JP2010081067A - Repeater, relay method, relay program, receiver, communication end method and communication end program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repeater for efficiently utilizing a network band when transmitting and receiving stream data. <P>SOLUTION: The repeater includes: a communication state storage part 121 for storing a communication state indicating whether or not communication used for transmitting and receiving the stream data between a stream transmitter 2 and a stream receiver 3 is established; a disconnection detection part 103 for detecting whether or not the stream receiver 3 is disconnected from a network 6; an abnormal end determination part 104 for determining whether or not it is detected that the stream receiver 3 is disconnected from the network 6 and it is indicated that the communication is established; and an end request transmission part 105 for transmitting a communication end request message to the stream transmitter 2 when it is detected that the stream receiver 3 is disconnected from the network 6 and it is determined that the establishment of the communication is indicated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a relay device, a relay method, a relay program, a reception device, a communication end method, and a communication end program that relay a message between a transmission device and a reception device that transmit stream data.

  In recent years, a VoD (Video on Demand) service and an IP broadcast service that provide high-quality video content using an IP network have begun to spread. For the former VoD service, a signaling communication protocol called RTSP (Real Time Streaming Protocol) is used for playback control such as content playback, pause, fast forward, and fast reverse.

  On the other hand, since IP multicast is also used for the latter IP broadcast service, protocols such as IGMP (Internet Group Management Protocol) and MLD (Multicast Listener Discovery) are used for multicast stream reception control.

  In addition, since there is a possibility that a bandwidth exceeding 10 Mbps may be used for high-quality video content transmission, it is also considered to use SIP (Session Initiation Protocol), which is a call control protocol for IP telephones, for bandwidth control of video content streams. It is being advanced and is likely to be actually used.

  Protocols such as RTSP and SIP have communication session status information between the client and the server. That is, it can be said to be a stateful signaling communication protocol. As described above, in IP broadcast services including a VoD service and an IPTV (Internet Protocol Television) service, stateful signaling communication is generally used for stream (playback) control and bandwidth guarantee.

  Japanese Patent Application Laid-Open No. 2006-94338 proposes a technique for preventing a suspended streaming session from being maintained and suppressing the occurrence of a user who cannot perform streaming playback.

JP 2006-94338 A

  However, the stateful signaling communication protocol has a problem that the communication bandwidth is wasted when the power is illegally cut off. For example, it is assumed that a receiving device of an IPTV service such as a digital television or a STB (Set Top Box) that uses a stateful signaling communication protocol suddenly changes to a power-off state due to the influence of a momentary interruption or the like. In such a case, since the receiving device cannot pass through a normal signaling communication end sequence with the transmitting device, for example, the following problem may occur.

  First, the bandwidth used for stream communication is not released for a certain period determined for each protocol. The IGMP query interval, the RTSP keep alive interval, the SIP communication session expiration interval, or the like corresponds to this fixed period. For example, if the digital TV main power is turned off while receiving a 15 Mbps video stream as an IP broadcast, the stream that has not been viewed during the IGMP query interval (for example, 1 minute) will reduce the communication bandwidth of the home network. Will occupy.

  Secondly, when the power is turned on immediately after the power is turned off and the reproduction is requested, it is regarded as ensuring a double band. This is a frequently performed operation in a consumer device such as a digital television. In this case, for example, a total bandwidth of 30 Mbps corresponding to two 15 Mbps streams is temporarily occupied by the subnet including the receiving device.

  The method disclosed in Patent Document 1 transmits a connection disconnection request to a server when the suspension is not canceled until a certain time has elapsed since the suspension. For this reason, similarly to the first problem, there may be a problem that the bandwidth is wasted for a certain period.

  The present invention has been made in view of the above, and is a relay device, a relay method, a relay program, a reception device, a communication end method, and a communication that can efficiently use a network bandwidth when transmitting and receiving stream data. The purpose is to provide a termination program.

  In order to solve the above-described problems and achieve the object, the present invention is connected to a transmission device that transmits stream data via a first network, and via a reception device that receives the stream data and a second network. A relay device that is connected and relays the stream data between the transmission device and the reception device, and communication used for transmission / reception of the stream data between the transmission device and the reception device is established. A communication state storage unit that stores a communication state indicating whether or not the communication device is disconnected; a disconnection detection unit that detects that the receiving device is disconnected from the second network; and that the disconnection detection unit detects disconnection. A determination unit that determines whether or not the communication is established, and a determination unit that determines that the communication is established by the determination unit. In, characterized by comprising a transmitter which transmits the request message for requesting termination of the communication to the transmitting device.

  Further, the present invention is a receiving device that receives stream data from a transmitting device connected via a network, and a communication state that indicates whether communication used for transmission / reception of the stream data is established; Whether or not the difference between the current date and time and the stored date and time is smaller than a predetermined period when the communication device is activated, and the communication status storage unit that stores the stored date and time when the communication status is stored, A determination unit that determines whether or not the communication is established; and the determination unit determines that the difference is smaller than the period and the communication is established. A transmission unit that transmits a request message for requesting termination of the communication to the transmission device.

  Further, the present invention is a method and program capable of executing the above-described apparatus.

  According to the present invention, there is an effect that it is possible to efficiently use a network band when transmitting / receiving stream data.

  Exemplary embodiments of a relay device, a relay method, a relay program, a reception device, a communication end method, and a communication end program according to the present invention will be explained below in detail with reference to the accompanying drawings.

(First embodiment)
The relay device according to the first embodiment relays content transmitted from a transmission device such as a content distribution server by multicast like an IP broadcast service to a reception device such as an STB. At this time, the connection state of the receiving device to the network is monitored, and communication is terminated on behalf of the receiving device when communication for content distribution is being established even though the receiving device is disconnected from the network. Run the sequence.

  FIG. 1 is a block diagram illustrating a configuration example of a content distribution system including a stream relay device 1 which is a relay device according to the first embodiment. As shown in FIG. 1, the stream relay device 1 is connected to both the network 5 and the network 6, and communication between the stream transmission device 2 on the network 5 and the stream reception device 3 on the network 6. Relay.

  The network 5 is a quality-guaranteed WAN (Wide Area Network) such as NGN (Next Generation Network). The network 6 is a home LAN (Local Area Network) such as a home network. The forms of the network 5 and the network 6 are not limited to these.

  The edge router 4 connects the stream relay device 1 and the network 5. The edge router 4 receives, for example, a Join packet to a multicast address that is transmitted when the stream receiving device 3 receives the IP broadcast, and a Leave packet that is transmitted when the viewing of the IP broadcast is terminated.

  The stream transmission device 2 is a content distribution server that provides an IP broadcast service. Note that the content is video data mainly including audio data. In the present embodiment, in particular, HD (High Definition) content that requires a wide band for transmission is assumed.

  The stream transmission device 2 may be directly connected to the network 5. For example, the stream transmission device 2 exists inside a service provider's corporate LAN or the like, and is connected to another device such as a router (not shown). It may be connected to the network 5.

