MXPA00003676A - Multichannel digital television system - Google Patents

Abstract

A digital television system including a transmission means (4,6) for transmitting digital audiovisual information on a plurality of channels (41) characterised in further comprising a means (44, 45) for introducing in real time an event message concerning a live event broadcast on at least one channel into the datastream of at least one other channel, the event message including information regarding the occurence of an event and the channel on which the event has occurred. Preferably, the transmission means further includes a delay device (3) for introducing a predetermined delay into the transmission time of the audiovisual information broadcast on each of the channels. The invention findsparticular application in the case of simultaneous transmission of sporting events, where a viewer watching one channel may be informed of the occurence of an event, such as a goal, on another channel.

Description

MULTI-CHANNEL DIGITAL TELEVISION SYSTEM The present invention relates to a digital television system that includes a transmission medium for transmitting audiovisual information in a digital data stream in a plurality of channels. Digital television systems are growing continuously, notably in the field of paid television systems. Encrypted or mixed audiovisual information is sent, commonly via a satellite or a satellite / cable link to a number of subscribers, each having a decoder or receiver / decoder capable of separating the transmitted program for later observation. The digital terrestrial transmission systems are also known. Recent systems have also used the transmission link to transmit other data, in addition to or as well as audiovisual data, such as computer programs or interactive applications to the decoder or to a connected personal computer. One of the advantages of digital television is in the number of channels that are available in such systems and the flexibility that is available to the television service provider over selections or channel menus that may be available to a subscriber of the service. . In addition to a standard group of subscription channels, the system may also include, for example, a pay-per-view function that allows a subscriber to pay for a particular movie, sports event, etc.

With the increasing availability of channels, a service that is becoming increasingly popular is the simultaneous transmission of the same sporting event that is viewed from a number of different camera angles. Similarly, for a tennis or soccer competition, a number of matches in the same cup can be broadcast simultaneously on the same evening in different channels. In combination with a pay-per-view service, the subscriber can choose to pay one of the games broadcast on a channel, all the games that afternoon, all the matches in the tournament during the following weeks, etc. Although the viewer benefits from the increase in available selections, the large number of channels that are available can cause distraction and, in practice, a viewer will generally have difficulty in managing the possibilities available to view. For example, some stations provide a menu or channel based on where the viewer can see what is currently being broadcast on all channels, each channel is displayed in a small section on a grid that is displayed on the television screen. However, when a large number of channels are deployed, it can be difficult for a viewer to adequately discern what is happening in any channel. For these reasons, this solution is not particularly suitable for simultaneous live broadcasts on more than a few channels.

An object of the present invention is to solve some of the disadvantages of a multi-channel service and to facilitate the navigation of a viewer in the channels. In accordance with the present invention there is provided a digital television system that includes a transmission medium for transmitting digital audiovisual information in a plurality of channels further characterized in that it comprises a means for real-time introduction of an event message about an event transmission in I live in at least one channel in the data stream of at least one other channel, the event message includes information about the occurrence of an event and the channel in which the event occurred. For example, in the case of the live broadcast of a number of football matches, the event message can be used to indicate the occurrence of a goal in one of the channels, as well as providing an indication of the channel in which this has occurred. The event message can be generated manually by an operator in the transmission center who is watching all the matches simultaneously. As will be described, this information can be treated by an application in the decoder in a number of ways to facilitate the selection of the channel to a viewer and to allow the viewer to change to a channel where an event has occurred. In a particularly convenient embodiment of the invention, the transmission means additionally includes a display device for introducing a predetermined delay in the transmission time of the audiovisual information transmission in each of the channels. For example, digital audio information can be temporarily stored on a random access memory or memory device for about 30 seconds before it is transmitted. Other delay means include analog tape circuits to delay analog audio signals before carrying out digital conversion, etc. The delay can also be introduced downstream in the decoder. The advantage of this mode is that, for the viewer, the signal indicating the event (which is transmitted without delay) will be before the event in question. Thus, changing channels in response to this signal will mean that the viewer will see both the accumulation to the event and the event itself. Additionally, the delay will actually be invisible to the viewer, who will have the sensation of seeing the game "live". Alternatively, given