JP5472228B2 - Receiving terminal and its program - Google Patents

Description

  The present invention relates to a receiving terminal that receives a multicast broadcast.

  In recent years, broadcast data distribution services using IP multicast (hereinafter referred to as multicast) have been provided. In general, in multicast, a receiving terminal that receives data distributed from a multicast server (hereinafter referred to as a server) transmits a request to join a multicast group (hereinafter referred to as a group) to the network side. Then, a router corresponding to multicast (hereinafter referred to as a multicast router) receives a request to join the group from the receiving terminal, and adds the receiving terminal that desires to join to the multicast path. As a result, the receiving terminal can receive broadcast data distributed by the server.

  A server that performs multicast distribution transmits broadcast data of a plurality of channels to one group. The receiving terminal participates in one or more groups and simultaneously receives data of a plurality of channels distributed in the groups. In addition, there are a plurality of groups, and the distributed channels differ for each group. For example, broadcast data of channels 1 to 5 is distributed from the server to group 1, and broadcast data of channels 6 to 8 is distributed from the server to group 2.

  Two or more servers may be installed in order to improve maintainability and operability. If a server that operates normally (hereinafter referred to as the primary server) temporarily becomes inactive due to maintenance or inspection, a spare server (hereinafter referred to as the secondary server) operates, and the primary server Act as a proxy. There is also a situation where both the primary server and the secondary server operate simultaneously, broadcast data of a certain channel is distributed by the primary server, and broadcast data of another certain channel is distributed by the secondary server.

  The user operates the receiving terminal and designates one channel to be reproduced from among a plurality of channels. The receiving terminal receives broadcast data of a plurality of channels adjacent to the channel being reproduced simultaneously with the broadcast data of the channel to be reproduced, and accumulates it in a buffer in the receiving terminal. When a channel is switched by a user operation at the receiving terminal, broadcast data is read from the buffer, and playback of the switched channel is started. As a result, when the channel to be played back at the receiving terminal is switched by a user operation, the receiving terminal can quickly start playback of the switching destination channel.

  By the way, at the time when the receiving terminal starts operation, generally all servers of the distribution source are primary servers. The receiving terminal specifies a group to which a channel that needs to be received belongs, and participates in the specified group. Communication between the receiving terminal and the multicast router (the same applies between the multicast router and the server) is performed for the number of combinations of the primary server and the group to which the channel received by the receiving terminal belongs. For example, there are five channels simultaneously received by the receiving terminal, channels 1 to 3 are distributed from the server by group 1, and channels 4 and 5 are distributed from the server by group 2. At this time, the receiving terminal participates in group 1 and group 2 in order to receive the broadcast data of channels 1 to 5. As a result, communication by the combination of the group 1 and the primary server and communication by the combination of the group 2 and the primary server are executed on the network. That is, two communication paths are established between the receiving terminal and the server.

  In the process of operating the receiving terminal, the primary server may temporarily stop, or the primary server may be unable to distribute broadcast data of a specific channel distributed by the primary server for some reason. At this time, the receiving terminal switches the server that distributes the broadcast data of the channel that cannot be received from the primary server to the secondary server. Alternatively, the server administrator switches the server that distributes the data of the channel that cannot be distributed from the primary server to the secondary server. As a result, the number of combinations of servers and groups increases. For example, when the channels 2 and 5 are switched from distribution by the primary server to distribution by the secondary server, the network includes communication by a combination of the group 1 and the primary server, and communication by a combination of the group 1 and the secondary server. The communication by the combination of the group 2 and the primary server and the communication by the combination of the group 2 and the secondary server are executed. That is, four communications are executed on the network. That is, when the distribution server of the channel being received by the receiving terminal is changed, the communication path on the network increases. As a result, the amount of data flowing between the receiving terminal and the multicast router increases. If the data exceeds the range that can be processed by the multicast router, packet loss occurs and the receiving terminal cannot receive broadcast data normally.

  The above problem is a problem specific to the multicast distribution system. In other words, in the case of a unicast distribution system, the server and the receiving terminal establish a connection for each channel received by the receiving terminal. Therefore, if an increase in bandwidth is expected, the multicast router can be reduced by reducing the number of channels simultaneously received. And the amount of communication packets between the receiving terminal and the receiving terminal can be reduced. However, in the case of a multicast distribution system, even if the number of channels received by the receiving terminal is not changed, as described above, the network use band increases.

Japanese Patent Laid-Open No. 2010-233175 discloses that a client terminal determines whether a received multicast transmission band satisfies a predetermined reference value, and the received multicast transmission band is a reference value. It is described that the multicast to be received is changed when the above is not satisfied.

JP 2010-233175 A

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide a receiving terminal capable of saving a use band of a communication path and preventing occurrence of packet loss in a multicast distribution system. Is to provide.

A receiving terminal according to a preferred embodiment of the present invention includes: a first server capable of distributing broadcast data of a plurality of channels by multicast; and a second server capable of distributing the broadcast data of the plurality of channels by the multicast. Multicast group joining means which is a receiving terminal capable of receiving the broadcast data to be distributed and participates in one or a plurality of multicast groups to which a zapping channel including a reproduction channel and one or a plurality of channels other than the reproduction channel belongs And a zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel, and a leaving means for leaving the participating multicast group when the broadcast data of the zapping channel is distributed from two or more servers. and, participation After withdrawal from the multicast group in said designating the server for distributing the broadcast data of the zapping channel to the first server or the second server, and re-connecting means to join the multicast group again Prepare.

