JP2012151622A - Receiving terminal, packet data receiving method, transmitting terminal, transmission/reception system, relay terminal, and relay method of packet data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a receiving terminal to recover a packet loss preferably without increasing its circuit scale unnecessarily, in a system distributing data simultaneously from a transmitting terminal to a plurality of points.SOLUTION: Receiving terminals 200A and 200B arrange and temporarily accumulate packet data of video stream received from a transmitting terminal 100 in a primary buffer. A data processing function part of the receiving terminal sequentially reads the packet data from the primary buffer, and writes the packet data in a secondary buffer. A data processing function part acquires missing packet data from another receiving terminal at detection of the packet loss, and writes the packet data in the secondary buffer. Due to this writing processing, continuous packet data, that is, packet data without missing parts, of video stream can be accumulated in the secondary buffer. A decoder of the receiving terminal sequentially reads the continuous packet data of the video stream accumulated in the secondary buffer and performs decoding processing to acquire received video data without missing parts.

Description

  The present technology relates to a receiving terminal, a packet data receiving method, a transmitting terminal, a transmission / reception system, a relay terminal, and a packet data relay method, and more particularly to a receiving terminal in a system that simultaneously distributes data from a transmitting terminal to a plurality of points.

  In a system that simultaneously distributes data such as a video stream from a transmission terminal to a plurality of points, a case is assumed in which only one stream flows from the transmission terminal by multicast or the like. In this case, when packet loss or the like occurs at a specific receiving terminal, retransmitting only the corresponding data to only the specific terminal is equivalent to managing and transmitting a session for each receiving terminal. Therefore, a distribution network such as multicast in which there are tens of thousands of receiving terminals does not make use of the advantages, and it is not efficient even if the load on the transmitting terminal is taken into consideration.

  For this reason, the re-transmission request processing of the specific terminal is not normally performed, and the video is played back as distorted video, and even when the corresponding video data is recorded, the file is not complete, so the video is partially distorted. .

  For example, Patent Document 1 describes a technique for interpolating missing packet data when packet loss occurs. In the case of this technology, the first to third receiving units receive data in parallel, and for example, when data received by a certain receiving unit is missing, it is supplemented by the received data of other receiving units. ing.

JP 2005-311792 A

  In the technique of the above-mentioned Patent Document 1, it is necessary to receive data in parallel by a plurality of receiving units, and the circuit scale of the receiving terminal (communication terminal) increases.

  An object of the present technology is to enable a receiving terminal to recover packet loss satisfactorily without unnecessarily increasing the circuit scale in a system that simultaneously distributes data from a transmitting terminal to a plurality of points.

The concept of this technology is
A packet data receiving unit for receiving packet data sequentially sent from the transmitting terminal;
A packet data obtaining unit that obtains the missing packet data from another receiving terminal when the packet data received by the packet data receiving unit is missing;
There is provided a receiving terminal comprising: the packet data receiving unit or a decoding processing unit that performs decoding processing on continuous packet data obtained by the packet data receiving unit and the packet data acquiring unit to obtain received data.

  In the present technology, the packet data receiving unit receives packet data sequentially transmitted from the transmission terminal. Further, when the packet data acquisition unit has a missing packet data received by the packet data receiving unit, the missing packet data is acquired from another receiving terminal. In this case, for example, a packet data storage buffer in another receiving terminal is accessed. Then, the decoding processing unit performs decoding processing on the continuous packet data obtained by the packet data receiving unit, or the packet data receiving unit and the packet data acquiring unit, and obtains received data.

  Thus, in the present technology, when the received packet data is missing, the missing packet data is acquired from another receiving terminal. Therefore, since data is not received in parallel by a plurality of receiving units, packet loss can be recovered well without unnecessarily increasing the circuit scale.

  In the present technology, for example, a primary buffer that arranges and temporarily stores the packet data received by the packet data receiving unit and a continuous packet data that is decoded by the decoding processing unit are temporarily stored. And a packet data acquiring unit sequentially reads the packet data from the primary buffer and writes the packet data to the secondary buffer, and when there is a missing packet data read from the primary buffer, It is also possible to acquire the packet data that is present and write it to the secondary buffer. By adopting a two-stage buffer structure in this way, the packet data acquisition unit can acquire the missing packet data from other receiving terminals with a margin.

  In the present technology, the packet data acquisition unit registers in advance a predetermined number of other receiving terminals for acquiring missing packet data based on a receiving terminal table periodically supplied from the transmitting terminal. , May be. In this case, registration can be dynamically updated to an optimum receiving terminal for acquiring missing packet data, and the acquisition can be performed smoothly.

