB/MPEG 2 standards which permit both programme data and
additional data (for example interactive service data) to be
transmitted in a single channel. DVB/MPEG 2 enables high
compression ratios to be achieved.
[0033] Descrambled data is supplied to a transport/demultiplexor 15
which separates the data into video data, audio data, user services
data, programme scheduling data etc. for distribution to various
locations within the decoder. Demultiplexed signals are input to a
video decompression and processing circuit 18 utilising dedicated
video RAM 17a, and an audio decompression and processing circuit
19, operating according to the MPEG standard for example.
Decompressed video signals are input to a SCART interface 20 for
direct input to the TV 2 and to a PAL encoder 21 where they are
encoded into the PAL format for modulation by a UHF modulator 22
for output to the UHF input of the TV if so desired.
[0034] The system 3 is controlled by a processor 23 which
communicates with the various units of the system via a bus 24. The
processor 23 has associated with it ROM 25 (optionally including a
CD-ROM drive 25a), RAM 26 (comprising both dynamic RAM and static
RAM) and a flash (non-volatile and writable) memory 27. As will be
explained in greater detail hereinafter the processor 23 controls
operation of the decoder 3 by controlling the tuner 12 to receive
signals for the desired channel from the dish antenna 4 and to
control demultiplexing, descrambling and decompression so that the
desired programme and/or interactive service data is displayed on
the screen of the TV 2. Viewer selection of desired programmes and
customer services is controlled by way of a remote control unit 28
which in response to viewer manipulation thereof transmits control
signals to a receiver 29 for input to the processor 23.
[0035] The system 3 further comprises a high-speed data interface
30 and an RS232 interface 31 providing a serial link. The
high-speed data interface 30 and the RS232 interface may be
connected to the PC 6 and/or the games console 8 of FIG. 1 and/or
other digital equipment (not shown). The high speed data interface
30 enables the system 3 to be connected to other devices (not
shown) for example to enable reception of services transmitted via
other media such as broadband cable and digital terrestrial
broadcast. The decoder 3 further comprises a modem interface 32 for
connecting to a telephone network.
[0036] Operation of the decoder 3, especially the processor 23, is
controlled by software that makes the processor 23 responsive to
control signals from the remote control unit 28 and to data
included in the signal received by the dish antenna 4 and in the
memory units 25 to 27. A schematic representation of the
interaction between hardware and software in the decoder 3 is shown
in FIG. 3 of the accompanying drawings. The data in an incoming
signal is separated by the transport/demultiplexer 15 into video
data and information data. The information data is distributed
around the hardware and software, as will be described in greater
detail hereinafter. The video data and the audio data is
demultiplexed and output in suitable form for supply to a TV by the
MPEG video and audio circuits 18 and 19. When information is to be
displayed either with or instead of the video, data representing
the information is output in suitable form for supply to the TV via
an on-screen display (OSD) driver 33 and the video circuit 18.
Signals from the OSD driver 33 and the video circuit 18 are
combined as appropriate before being supplied to the TV. Operation
of the software and hardware of the decoder 3 is based around an
operating system 35. The conditional access controller 16 has
associated software which interfaces with the operating system. The
processor 23 has its own base operating system 37 which interfaces
to the decoder operating system 35. Applications such as an
intelligent electronic programme guide (EPG) 39 and other
applications 40 including interactive services interface to the
operating system 35 via an applications interface 41 and associated
application interpreter 42.
[0037] The software for conditional access applications such as the
intelligent electronic programme guide 39 are installed permanently
within non-volatile memory, e. g. the ROM 25, of the decoder 3, but
variable information such as new access codes and TV programme
scheduling details is updated regularly via signals received from
the dish antenna 4. Demodulated signals from the demodulator 13 are
input to the transport demultiplexer 15 which examines the data to
decide where it should be sent. From time to time significant
changes may be made to conditional access codes or to the manner in
which the intelligent electronic programme guide (IEPG) 39 displays
programme information. Also, programmes for additional
applications, say an interactive shopping or banking service for
example, are also supplied via the satellite for the decoder. Such
application data is routed by the transporter 15 directly to the
appropriate areas 40 of the store.