  The stream receiving device 3 is a client device such as an STB, a digital TV, a personal computer, or an HDD (Hard Disk Drive) recorder that receives an IP broadcast service. The stream receiving device 3 communicates with the stream transmitting device 2 via the stream relay device 1. Note that the stream receiving device 3 may be directly connected to the stream relay device 1, for example, is present in a home LAN or the like, and is stream-relayed via another device such as a broad router or a switching hub. It may be connected to the device 1. A plurality of stream receiving devices 3 may exist on the network 6.

  The communication that occurs between the stream transmitting device 2 and the stream receiving device 3 includes not only multicast stream communication that transmits the content itself as an IP broadcast, but also signaling communication that participates in and leaves the multicast address. IGMP and MLD are used for signaling communication.

  In FIG. 1, a plurality of stream transmission devices 2 and stream reception devices 3 may exist. In the following, description will be given focusing on one stream transmission device 2 and one stream reception device 3.

  Next, details of the function and configuration of the stream relay device 1 will be described. As shown in FIG. 1, the stream relay device 1 includes a WAN port 111, a LAN port 112, a communication state storage unit 121, a relay unit 101, a packet monitoring unit 102, a disconnection detection unit 103, and an abnormal termination determination. Unit 104 and termination request transmission unit 105.

  The WAN port 111 is a port for connecting the stream relay device 1 to the network 5. The LAN port 112 is a port for connecting the stream relay device 1 to the network 6. The LAN port 112 need not be limited to one, and a plurality of LAN ports 112 may be provided.

  The communication state storage unit 121 stores a communication state of communication used for transmitting and receiving stream data between the stream transmission device 2 and the stream reception device 3. In the present embodiment, MLD used for multicast stream reception control corresponds to communication used to transmit / receive stream data.

  FIG. 2 is a diagram illustrating an example of data stored in the communication state storage unit 121. As illustrated in FIG. 2, the communication state storage unit 121 stores data in which the reception device identification information for identifying the stream reception device 3, the protocol type, the communication state, the communication information, and the connection state are associated with each other. is doing.

  The protocol type represents the type of communication protocol used for transmitting and receiving stream data. The communication state sets the communication state of the protocol represented by the protocol type. In the case of MLD, for example, Join indicating a state of participating in a multicast address for receiving an IP broadcast or Leave indicating a state of leaving from the multicast address is set as a communication state.

  As the communication information, information necessary for the end request transmission unit 105 (to be described later) to generate a request message for requesting the end of communication predetermined according to the protocol type is set. For example, as shown in the figure, information such as an address and a port number that can identify each device that has established communication is set. In the case of MLD, for example, a destination IP address (dst_ipaddr), a destination port number (dst_port) ), A source IP address (src_ipaddr), and a source port number (src_port) are set as communication information. Note that the communication information shown in the figure is merely an example, and other information included in the packet may be stored.

  The connection state indicates whether or not the stream reception device 3 is connected to the network 6. In this embodiment, the connection state = 1 indicates that the connection is established, and the connection state = 0 indicates that the connection is not established.

  Note that the communication state storage unit 121 may be configured to hold a constant history of transmitted and received protocol messages. Further, the communication state storage unit 121 can be configured by any generally used storage medium such as an HDD, an optical disk, a memory card, and a RAM (Random Access Memory).

  Returning to FIG. 1, the relay unit 101 executes communication packet relay processing, which is the main function of the stream relay device 1. Specifically, the relay unit 101 transfers a communication packet transmitted / received between a device on the network 5 and a device on the network 6 via the LAN port 112 and the WAN port 111.

  The packet monitoring unit 102 monitors a signaling communication packet that passes through the relay unit 101, and stores a communication state of communication between the stream transmission device 2 and the stream reception device 3 in the communication state storage unit 121. In the present embodiment, the packet monitoring unit 102 monitors an MLD communication packet, and from the communication packet, the identification information of the stream receiving device 3, the protocol type, and source and destination address information (IP address and port). Number) and a communication state indicating whether the user is participating in the multicast address (Join) or leaving (Leave), and stores the communication state in the communication state storage unit 121.

  The disconnect detection unit 103 detects whether or not the stream receiving device 3 is disconnected from the network 6. For example, the disconnection detection unit 103 first periodically transmits a multicast packet for confirmation of survival on the network 6. Then, a device that does not transmit a response packet to the multicast packet within a certain period is detected as disconnected from the network 6.

  On the other hand, the stream receiving device 3 transmits an existence notification multicast packet to the network 6 at regular intervals, and the disconnection detection unit 103 sends an apparatus that cannot receive the existence notification multicast packet from the network 6 within a certain period. You may comprise so that it may detect as cut | disconnected.

  The disconnection detection unit 103 uses, for example, ARP (Address Resolution Protocol), NDP (Neighbor Discovery Protocol), LLDP (Link Layer Discovery Protocol), LLTD (Link Layer Topology Discovery), and SSDP (Simple Service Discovery Protocol). , It can be configured to send and receive a survival confirmation packet.

  The cutting detection method is not limited to this. For example, the disconnection detection unit 103 may be configured to detect disconnection using unicast communication. Specifically, first, the disconnection detection unit 103 establishes unicast communication for survival confirmation with respect to a device whose connection state of the communication state storage unit 121 is “1” (connected to the network 6). This communication is maintained by periodically sending keep-alive packets. When detecting that the communication has been closed, the disconnection detection unit 103 detects that the communication destination device has been disconnected from the network 6. As the unicast communication, for example, a TCP (Transmission Control Protocol) connection can be used. In the following description of the present embodiment, it is assumed that disconnection is detected using a TCP connection.

  In addition, referring to the communication state of the communication state storage unit 121, it may be configured to establish unicast communication for survival confirmation only for a device whose communication state is “Join”. Thereby, since communication can be established only for necessary devices, unnecessary network traffic can be reduced. As described above, in the configuration for the device whose connection state is “1”, the process for determining the communication state becomes unnecessary, and thus the process is simplified.

  The abnormal termination determination unit 104 determines that the stream reception device 3 has terminated communication with the stream transmission device 2 without going through a normal termination sequence. Specifically, the abnormal end determination unit 104 detects that the communication state of the communication state storage unit 121 indicates that the multicast stream is being received (Join), and that the disconnection detection unit 103 has disconnected from the network 6. If it is determined that the corresponding stream receiving device 3 has ended without passing through a normal end sequence.

  The termination request transmission unit 105 generates a request message (multicast leaving packet) for requesting termination of signaling communication when it is determined that the stream reception device 3 has terminated without passing through a normal termination sequence, and the stream transmission device 2 to send. Specifically, the termination request transmission unit 105 refers to the protocol type and communication information in the communication state storage unit 121, generates an MLD Leave packet, and transmits the MLD Leave packet to the stream transmission device 2.

  In the case of MLD, the end sequence is completed by transmission of the Leave packet. Depending on the protocol, it is necessary to determine that the end sequence has been completed normally by receiving a response message indicating that the request message has been completed normally. In the case of such a protocol, for example, the termination request transmission unit 105 is configured to retransmit the request message until it receives a response message indicating that the termination was successful.