  When there are two or more servers that distribute zapping channel broadcast data received by the receiving terminal, the receiving terminal changes the zapping channel distribution source server from the first server to the second server, or from the second server to the first server. Change to the server and join the multicast group again. Since the receiving terminal unifies the zapping channel distribution source server, the number of combinations of multicast groups and servers is minimized, the network bandwidth usage is reduced, and the receiving terminal can receive broadcast data normally.

In a preferred embodiment, the broadcast distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A receiving terminal capable of receiving data,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a reproduction channel and one or more channels other than the reproduction channel belongs, and zapping channel reception for simultaneously receiving the broadcast data of the zapping channel Means, communication determining means for determining whether the broadcast data of the zapping channel is being normally received, and when the communication determining means determines that the broadcast data of the zapping channel is not being normally received, and withdrawal means for withdrawal from the multicast group of participating, it said after withdrawal from the multicast group, have the server said first server and said second server for distributing the broadcast data of the zapping channel participating Of unified server Re, and a re-connection means to join the multicast group again.

When the receiving terminal cannot normally receive broadcast data of one or more channels among a plurality of channels received by the receiving terminal, the receiving terminal leaves the participating multicast group and sets the distribution source servers of all channels to the first. Change from the first server to the second server, or from the second server to the first server, and join the multicast group again. The receiving terminal specifies the distribution source server of the channel in which the reception error has occurred, and changes to a server different from the specified server, so that broadcast data can be received normally. In addition, since the receiving terminal unifies the zapping channel distribution source servers, the number of combinations of multicast groups and servers is minimized.

A receiving terminal according to another preferred embodiment of the present invention includes: a first server capable of distributing broadcast data of a plurality of channels by multicast; and a second server capable of distributing the broadcast data of the plurality of channels by multicast. Multicast group that is capable of receiving the broadcast data distributed from the network and that participates in one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs The participation means, the zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel, the communication determining means for determining whether or not the broadcast data of the zapping channel is being received normally, and the communication determining means Broadcast data is being received normally When it is determined that the broadcast data is not normally received, an error channel specifying unit that specifies a channel that is not normally receiving the broadcast data, and whether the channel specified by the error channel specifying unit is the reproduction channel are determined. when the reproduction channel error determining means, said channel identified by said error channel specifying means is judged to be the reproduction channels, a withdrawal means for withdrawal from the multicast group of participating, from the multicast group of participating And reconnecting means for unifying the server that distributes the broadcast data of the zapping channel into one of the first server and the second server and rejoining the multicast group. .

  The receiving terminal specifies a distribution source server of a channel in which a reception error has occurred, and determines whether or not the specified server is a reproduction channel. When the receiving terminal determines that the playback channel cannot be normally received, the receiving terminal leaves the participating multicast group, and the distribution source server of the zapping channel is changed from the first server to the second server, or the second server. Change to the first server and join the multicast group again. Since the receiving terminal executes the above-described process of leaving and joining when a reception error occurs in the playback channel, the receiving terminal can play back the playback channel without sound interruption. Also, even if a receiving error occurs in a channel other than the playback channel, the receiving terminal does not stop and join, so that playback does not stop.

A receiving terminal according to another preferred embodiment of the present invention includes: a first server capable of distributing broadcast data of a plurality of channels by multicast; and a second server capable of distributing the broadcast data of the plurality of channels by multicast. Multicast group that is capable of receiving the broadcast data distributed from the network and that participates in one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs The participation means, the zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel, the communication determining means for determining whether or not the broadcast data of the zapping channel is being received normally, and the communication determining means Broadcast data is being received normally When it is determined that there is no, an error channel specifying means for specifying a channel not normally in receiving the broadcast data, switches the reproduction channel by a user operation, the playback channel switching means, specified by the error channel specifying means when the channel determines that a said channel specified by the reproduction channel switching means, and withdrawal means for withdrawal from the multicast group of participating, after withdrawal from the multicast group of participating, the zapping channel And a reconnection unit that unifies the server that distributes the broadcast data into one of the first server and the second server and rejoins the multicast group .

When the playback channel of the receiving terminal is switched by a user operation, the receiving terminal determines whether or not the switching destination channel is being received normally. If it is determined that the receiving channel is not receiving normally, the receiving terminal determines from the participating multicast groups. Leave, change the zapping channel distribution source server from the first server to the second server, or from the second server to the first server, and join the multicast group again. If the receiving terminal cannot normally receive the broadcast data of the switching destination channel, the receiving terminal executes the above-described process of leaving and joining before switching the channel, so that the receiving terminal can normally reproduce the switching destination channel. Further, when the receiving terminal cannot normally receive any channel other than the switching destination channel, it does not execute the process of leaving and joining, so that the playback channel can be switched at high speed.

Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs, and the broadcast data of the zapping channel simultaneously A zapping channel receiving means for receiving, a number of combinations acquiring means for acquiring the number of combinations of the participating multicast group and the server distributing the broadcast data of the zapping channel, and the number of combinations acquiring means By The number of the combinations is obtained Te is, the number of combinations determination means for determining whether it is within a range of a predetermined number of combinations, the number is the number of combinations of said predetermined number of said combinations by the number of combinations determination means If it is determined not to be within the range, a withdrawal means for withdrawal from the multicast group of participating, after leaving from the multicast group of participating, said server for distributing the broadcast data of the zapping channel the first server And a reconnection unit that unifies the second server and joins the multicast group again .