[0038] Operating data 43 is supplied on a substantially continuous
basis in every channel. The operating data 43 includes conditional
access data 44 associated with a channel and/or programmes therein
which enables the conditional access controller 16 to determine
whether or not access should be allowed to a particular programme
by descrambling the data therefor. Additionally, operating data
relating to interactive services is transmitted in dedicated
interactive service channels which carry control and information
data for use by the hardware and software of the processor 23 and
the associated memory devices 25 to 27. Thus, the operating data 43
depicted in FIG. 3 also includes interactive service programs and
information 46 (for example relating to personal banking services)
and indeed any other data 47 required on a substantially continuous
or regular basis for the aforementioned interactive services.
[0039] The transport/demultiplexer 15 is arranged to supply the
operating data 43 to the processor 23. The data is acted upon by
the operating system 35, the conditional access and/or other
operating software. The processor 23 responds to the data by
sending appropriate commands or information to other units within
the system. Control data is also transferred between the processor
23 and such units as the demultiplexer 15, the video and audio
decompressors 18,19, the remote control receiver 29 and the
high-speed data interface 30 via respective drivers 48 to 52.
[0040] The combined hardware and software of the decoder 3 enables
the data in received channels to be decoded for display of viewer
selected programmes and customer services. The scrambling is
controlled on a continuous basis and the decoder can be updated
with new descrambling codes as and when required. Data for
interactive services is supplied and updated substantially
continuously and programmes relating to newly selected interactive
services are downloaded into the decoder.
[0041] Operation of the decoder 3 in receiving and decoding data
representing television programmes and data defining scheduling and
other information related to the programmes is described in detail
in our International (PCT) patent application published as WO
96/37996, aforementioned. Operation of the decoder 3 in providing
interactive services is described in our International (PCT)
application published as WO 97/23997, aforementioned.
[0042] Within the Digital Video Broadcasting (DVB) standards for
digital TV transmission there exists a standard for the
transmission of schedule information such that it can be decoded
and presented correctly to subscribers in the form of an Electronic
Programme Guide (EPG).
[0043] This DVB standard is known generally as the SI standard and
can be found in the specification: ETS 300 468, ETSI Digital
Broadcasting Systems for Television, Sound and Data Services;
Specification for Service Information (SI) in Digital Video
Broadcasting (DVB) Systems 2nd edition. Guidelines for using the
specification are given in ETSI ETR 211-DVB SI Guidelines.
[0044] In order to allow broadcasters to utilise any proprietary
features of their EPGs the SI standard includes a methodology for
extending the format of the service information (SI) stream by the
inclusion of private data tables and descriptors.
[0045] The above-described decoder 3 is, of course, designed to
support the mandatory parts of the SI specification. We have,
however, extended considerably certain aspects of the standard as
is allowed by the standard. The extended standard will be referred
to herein as the XSI specification. Among other things, the XSI
includes the following additional features: [0046] 1. Compression,
regionalisation, ordering and sorting techniques which are used for
bandwidth efficient transmission of data; [0047] 2. Organization
and implementation of data caching; [0048] 3. Implementation of
time-shifted services.
[0049] These additional features unique to the XSI specification,
will be described in detail in the following.
[0050] Compression
[0051] In order to save bandwidth on the transmission medium and
memory in the receiver text is compressed. A compression algorithm
resident in the decoder 3 uses "dictionaries" which are received
from the transmission medium and held in memory, e. g. the RAM 26.
The dictionaries may be regarded as look-up tables in which
portions of text are stored against table addresses in the form of
compressed text strings. Thus, instead of transmitting full text
over the transmission medium it is only necessary to transmit the
compressed text strings, thereby reducing the bandwidth requirement
for the transmission of text over the transmission medium.
[0052] An example of a compressed text string 60 is shown in FIG. 4
of the accompanying drawings. The string 60 comprises a field 61 of
two bits which identifies the version of the dictionary in which
the relevant text is held. The string also comprises a field 62 of
indefinite length containing data pertaining to compressed
text.
[0053] Two versions of the dictionary are normally transmitted and
a further dictionary may be stored permanently (or for an extended
period of time) in the memory of the decoder 3. The transmission of
two versions of the dictionary enables the text compression to be
optimised according to the data currently being transmitted by
allowing the dictionary to be updated over time. Special promotions
in one week may no longer be available in the next or may be
replaced by another, different promotion causing different
dictionaries to be required for full efficiency. The transmission
of two dictionaries reduces the amount of memory required to store
a dictionary because at any given time only a single dictionary
need be stored in the decoder 3. Typically the decoder 3 will be
arranged to store in memory the most recently accessed dictionary,
be it for the present week or for the next week, and download the
other dictionary if necessary the next time data for the dictionary
is broadcast (typically every five seconds).