  Next, a stream relay process performed by the stream relay device 1 according to the first embodiment configured as described above will be described with reference to FIG. FIG. 3 is a flowchart showing an overall flow of the stream relay processing in the first embodiment.

  First, the stream receiving device 3 is activated and connected to the network 6 (step S301). The stream receiving device 3 transmits a UPnP (Universal Plug and Play) SSDP (Simple Service Discovery Protocol) packet at the time of activation (step S302).

  The packet monitoring unit 102 of the stream relay device 1 detects the connection of the stream receiving device 3 by receiving this SSDP packet (step S303). The packet monitoring unit 102 may be configured to detect the connection of the stream receiving device 3 using ARP (Address Resolution Protocol) in the case of an IPv4 network and NDP (Neighbor Discovery Protocol) in the case of an IPv6 network. Good. The packet monitoring unit 102 stores the identification information and connection state of the stream receiving device 3 that has detected the connection in the communication state storage unit 121.

  When a packet of the signaling communication protocol is received (step S305 described later), the communication type storage unit 121 associates the protocol type, the communication state, and the communication information acquired from this packet with the identification information and the connection state. May be stored. Further, the packet monitoring unit 102 may be configured to detect the connection of the stream receiving device 3 when receiving a packet of the signaling communication protocol.

  Next, the stream receiving device 3 receives a viewing request for the IP broadcast service by the user (step S304). The stream receiving device 3 transmits an MLD Join packet corresponding to the multicast address of the corresponding IP broadcast to the stream relay device 1 (step S305).

  The relay unit 101 of the stream relay device 1 receives the MLD Join packet. The packet monitoring unit 102 acquires a protocol type (MLD), a communication state (Join), and communication information from the detected MLD Join packet information, and accumulates them in the communication state storage unit 121 (step S306).

  Further, the disconnection detection unit 103 of the stream relay apparatus 1 establishes a survival confirmation TCP connection with the stream reception apparatus 3, and keeps the TCP connection by transmitting keep-alive packets at regular intervals (step S1). S307). The disconnect detection unit 103 determines that the stream receiving device 3 is disconnected from the network 6 when detecting that the TCP connection is disconnected.

  As a result of transmitting the MLD Join packet, the stream receiving device 3 starts receiving an RTP (Real Time Transport Protocol) stream of content (step S308).

  Thereafter, it is assumed that the power supply of the stream receiving device 3 is changed to the off state during the stream reception (step S309). In this case, the disconnection detection unit 103 of the stream relay device 1 detects that the stream reception device 3 is disconnected from the network 6 due to the disconnection of the TCP connection established in step S307 (steps S310 and S311). . In this case, the disconnection detection unit 103 updates the connection state of the communication state storage unit 121 to “0”.

  The abnormal end determination unit 104 of the stream relay apparatus 1 refers to the communication state storage unit 121 and detects that the connection state is “0” even though the communication state is communication established (Join). As a result, the abnormal end determination unit 104 shifts to the power-off state without the stream receiving device 3 executing the normal end sequence for the IP broadcast multicast address, that is, without transmitting the MLD Leave packet. This is detected (step S312).

  Instead of referring to the connection state of the communication state storage unit 121, the abnormal end determination unit 104 receives the notification of the detection result from the disconnection detection unit 103, and executes the above determination with reference to the notified detection result. You may comprise.

  Finally, the end request transmission unit 105 of the stream relay device 1 generates an MLD Leave packet using the communication information stored in Step S306, and transmits the MLD Leave packet to the edge router 4 (Step S313). Thereby, the inflow of the multicast stream to the network 6 is stopped.

  Through the processing as described above, the stream relay device 1 does not wait for the interval of the MLD query that the edge router 4 periodically transmits, and the stream reception device 3 that has transitioned to the power-off state without following the normal end sequence. It is possible to stop the joined multicast stream and prevent the communication band of the network 6 from being wasted.

  As described above, in the relay device according to the first embodiment, the connection state of the receiving device to the network is monitored, and communication for content distribution is being established even though the receiving device is disconnected from the network. If there is, the communication end request packet is transmitted to the transmitting device instead of the receiving device. As a result, it is possible to avoid wasting network bandwidth when stream data is transmitted and received, and to efficiently use the bandwidth.

(Second Embodiment)
In the first embodiment, a relay apparatus that transmits stream data by multicast as in the IP broadcast service has been described as an example. In the second embodiment, an example will be described in which the present invention is applied to a relay device that relays stream data transmitted by unicast, such as a VoD service.

  FIG. 4 is a block diagram illustrating a configuration example of a content distribution system including the stream relay device 21 according to the second embodiment. As shown in FIG. 4, the stream relay device 21 relays communication between the stream transmission device 22 on the network 5 and the stream reception device 23 on the network 6.

  As shown in the figure, in this embodiment, the edge router 4 is not included as a component of the network 5. The stream transmission device 22 is a content distribution server that provides a VoD service. The stream receiving device 23 is a client device such as an STB, a digital television, a personal computer, or an HDD recorder that receives a VoD service.

  The communication that occurs between the stream transmission device 22 and the stream reception device 23 includes unicast stream communication that transmits the content itself. In this embodiment, an example in which RTSP is used for stream reproduction control will be described.

  Next, details of the function and configuration of the stream relay device 21 will be described. As shown in the figure, the stream relay device 21 includes a WAN port 111, a LAN port 112, a communication state storage unit 221, an interruption state storage unit 222, a relay unit 101, a packet monitoring unit 202, and a disconnection detection. Unit 103, abnormal termination determination unit 204, and termination request transmission unit 205.

  In the second embodiment, the data stored in the communication state storage unit 221, the functions of the packet monitoring unit 202, the abnormal end determination unit 204, the end request transmission unit 205, and the interruption state storage unit 222 are added. Is different from the first embodiment. Other configurations and functions are the same as those in FIG. 1 which is a block diagram showing the configuration of the stream relay device 1 according to the first embodiment, and thus are denoted by the same reference numerals and description thereof is omitted here.

  The communication state storage unit 221 stores the communication state of communication used for transmitting and receiving stream data, similar to the communication state storage unit 121 of the first embodiment. In the second embodiment, RTSP corresponds to communication used for transmitting and receiving stream data as described above. For this reason, the point which memorize | stores the communication state of RTSP differs from the communication state memory | storage part 121 of 1st Embodiment.

  FIG. 5 is a diagram illustrating an example of data stored in the communication state storage unit 221. As shown in FIG. 5, in the present embodiment, the protocol type, the communication state, and the contents of data stored in the communication information are different from those in the first embodiment.

  RTSP is set as the protocol type. The communication status includes RTSP session status information such as before session construction (Init), after session construction (Ready), and during playback of stream data (Playing) transitioned by an RTSP PLAY request, indicating the state before transmission of the RTSP SETUP request packet. Is set. Communication information includes destination IP address (dst_ipaddr), destination port number (dst_port), source IP address (src_ipaddr), source port number (src_port), and identification information (Session) that identifies the negotiated session. Is done.