  In the present technology, the packet data acquisition unit may further include a remote access buffer for temporarily storing packet data acquired from another receiving terminal. By providing the remote access buffer in this way, packet data acquired from other receiving terminals can be used also by other receiving terminals.

Other concepts of this technology are
A packet data transmitter that transmits packet data to a plurality of receiving terminals simultaneously;
Receiving terminal information is periodically obtained from the plurality of receiving terminals, and a receiving terminal table including information on receiving terminals that are candidates for obtaining missing packet data is generated based on the obtained receiving terminal information. And a configuration management unit that supplies the generated reception terminal table information to the plurality of reception terminals.

  In the present technology, the packet data transmission unit transmits packet data to a plurality of receiving terminals simultaneously. In addition, the configuration management unit periodically supplies information of a receiving terminal table including information of receiving terminals that are candidates for acquiring missing packet data to a plurality of receiving terminals. This receiving terminal table is generated by the configuration management unit. In the configuration management unit, receiving terminal information is periodically acquired from a plurality of receiving terminals, and a receiving terminal table is generated based on the acquired receiving terminal information. Note that the receiving terminal mentioned here includes a relay terminal that transmits received packet data to a lower-level terminal.

  As described above, in the present technology, information in the receiving terminal table including information on receiving terminals that are candidates for acquiring missing packet data is periodically supplied to a plurality of receiving terminals. Therefore, the receiving terminal can dynamically update the registration to the optimum number of other receiving terminals for acquiring the missing packet data based on this receiving terminal table, and the acquisition is smooth. To be done.

  In the present technology, for example, receiving terminal information acquired from a plurality of receiving terminals includes packet loss occurrence frequency information and connection number information of other receiving terminals, and the configuration management unit A reception terminal table including information on reception terminals whose frequency does not exceed the threshold and the number of connections of other reception terminals does not exceed the threshold may be generated. By generating such a receiving terminal table, the receiving terminal has a high probability of acquiring the packet data as another receiving terminal to acquire the missing packet data, and has a relatively low load. The receiving terminal can be registered, and the packet data can be acquired more smoothly.

Still another concept of this technology is
A packet data receiving unit for receiving packet data sequentially sent from the host terminal;
A packet data acquisition unit that acquires the missing packet data from another relay terminal when the packet data received by the packet data reception unit is missing;
A relay terminal comprising: the packet data receiving unit, or a packet data transmitting unit that sequentially transmits continuous packet data obtained by the packet data receiving unit and the packet data acquiring unit to a lower terminal.

  In the present technology, the packet data receiving unit sequentially receives packet data sent from the host terminal. Further, when the packet data acquisition unit has a missing packet data received by the packet data receiving unit, the missing packet data is obtained from another relay terminal. In this case, for example, the packet data storage buffer in another relay terminal is accessed. Then, the packet data transmission unit sequentially transmits the continuous packet data obtained by the packet data reception unit or the packet data reception unit and the packet data acquisition unit to the lower terminal.

  As described above, in the present technology, when the received packet data is missing, the missing packet data is acquired from another relay terminal. Since data is not received in parallel by a plurality of receiving units, packet loss can be recovered well without unnecessarily increasing the circuit scale. Further, since the packet loss can be recovered at the stage of the relay terminal before reaching the terminal receiving terminal, it is possible to improve data distribution quality such as video.

  In the present technology, for example, a primary buffer that arranges and temporarily stores the packet data received by the packet data receiving unit and a continuous packet data that is sequentially transmitted by the packet data transmitting unit are temporarily stored. The packet data acquisition unit further reads the packet data from the primary buffer and writes the packet data to the secondary buffer, and when there is a missing packet data read from the primary buffer, It is also possible to acquire the packet data that is present and write it to the secondary buffer. With the two-stage buffer structure as described above, the packet data acquisition unit can acquire the missing packet data from other relay terminals with a margin.

  According to the present technology, in a system that simultaneously distributes data from a transmitting terminal to a plurality of points, a receiving terminal or a relay terminal can recover packet loss well without unnecessarily increasing the circuit scale.