[0054] This approach minimises delay, at most, to ten seconds if
data for the required dictionary is not in the decoder's memory. It
also minimises bandwidth requirements because, instead of
transmitting all text for every page of the programme guide each
time data for a page is transmitted, each text string is
transmitted only one in the dictionaries and the data for each page
is reduced to the compressed text strings, such as the compressed
text string 60 in FIG. 4. On receipt of data for a page the decoder
uses the compressed text strings therein to look up the complete
text in the appropriate dictionary and uses the text from the
dictionary to reconstruct the full text of the page.
[0055] Several text fields are compressed including: [0056]
Extended service descriptions (including information about the
channel) [0057] Names of each linked event (including the name or
tile of a programme) [0058] Short event names [0059] Extended event
descriptions (including a brief synopsis of the programme) [0060]
Special event messages (including discounts, say, for early
ordering on pay-per-view (PPV) services).
[0061] Regionalization
[0062] The DVB standard requires broadcasters to register with ETSI
so-called "bouquet" identities. Channel line-up information is
carried in a Bouquet Association Table (BAT) which is an optional
DVB standard table.
[0063] One way in which services could be regionalized would be to
register with ETSI a different Bouquet ID for each region of
interest, i. e. one Bouquet ID for England, one for Wales and one
for Scotland for example. There are, however, only a limited number
of Bouquet IDs available which limits the number of regions that
may be defined for a given broadcast company. Another problem is
that the number of BATs increases with the number of regions,
thereby increasing bandwidth overheads.
[0064] In order to overcome this problem XSI introduces the notion
of sub-bouquets. Services are listed within sub-bouquets according
to the contents of sub-bouquet descriptors found within the BAT.
FIG. 5 of the accompanying drawings shows a bouquet 70 which is
identified by a bouquet ID and plural sub-bouquets 71 to 75 each
identified by a respective sub-bouquet ID. This information is
broadcast in a BAT. One of the sub-bouquets 71 may contain
information identifying services that are common to all regions,
for example nationwide services such as SKY1, SKY2, BBC1. Other
sub-bouquets contain information identifying services that are
specific to each region, for example the British ITV companies.
[0065] When a subscriber is first connected he or she provides
information (such as a post code) which is used to transmit to the
decoder relevant bouquet and sub-bouquet IDs to enable the
subscriber to receive and store the common services and
regionalized services for his region. Each decoder will receive the
bouquet ID together with the common sub-bouquet ID and the specific
region sub-bouquet ID for the location of the decoder. A default
may be set up to enable, say, a non-subscribing viewer to receive
free services from within the common and/or specific region
sub-bouquets. The regional information may be prestored in the
viewing card. It will be appreciated from the foregoing that such a
scheme allows significant reduction in the bandwidth used in
describing regional channel line-ups.
[0066] Ordering
[0067] Channels are defined in a predetermined order and are
designated a channel number depending on that order. In order to
enable the order in which channels appear in the EPC to be
different than the channel number order, each sub-bouquet includes
order numbers which are separate from the channel number.
[0068] All services are assigned a unique service key which is
their identifier in XSI. Basically, the service key corresponds to
the triplet (original network id, transport stream id, service id)
which is the unique identifier of a service as defined in ETSI, ETS
3000 468.
[0069] Services are given attributes which vary on a sub-bouquet
basis. These attributes are used to inform the EPG application of
the display strategy for the service. The attributes are: [0070]
Logical channel number (this is the "channel number" as seen by the
viewer). [0071] Order number (this number is used to define the
order in which services appear in the EPG grid and listings).
[0072] Navigation and display indicators (four flags tell whether
the service is accessible in channel surf mode, in search &
scan mode where listings are displayed over TV viewing, whether the
service is to be displayed in the full listings screens and whether
it cannot be locked out by parental control).
[0073] Sorting
[0074] Data broadcast for the EPG includes true information such as
the time at which broadcast of a programme is scheduled to start.
It would, however, be desirable to be able to sort programmes in
another order within the EPG, for example alphabetical order.