  Returning to FIG. 4, the interruption state storage unit 222 stores the interruption state stream state included in the response packet received by the end request transmission unit 205 as a response to the request packet (request message) requesting the end of the stream communication. For example, the interruption state storage unit 222 stores a stream state including position information indicating a position where reproduction of the stream data is interrupted.

  The packet monitoring unit 202 monitors the RTSP communication packet instead of the MLD, and stores the communication state acquired from the packet in the communication state storage unit 221. This is the same as the packet monitoring unit 102 of the first embodiment. Is different. In this embodiment, the packet monitoring unit 202 monitors RTSP communication packets, and from the communication packets, protocol type (RTSP), source and destination address information (IP address and port number), RTSP The communication state (RTSP session status information) and communication information are determined and stored in the communication state storage unit 221.

  The packet monitoring unit 202 acquires the communication information stored in the communication state storage unit 221 from the RTSP communication packet header information and the like. For example, the negotiated session information (Session) can be obtained from the session header information of RTSP.

  The abnormal end determination unit 204 detects that the communication state of the communication state storage unit 221 indicates that the session has been established (Ready) or that the stream data is being reproduced (Playing), and that the disconnection detection unit 103 has disconnected from the network 6. If it is determined that the corresponding stream receiving device 23 has ended without passing through a normal end sequence.

  The end request transmitting unit 205 generates and transmits an RTSP PAUSE packet requesting stop of stream transmission instead of a multicast leave packet (MLD Leave packet) as a request message for requesting the end of communication. This is different from the end request transmission unit 105 of the embodiment.

  Next, stream relay processing by the stream relay device 21 according to the second embodiment configured as described above will be described with reference to FIG. FIG. 6 is a flowchart illustrating an overall flow of the stream relay processing in the second embodiment.

  Although the response to each RTSP request is omitted in the figure, a 200 OK response is actually responded to each RTSP request.

  First, the stream receiving device 23 is activated and connected to the network 6 (step S601). Next, the stream receiving device 23 receives a content reproduction request for the VoD service from the user (step S602). The stream receiving device 23 transmits a session establishment and playback request packet using RTSP to the source address of the corresponding VoD content (step S603, step S604, step S605). Specifically, the stream receiving device 23 transmits an RTSP DESCRIBE packet, an RTSP SETUP packet, and an RTSP PLAY packet. The transmission of the RTSP DESCRIBE packet may be omitted.

  The packet monitoring unit 202 of the stream relay device 21 that has received these packets detects the connection of the stream reception device 23 (step S606). Then, the packet monitoring unit 202 acquires the protocol type (RTSP), the communication state, and the communication information from the RTSP packet information, and accumulates them in the communication state storage unit 221 (step S607).

  Furthermore, the disconnection detection unit 103 of the stream relay device 21 establishes a TCP connection for liveness confirmation with the stream reception device 23, and keeps the TCP connection by transmitting keep-alive packets at regular intervals (step). S608).

  As a result of the RTSP PLAY packet transmission, the stream receiving device 23 starts receiving the RTP stream of the content (step S609).

  Thereafter, it is assumed that the power of the stream receiving device 23 is changed to the off state during the stream reception (step S610). In this case, the disconnection detection unit 103 of the stream relay device 21 detects that the stream reception device 23 has been disconnected from the network 6 due to the disconnection of the TCP connection established in step S608 (steps S611 and S612). .

  The abnormal end determination unit 204 of the stream relay device 21 confirms that the stream reception device 23 has made a transition to the power-off state without requesting the stream transmission device 22 to stop playback, that is, without transmitting the RTSP PAUSE packet. Detection is performed (step S613).

  Finally, the end request transmission unit 205 of the stream relay device 21 generates an RTSP PAUSE packet using the communication information stored in step S607 and transmits the RTSP PAUSE packet to the stream transmission device 22 (step S614). Thereby, the inflow of the unicast stream to the network 6 is stopped.

  Through the processing as described above, the stream relay device 21 stops the unicast stream established by the stream receiving device 23 that has transitioned to the power-off state without following the normal termination sequence without waiting for the timeout interval of the RTSP communication session. It is possible to prevent the communication band of the network 6 from being wasted.

  In the conventional VoD service, when playback is interrupted due to power interruption or the like, the playback interruption position cannot be grasped. For this reason, the stream receiver 23 cannot be watched again after the interruption position is turned on again.

  Therefore, in the present embodiment, the response information (reproduction interruption position information and the like) for the RTSP PAUSE packet transmitted in step S614 is accumulated in the interruption state storage unit 222, so that the reproduction request for the same content from the stream reception device 23 is performed again. Is generated, the reproduction interruption position is presented to the stream receiving device 23 using the accumulated information. Thereby, the stream receiving device 23 can specify the position where the reproduction is interrupted, and can resume the reproduction from the reproduction interruption position.

  Steps S615 to S620 in the figure represent an overview of the processing when the reproduction is resumed in this way.

  That is, first, the stream receiving device 23 is restarted and connected to the network 6 (step S615). The stream receiving device 23 transmits a UPnP SSDP packet when activated (step S616).

  The packet monitoring unit 202 of the stream relay device 21 detects the connection of the stream receiving device 23 by receiving the SSDP packet (step S617). The stream relay device 21 notifies the reproduction interruption position saved in the interruption state storage unit 222 to the reception port of the stream reception device 23 notified at this time (step S618). The reproduction interruption position may be performed using a POST method of HTTP (Hypertext Transfer Protocol), or may be notified by a unique protocol using a TCP connection established for existence confirmation.

  The stream receiving device 23 displays the notified reproduction interruption position, the name of the content for which reproduction has been interrupted, and the like on the screen (step S619), and prompts the user to resume viewing. Then, the stream receiving device 23 receives a content reproduction restart request from the user (step S620). Since the subsequent processing is the same as the processing after step S603, the description thereof is omitted.

  As described above, in the relay device according to the second embodiment, even when the stream data transmitted by unicast is relayed as in the case of the VoD service, the content distribution is performed even though the receiving device is disconnected from the network. When the communication for the communication is being established, the communication end request packet can be transmitted to the transmission device instead of the reception device.

(Third embodiment)
In the second embodiment, RTSP is the only signaling communication used between the transmission device and the reception device for stream communication. In the third embodiment, an example in which a plurality of signaling communication protocols are used for stream communication will be described. Specifically, an example in which SIP is used for bandwidth control of stream communication and RTSP is used for playback control will be described.

  FIG. 7 is a block diagram illustrating a configuration example of a content distribution system including the stream relay device 31 according to the third embodiment. As illustrated in FIG. 7, the stream relay device 31 relays communication between the stream transmission device 32 on the network 5 and the stream reception device 33 on the network 6.

  The stream transmission device 32 is a content distribution server that provides a VoD service using RTSP after securing a bandwidth using SIP. The stream receiving device 33 is a client device such as an STB, a digital television, a personal computer, or an HDD recorder that receives a VoD service by RTSP in a band secured by SIP.