the fact that there is often a repetition of an event such as a goal, the system can be established without a delay between the event signal and the audiovisual data. In this case, the viewer can change the channels after the event, in time to see the repetition. However, although it is possible, this solution is considerably less satisfactory to the viewer than the solution described above. In a practical mode, the means for introducing an event message may comprise a computer, such as a personal computer or a combination of client / server device, adapted to generate an event message in response to a command by an operator, the Event message is sent, for example, via a data injector to a multiplexer that receives audiovisual information for each channel as well as the event message. In particular, when the audiovisual data is supplied to the multiplexer in an MPEG format, the computer can be adapted to send an event message in the form of a predetermined MPEG section to the multiplexer. MPEG is a well-known standard for the digital transmission field in which the data is configured in a series of tables, each table includes a package identifier, etc. In the context of the present patent application, the term includes all variants, modifications or developments of the basic MPEG format such cpmq MPEG-2 as defined in ISO 13818-1 to ISO 13813-4 standards. In one embodiment, the digital television system additionally comprises a decoder adapted to display an icon on the screen upon receipt of an event message to indicate the occurrence of an event. After the display of this icon, the viewer can change channels, for example, by means of a remote control associated with the decoder. Alternatively, the viewer can pre-program the decoder to automatically change channels to a channel where a goal has occurred, for example. In the case where a cone is deployed, the decoder is adapted to display an additional icon after a channel change in response to the first displayed icon, for example to ask if the viewer wishes to return to the first channel he was watching. This predetermined time will naturally depend on the time delay (if any) introduced in the transmission stream of the audiovisual data. For example, when a delay of 30 seconds is introduced in the transmission, the indicated event will continue approximately 30 seconds after the event signal. If the application has received a channel change command, the application will ask the viewer if he wants to change the channel 45 seconds or later, that is, after the event has been shown. The application can use either the channel change message or the arrival of the event message as the starting point for the delay. As will be understood, conventional digital decoders are a combination of computing program devices and physical equipment and the greatest functionality can be added by programming the decoder with a computer program application. Depending on the complexity of the application, more or less memory space will be required in the decoder to carry out each of the functions described. Once this application can be stored permanently in the decoder, in a convenient mode the application is downloaded to the decoder by means of the transmission medium. For example, at the start of a game, the application can be included in the stream of digital data transmitted, you can ask the viewer when you want to download the application. If you accept, the application will remain in the decoder and will work for at least the duration of the match. If not, the decoder will not download the application. Preferably, the transmission means additionally includes an encryption means for encrypting transmitted digital data, including the transmitted audiovisual data and the transmitted event message, the decoder comprises an encryption means adapted to decrypt the digital data of transmission prior to observation and processing of the event message. After a known encryption technique used in a digital television system, the mixed data can be transmitted together with a control word for ordering the data, the control word itself is encrypted by a key operation call and transmitted in the form encrypted The decoder has an equivalent of the operation key to decrypt the control word and sort the data. Other generally known security measures of pay television systems can also be used in the present system to restrict access. The present invention also extends to a decoder for its use in a digital television system as described above, in particular a decoder equipped with an application adapted to generate an icon on the screen to indicate the reception of an event message. The present invention also extends to a method for digitally transmitting and receiving audiovisual information in a stream of digital data in a plurality of channels. Although the description refers to "receivers / decoders" and "decoders" it will be understood that the present invention equally applies to embodiments having a receiver integrated with the decoder as a decoding unit operating in combination with a physically separate receiver or, in fact, a decoder that includes other functions or integrated with other devices, such as combined television / decoder devices. Similarly, the term "digital television system" refers to any system of digital transmission, satellite, terrestrial or cable. Now, by way of example only, a preferred embodiment of the present invention will be described, with reference to the attached Figures in which: Figure 1 shows a digital television system as it can be adapted in accordance with the present invention; Figure 2 shows a general overview of the elements of a decoder for use in a digital television system; Figure 3 shows the digital television system of Figure 1, adapted to include a means for generating in real time an event message introduced in the transmitted data stream; and Figure 4 shows the decision flow diagram of the application present in the decoder to handle the