[0075] Index lists of sorted events by time or alphabetically are
computed in the head end, sent over the air as part of the XSI and
cached in the decoder 3. This saves computer power in the decoder
because sorting listings can be a very CPU intensive job. The
sorted indices also convey information such as genre/sub-genre, PPV
post-buying window and other marketing-oriented flags (PPV,
Critic's Choice, New Show, Event) that are used for filtering
purposes and to support the Box Office functionality.
[0076] In addition to the above-described XSI, other improvements
have been made to the EPG in the decoder 3. The improvements will
be described in the following.
[0077] Caching
[0078] A cache store 26a (see FIG. 2) is provided in the decoder to
enable EPG data to be broadcast and built-up slowly over time,
rather than being broadcast continuously. The cache store 26a is a
RAM device which may be separate from or part of the RAM store 26.
The cache store 26a is shown separate from the RAM store 26 for the
purpose of illustration in FIG. 2.
[0079] Data caching is also used by the decoder to enable the
decoder to be used for a number of different broadcast networks.
Typically, the decoder will be required to be able to receive
broadcasts from a digital satellite television network and a
digital terrestrial television network. Conceptually, a separate
EPG is provided within the decoder for each network. Thus, in the
case where the decoder is required to receive both satellite and
terrestrial broadcasts, the decoder may be regarded as providing
both a satellite EPG and a terrestrial EPG.
[0080] The satellite EPG in the decoder is arranged to cache data
as and when required taking information from the EPG transponder of
the satellite network. Information on the EPG transponder is cycled
at a high transmission rate in order that the EPG performs with a
reasonable response period.
[0081] The bandwidth available for delivery of data to the
terrestrial EPG in the digital terrestrial environment is
considerably less than that available in the satellite environment.
Therefore, unlike in the satellite environment, within the
terrestrial environment it is not possible to dedicate one
multiplex to transmit the full seven day schedule of EPG data at
high speed.
[0082] Therefore in order to enable the full schedule of listings
to be displayed with a reasonable response rate the full schedule
is "trickle" transmitted on all terrestrial multiplexes and the
terrestrial EPG stores the complete schedule in the cache memory.
This is possible even with the smaller amount of memory available
in the set top box because there are a small number of channels
carried on the terrestrial network.
[0083] As shown in FIG. 2, the decoder is made able to tune to
digital terrestrial TV by the addition of terrestrial tuner 12a to
the high speed port 30 of the set top box. (Similarly, a
terrestrial set top box will be able to tune to digital satellite
TV by the addition of a satellite tuner.) Ideally, in these cases
the EPG resident in the set top box will be capable of seemlessly
merging data from the two environments.
[0084] An issue that because of memory limitations the combined
network set top box will not be capable of storing the entire
satellite network schedule in its memory, neither would it be a
good use of memory to store the entire terrestrial schedule when
only part of the satellite schedule is available.
[0085] In order to solve these difficulties when a terrestrial only
set top box is upgraded to be capable of tuning to the satellite
network then the caching algorithm is changed to be that of a
satellite set top box. Thus, the full schedule is no longer held in
set top box memory but sections of the schedule are obtained as
required from the fast continuous transmission on the EPG
transponder of the satellite service. In order for this to work the
schedule for the terrestrial listings schedule must also be
transmitted in the data transmitted on the satellite EPG
transponder.
[0086] With this design any satellite capable set top box (i. e. a
satellite only system, a satellite system with a terrestrial
"side-car", or a terrestrial system with a satellite side-car) will
obtain its schedule from the satellite EPG transponder on demand
and only caches the piece of the schedule currently in use. A
terrestrial only set top box however will have a different caching
algorithm and caches the entire schedule for the terrestrial
transmission.
[0087] The caching strategy can be refined by sending new caching
parameters over the air on a per platform basis. A platform is one
type of hardware from a certain manufacturer. This enables
manufacturers to vary the cost and performance of different models
in their ranges by specifying different sizes of cache store for
different models. The parameters indicate the schedule depth of the
listings that are to be cached and maintained in the decoder as
well as the schedule depth of the sorting indexes. Thus models with
larger cache stores will be able to store more information allowing
the owner to access the information more quickly.
[0088] Time-Shifted Services
[0089] Standard DVB SI allows time-shifted services to be defined.
By way of example, time-shifted services include the broadcasting
of a single movie in different channels at different start times.