  In the present embodiment, communication occurring between the stream transmission device 32 and the stream reception device 33 is not only unicast stream communication (RTSP) for transmitting content itself, but also establishes and controls this stream communication session. Signaling communication (SIP) is also included. For bandwidth control, for example, RSVP (Resouce Reservation Protocol) can be used in addition to SIP.

  Next, details of the function and configuration of the stream relay device 31 will be described. As shown in the figure, the stream relay device 31 includes a WAN port 111, a LAN port 112, a communication state storage unit 321, an interruption state storage unit 222, a relay unit 101, a packet monitoring unit 302, and disconnection detection. Unit 103, abnormal end determination unit 304, and end request transmission unit 305.

  In the third embodiment, the data stored in the communication state storage unit 321 and the functions of the packet monitoring unit 302, the abnormal end determination unit 304, and the end request transmission unit 305 are different from those in the second embodiment. ing. The other configurations and functions are the same as those in FIG. 4 which is a block diagram showing the configuration of the stream relay device 21 according to the second embodiment, and thus the same reference numerals are given and description thereof is omitted here.

  The communication state storage unit 321 stores the communication state of communication used for transmitting and receiving stream data in the same manner as the communication state storage unit 221 of the second embodiment. In the third embodiment, as described above, RTSP and SIP correspond to communication used for transmitting and receiving stream data. For this reason, the point which memorize | stores the communication state of RTSP and SIP differs from the communication state memory | storage part 221 of 2nd Embodiment.

  FIG. 8 is a diagram illustrating an example of data stored in the communication state storage unit 321. As shown in FIG. 8, this embodiment is different from the second embodiment in that not only the communication state of RTSP but also the communication state of SIP is stored.

  As shown in the second line of the figure, in the case of the SIP communication state, SIP is set as the protocol type. In the communication state, one of SIP session states such as SIP session establishment (Session Initiated) that is transitioned by SIP invitation and negotiation for session establishment (Session Negotiating) is set. The communication information includes a destination IP address (dst_ipaddr), a destination port number (dst_port), a source IP address (src_ipaddr), a source port number (src_port), and a call ID (Call-ID) for identifying a SIP dialog. Is set.

  Returning to FIG. 7, the packet monitoring unit 302 monitors not only RTSP but also a SIP communication packet, and stores the communication state and the like acquired from the packet in the communication state storage unit 321 in the second embodiment. Different from the packet monitoring unit 202. That is, the packet monitoring unit 202 monitors a SIP communication packet in addition to RTSP, and from the communication packet, the protocol type (SIP), source and destination address information (IP address and port number), and SIP The communication state (SIP session state information) and the communication information are determined and stored in the communication state storage unit 321.

  The packet monitoring unit 302 acquires the communication information stored in the communication state storage unit 321 from the header information of the SIP communication packet. For example, a call ID (Call-ID) can be obtained from a SIP Call-ID header.

  The abnormal termination determination unit 304 is in the state where one of the communication states of the plurality of signaling communications (RTSP and SIP) in the communication state storage unit 321 is established (“Ready” or “Playing” in the case of RTSP, and “Session Initiated” in the case of SIP). ”), And when the disconnection detection unit 103 detects disconnection from the network 6, it determines that the corresponding stream reception device 33 has ended without passing through a normal end sequence.

  The end request transmission unit 305 generates and transmits not only an RTSP PAUSE packet requesting stop of stream transmission but also a SIP BYE packet requesting SIP session end as a request message for requesting the end of communication. This is different from the end request transmission unit 205 of the second embodiment.

  Note that the termination request transmission unit 305 determines the transmission order of the plurality of request messages in consideration of the order of establishment of the plurality of communications. Specifically, end request transmission section 305 transmits a request message for ending communication established later before the communication request message established earlier. For example, an RTSP communication session is normally established after a communication band is secured by a SIP INVITE request. Therefore, the termination request transmission unit 305 first generates and transmits an RTSP PAUSE packet, and then generates and transmits a SIP BYE packet.

  Further, the end request transmission unit 305 does not transmit a request message for communication in which the communication state indicates the end of communication among the plurality of signaling communications (RTSP and SIP) in the communication state storage unit 321.

  Next, stream relay processing by the stream relay device 31 according to the third embodiment configured as described above will be described with reference to FIG. FIG. 9 is a flowchart illustrating an overall flow of the stream relay processing in the third embodiment.

  In the figure, responses to the SIP request and the RTSP request are omitted, but a 200 OK response is actually responded to each request.

  First, the stream receiving device 33 is activated and connected to the network 6 (step S901). At this time, the stream receiving device 33 transmits a SIP REGISTER request to the SIP registrar in the home to perform registration processing (step S902). In the figure, it is assumed that a SIP registrar function is installed in the stream relay device 31.

  The stream relay device 31 detects the connection of the stream reception device 33 by receiving the SIP REGISTER request (step S903). The connection may be detected by the same method as in the first and second embodiments.

  Next, the stream receiving device 33 receives a content reproduction request for the VoD service from the user (step S904). The stream receiving apparatus 33 secures a communication band for stream (and for reproduction control) by transmitting a SIP INVITE request to the stream relay apparatus 31 (steps S905 and S906). Further, the stream receiving device 33 transmits a session establishment and reproduction request packet using RTSP to the source address of the corresponding VoD content (steps S907 and S908).

  The packet monitoring unit 302 of the stream relay device 31 that has received these packets acquires the protocol type (SIP and RTSP), communication status, and communication information from the SIP packet information and RTSP packet information, and a communication status storage unit 321. (Step S909).

  As a result of the RTSP PLAY packet transmission, the stream receiving device 33 starts receiving the RTP stream of the content (step S910).

  In the present embodiment, it is assumed that the disconnection detection unit 103 uses a method of detecting disconnection based on whether or not a response packet for a survival confirmation multicast packet is detected, instead of using a TCP connection. As in the second embodiment, a method using a TCP connection may be applied.

  Thereafter, it is assumed that the power supply of the stream receiving device 33 is changed to the off state during the stream reception (step S911). In this case, the disconnection detection unit 103 of the stream relay apparatus 31 disconnects the stream reception apparatus 33 from the network 6 because there is no response for a certain period of time with respect to the multicast packet for life confirmation that is periodically transmitted on the network 6. It is detected (step S912, step S913).

  The abnormal end determination unit 304 of the stream relay device 31 sets the power off state without the stream reception device 33 requesting the stream transmission device 32 to stop the reproduction, that is, without transmitting the SIP BYE packet and the RTSP PAUSE packet. The transition is detected (step S914).

  Finally, the end request transmission unit 305 of the stream relay apparatus 31 uses the communication information stored in step S909 to generate an RTSP PAUSE packet and a SIP BYE request packet in order and transmit them to the stream transmission apparatus 32 ( Step S915, Step S916). Thereby, the inflow of the unicast stream to the network 6 is stopped.

  Note that, after this, the processing when restarting the stream receiving device 33 and restarting the reproduction is the same as steps S615 to S620 in FIG.