real-time event message. An overview of a digital television system 1 in accordance with the present invention is shown in Figure 1. The invention includes a highly conventional digital television system 2 which uses the known compression system MPEG-2 to transmit compressed digital signals. In more detail, the MPEG-2 compressor 3 in a transmission center receives a stream of digital signals (commonly a stream of video signals). The compressor 3 is connected to a multiplexer and mixer 4 via the link 5. The multiplexer 4 receives a plurality of additional input signals, forms one or more transport streams and transmits the compressed digital signals to a transmitter 6 of the transmission center via link 7, which can of course a wide variety of forms including communications links. The transmitter 6 transmits electromagnetic signals via the uplink 8 to a satellite transponder 9, where they are electronically processed and transmitted via the down link from notion 10 to the ground receiver 12, conventionally in the form of a dish owned or rented by the end user. The signals received by the receiver 12 are transmitted to an integrated receiver / decoder 13 owned or rented by the end user and connected to the television set of the end user 14. The receiver / decoder 13 decodes the compressed MPEG-2 signal into a signal of television for the television set 14. In a multi-channel system, the multiplexer 4 handles audio and video information received from a number of parallel sources and interacts with the transmitter 6 to transmit the information along a corresponding number of channels . In addition to audiovisual information, messages or applications or any other type of digital data can be entered into some or all of these interlaced channels with the digital audio and video information transmitted. A conditional access system 15 is connected to the multiplexer 4 and the receiver / decoder 13, and is located partially in the transmission center and partially in the decoder. It allows the end user to access digital television transmissions from one or more transmission providers. A smart card, capable of deciphering messages relating to commercial offers (i.e., one or more television programs sold by the transmission provider) can be inserted into the II receiver / decoder 13. Using the decoder 13 and the smart card, the end user can buy commercial offers in either a subscription mode or a pay-per-event mode. As mentioned above, the programs transmitted by the system are mixed in the multiplexer 4, the conditions and encryption keys are applied to a given transmission determined by the access control system 15. The transmission of data mixed in this way is well known in the field of pay television systems. Commonly, the mixed data is transmitted together with a control word to separate the data, the control word itself is encrypted by a key operation call and transmitted in encrypted form. The encrypted data and the encrypted control word are then received by the decoder 13 which has access to the equivalent number of the operating key stored in a smart card inserted in the decoder to decrypt the encrypted control word and subsequently separate the transmitted data. A subscriber who has paid will receive, for example, in a monthly EMM (Rights Management Message) transmitted the operating key necessary to decrypt the encrypted control word to allow to see the transmission. An interactive system 16, also connected to the multiplexer 4 and the receiver / decoder 13 and again partially placed in the transmission center and partially in the decoder, allows the end user to interact with several applications via a modem 17 channel. modem channel 17 can also be used for communications used in the conditional access system 15. An interactive system can be used, for example, to allow the viewer to immediately communicate with the transmission center to request authorization to view a particular event, download an application, etc. With reference to Figure 2, the elements of the receiver / decoder 13 or box on the apparatus that can be adapted for use in the present invention will be described below. As will be understood, the elements of this decoder are highly conventional and their implementation will be within the capabilities of those skilled in the art. As shown, the decoder 13 is equipped with several interfaces for receiving and transmitting data, in particular an MPEG tuner and demultiplexer 20 for receiving transmitted MPEG transmissions, a serial interface 23, a parallel interface 24, and a modem 25. for sending and receiving data via the modem channel 17. In this mode, the decoder also includes a first and second smart card reader 26 and 27, the first reader 26 for accepting a subscription card containing decryption keys associated with the system and the second reader 27 to accept bank cards or other specialized cards. The decoder also includes a receiver 28 for receiving infrared control signals from a manual remote control 29 and a "Peritel" salic-a 30 for sending audiovisual signals to the television 14 connected to the decoder. The data processing in the decoder is handled by a central control unit 40. The architecture of the counting programs of the control unit may correspond to that used in a known decoder and will not be described in detail herein. For example, it may be based on a virtual machine that interacts via an interface layer with a lower level operation system implanted in the hardware components of the decoder. In terms of the architecture of the physical equipment, the decoder will be equipped with a processor, memory elements such as read-only memory, random access memory, flash memory, etc. as in known decoders. The control unit 40 can be adapted to run a number of applications that define the functionality of the decoder. An application introduced to the decoder corresponds to a section d, e code entered in the machine that allows the control, for example, of functions of higher level of the