Patent Publication Number: US-2009228942-A1

Title: System and a method for managing audiovisual programs in a telecommunications network

Description:
BACKGROUND OF THE INVENTION 
     The field of the invention is that of broadcasting audiovisual contents in IP (Internet Protocol) networks. 
     In the present document, the expression “audiovisual content” refers to content associated with the IPTV (Internet Protocol Television) service and all associated services, in particular VoD (Video on Demand), TVoD (Television on Demand), NTS (Network-based Time Shifting), and NPVR (Network-based Personal Video Recorder). 
     The term “streaming” refers to the method of broadcasting a multimedia stream (video, TV, etc.) from a server to a client in an IP network. Among other things, streaming enables “live” (real-time) broadcasting of audiovisual programs in unicast mode or in multicast mode. 
     In multicast mode a single copy of each multimedia stream is sent to each branch of the network. This relies on constructing a multicast tree between the source and the receiver terminals. 
     In solutions that broadcast audiovisual content in an IP network, the operator enables subscribers to view a plurality of audiovisual programs. To optimize the use of network resources, not all programs are broadcast continuously to each client. All clients watching the same audiovisual program broadcast by the same source form a subscriber group defined by the source/program pair. Consequently, a client wishing to receive a new audiovisual program (in other words to change channel or “zap”) has to unsubscribe from the group corresponding to the current program and subscribe to the group corresponding to the new program. 
     These subscription and unsubscription operations are generally carried out using the Internet Group Management Protocol (IGMP). 
     Historically, to manage live broadcasting, equipment installed on the user premises has recorded the audiovisual program being viewed, starting from a point that moves with time. 
     The person skilled in the art calls this process time shifting. 
     More recently, some operators and equipment manufacturers have deployed network-based time-shifting solutions. 
     To be more precise, a server of the network implements a centralized version of the role of the subscriber premises equipment and user commands are sent to this server, for example using the Real Time Streaming Protocol (RTSP). 
     The RTSP controls the distribution of multimedia streams in an IP network in unicast mode. It is an application level protocol offering the functions of a remote recorder (play, pause, fast forward, fast rewind, stop, etc.). 
     A receiver terminal seeking to use one of these functions contacts the streaming server using the RTSP. 
     In response, the server broadcasts the multimedia streams providing the service, separately from RTSP exchanges, using the streaming protocol, for example the Real Time Protocol (RTP) or the MPEG2-TS (Transport Stream) Protocol. 
     For example, if the client wishes to pause the current audiovisual program (using the PAUSE function), an associated RTSP message is sent to the server, which starts to record the audiovisual program the client is watching. 
     At present, and for all types of television broadcasting, viewers are restricted by the strict synchronism of television channels. Thus a viewer cannot watch different programs transmitted simultaneously on different channels, even if all the transmissions are potentially of interest. At best, one transmission can be viewed while a second transmission is being recorded to be viewed later. If there are more than two simultaneous transmissions, the viewer has no solution. 
     The synchronized transmission of channels also prevents television viewers from watching the whole of two programs transmitted at times that overlap. 
     Furthermore, the increasing number of channels offered to viewers obliges them to “zap” constantly, if they are to be able to view all transmissions of interest. It is rare for all programs potentially of interest to a user to be transmitted on the same channel. A viewer who fails to change channel at the end of a transmission, runs the risk of missing another interesting program transmitted on another channel. 
     It is therefore necessary for the viewer to pay close attention to the program guide and to zap from one channel to another, which proves irksome. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The invention relates to a system for managing audiovisual programs in a telecommunications network, each program being broadcast by a source to receivers that are subscribed to a broadcast group. 
     This system includes:
         means for interpreting a sequence of audiovisual programs programmed by a user of a receiver in the form of a succession of commands to change program, a command to change program being conditional on a preceding program in said sequence ending;   means for detecting a predetermined event corresponding to the start of the first program in the sequence, or to the end of one of said programs in the sequence; and   means for sending said receiver, after said event is detected, a first message adapted to trigger sending by said receiver to said management system of a first request to subscribe to a broadcast group for the first program in the sequence, or the program in said sequence following the program for which the end has been detected.       

     In a correlated way, the invention relates to a method of managing audiovisual programs in a telecommunications network, each program being broadcast by a source to receivers that are subscribed to a broadcast group. 