  As described above, in the relay apparatus according to the third embodiment, even when stream data is transmitted / received using a plurality of signaling communications, any of the plurality of signaling communications is performed regardless of whether the receiving apparatus is disconnected from the network. Can be transmitted to the transmitting device instead of the receiving device.

  The first to third embodiments can be implemented in any combination. This means that the information of the multicast stream control packet, the reproduction control packet, and the bandwidth control packet can be mixed in the communication state storage unit of the stream relay device.

(Fourth embodiment)
In the first to third embodiments, the relay apparatus that relays stream data is configured to execute a communication end sequence on behalf of the stream receiving apparatus. In the fourth embodiment, when restarting after power off, it is determined whether or not the stream reception device itself has ended abnormally, and if it is determined that it has ended abnormally, a normal end sequence is executed. Terminate communication established before restart.

  FIG. 10 is a block diagram illustrating a configuration example of a content distribution system including the stream receiving device 43 according to the third embodiment. As shown in FIG. 10, the stream receiving device 43 is connected to the network 5, and at the same time, the stream transmitting device 42 is connected to the network 5.

  As described above, the network 5 is assumed to be a quality-guaranteed WAN such as NGN, but is not limited to this. Rather, it is more practical to regard the network 5 as a network that combines the network 5 and the network 6 described above, that is, a network that includes a WAN and a home network (LAN) interconnected by a broadband router device or the like. It can be said that it is close to form.

  The stream transmission device 42 is a content distribution server that provides an IP broadcast service and a VoD service.

  The stream receiving device 43 is a client device such as an STB, a digital television, a personal computer, or an HDD recorder that receives an IP broadcast service and a VoD service.

  As for the communication that occurs between the stream transmitting device 42 and the stream receiving device 43, with respect to the IP broadcast service, not only multicast stream communication that transmits the content itself as IP broadcast, but also participation in and withdrawal from this multicast address are performed. Signaling communications are also included. For this signaling communication, for example, IGMP or MLD is used. The VoD service includes not only unicast stream communication for transmitting content, but also signaling communication for content stream reproduction control and band control. For reproduction control, for example, RTSP is used. For bandwidth control, for example, SIP or RSVP is used.

  Next, details of the function and configuration of the stream receiving device 43 will be described. As shown in the figure, the stream receiving device 43 includes a LAN port 412, a communication state storage unit 421, an interruption state storage unit 422, a communication unit 401, a packet monitoring unit 402, an abnormal end determination unit 404, An end request transmission unit 405.

  The LAN port 412 is a port for connecting the stream receiving device 43 to the network 5.

  The communication state storage unit 421 stores a communication state of communication used for transmitting / receiving stream data to / from the stream transmission device 42. For example, when using an IP broadcast service, IGMP, MLD, and the like correspond to communication used for transmitting and receiving stream data. For example, when using the VoD service, SIP, RTSP, and the like correspond to communication used for transmitting and receiving stream data.

  FIG. 11 is a diagram illustrating an example of data stored in the communication state storage unit 421. As illustrated in FIG. 11, the communication state storage unit 421 stores data in which a protocol type, a communication state, communication information, and a time stamp indicating the date and time when the communication state is stored are associated with each other. The protocol type, the communication state, and the contents of the communication information are the same as those in the first to third embodiments.

  The interruption state storage unit 422 stores reproduction interruption position information indicating a position where reproduction of stream data is interrupted. The reproduction interruption position information is stored by the packet monitoring unit 402 described later.

  The communication unit 401 receives and transmits a content stream and a message related to signaling communication for receiving the content stream with the stream transmission device 42.

  The packet monitoring unit 402 monitors a signaling communication packet transmitted / received by the communication unit 401, and stores a communication state of communication with the stream transmission device 42 in the communication state storage unit 421. In the present embodiment, the packet monitoring unit 402 monitors communication packets such as IGMP, MLD, SIP, and RTSP according to the service to be used, and from the communication packet, the protocol type, the source and destination addresses Information (IP address and port number) and the communication state of signaling communication are determined, and a time stamp is added and stored in the communication state storage unit 421.

  Further, the packet monitoring unit 402 saves a reproduction position snapshot (reproduction interruption position information) in the interruption state storage unit 422 periodically (for example, at intervals of 10 seconds) during reception of the stream data. Thereby, even if the stream receiving device 43 transitions to the power-off state without going through a normal end sequence during the VoD viewing due to a momentary interruption or the like, the stream receiving device 43 can refer to the reproduction interruption position information at the time of restart. VoD viewing can be resumed from an appropriate position.

  The abnormal end determination unit 404 determines at the time of activation that the stream reception device 43 has ended communication with the stream transmission device 42 without going through a normal end sequence. Specifically, the abnormal end determination unit 404 determines that the own device has ended without passing through a normal end sequence when the communication state of the communication state storage unit 421 represents a state in which communication is established.

  Note that when the process ends in a normal end sequence, the data stored in the communication state storage unit 421 is deleted, and when the abnormal end determination unit 404 has data left in the communication state storage unit 421, May be determined to have ended without passing through a normal end sequence.

  Even when the abnormal end determination unit 404 determines that the process has ended without going through a normal end sequence, the communication may be ended depending on the function of each protocol if a predetermined period has elapsed. For example, when the RTSP keep alive interval elapses, the RTSP communication is disconnected. Therefore, the abnormal end determination unit 404 further determines whether or not the time from the date / time of the time stamp to the current date / time is smaller than a certain period determined according to the protocol.

  The end request transmitting unit 405 determines that the stream receiving device 43 ends without going through a normal end sequence, and that the time from the date / time of the time stamp to the current date / time is smaller than a certain period determined according to the protocol. If it is determined, a request message for requesting termination of signaling communication is generated and transmitted to the stream transmitting device 42. Specifically, the termination request transmission unit 405 refers to the protocol type and communication information of the communication state storage unit 421, and, for example, a multicast leave packet (MLD Leave packet), or, depending on the communication protocol being used, A signaling request disconnection request packet (RTSP PAUSE packet) is generated and transmitted to the stream transmitter 42.

  Next, a stream reception process performed by the stream reception device 43 according to the fourth embodiment configured as described above will be described with reference to FIG. FIG. 12 is a flowchart illustrating an overall flow of the stream reception process according to the fourth embodiment.

  In the same figure, as in the first embodiment, a stream reception process when the stream transmission device 42 provides an IP broadcast service using MLD will be described as an example.

  First, the stream receiving device 43 is activated and connected to the network 5 (step S1201). Next, the stream receiving device 43 receives a viewing request for the IP broadcast service from the user (step S1202). The communication unit 401 of the stream receiving device 43 transmits an MLD Join packet corresponding to the multicast address of the corresponding IP broadcast to the stream transmitting device 42 (step S1203).

  The packet monitoring unit 402 of the stream receiving device 43 acquires the protocol type (MLD), communication state (Join), and communication information from the transmitted MLD Join packet, and accumulates them in the communication state storage unit 421 (step S1204).

  The communication unit 401 of the stream receiving apparatus 43 starts receiving an RTP (Real Time Transport Protocol) stream of content (step S1205).