  The receiving terminal determines whether or not the number of combinations of the multicast group in which the receiving terminal is participating and the server delivering the zapping channel is within a specified number range. If it is determined, it leaves the participating multicast group, changes the distribution server of the zapping channel from the first server to the second server, or from the second server to the first server, and joins the multicast group again. To do. Since the number of combinations of multicast groups and servers is suppressed to a certain number or less, it is possible to prevent the amount of communication data that cannot be processed by the multicast router, so that the receiving terminal can normally receive the zapping channel.

A receiving terminal according to another preferred embodiment of the present invention includes: a first server capable of distributing broadcast data of a plurality of channels by multicast; and a second server capable of distributing the broadcast data of the plurality of channels by multicast. Multicast group that is capable of receiving the broadcast data distributed from the network and that participates in one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs The participation means, the zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel, the communication determining means for determining whether or not the broadcast data of the zapping channel is being received normally, and the communication determining means Broadcast data is being received normally A multicast group specifying means for specifying the multicast group to which the playback channel does not belong, and distributing the broadcast data of the channel in the multicast group specified by the multicast group specifying means Determining whether a server is the same server of the first server and the second server; a distribution server identification determining unit; and a multicast server in the multicast group identified by the multicast group identifying unit wherein if the server is determined not to be identical, and withdrawal means for withdrawal from the multicast group identified by the multicast group specifying unit, the multicast group identified by the multicast group specifying means Reconnection means for unifying the server that distributes the broadcast data of the zapping channel into one of the first server and the second server and rejoining the multicast group after leaving the network Is provided .

  The receiving terminal specifies a multicast group to which the playback channel does not belong. Then, the receiving terminal determines whether or not the distribution source servers of the channels belonging to the specified multicast group are the same, and when determining that they are not the same, the receiving terminal leaves the participating multicast group, and the zapping channel The distribution source server is changed from the first server to the second server, or from the second server to the first server, and rejoins the multicast group. As a result, the receiving terminal can reduce the number of combinations of multicast groups and servers and the network traffic without stopping playback.

  In the multicast distribution system, it is possible to reduce the use band of the network and prevent packet loss and the like from occurring.

FIG. 2 is a multicast distribution system diagram according to a preferred embodiment of the present invention. FIG. 4 is a block diagram of a receiving terminal according to a preferred embodiment of the present invention. It is a figure which shows a reception status table. 3 is a flowchart showing processing of a control unit 11. It is a figure which shows a reception status table. It is a multicast distribution system diagram. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11. 3 is a flowchart showing processing of a control unit 11.

  Hereinafter, although the receiving terminal by preferable embodiment of this invention is demonstrated concretely with reference to drawings, this invention is not limited to these embodiment. FIG. 1 is a block diagram of a multicast distribution system according to a preferred embodiment of the present invention.

  The receiving terminal 100 is, for example, a set top box, an AV receiver and AV amplifier having a network interface, and the like, and is a device that can receive broadcast data by multicast from a server.

  Channels A1 to A5 indicate broadcast data of different channels, respectively. The primary server 200 (a) is a server that can distribute broadcast data of channels A1 to A5 by multicast. The secondary server 200 (b) is also a server that can distribute broadcast data of A1 to A5 by multicast. Both the primary server 200 (a) and the secondary server 200 (b) may be operating simultaneously, or only one of them may be operating. Normally, the primary server 200 (a) operates preferentially. In the multicast distribution system of FIG. 1, only the primary server 200 (a) is operating. Note that the broadcast data of the channels A1 to A5 may be stored in the primary server 200 (a) or the secondary server 200 (b), and the broadcast data of each channel may be stored in the primary server 200 (a) or the secondary server 200 ( There may be another server sending to b). In the following description, it is assumed that the broadcast data of each channel is stored in the primary server 200 (a) and the secondary server 200 (b). Hereinafter, “broadcast data of channel A1” will be simply abbreviated as “channel A1” or the like.

  In the multicast distribution system of FIG. 1, the primary server 200 (a) distributes channels A1 to A3 in group G1 and distributes channels A4 and A5 in group G2 among channels A1 to A5. Note that the primary server 200 (a) and the secondary server 200 (b) are simply referred to as the server 200 when it is not necessary to distinguish between them. The multicast router 300 routes the packet from the server 200 and transmits it to the receiving terminal 100. The receiving terminal 100 can receive channels A1 to A3 by joining the group G1, and can receive channels A4 and A5 by joining the group G2. That is, the receiving terminal 100 participates in a group including a channel that needs to be received. Here, participation is a join message of IGMP (Internet Group Management Protocol) v3 or MLD (Multicast Listener Discovery) v2. The multicast router 300 recognizes that there is a receiving terminal 100 that receives group data ahead of the multicast router 300 by receiving the participation message from the receiving terminal 100. As a result, the multicast router 300 transfers data distributed from the server 200 to the group to the receiving terminal 100. As a result, the receiving terminal 100 can receive broadcast data of channels belonging to the group.

  FIG. 2 shows a block diagram of a receiving terminal 100 according to a preferred embodiment of the present invention. The receiving terminal 100 includes a control unit 11, a memory 12, a communication unit 13, channel receiving units 14 (a) to 14 (e), a reproducing unit 15, an operation unit 16, and buffers 17 (a) to 17 (e). The channel receivers 14 (a) to 14 (e) are simply referred to as channel receivers 14 when it is not necessary to distinguish them. In addition, the buffers 17 (a) to 17 (e) are simply referred to as the buffer 17 when it is not necessary to distinguish them. Preferably, the channel receiving unit 14 and the buffer 17 are provided for the number of channels that the receiving terminal 100 needs to receive simultaneously, but may not necessarily be the number of channels to be received. For example, one channel receiver 14 and buffer 17 may be shared by a plurality of channels.