     This method includes:
         a step of interpreting a sequence of audiovisual programs programmed by a user of a receiver in the form of a succession of commands to change program, a command to change program being conditional on a preceding program in said sequence ending;   a step of detecting a predetermined event corresponding to the start of the first program in the sequence, or to the end of one of said programs in the sequence; and   a step of sending said receiver, after said event is detected, a message adapted to trigger sending by said receiver of a first request to subscribe to a broadcast group for the first program in the sequence, or the program in said sequence following the program for which the end has been detected.       

     Thus the invention proposes a novel and inventive approach to managing audiovisual programs that a user can view. 
     Using the invention, and by logging onto an interactive portal, for example, a client user can program a sequence of programs (football match, news, film, etc.) to be viewed over a particular time period, for example an entire evening. 
     The portal then interprets the programming entered by the client as a succession of zaps, each conditional on the previous transmission in the sequence entered by the client coming to an end. 
     The portal can then transmit these zapping instructions to a server, which executes them at the required time. 
     To be more precise, on detecting a predetermined event, for example the beginning of the first transmission in the sequence, the invention sends the receiver a message that automatically triggers sending by the receiver of a request to subscribe to a broadcast group for the audiovisual program that is starting. 
     Similarly, on detecting the end of an audiovisual program of the sequence preprogrammed by the client, the invention sends the receiver a message that automatically triggers the sending by the receiver of a request to subscribe to a broadcast group of the next audiovisual program in the sequence. 
     The invention therefore overcomes the drawback of the prior art because the user no longer needs to change channel as and when programs start and end. It suffices to program in advance the sequence of broadcasts to be watched and channel changing is then automatic, without the user having to do anything. 
     In one particular embodiment, the management system and the management method of the invention are adapted to store an audiovisual program broadcast in a network in a sliding time window. In particular, the management system and the management method of the invention are adapted, on detection of the start of one of the programs in the sequence selected by the user, to start recording that program if the end of the preceding program in the sequence has not yet been detected. 
     The invention therefore provides a solution to the prior art problem of the client being restricted by the strict synchronism of TV channels and being unable to view different transmissions broadcast simultaneously on different channels, even if all those transmissions are potentially of interest. 
     By means of the invention, the client can watch live a first broadcast (for example the news) and then watch off-line a second broadcast (for example a football match) which started before the end of the first broadcast, and so on for a predetermined sequence of broadcasts that the user has preprogrammed. 
     In one particular embodiment, the management system and method of the invention are adapted, after detecting the end of a program in the sequence whose transmission time at least partly overlaps the next program in the sequence, to send the receiver a second message adapted to trigger sending by the receiver to the management system of a second request to set up a communications channel with the management system to obtain, in that channel, at least part of the audiovisual program recorded by the system, corresponding to the program following the program in the sequence the end of which has been detected. 
     This kind of message naturally replaces the message described above that triggers sending of a request to subscribe to a broadcast group for the program following the program in the sequence the end of which has been detected. It is used if two successive broadcasts in the sequence programmed by the user have overlapping broadcast times, in contrast to the first message referred to, which is used if the broadcast times of the successive transmissions do not overlap. 
     By means of this feature, after the end of a program has been detected by the management system of the invention, a user can receive off-line an audiovisual program that is no longer being broadcast in multicast mode, but in unicast mode, on a logical communications channel set up to the receiver of that user. 
     In one particular embodiment, the management system and the management method of the invention include, before the message is sent to a receiver, a step of the receiver or the user of the receiver confirming the subscription to the new broadcast group, in other words the change of channel. 
     This can be confirmed explicitly by reception of a command coming from the receiver or implicitly by the absence of reception of a command during a predetermined time period. 
     In one particular embodiment of the invention, the receiver sends requests to the management system using the RTSP. 
     In one particular embodiment of the invention, the management system of the invention sends messages to the receiver in the form of an SNMP (Simple Network Management Protocol) frame encapsulating an IGMP command. 
     Thus, on reception of the SNMP frame, the receiver automatically executes the IGMP command contained in the frame and subscribing the receiver to the new broadcast group. 
     In one particular embodiment, the various steps of the audiovisual program management method are determined by computer program instructions. 
     Consequently, the invention is also directed to a computer program on an information medium and adapted to be executed in an audiovisual program management device, or more generally in a computer, the program including instructions adapted to execute the steps of an audiovisual program management method as described above. 
     That program can use any programming language and take the form of source code, object code or an intermediate code between source code and object code, such as a partially compiled form, or any other desirable form. 