  Thereafter, it is assumed that the power of the stream receiving device 43 is turned off during stream reception (step S1206), and the power is further turned on to restart the stream receiving device 43 (step S1207).

  The abnormal termination determination unit 404 of the stream receiving device 43 is in a state where the communication state of the communication state storage unit 421 is in communication establishment, and the time from the corresponding time stamp date to the current date is determined according to the protocol. It is determined whether or not the period is shorter than a predetermined period (step S1208). When this condition is satisfied, the abnormal end determination unit 404 determines that the stream reception device 43 has ended abnormally without going through a normal end sequence.

  If it is determined that the processing has ended abnormally, the end request transmission unit 405 of the stream reception device 43 generates an MLD Leave packet using the communication information stored in step S1204, and transmits the MLD Leave packet to the stream transmission device 42 (step). S1209). Thereby, the inflow of the multicast stream to the network 5 is stopped.

  In the present embodiment, thereafter, reproduction can be resumed with reference to the reproduction interruption position in the interruption state storage unit 422. That is, the stream receiving device 43 first acquires the reproduction interruption position from the interruption state storage unit 422 (step S1210). Then, the stream receiving device 43 displays the acquired reproduction interruption position, the name of the content for which reproduction has been interrupted, and the like on the screen (step S1211), and prompts the user to resume viewing. Then, the stream receiving device 43 receives a content reproduction restart request from the user (step S1212). Since the subsequent processing is the same as the processing after step S1203, description thereof will be omitted.

  Note that, as in the second and third embodiments, even when the stream transmitting device 42 provides the VoD service, the normal end sequence may be executed after the restart by the same process. it can.

  As described above, in the receiving apparatus according to the fourth embodiment, when restarting after power-off, it is determined whether or not the stream receiving apparatus itself has ended abnormally. The normal end sequence can be executed to end the communication established before the restart. This makes it possible to efficiently use the network bandwidth when transmitting / receiving stream data.

  Next, the hardware configuration of each device (relay device or receiving device) according to the first to fourth embodiments will be described with reference to FIG. FIG. 13 is an explanatory diagram illustrating the hardware configuration of the devices according to the first to fourth embodiments.

  The devices according to the first to fourth embodiments communicate with a control device such as a CPU (Central Processing Unit) 51 and a storage device such as a ROM (Read Only Memory) 52 and a RAM 53 by connecting to a network. A communication I / F 54 and a bus 61 for connecting each unit are provided.

  Each program executed by the devices according to the first to fourth embodiments (relay program executed by the relay device or communication end program executed by the receiving device) is provided by being incorporated in advance in the ROM 52 or the like. .

  A program executed by the apparatus according to the first to fourth embodiments is a file in an installable format or an executable format, and is a CD-ROM (Compact Disk Read Only Memory), a flexible disk (FD), a CD- You may comprise so that it may record and provide on computer-readable recording media, such as R (Compact Disk Recordable) and DVD (Digital Versatile Disk).

  Furthermore, the program executed by the apparatus according to the first to fourth embodiments may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Good. Moreover, you may comprise so that the program run with the apparatus concerning the 1st-4th embodiment may be provided or distributed via networks, such as the internet.

  The relay program executed by the relay apparatus according to the first to third embodiments includes a module configuration including the above-described units (relay unit, packet monitoring unit, disconnection detection unit, abnormal end determination unit, end request transmission unit). As actual hardware, the CPU 51 reads the relay program from the ROM 52 and executes it, so that the above-described units are loaded onto the main storage device, and the respective units are generated on the main storage device. Yes.

  The communication termination program executed by the receiving apparatus according to the fourth embodiment has a module configuration including the above-described units (communication unit, packet monitoring unit, abnormal termination determination unit, termination request transmission unit). As actual hardware, the CPU 51 reads out the communication end program from the ROM 52 and executes it, so that the above-described units are loaded onto the main storage device, and the respective units are generated on the main storage device.

  As described above, the relay device, the relay method, the relay program, the receiving device, the communication end method, and the communication end program according to the present invention are an apparatus, a method, and a method for transmitting and receiving stream data such as an IP broadcast service and a VoD service. Suitable for the program.

It is a block diagram which shows the structural example of the content delivery system concerning 1st Embodiment. It is a figure which shows an example of the data memorize | stored in the communication status memory | storage part of 1st Embodiment. It is a flowchart which shows the whole flow of the stream relay process in 1st Embodiment. It is a block diagram which shows the structural example of the content delivery system concerning 2nd Embodiment. It is a figure which shows an example of the data memorize | stored in the communication status memory | storage part of 2nd Embodiment. It is a flowchart which shows the whole flow of the stream relay process in 2nd Embodiment. It is a block diagram which shows the structural example of the content delivery system concerning 3rd Embodiment. It is a figure which shows an example of the data memorize | stored in the communication status memory | storage part of 3rd Embodiment. It is a flowchart which shows the whole flow of the stream relay process in 3rd Embodiment. It is a block diagram which shows the structural example of the content delivery system concerning 4th Embodiment. It is a figure which shows an example of the data memorize | stored in the communication status memory | storage part of 4th Embodiment. It is a flowchart which shows the whole flow of the stream reception process in 4th Embodiment. It is explanatory drawing which shows the hardware constitutions of the apparatus concerning 1st-4th embodiment.

Explanation of symbols

1, 21, 31 Stream relay device 2, 22, 32, 42 Stream transmission device 3, 23, 33, 43 Stream reception device 4 Edge router 5, 6 Network 51 CPU
52 ROM
53 RAM
54 Communication I / F
61 Bus 101 Relay unit 102, 202, 302, 402 Packet monitoring unit 103 Disconnection detection unit 104, 204, 304, 404 Abnormal termination determination unit 105, 205, 305, 405 Termination request transmission unit 111 WAN port 112, 412 LAN port 121 221 321 421 Communication state storage unit 222 422 Interruption state storage unit 401 Communication unit

Claims (21)