  The control unit 11 controls the receiving terminal 100 and is, for example, a microcomputer or a CPU. The control unit 11 extracts broadcast data of each channel from the packet received by the communication unit 13 and transmits it to the channel reception unit 14. The control unit 11 transmits the data received by the channel receiving unit 14 to the buffer 17 and stores it. In addition, the control unit 11 causes the buffer 17 to transmit the broadcast data of the channel that is instructed to be played by the user operation from the buffer 17 to the playback unit 15.

The memory 12 is, for example, a ROM or a RAM. The memory 12 has a reception state table 12A. The reception status table 12A manages the channel being received by the receiving terminal 100, the channel distribution server 200, the group to which the channel belongs, and the like. Details of the reception state table 12A will be described later.

The communication unit 13 receives a packet transmitted from the network, and transmits a packet from the receiving terminal 100 to the network.

  The channel receiving unit 14 receives broadcast data of each channel distributed from the server 200. The receiving terminal 100 includes as many channel receivers 14 as the number of channels that the receiving terminal 100 simultaneously receives. For example, the channel A1 is received by the channel receiver 14 (a), and the channel A2 is received by the channel receiver 14 (b). Receive. The process of distributing data from the data received by the communication unit 13 to each channel receiving unit 14 is executed by the control unit 11.

  Broadcast data of a channel designated for reproduction is input to the reproduction unit 15 from the buffer 17 by the control unit 11. The reproduction unit 15 performs audio signal processing or the like on the input data, and outputs it to a speaker or the like (not shown).

  The operation unit 16 receives an operation performed by the user on the receiving terminal 100 and transmits the received operation content to the control unit 11. The user performs playback channel switching and the like on the operation unit 16.

  The buffer 17 is a storage area for temporarily storing broadcast data of each channel received by the channel receiver 14 and is generally a RAM or the like. For example, the buffer 17 (a) stores broadcast data received by the channel receiver 14 (a), and the buffer 17 (b) stores broadcast data received by the channel receiver 14 (b). . The distribution of broadcast data from the channel receiving unit 14 to the buffer 17 is executed by the control unit 11.

  The control unit 11 of the receiving terminal 100 having the above configuration joins the group to which the zapping channel belongs, and starts receiving broadcast data of the zapping channel. When receiving the zapping channel broadcast data, the control unit 11 determines whether or not the servers 200 that distribute the zapping channel broadcast data are all the same. Leaves the participating group. Then, the control unit 11 unifies the zapping channel distribution source server 200 into either the primary server 200 (a) or the secondary server 200 (b) and rejoins the multicast group.

  FIG. 3 shows a reception state table 12A (a) stored in the memory 12 of the reception terminal 100. The reception state table 12A (a) manages information regarding each channel being received by the receiving terminal 100. The reception state table 12A (a) includes five items of status, channel, group, server, and reception state. The status indicates whether the receiving terminal 100 is reproducing each channel. The channel indicates a channel that the receiving terminal 100 is receiving. The group indicates a multicast group to which each channel belongs. The server indicates a distribution source server 200 that distributes each channel. P indicates the primary server 200 (a), and S indicates the secondary server 200 (b). The reception state indicates whether or not the receiving terminal 100 can normally receive the broadcast data of each channel. T indicates that the receiving terminal 100 can normally receive broadcast data, and F indicates that the receiving terminal 100 cannot normally receive broadcast data. The reception status table 12A (a) shows that the receiving terminal 100 is receiving channels A1 to A5, is reproducing channel A3, is receiving channels A1 to A3 in group G1, and is channel A4 and A5 is group G2. And the channels A1 to A5 are received from the primary server 200 (a), and the reception status is all normal.

  FIG. 4 shows a flowchart in which the control unit 11 of the receiving terminal 100 receives a channel distributed by the server 200, and generates and updates the reception state table 12A.

  The control unit 11 sets a reproduction channel (hereinafter referred to as a reproduction channel) by a user operation (S11). The control unit 11 identifies one or more channels adjacent to the channel set by the processing of S11 as channels that are received simultaneously with the reproduction channel (S12). For example, when the channel A3 is set by the process of S11, the channels A1, A2, A4, and A5 are specified by the process of S12. Hereinafter, the channels specified as the channels adjacent to the reproduction channel are collectively referred to as zapping channels. In this example, channels A1, A2, A3, A4, and A5 are zapping channels. Note that the zapping channels are not necessarily adjacent to each other.

  The control unit 11 determines a group to which each channel of the zapping channel belongs, and participates in the determined group (S13). For example, when the channels A1 to A3 belong to the group 1 and the channels A4 and A5 belong to the group 2, the control unit 11 participates in the group 1 and the group 2. The receiving terminal 100 previously receives data describing the group to which each channel belongs from the server 200, and grasps the group to which each channel belongs.

  The control unit 11 requests the server 200 for broadcast data of the zapping channel (S14). And the control part 11 transmits the broadcast data which the channel receiver 14 receives to the buffer 17 corresponding to each channel (S15). The receiving terminal 100 simultaneously receives broadcast data of a plurality of channels and stores them in the buffer 17, so that when the playback channel is continuously switched by a user operation, playback of the switching destination channel can be started immediately. The amount of data stored in the buffer 17 is, for example, an amount that can be reproduced for about 10 seconds, and a ring buffer or the like is employed as the buffer 17.