     The invention is also directed to a computer-readable information medium containing instructions of a computer program as referred to above. 
     The information medium can be any entity or device capable of storing the program. For example, the medium can include storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or magnetic storage means, for example a diskette (floppy disk) or a hard disk. 
     Moreover, the information medium can be a transmissible medium such as an electrical or optical signal, which can be routed via an electrical or optical cable, by radio or by other means. The program of the invention can in particular be downloaded over an Internet-type network. 
     Alternatively, the information medium can be an integrated circuit into which the program is incorporated, the circuit being adapted to execute the method in question or to be used in its execution. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention emerge from the description given below, with reference to the appended drawings, which show one non-limiting embodiment. In the figures: 
         FIG. 1  represents a management system of the invention and the main steps of a management method of the invention; 
         FIG. 2  represents a configuration table used in the  FIG. 1  embodiment; and 
         FIG. 3  represents a preferred embodiment of a computer according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  represents a management system of the invention and a management method of the invention enabling a user to program a sequence of transmissions that he wishes to watch. 
     The system essentially comprises a network equipment  20  and a server  40  connected to a database  50 . 
     The network equipment  20  can set up a call between an audiovisual program source  30  and receivers  10  over an IP network that is not shown. 
     The source  30  is also known as the network head end. 
     The receivers  10  are set top boxes, for example. 
     If a user of a terminal  10  wishes to receive an audiovisual program CH 1 , he selects that program using his remote controller and the receiver  10  sends the network equipment  20  a subscription request AB(CH 1 ) including the identifier CH 1  of the audiovisual program. 
     In response to this request AB(CH 1 ), the network equipment adds the address of the receiver  10  to the multicast group for the audiovisual program CH 1  broadcast by the source  30 . 
     According to the invention, the user of the receiver  10  can program a sequence of transmissions that he wishes to view that are broadcast successively or simultaneously on different channels or in time periods that overlap at least in part. Thus the user can program a personalized chart of his evening&#39;s viewing by accessing an interactive portal  60 , for example. 
     The interactive portal  60  interprets this programming as a succession of zappings conditional on the end of a transmission. It sends a list of these conditions to the server  40 , which stores them in its database  50 , in order to manage recording of transmissions that the user cannot view live and broadcasting of transmissions requested by the user in accordance with time constraints set in his program chart. 
     To implement this scenario, the management system of the invention is configured using a configuration table TC shown in  FIG. 2 . 
     This table includes:
         a first column storing an identifier of the receiver concerned;   a second column storing events PRi(ON) and PRi(OFF) respectively corresponding to the start and to the end of the transmission PRi of an audiovisual program CHi;   a third column storing audiovisual programs that must be broadcast or sent to the receiver of the network on detection of the associated event in the first column; and   a fourth column specifying audiovisual programs that the management system of the invention must record on detection of the event in the first column.       

     The configuration table TC can be sent to the server  40  by the portal  60  during a preliminary phase PROG in which the user programs the management system of the invention. 
     This programming step primarily specifies in the configuration table TC a number of events and associated actions. 
     In the example described here, on reception of this configuration table TC, the server  40  stores it in the database  50 . 
     The configuration table TC must be interpreted as follows:
         If the server  40  of the invention detects the event PR 1 (ON), it must force broadcasting of the audiovisual program CH 1  to the receiver  10 , there being no need to record it.       

     The event PR 1 (ON) corresponds to the start of the transmission PR 1  of the audiovisual program CH 1 , and is sent to the server  40  by the source  30  in the form of information in the broadcast stream of the channel CH 1 . 
     The second line of the configuration table TC shows that the management system of the invention must start to record the audiovisual program CH 2  when the source  30  sends an event PR 2 (ON) representing the start of the transmission PR 2  in the audiovisual program CH 2 . 
     Finally, the third line of the configuration table TC must be interpreted by the management device of the invention as indicating that it is to send the audiovisual program CH 2  to the client  10  off-line when the server  40  receives a message PR 1 (OFF) from the source  30  representing the end of the transmission PR 1  of the audiovisual program CH 1 . 
     Accordingly, when the transmission PR 1  of the audiovisual program CH 1  starts, the source  30  sends the server  40  a message PR 1 (ON) via the network equipment  20 . 
     According to the configuration table, the server  40  then sends the receiver  10  a message ZAP(CH 1 ) via the network equipment  20  to force broadcasting of the audiovisual program CH 1  to the receiver  10 . 