Connected via a first network to a transmitting device that transmits stream data, connected via a second network to a receiving device that receives the stream data, and transmits the stream data between the transmitting device and the receiving device. A relay device for relaying,
A communication state storage unit that stores a communication state indicating whether communication used for transmission / reception of the stream data between the transmission device and the reception device is established;
A disconnection detecting unit for detecting that the receiving device is disconnected from the second network;
A determination unit that determines whether the communication is established when it is detected by the disconnection detection unit;
A relay device, comprising: a transmission unit that transmits a request message for requesting termination of communication to the transmission device when the determination unit determines that communication is established.   The disconnection detection unit transmits a confirmation message for confirming connection to the second network to the second network by multicast, and determines whether a response message to the confirmation message is received from the receiving device. The relay apparatus according to claim 1, wherein if the reception apparatus is not received, the relay apparatus detects that the reception apparatus is disconnected from the second network.   The confirmation message conforms to ARP (Address Resolution Protocol), NDP (Neighbor Discovery Protocol), LLDP (Link Layer Discovery Protocol), LLTD (Link Layer Topology Discovery), or UPnP SSDP (Universal Plug and Play Simple Service Discovery Protocol) The relay apparatus according to claim 2, wherein the relay apparatus is a message.   The disconnection detection unit establishes communication for connection confirmation with the receiving device, determines whether the communication for connection confirmation is disconnected, and when the communication is disconnected, The relay apparatus according to claim 1, wherein the relay apparatus detects disconnection from the network. The communication state storage unit stores the communication state for each of a plurality of communications used for transmission / reception of the stream data between the transmission device and the reception device,
The determination unit determines whether or not it represents that at least one communication among the plurality of communications is established when it is detected that the receiving device is disconnected;
When the determination unit determines that at least one communication among the plurality of communications is established, the transmission unit sends the request message for requesting termination of the established communication. The relay apparatus according to claim 1, wherein the relay apparatus transmits to the transmission apparatus.   6. The transmission unit according to claim 5, wherein, when transmitting the request message of the plurality of communications, the transmission unit prioritizes communication established later among the plurality of communications. Relay device.   The relay apparatus according to claim 1, wherein the communication used for transmission / reception of the stream data is communication based on a protocol for controlling reproduction of the stream data, including RTSP (Real Time Streaming Protocol). . The stream data transmitted / received between the transmitting device and the receiving device is stream data transmitted / received by multicast,
The communication used for transmission / reception of the stream data is communication compliant with a protocol for controlling a multicast stream for transmitting the stream data, including IGMP (Internet Group Management Protocol) and MLD (Multicast Listener Discovery). The relay device according to claim 1.   The communication used for the transmission / reception of the stream data is a communication conforming to a protocol for controlling the bandwidth of the communication for transmitting / receiving the stream data, including SIP (Session Initiation Protocol) and RSVP (Resource Reservation Protocol). The relay device according to claim 1. An interruption state storage unit capable of storing position information for specifying a position where transmission of the stream data is interrupted;
The transmission unit further stores the position information in the interruption state storage unit when transmitting the request message, and performs communication used for transmission / reception of the stream data between the transmission device and the reception device. The relay apparatus according to claim 1, wherein, when established again, the stored position information is transmitted to the receiving apparatus. Connected via a first network to a transmitting device that transmits stream data, connected via a second network to a receiving device that receives the stream data, and transmits the stream data between the transmitting device and the receiving device. A relay method executed by a relay device that relays,
The relay device includes a communication state storage unit that stores a communication state indicating whether communication used for transmission / reception of the stream data between the transmission device and the reception device is established,
A disconnection detecting step for detecting that the receiving device is disconnected from the second network;
A determination step of determining whether or not it represents that the communication is established when it is detected that the determination unit is disconnected by the disconnection detection unit;
And a transmission step of transmitting a request message for requesting termination of communication to the transmission device when the transmission unit determines that communication is established by the determination unit. Relay method. Connected via a first network to a transmitting device that transmits stream data, connected via a second network to a receiving device that receives the stream data, and transmits the stream data between the transmitting device and the receiving device. A relay program executed by a relay device that relays,
The relay device includes a communication state storage unit that stores a communication state indicating whether communication used for transmission / reception of the stream data between the transmission device and the reception device is established,
The relay device;
A disconnection detecting unit for detecting that the receiving device is disconnected from the second network;
A determination unit that determines whether the communication is established when it is detected by the disconnection detection unit;
A relay program for causing a request message for requesting termination of communication to function as a transmission unit that transmits to the transmission device when it is determined by the determination unit that communication is established. A receiving device that receives stream data from a transmitting device connected via a network,
A communication state storage unit for storing a communication state indicating whether or not communication used for transmission and reception of the stream data has been established, and a storage date and time storing the communication state;
When the receiving device is activated, it is determined whether or not the difference between the current date and time and the stored date and time is smaller than a predetermined period and whether or not the communication is established. A determination unit;
Transmission that transmits a request message for requesting termination of the communication to the transmission device when the determination unit determines that the difference is smaller than the period and indicates that the communication is established. And a receiver. The communication state storage unit stores the communication state for each of a plurality of communications used for transmission / reception of the stream data,
The determination unit determines whether or not a difference between a current date and time and the storage date and time is smaller than a predetermined period when the receiving device is activated, and at least one of the plurality of communications Determine whether communication is established or not,
The transmission unit is established when the judgment unit determines that the difference is smaller than the period and that at least one of the plurality of communications is established. The receiving apparatus according to claim 13, wherein the request message for requesting termination of the communication is transmitted to the transmitting apparatus.   15. The transmission unit according to claim 14, wherein when transmitting the request message of the plurality of communications, the transmission unit prioritizes communication established later among the plurality of communications. Receiver.   The receiving apparatus according to claim 13, wherein the communication used for transmission / reception of the stream data is communication conforming to a protocol for controlling reproduction of the stream data, including RTSP (Real Time Streaming Protocol). . The stream data transmitted / received between the transmitting device and the receiving device is stream data transmitted / received by multicast,
The communication used for transmission / reception of the stream data is communication compliant with a protocol for controlling a multicast stream for transmitting the stream data, including IGMP (Internet Group Management Protocol) and MLD (Multicast Listener Discovery). The receiving device according to claim 13.   The communication used for the transmission / reception of the stream data is a communication conforming to a protocol for controlling the bandwidth of the communication for transmitting / receiving the stream data, including SIP (Session Initiation Protocol) and RSVP (Resource Reservation Protocol). The receiving device according to claim 13. An interruption state storage unit capable of storing position information for specifying a position where transmission of the stream data is interrupted;
The transmission unit further stores the position information in the interruption state storage unit when transmitting the request message, and performs communication used for transmission / reception of the stream data between the transmission device and the reception device. 14. The receiving apparatus according to claim 13, wherein when it is established again, the stored location information is transmitted to the receiving apparatus. A communication termination method executed by a receiving device that receives stream data from a transmitting device connected via a network,
The receiving device includes a communication state storage unit that stores a communication state indicating whether or not communication used for transmission and reception of the stream data is established, and a storage date and time when the communication state is stored,
Whether the determination unit indicates whether or not the difference between the current date and time and the stored date and time is smaller than a predetermined period when the receiving device is activated, and whether or not the communication is established A determination step for determining whether or not
When the transmission unit determines that the difference is smaller than the period and the determination unit indicates that the communication is established, the transmission unit transmits a request message for requesting termination of the communication to the transmission device. And a transmission end method. A communication termination program executed by a receiving device that receives stream data from a transmitting device connected via a network,
The receiving device includes a communication state storage unit that stores a communication state indicating whether or not communication used for transmission and reception of the stream data is established, and a storage date and time when the communication state is stored,
The receiving device;
When the receiving device is activated, it is determined whether or not the difference between the current date and time and the stored date and time is smaller than a predetermined period and whether or not the communication is established. A determination unit;
A transmission unit that transmits a request message for requesting termination of the communication to the transmission device when the determination unit determines that the difference is smaller than the period and that the communication is established. Communication termination program for functioning.

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