  The control unit 11 transmits the broadcast data of the playback channel to the playback unit 15 (S16). Thereby, playback of the playback channel is started in the receiving terminal 100. Note that the control unit 11 may start the data reception of the group including the reproduction channel prior to the data reception of the group not including the reproduction channel, thereby enabling the reproduction channel to be reproduced earlier.

  The control unit 11 identifies the server 200 that distributes the broadcast data of each channel from information (such as the IP address of the server 200) described in the packet at the time of receiving the broadcast data (S17), and sets the reception state table 12A. Update. For example, when all broadcast data of channels A1 to A5 are distributed from the primary server 200 (a), P is written in the server item of the reception state table 12A.

  The control unit 11 periodically receives information indicating the reception state of the channel from all of the channel reception units 14 (a) to 14 (e) (S19). The information indicating the reception state is information indicating whether or not the broadcast data packet received by the channel receiving unit 14 is lost, and identifies the server 200 that distributes each channel of the channel receiving unit 14 Information. “Periodic” means, for example, every second.

The control unit 11 determines the server 200 that distributes the broadcast data of the channel from the information received by the process of S19, and determines whether or not the distribution source server 200 has been changed (S20). The determination as to whether or not the server 200 has been changed is performed based on whether or not the value set in the server item of the reception state table 12A is the same as the information of the distribution source server 200 received in S19. . Note that the server 200 may transmit an instruction to switch the server 200 that distributes the channel to the receiving terminal 100, and the receiving terminal 100 may receive the instruction and switch the server 200 that is the distribution source. In that case, after executing the process of S20, the process of S22 described later is executed. When determining that the distribution source server 200 has been changed (YES in S20), the control unit 11 writes and updates information on whether or not the channel is normally received in the reception state item of the reception state table 12A (S23). . Then, the server item in the reception state table 12A is updated to the server 200 that is newly receiving the distribution (S24). Note that the distribution server 200 may be changed when the server 200 is stopped due to maintenance or inspection, or when the server 200 is unable to distribute a specific channel.

When the control unit 11 determines that the distribution source server 200 has not been changed (NO in S20), the control unit 11 obtains the channel according to the information on whether or not the broadcast data packet is lost, which is obtained by the process of S19. Is received or not (S21). When the control unit 11 determines that the channel cannot be normally received (NO in S21), the control unit 11 changes the distribution source server 200 of the channel (S22). For example, when the receiving terminal 100 cannot normally receive the channel A2 from the primary server 200 (a), the control unit 11 switches the distribution source server of the channel A2 to the secondary server 200 (b). And the process of S23 and S24 is performed. When the control unit 11 determines that the broadcast data of the channel can be normally received (YES in S21), the control unit 11 executes the process of S24. In the case of YES in S21, the same server 200 may be overwritten on the server item in the reception state table 12A in the process of S24, or the process of S24 may not be executed.

  The control unit 11 executes the processes from S19 to S24 based on information transmitted from all the channel receiving units 14 of the channel receiving units 14 (a) to 14 (e). Note that the control unit 11 performs control if the channel reception unit 14 determines that a packet loss occurs even when broadcast data is distributed from either the primary server 200 (a) or the secondary server 200 (b). The unit 11 fixes the distribution source server to any one of the servers 200, and prevents the server switching process of S22 from being repeated.

  FIG. 5 shows the reception state table 12A (b) when the distribution source servers of the channels A2 and A5 are changed from the primary server 200 (a) to the secondary server 200 (b). Further, the reception state table 12A (b) indicates that the receiving terminal 100 cannot normally receive the broadcast data of the channel A4 and the reception state of the channel A4 is FALSE.

  FIG. 6 shows a multicast distribution system diagram in the reception state of the reception state table 12A (b). The receiving terminal 100 receives broadcast data from both the primary server 200 (a) and the secondary server 200 (b). In the multicast distribution system of FIG. 1, there are two types of combinations of groups and distribution source servers: “Group 1: Primary Server 200 (a)” and “Group 2: Primary Server 200 (a)”. On the other hand, in the multicast distribution system of FIG. 6, the combinations of the group and the distribution source server are “group 1: primary server 200 (a)”, “group 2: primary server 200 (a)”, “group 1”. : Secondary server 200 (b) "and" group 2: secondary server 200 (b) ". That is, the receiving terminal 100 performs four communications with the multicast router 300. Assuming that the communication executed by the combination of each group and the server 200 uses a bandwidth of 1 Mbps, the multicast distribution system of FIG. 1 uses a bandwidth of 2 Mbps (1 Mbps × 2), whereas FIG. In the case of the multicast distribution system, a bandwidth of 4 Mbps (1 Mbps × 4) is used. In other words, when the distribution source server 200 is switched during operation of the multicast distribution system, the bandwidth used in the network increases compared to the initial state. When the bandwidth used exceeds the allowable range that can be processed by the multicast router 300, the receiving terminal 100 cannot receive broadcast data normally, and the receiving terminal 100 is interrupted during reproduction.

[First Embodiment of Bandwidth Reduction Processing]
A first embodiment for reducing the network bandwidth used by the receiving terminal 100 will be described. FIG. 7 shows a flowchart of the first embodiment in which the control unit 11 of the receiving terminal 100 reduces the use band. The receiving terminal 100 executes the process of FIG. 7 in parallel with the process of FIG.

  The control unit 11 determines whether or not all the zapping channels are normally received (S31). If the control unit 11 determines that all the zapping channels have been received normally (YES in S31), the process ends. When it is determined that there is a channel that cannot be normally received among the zapping channels (NO in S31), the control unit 11 executes the connection switching process 1 or 2 (S32). By executing the connection switching process, it is possible to reduce the use band of the network. Details of the connection switching process 1 and the connection switching process 2 will be described later.