For example, as shown in FIG. 6, a movie may first be broadcast
starting at 6:00pm on a channel 75, then broadcast of the same
movie will start again on a different channel 76 at 6:30pm, then
again at 7:00pm on channel 77 and so on. According to the standard
DVB SI one of the channels, i. e. channel 75, is a reference
channel with a reference schedule and all other channels 76,77 have
schedules which are time-shifted versions of the reference
schedule. That is, the other channels 76,77 only differ from the
reference channel 75 by the time-shift and cannot have a channel
name of their own.
[0090] Our XSI provides greater flexibility by allowing each
time-shifted channel to have a name which is different than that of
the reference channel.
[0091] Thus, for example, a reference channel called "Box Office"
could have time-shifted channels called "Box Office 1", "Box Office
2", "Box Office 3", etc.
[0092] The "Box Office"
[0093] As discussed within our aforementioned earlier applications,
within the EPG there is a dedicated section for the display of
Pay-Per-View (PPV) programmes. PPV events include both one-off PPV
events and near video on demand PPV events. This is the "Box
Office" section of the EPG.
[0094] Although the PPV programmes are also listed in the TV Guide
section of the EPG, Box Office has been created to encourage
subscribers to browse PPV programming. The benefit of having a
separate section that lists only PPV events is that it will create
a subscriber perception that because all programming listed in this
area incurs an extra charge it contains only programmes of the
highest value. This encourages the subscriber to use this section
of the EPG.
[0095] Whilst other EPGs list PPV programming within their normal
listings (some allow subscribes to apply filters within the normal
listings to find the PPV events), as far as we can establish only
the Sky EPG has an entire section dedicated to this purpose.
[0096] FIG. 6 of the accompanying drawings shows an example of a
Box Office menu 80. The Box Office menu items allow access to
listings by Movies, Sport and other programming genres. For each of
these genres programmes can be listed in start time order, e.g.
"Movies" 81, "Sports" 82 or "Events" 83. Programmes can also be
listed by alphabetic order by title, e. g. "Movies A-Z" 84, "Sports
A-Z" 85 or "Events A-Z" 86. Listings of new PPV programmes of each
genre are also available, e. g. "New Movies" 87, "New Sports" 88 or
"New Events" 89.
[0097] Another menu item "Free Previews" 90, when selected, tunes
the set top box to a PPV barker channel which continuously promotes
PPV programming.
[0098] FIG. 7 of the accompanying drawings shows an example of a
Box Office Movies listing screen 100. Within each Box Office
listing screen a section 101 of the screen area is dedicated to a
video or still image used to promote PPV programming. This
promotion can continue whilst the subscriber is browsing through
the listings or booking a PPV event. The video or still image on
the section 101 is switchable according to which title is selected
from a menu 102 of programmes in the lower half of the screen 100.
In FIG. 7 the bar 103 for the movie "Die Hard II" is highlighted
and a video or still image representing that movie would be
displayed in the section 101. Thus, as the subscriber browses
through the Box Office listings the video/still inset will change
to denote the programme selected-the video/still being a trailer or
promotion for the particular title.
[0099] In order to reduce bandwidth any video image is transmitted
at a reduced size and is scaled up to the required size by the set
top box as described in our aforementioned patent applications.
[0100] As a further advancement the video or still image is itself
schedulable. This enables the high bandwidth required for video
promotions to be used to greatest effect. For example, during the
daytime PPV titles targeted at families and children may be
scheduled for video promotions. However, in peak viewing time
stills may be used to promote these events, and the video
promotions allocated to titles appealing to a more mature
audience.
[0101] Other areas 104,105 of the screen 100 are given over to the
display of a company and/or channel banner and text which may
change depending on which movie is highlighted in the menu 102.
Icons 106 to 109 below the menu 102 enable the user to select movie
listings by movie type, e. g. "Western" movies, "Action "movies",
"Comedy" movies or "Classic" movies. Selection of one of the icons
106 to 109 causes the EPG to apply the aforementioned filtering to
the movie information before it is displayed on the screen 100.
[0102] Having thus described the present invention by reference to
a preferred embodiment it is to be well understood that the
embodiment in question is exemplary only and that modifications and
variations such as will occur to those possessed of appropriate
knowledge and skills may be made without departure from the spirit
and scope of the invention as set forth in the appended claims and
equivalents thereof.
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