machine. Common applications may include generating a graphic sequence on the television display screen in response to a remote control command, or issuing a message via the modem 5 to the server associated with the digital transmission system. As will be described below, an application in accordance with the present embodiment of the invention allows the generation of an icon in response to an event message received in the transmitted MPEG stream, together with a channel change operation depending on the received signals via remote control 29, Applications can be resident applications stored in read-only memory or flash memory of the decoder or applications transmitted and downloaded via the M PEG 20 interface of the decoder, or in fact, any other interface of the decoder. decoder such as the serial port 23, a smart card reader 27, etc. Applications may include program guide applications, games, interactive services, television shopping applications, as well as initiate applications to allow the decoder to operate immediately after startup and the applications to configure the decoder. The applications are stored in memory locations in the decoder and are represented as resource files comprising graphic object description files, unit files, variable lock files, instruction sequence files, application files, data files , etc. The applications downloaded to the decoder can also be retransmitted from the decoder to a personal computer connected to the decoder. Conventionally, the applications downloaded to the decoder via the transmission link are divided into modules, each module corresponding to one or more MPEG tables. Each M PEG table can be divided into a number of sections. For data transfer via serial and parallel ports, the modules are also divided into tables and sections, the size of the section depends on the channel used. In the case of a transmission, the modules are transported in the form of data packets in respective types of data stream, for example, the video data stream, the audio data stream, a text data stream. In accordance with the MPEG standards, each packet is preceded by a packet identifier (PI D) of 13 bits, a packet identifier for each packet transported in the MPEG stream. A program map table (PMT) contains a list of the different streams and defines the content of each stream in accordance with the respective Package Identifier. A Packet Identifier can alert the device to the presence of applications in the data stream, the Packet Identifier is identified by the program map table. With reference to Figure 3, one embodiment of the invention will now be described. As shown, the digital audio and video information for a number of channels 41 passes via a digital delay device 48 to a multiplexer 4 for subsequent transmission. In the present case, a delay of approximately 30 seconds in the transmission of the audiovisual information is introduced. This can be carried out, for example, by simply placing the digital signals on a hard disk of the server or the like before transmission to the multiplexer. In an alternative mode, the delay can be carried out by the decoder at the end of the receiver. In one embodiment, digital audiovisual signals can be compressed and multiplexed in a first multiplexing stage, before moving to a digital delay. After the delay, the signal passes to a second multiplexer to multiplex with other data, including an event message (see below). This has the advantage of reducing the amount of information stored on the disk, but may increase the risks of signal error. In the present embodiment, the digital audio-visual signals are delayed and then passed directly to the multiplexer 4. In Figure 4, the MPEG compression of the signal is carried out by the multiplexer 4 itself, rather than a separate compression unit, as It is shown in Figure 1. In the case, for example, of a soccer tournament, the video and sound data for each match are transmitted on a separate channel by means of the multiplexer and transmitter configuration. A "channel" can be defined by a frequency channel, or as is usually the case in digital television, simply by a logical definition of the channel in the data sent, such as the DVB coordinates of the channel. An operator 42 located in the transmission center sees all matches simultaneously deployed in a bank of monitors 43. The operator has a dedicated personal computer or computer 44 equipped with an application adapted to generate an event message that can be transmitted via a single shot injection unit 45 and multiplexer 4 in the MPEG stream it is transmitted by the transmitter 6. The injection unit 45 is a standard piece of equipment used to ensure the synchrony of the data injected with the multiplexer. In the case of a goal in one of the matches, the operator enters in real time to the computer 44 (i) the information that a goal event has occurred and (ii) in which channel the goal event has occurred. The computer 44 generates an MPEG section that contains this information in a form to be read by an application based on the decoder 13. Then, this section is multiplexed into the data stream associated with each or all of the channels by the multiplexer 4. As will be understood, a designated event message is immediately entered into the transmitted data stream while the video and audio data is input approximately 30 seconds later. In practice, the injection and multiplexing of the event message in the data stream may introduce a small delay, but this is insignificant compared to the delay introduced in the audio and video information. As will be described, the decoder is equipped with an application adapted to receive and interpret the arrival of an event message. This application may be included in the decoder since its manufacture. However, in view of the need to conserve memory space in the decoder, this application is preferably transmitted to the decoder in the same way as other applications of the decoder, ie, via the MPEG transmission