  According to the first embodiment described above, when the receiving terminal 100 determines that a packet loss has occurred due to reception of one or more channels among the zapping channels, the processing for reducing the network bandwidth is executed. The receiving terminal 100 can reproduce without interruption when playing any of the zapping channels.

[Embodiment 1 of connection switching processing]
A first embodiment of the connection switching process, which is the process of S32 in FIG. 7, will be described. FIG. 8 shows a flowchart of the first embodiment of the connection switching process executed by the control unit 11. Note that the first embodiment of the connection switching process is referred to as a connection switching process 1. According to the present embodiment, the receiving terminal 100 temporarily leaves all of the participating groups, specifies all the distribution source servers 200 as the same, and rejoins the group. Here, the term “leave” refers to a leave message of IGMP (Internet Group Management Protocol) v3 or MLD (Multicast Listener Discovery) v2. The multicast router 300 recognizes that there is no receiving terminal 100 that receives group data ahead of the multicast router 300 by receiving the leave message from the receiving terminal 100. As a result, the multicast router 300 does not transfer data distributed from the server 200 to the group to the receiving terminal 100. Accordingly, the receiving terminal 100 does not receive broadcast data of channels belonging to the group.

  The control unit 11 leaves from all the groups in which the receiving terminal 100 is participating (S41). That is, the control unit 11 leaves the group 1 and the group 2. Note that, when the control unit 11 leaves the group, the receiving terminal 100 cannot receive broadcast data, and thus the playback in the receiving terminal 100 is temporarily stopped.

  The control unit 11 changes the priority of the server 200 as a distribution source (S42). For example, when the server 200 that has distributed the broadcast data of the channel determined to have lost the packet in S31 of the flowchart of FIG. 7 is the primary server 200 (a), the secondary server 200 (b) is changed. specify. When packet loss has occurred in a plurality of channels, the control unit 11 may designate any server 200, but preferably designates a server 200 with few channels in which packet loss has occurred.

  The control part 11 performs the process after S13 of the flowchart of FIG. 4 (S43). That is, it joins the group to which the zapping channel belongs again and resumes the connection. Since the control unit 11 designates either the primary server 200 (a) or the secondary server 200 (b) as the zapping channel distribution source server 200, the distribution source servers of all reception channels are unified into one, The number of combinations of groups and servers 200 is the same as in the initial state, and the number of combinations is minimized.

  According to the first embodiment described above, since the number of combinations of groups and servers 200 is minimized, the receiving terminal 100 can minimize the bandwidth used for the network. For example, when the connection switching process 1 in FIG. 8 is executed in the state of the reception state table 12A (b) in FIG. 5, the server items in the reception state table 12A (b) are unified to P or S. Therefore, the number of combinations of groups and servers becomes the same as in the case of the reception state table 12A (a) in FIG. 3, and is minimized. Furthermore, since the receiving terminal 100 specifies and reconnects the server 200 different from the server 200 to which the channel in which the packet loss has occurred is connected, there is a possibility that the receiving terminal 100 can receive the zapping channel without packet loss. high.

[Embodiment 2 of connection switching processing]
A second embodiment of the connection switching process, which is the process of S32 in FIG. 7, will be described. FIG. 9 shows a flowchart of a second embodiment of connection switching processing executed by the control unit 11. According to the present embodiment, since the connection switching process 2 is executed only for the group to which the channel being played does not belong, the network bandwidth can be reduced without stopping the reproduction. The second embodiment of the connection switching process is referred to as a connection switching process 2.

  The control unit 11 acquires a group to which a channel that is not being played belongs (S51). For example, in the reception state of the reception state table 12A (b) in FIG. 5, since the channel A3 belonging to the group 1 is being reproduced, the group 2 is specified. In the case of a multicast distribution system having three or more groups, a plurality of groups are specified by the process of S51. The control part 11 performs the process after S52 with respect to all the groups specified by the process of S51.

  The control unit 11 determines whether or not the servers 200 that distribute the broadcast data of the channels in the group specified by the process of S51 are the same (S52). For example, in the case of the reception state table 12A (b) in FIG. 5, since the distribution servers 200 of the channels (A4 and A5) belonging to the group 2 are P and S, it is determined that they are not the same.

  When determining that the servers 200 of the channels in the group are not the same (NO in S52), the control unit 11 leaves the group (S53).

  The control unit 11 sets all the distribution source servers 200 of the channels in the group to the same (S54). The control unit 11 may be unified with the primary server 200 (a) or may be unified with the secondary server 200 (b). For example, in the reception state table 12A (b) of FIG. 5, the server items of the channels A4 and A5 are unified as either P or S. And the control part 11 participates in the same group again (S55).

  The control unit 11 determines whether or not the processing after S52 has been executed for all of the groups acquired by the processing of S51 (S56), and when determining that it has been executed (YES in S56), FIG. The processes after S14 in the flowchart are executed (S57). When the control unit 11 determines that the processes after S52 are not executed for all the groups (NO in S56), the control unit 11 acquires the next group acquired by the process of S51 (S57), and after S52. Repeat the process. Note that the control unit 11 unifies all the servers 200 set in S54 in either the primary server 200 (a) or the secondary server 200 (b) for the group acquired in S51. This is to reduce the number of combinations of the server 200 and the group. For example, in the reception state table 12A (b) of FIG. 5, when the server 200 of the channel included in the group G2 is unified to P, the combination of the group and the server 200 is “group 1: primary server 200 (a)”. ”,“ Group 2: primary server 200 (a) ”, and“ Group 1: secondary server 200 (b) ”. That is, the number of combinations of groups and servers 200 is reduced from four to three.