     In the embodiment described here, this message ZAP(CH 1 ) is an SMNP frame that encapsulates the IGMP AB(CH 1 ) command. 
     On reception of this message, the receiver  10  automatically sends a subscription request AB(CH 1 ) to the network equipment that is to be subscribed to the audiovisual program CH 1  broadcast by the source  30 . 
     The person skilled in the art will understand that this request is sent automatically through the advantageous use of the SMNP to send the message to the receiver  10 . 
     On reception of the subscription request AB(CH 1 ), the management device of the invention subscribes the receiver  10  to the broadcast group for the audiovisual program CH 1  so that the receiver can receive the program. To be more precise, the network equipment  20  adds the identifier of the receiver  10  to the broadcast list for the audiovisual program CH 1 . 
     At the same time, in the example described here, the network equipment  20  sets up a communications channel with the server  40  on which the audiovisual program CH 1  is broadcast. 
     When the transmission PR 2  of the audiovisual program CH 2  starts, the source  30  sends the server  40  via the network equipment  20  the message PR 2 (ON) representing the start of transmission and the audiovisual program CH 2 . 
     According to the second line of the configuration table TC, the server  40  starts to record the audiovisual program CH 2  in a memory of the database  50 . 
     When the transmission PR 1  of the audiovisual program CH 1  ends, the source  30  sends a message PR 1 (OFF) via the network equipment  20  representing the end of transmission. 
     The reception of this PR 1 (OFF) message constitutes the event in the third line of the configuration table TC. 
     Consequently, the server  40  sends the receiver  10  via the network equipment  20  a message ZAP(CH 2 ) that triggers sending by the receiver  10  of a request AB(CH 2 ) to subscribe to the audiovisual program CH 2 . 
     The server  40  can first request the client to confirm that they wish to change channel. The subscription request AB(CH 2 ) is sent if the client terminal  10  approves this zapping instruction, either explicitly or tacitly. If not, the server  40  stops recording the audiovisual program CH 2 . 
     In the embodiment described here, the management system of the invention understands that it is not to subscribe the receiver  10  to the broadcast group of the audiovisual program CH 2  but instead set up a communications channel between the receiver  10  and the server  40  for off-line broadcasting of the audiovisual program CH 2  that has been being recorded in the database  50  since the start of the transmission PR 2 . 
     The invention proposes other possibilities for configuring the management system. 
     For example it is possible to specify in a configuration table that an audiovisual program is to be recorded or a message is to be sent to the client  10  after a predetermined delay associated with an event. 
     During the programming phase PROG effected by the user via the interactive portal  60 , the user can be required to select only transmissions with times that can overlap within a limit (the duration of the sliding window) of the time shifting facility (for example 30 minutes). 
       FIG. 3  represents a preferred embodiment of a computer of the invention. 
     The computer  80  combines in a single machine the functions of the network equipment  20  and the server  40  described with reference to  FIG. 1 . 
     The computer  80  includes a processor  81 , a read-only memory (ROM)  82 , and a random-access memory  83 . 
     The read-only memory  82  stores a computer program of the invention, i.e. a program including instructions for executing the steps of the management method described above. 
     The computer  80  of the invention includes means  84  for setting up an IP call with the receiver  10 . 
     The communication means  84  in particular send SNMP format ZAP messages to the receiver  10  and receive RTSP requests from the receiver. 
     The computer  80  of the invention also includes means  85  for receiving a video stream coming from the source  30  and directing such streams to the receiver  10 . 
     Finally, the computer  80  of the invention can access a database  50  to store configuration tables of the same type as the table TC described above. 
     Note that the whole of the present document describes the sequencing of transmissions whereby the user begins by watching a live transmission and sequences to a second live transmission or an off-line transmission recorded beforehand. 
     The invention is not limited to such embodiments, of course, and applies to all possible ways to sequence transmissions. In particular, the user&#39;s chart of programs could correspond to a sequence comprising only recorded transmissions (for example transmissions recorded during the day for viewing in the evening), which are therefore all viewed off-line. 
     This would also enable the user to watch a first off-line transmission recorded beforehand and then to sequence to one or more live transmissions. Reciprocally, the user could start by watching a transmission live and then sequence to one or more off-line transmissions. In other words, the system of the invention and the method of the invention cater for all configurations for sequencing live and off-line transmissions.