path. In this case, the application can be introduced via an injection device 46 to the multiplexer, for example before the match begins, either automatically or at the request of the viewer. The injection device 46 is similar to the injection device 45, with the difference that the application is sent in a continuous cycle to the multiplexer for transmission, while the event message is a single transmission. Referring now to Figure 4, the decision steps in an application input to the decoder 13 for handling event messages received from the transmission center will be described below. In step 50, the viewer is watching an A match on one of the transmitted channels. At time 51, an event message is received informing the decoder of a goal event that is occurring on another channel associated with match B. As will be appreciated, in view of the time delay introduced in the transmission of the audio data and video, this event message will arrive approximately 30 seconds before the goal is displayed on the associated channel. In practice, the emission of the event message will depend on the reflections of the operator at the observation point and the event message may arrive approximately 25 seconds before the event. In the unusual case of two events occurring simultaneously in two different channels, the operator will have to decide which of the goals represents the greatest interest for the viewing public, and again, this may slightly reduce the anticipation time of the event message in comparison with the event itself. In response to the arrival of an event message indicating a goal event on a channel other than the one being viewed at that moment, the application displays an icon on the television screen for a period of approximately 5 seconds, informing the viewer of the imminence of a goal in step 52. The "ACCEPT" icon will be removed from the screen when the viewer changes channels or after the end of the 5 second period if the viewer has not changed the channel. If desired, the icon can indicate the channel or game in which the goal occurred to allow the viewer to decide if he or she wants to see the goal. However, in its simplest form, the icon can only indicate that a goal has occurred, for example, by displaying an "ACCEPT" icon. In the event that the viewer answers the query in step 52 with a "yes" 53 command, the application will change to the channel showing the match B in question in step 55. The "Yes" command may correspond, for example, upon receiving the decoder of a remote control signal associated with the decoder indicating that any of the buttons or a specific button of the remote control (eg, an "ACCEPT" button) has been pressed.

In the event that a "no" instruction 54 is received, the decoder will remain tuned to match A. The command "no" can, for example, simply correspond to the absence of a remote control command within 5 seconds after the icon is deployed in step 52. Alternatively, the decoder can be programmed by the application in the opposite direction. , that is, the application will automatically switch to the channel where the goal has occurred unless the remote control was received within 5 seconds after the icon was displayed on the screen. Note that in the event that an event message arrives indicating a goal event in the channel to which the decoder is tuned, the application can either display the same or another icon indicating to the viewer the presence of a goal in that channel or You can display a warning icon ("CO NFIR MA R CA MB IO") in case the viewer tries to change the channel during the delay before the event arrives. As described above, in view of the time delay introduced in the broadcast of the televised match, a viewer changing the channel will arrive approximately 20 seconds before the occurrence of the goal in that channel. Thus, while the viewer will have the sensation of seeing all the matches "live", he will also have the advantage of being able to quickly and easily re-tune a match where a goal occurs. After a predetermined additional time, for example approximately 45 seconds after the channel change, the application can be configured to display a second icon in step 56 by asking the viewer if he wishes to change back to the original match A shown in the first channel. After this time has elapsed, it can be assumed that the goal has been shown, along with all repetitions, analysis, etc. This time can be measured from the start of receipt of the original command to change channel, or from the beginning of the receipt of the event message, with a provision not to display the message if the viewer stayed in match A. Again, the icon that asks the viewer if he wants to return to the original match A can simply be an "ACCEPT" icon or similar. In the event that the viewer presses the "ACCEPT" button on the remote control, this will be interpreted as a "yes" command 57 and the decoder will return to match A. In the event that a signal is received not "ACCEPT" in 5 seconds after of the display of this icon, the decoder will remain tuned to match B. Modifications of the system can be contemplated, for example, allowing the application to receive and process a plurality of messages arriving at the same time or within the time structure of operations between Steps 50 and 56 described above. For example, the application may indicate the arrival of a new goal event after the first channel change to allow the viewer to change the channel again if desired. In addition or alternatively, it may be possible to display two or more event messages simultaneously indicating a first goal event on channel X for match C, a second goal event on channel Y for match D, etc. Similarly, although the present modality has been described in relation to the indication of goal events during a football game, the same system can be used in other live broadcast contexts where it would be desirable to inform a viewer who is watching a game. channel of the occurrence of one event in another.