  When the control unit 11 determines that the servers 200 that distribute the broadcast data of the channels in the group are the same (YES in S52), the control unit 11 performs the processes after S56.

According to the second embodiment described above, since the control unit 11 does not perform the leaving process on the group to which the channel being reproduced belongs, it is possible to reduce the use band without stopping the reproduction. Even after this process is executed, if the use band is not within the allowable range, the processes after S52 may be executed for the group to which the reproduction channel belongs.

[Second Embodiment of Bandwidth Reduction Processing]
A second embodiment for reducing the network bandwidth used by the receiving terminal 100 will be described. FIG. 10 shows a flowchart of the second embodiment in which the control unit 11 reduces the use band. The same processes as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted.

  If the control unit 11 determines that the zapping channel has not been normally received (NO in S31), whether or not the receiving terminal 100 is reproducing the channel that has been determined not to be normally received in the process of S31. Is determined (S61). Specifically, the determination is made based on whether or not the status of a channel that cannot normally receive a packet is set to “reproducing” in the reception state table 12A. When the control unit 11 determines that the channel is being reproduced by the receiving terminal 100 (YES in S61), the control unit 11 executes connection switching processing 1 (S32). When the control unit 11 determines that the channel is not being played back by the receiving terminal 100 (NO in S61), the control unit 11 ends the process.

According to the second embodiment, the control unit 11 executes the connection switching process 1 only when the broadcast data of the channel being played cannot be normally received, so that the reception state of the playback channel is automatically returned to the normal state. be able to. The control unit 11 does not execute the connection switching process 1 when any channel other than the reproduction channel cannot be normally received. Thereby, the connection process switching process is not executed due to a reception error of a channel other than the reproduction channel, and the reproduction of the reproduction channel is not stopped.

[Third Embodiment of Bandwidth Reduction Processing]
A third embodiment for reducing the network bandwidth used by the receiving terminal 100 will be described. FIG. 11 shows a flowchart of the third embodiment in which the control unit 11 reduces the use band. According to the present embodiment, the control unit 11 determines whether or not the reception state of the change-destination channel is normal. If it is determined that the change is not normal, the control unit 11 performs connection switching processing. The same processes as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted.

  The control unit 11 determines whether or not the playback channel has been switched by a user operation (S71). If it is determined that the playback channel has been switched (YES in S71), the control unit 11 indicates that the reception state of the switching destination channel is False. It is determined with reference to the reception state table 12A (S72).

  When it is determined that the reception state of the switching destination channel in the reception state table 12A is False (YES in S72), the control unit 11 executes the connection switching process 1 or 2 (S32). When the control unit 11 determines that the reception state of the reception state table 12A of the switching destination channel is not False (NO in S72), the process ends.

According to the third embodiment described above, the receiving terminal 100 confirms the reception state of the switching destination channel before executing the channel switching, and after performing the connection switching process 1 or 2 if the receiving terminal 100 is not normally receiving, Play the destination channel. As a result, the receiving terminal 100 can reliably start reproduction of the newly designated channel. Further, the receiving terminal 100 does not execute the connection switching process when any of the channels other than the switching destination channel has not been received normally. This is because when the connection switching process is executed, the receiving terminal 100 executes the group leaving process and the joining process, and it takes time to switch the channel.

[Fourth Embodiment of Bandwidth Reduction Processing]
A fourth embodiment for reducing the network bandwidth used by the receiving terminal 100 will be described. FIG. 12 shows a flowchart of the fourth embodiment in which the control unit 11 reduces the use band. According to this embodiment, the control part 11 performs a connection switching process, when the number of the combinations of a group and the server 200 is more than a regulation value. The same processes as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted.

  The control unit 11 acquires the number of combinations of the group being received by the receiving terminal 100 and the server 200 (S81). For example, in the case of the reception state of FIG.

  The control unit 11 determines whether or not the number of combinations of the group acquired by the process of S81 and the server 200 is equal to or greater than a specified number (S82). The specified number is, for example, 3.

  When it is determined that the number of combinations acquired by the process of S81 is equal to or greater than the specified number (YES in S82), the control unit 11 executes the connection switching process 1 or 2 (S32). If the control unit 11 determines that the number of combinations acquired by the process of S81 is less than the specified number (NO in S82), the process ends.

According to the fourth embodiment described above, the receiving terminal 100 executes the process of reducing the number of combinations when the number of combinations of groups to be received and the server 200 exceeds a specified value. Can be prevented from occurring, and the amount of communication data that cannot be processed by the multicast router 300 can be prevented.

[Fifth Embodiment of Bandwidth Reduction Processing]
A fifth embodiment for reducing the network bandwidth used by the receiving terminal 100 will be described. FIG. 13 shows a flowchart of the fifth embodiment in which the control unit 11 reduces the use band. According to the present embodiment, the control unit 11 performs the connection switching process when the total amount of data currently being received by the receiving terminal 100 is equal to or greater than a specified value. The same processes as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted.

  The control unit 11 determines whether all the zapping channel distribution servers 200 are the same (S91). For example, the reception state table 12A (a) in FIG. 3 is determined to be the same, and the reception state table 12A (b) in FIG. 5 is determined to be not the same. When it is determined that all the zapping channel distribution servers 200 are the same (YES in S91), the control unit 11 ends the process. When the distribution servers 200 of the zapping channel are all the same, the number of combinations of the group and the server 200 is the smallest, so that the control unit 11 does not need to execute the processes after S92.