1 is a block diagram illustrating a configuration example of a video transmission / reception system as a first embodiment of the present technology. It is a block diagram which shows the structural example of the transmission terminal which comprises a video transmission / reception system. It is a block diagram which shows the structural example of the receiving terminal which comprises a video transmission / reception system. It is a sequence diagram which shows the sequence at the time of a transmitting terminal producing | generating a receiving terminal table and registering the other receiving terminal for a receiving terminal to acquire the missing packet data based on this receiving terminal table. It is a flowchart which shows an example of the production | generation (update) process of the receiving terminal table performed regularly in the structure management part of a transmission terminal. It is a sequence diagram for demonstrating the operation example of the video transmission / reception system in case packet loss does not generate | occur | produce in both receiving terminal 200A, 200B. FIG. 10 is a sequence diagram for explaining an operation example of the video transmission / reception system when no packet loss occurs in the receiving terminal 200A but packet loss occurs in the receiving terminal 200B. An operation example of the video transmission / reception system when packet loss occurs in the receiving terminal 200B and the corresponding packet data cannot be read from the primary buffer of the receiving terminal 200A and is read from another receiving terminal will be described. FIG. 1 is a block diagram illustrating a configuration example of a video transmission / reception system as a first embodiment of the present technology. It is a block diagram which shows the structural example of the relay terminal which comprises a video transmission / reception system. FIG. 10 is a sequence diagram for explaining an operation example of the video transmission / reception system when no packet loss occurs in relay terminal 300A but packet loss occurs in relay terminal 300B. It is a figure for demonstrating the primary buffer for remote access which accumulate | stores the packet data temporarily, when the packet data missing from the other terminal in a receiving terminal or a relay terminal is acquired.

Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described. The description will be given in the following order.
1. 1. First embodiment 2. Second embodiment Modified example

<1. First Embodiment>
[Configuration of video transmission / reception system]
FIG. 1 shows a configuration example of a video transmission / reception system 10 according to the first embodiment. The video transmission / reception system 10 is a system in which a video stream (video data) is simultaneously distributed from a transmission terminal to a plurality of points.

  The video transmission / reception system 10 includes a transmission terminal 100, a plurality of reception terminals, and in this embodiment, two reception terminals 200A and 200B. The transmission terminal 100 includes a configuration management unit 110 and a transmission processing unit 120. The configuration management unit 110 transmits / receives management data to / from the receiving terminals 100A and 100B. The transmission processing unit 120 sequentially transmits packet data of a video stream (video data) to the receiving terminals 100A and 100B.

  The receiving terminal 200A includes a configuration management unit 210A, a reception processing unit 221A, a primary buffer 222A, a data processing function unit 223A, a secondary buffer 224A, and a decoder 225A. The reception processing unit 221A constitutes a packet data receiving unit, the data processing function unit 223A constitutes a packet data acquisition unit, and the decoder 225A constitutes a decoding processing unit.

  The configuration management unit 210 </ b> A transmits and receives management data to and from the transmission terminal 100. The reception processing unit 221 </ b> A receives video stream packet data sequentially transmitted from the transmission terminal 100. The primary buffer 222A aligns and temporarily accumulates the packet data received by the reception processing unit 221A. The secondary buffer 224A temporarily accumulates continuous packet data that is decoded by the decoder 225A. The decoder 225A decodes the continuous packet data of the video stream stored in the secondary buffer 224A to obtain received video data.

  When the packet data received by the reception processing unit 221A is missing, that is, when there is a packet loss, the data processing function unit 223A is missing from another receiving terminal, in this embodiment, the receiving terminal 200B. Get packet data. That is, the data processing function unit 223A reads the packet data from the primary buffer 222A and sequentially writes the packet data to the secondary buffer 224A. At this time, the data processing function unit 223A checks whether there is any missing packet data.

  When the packet data is missing, the data processing function unit 223A acquires the packet data from the receiving terminal 200B and writes the packet data in the secondary buffer 224A. As a result, packet data having a continuous video stream, that is, no missing packet is accumulated in the secondary buffer 224A. When acquiring packet data from the receiving terminal 200B, the data processing function unit 223A accesses the packet data storage buffer (primary buffer) in the receiving terminal 200B via the network.

  The receiving terminal 200B includes a configuration management unit 210B, a reception processing unit 221B, a primary buffer 222B, a data processing function unit 223B, a secondary buffer 224B, and a decoder 225B. The reception processing unit 221B constitutes a packet data receiving unit, the data processing function unit 223B constitutes a packet data acquisition unit, and the decoder 225B constitutes a decoding processing unit.

  The configuration management unit 210B transmits and receives management data to and from the transmission terminal 100. The reception processing unit 221B receives packet data of video streams that are sequentially transmitted from the transmission terminal 100. The primary buffer 222B arranges and temporarily stores the packet data received by the reception processing unit 221B. The secondary buffer 224B temporarily accumulates continuous packet data that is decoded by the decoder 225B. The decoder 225B decodes the continuous packet data of the video stream stored in the secondary buffer 224B to obtain received video data.