Claims (19)

1. REINVENTING DICATIONS 1. A digital television system that includes a transmission medium for transmitting digital audiovisual information in a plurality of channels characterized by comprising a means to introduce in real time an event message about a transmission of a live event in at least one channel in the data stream of at least one other channel, the event message includes information about the occurrence of an event and the channel in which the event has occurred.
2. 2. A digital television system according to claim 1, wherein the transmission means further includes a delay device for introducing a predetermined delay in the transmission time of the audiovisual information transmission in each of the channels.
3. 3. A digital television system according to claim 1 or 2, wherein the audiovisual data is transmitted in an MPEG format.
4. 4. A digital television system according to any of the preceding claims, wherein the means for entering an event message comprises a computer adapted to generate an event message in response to a command by an operator.
5. 5. A digital television system according to claim 4, wherein the computer is adapted to send an event message in the form of a predetermined MPEG section.
6. 6. A digital television system, according to any of claims 1 to 5, which additionally comprises a decoder adapted to display an icon on the screen upon receipt of an event message to indicate the occurrence of an event.
7. 7. A digital television system, according to claim 6, wherein the decoder is adapted to automatically switch to the channel in which the event has occurred after a "yes / no" response by the viewer to the displayed icon.
8. 8. A digital television system according to claim 7 in which the "yes" response corresponds to a signal from a remote control associated with the decoder indicating that any of the buttons or a predetermined button of the remote control has been held down.
9. 9. A digital television system according to claim 7 or 8, in which the answer "no" corresponds to a lack of response by the viewer to the displayed icon. 1 0.
10. A digital television system according to any of claims 6 to 9, wherein the decoder is adapted to display an additional icon on the screen after a channel change by the viewer in response to the first icon unfolded. eleven .
11. A digital television system, any of claims 6 to 10, wherein the increased functionality in the decoder is implemented by programming the decoder with an application of computer programs.
12. 12. A digital television system according to claim 1, wherein the application is downloaded to the decoder by the transmission medium.
13. 13. A digital television system according to any of the preceding claims, wherein the transmission means further includes an encryption means for encrypting transmitted digital data, including the transmitted audiovisual data and the transmitted event message.
14. A digital television system according to claim 13, further comprising a decoder provided with a decryption means adapted to decrypt the transmitted digital data before viewing the audiovisual data and processing the event message.
15. 15. A decoder for use in a digital television system according to any of the preceding claims and adapted to receive and process an event message in real time.
16. 16. A decoder according to claim 15, adapted to display an icon in response to an event message received.
17. 17. A method for transmitting digital audiovisual information in a plurality of channels characterized by entering in real time an event message about a real-time live event transmitted on at least one channel in the data stream of at least one other channel , the event message includes information about the occurrence of an event and the channel in which the event has occurred.
18. 18. A digital television system substantially as described herein.
19. 19. A method for transmitting digital audiovisual information substantially as described herein.