  When it is determined that the zapping channel distribution servers 200 are not all the same (NO in S91), the control unit 11 acquires the received data amount per unit time of all channels being received (S92). The communication unit 13 or each channel receiving unit 14 periodically notifies the control unit 11 of the amount of received data being received.

  The control unit 11 determines whether the amount of data being received is within the allowable range of the multicast router 300 (S93). The allowable range of the multicast router 300 may be acquired and set by the receiving terminal 100 by inquiring the multicast router 300 from the control unit 11, or a fixed value may be set in the receiving terminal 100.

  When the control unit 11 determines that the amount of data being received is not within the allowable range of the multicast router 300 (NO in S93), the control unit 11 executes the connection switching process 1 or 2 (S32). When the control unit 11 determines that the amount of data being received is within the allowable range of the multicast router 300 (YES in S93), the process ends.

According to the fifth embodiment described above, when the receiving terminal 100 determines that it uses a bandwidth higher than the multicast router 300 allows, the connection switching processing 1 or 2 is executed to reduce the network bandwidth usage. Accordingly, it is possible to prevent an amount of data that cannot be processed by the multicast router 300 from being communicated between the receiving terminal 100 and the multicast router.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment.
Two or more servers 200 may be provided. The channels that each server 200 can distribute may be different. Broadcast data distributed from the server 200 may be video data or still image data in addition to audio data. Further, the receiving terminal 100 may reproduce a plurality of channels at the same time.

  The present invention can be suitably employed in devices such as set-top boxes, AV receivers, and audio / video output devices.

100 receiving terminal 200 (a) primary server 200 (b) secondary server 11 control unit 12 memory 13 communication unit 14 (a) to 14 (e) channel receiving unit 15 reproduction unit 16 operation unit 17 (a) to 17 (e) buffer

Claims (7)

Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
When the broadcast data of the zapping channel is distributed from two or more servers, leaving means for leaving the participating multicast group;
After leaving from the participating multicast group, the server that distributes the broadcast data of the zapping channel is unified to one of the first server and the second server and joined to the multicast group again. A receiving terminal. Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
Communication determining means for determining whether the broadcast data of the zapping channel is being normally received ;
Leaving means for leaving the participating multicast group when the communication judging means determines that the broadcast data of the zapping channel is not being received normally ;
After leaving from the participating multicast group, the server that distributes the broadcast data of the zapping channel is unified to one of the first server and the second server and joined to the multicast group again. A receiving terminal. Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
Communication determining means for determining whether the broadcast data of the zapping channel is being normally received;
An error channel specifying means for specifying a channel that is not normally receiving the broadcast data when the communication determining means determines that the broadcast data is not normally received;
Playback channel error determining means for determining whether the channel specified by the error channel specifying means is the playback channel;
When the channel identified by said error channel specifying means is judged to be the reproduction channels, a withdrawal means for withdrawal from the multicast group of participating,
After leaving from the participating multicast group, the server that distributes the broadcast data of the zapping channel is unified to one of the first server and the second server and joined to the multicast group again. A receiving terminal. Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
Communication determining means for determining whether the broadcast data of the zapping channel is being normally received ;
An error channel specifying means for specifying a channel that is not normally receiving the broadcast data when the communication determining means determines that the broadcast data is not normally received;
Playback channel switching means for switching the playback channel by a user operation ;
When the channel specified by the error channel specifying means has determined that the said channel specified by the reproduction channel switching means, and withdrawal means for withdrawal from the multicast group of participating,
After leaving from the participating multicast group, the server that distributes the broadcast data of the zapping channel is unified to one of the first server and the second server and joined to the multicast group again. A receiving terminal. Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
A number-of-combinations acquisition means for acquiring the number of combinations of the participating multicast group and the server delivering the broadcast data of the zapping channel;
A combination number determining means for determining whether or not the number of combinations acquired by the combination number acquiring means is within a predetermined number of combinations;
If the number of the combinations is judged not to be within the number of combinations of the predetermined number by the number of combinations determination means, a withdrawal means for withdrawal from the multicast group of participating,
After leaving the participating multicast group, unify the server that distributes the broadcast data of the zapping channel into either the first server or the second server and rejoin the multicast group A receiving terminal comprising reconnection means . Reception capable of receiving broadcast data distributed from a first server capable of distributing broadcast data of a plurality of channels by multicast and a second server capable of distributing the broadcast data of the plurality of channels by multicast. A terminal,
Multicast group joining means for joining one or more multicast groups to which a zapping channel including a playback channel and one or more channels other than the playback channel belongs;
Zapping channel receiving means for simultaneously receiving the broadcast data of the zapping channel;
Communication determining means for determining whether the broadcast data of the zapping channel is being normally received ;
A multicast group specifying means for specifying the multicast group to which the playback channel does not belong, when the communication determining means determines that the broadcast data is not being received normally;
Whether the server that distributes the broadcast data of the channel in the multicast group specified by the multicast group specifying means is the same server of the first server and the second server. A distribution server identity determination means for determining ;
If the server in the multicast group identified by the multicast group specifying means is determined not to be identical, and withdrawal means for withdrawal from the multicast group identified by the multicast group specifying means,
After leaving from the multicast group specified by the multicast group specifying means, unify the server that distributes the broadcast data of the zapping channel to either the first server or the second server, Receiving terminal comprising reconnection means for rejoining the multicast group .   A receiving program for causing a computer to execute each means of the receiving terminal according to claim 1.

Images