  When the packet data received by the reception processing unit 221B is missing, that is, when there is a packet loss, the data processing function unit 223B is missing from other receiving terminals, in this embodiment, the receiving terminal 200A. Get packet data. That is, the data processing function unit 223B reads the packet data from the primary buffer 222B and sequentially writes the packet data to the secondary buffer 224B. At this time, the data processing function unit 223B checks whether the packet data is missing.

  When the packet data is missing, the data processing function unit 223B acquires the packet data from the receiving terminal 200A and writes it in the secondary buffer 224B. As a result, packet data having a continuous video stream, that is, no missing data is accumulated in the secondary buffer 224B. When acquiring packet data from the receiving terminal 200A, the data processing function unit 223B accesses the packet data storage buffer (primary buffer) in the receiving terminal 200A via the network.

  The configuration management unit 110 of the transmission terminal 100 periodically acquires reception terminal information from a plurality of reception terminals, in this embodiment, the reception terminals 200A and 200B. This receiving terminal information includes connection information for enabling access to the primary buffers 222A and 222B from other receiving terminals via the network, such as an IP address and a port number. The receiving terminal information includes packet loss occurrence frequency information and connection number information of other receiving terminals.

  Here, the configuration management unit 110 of the transmission terminal 100 periodically requests the reception terminal information from the configuration management units 210A and 210B of the reception terminals 200A and 200B. The packet loss occurrence frequency information is information indicating the frequency of packet loss that has occurred between the previous receiving terminal information request and the current receiving terminal information request. The connection number information of other receiving terminals is information indicating the number of accesses from other receiving terminals between the previous receiving terminal information request and the current receiving terminal information request.

  The configuration management unit 110 of the transmission terminal 100 includes information on reception terminals that are candidates for acquiring missing packet data based on the reception terminal information acquired from the configuration management units 210A and 210B of the reception terminals 200A and 200B. Generate a receiving terminal table. Then, the configuration management unit 110 of the transmission terminal 100 transmits this reception terminal table to the configuration management units 210A and 210B of the reception terminals 200A and 200B.

  Here, the configuration management unit 110 of the transmission terminal 100, for example, creates a reception terminal table that includes information on reception terminals whose packet loss occurrence frequency does not exceed the threshold and the number of connections of other reception terminals does not exceed the threshold. Generate. In this embodiment, it is assumed that the receiving terminal table includes information on receiving terminals 200A and 200B.

  The data processing function units 223A and 223B of the receiving terminals 200A and 200B have a predetermined number for acquiring missing packet data based on the receiving terminal table received from the transmitting terminal 100 by the configuration management units 210A and 210B. Are registered in advance. In this embodiment, the data processing function unit 223A of the receiving terminal 200A registers the receiving terminal 200B, and the data processing function unit 223B of the receiving terminal 200B registers the receiving terminal 200A.

  FIG. 2 shows a configuration example of the transmission terminal 100. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate. The transmission terminal 100 includes an encoder 130 in addition to the configuration management unit 110 and the transmission processing unit 120 described above. The encoder 130 encodes the transmission video data and supplies it to the transmission processing unit 120. The transmission processing unit 120 packetizes the encoded video data and sequentially transmits the packet data of the video data. In this case, the transmission processing unit 120 performs transmission using, for example, RTP (Real-time Transport Protocol).

  FIG. 3 shows a configuration example of the receiving terminal 200 (200A, 200B). 3, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate. As described above, the data processing function unit 223 registers in advance a predetermined number of other receiving terminals for acquiring the missing packet data, and stores them in a primary buffer (packet data storage buffer) in the other receiving terminals. Can be accessed through the network.

  The sequence diagram of FIG. 4 shows a sequence when the transmitting terminal 100 generates a receiving terminal table and the receiving terminal registers another receiving terminal for acquiring the missing packet data based on the receiving terminal table. Yes. In this example, two receiving terminals 200A and 200B exist as receiving terminals, and other receiving terminals are registered with each other as an example.

  (1) The configuration management unit 110 of the transmission terminal 100 requests the reception terminal information from the configuration management units 210A and 210B of the reception terminals 200A and 200B. (2) As a response to this request, the configuration management units 210A and 210B of the receiving terminals 200A and 200B send the receiving terminal information to the configuration management unit 110 of the transmitting terminal 100. As described above, the receiving terminal information includes packet loss frequency information, other receiving terminal connection number information, and the like in addition to connection information for enabling access from other receiving terminals. Here, the connection information is information such as an IP address and a port number.

  (3) Based on the receiving terminal information acquired from the receiving terminals 200A and 200B, the configuration management unit 110 of the transmitting terminal 100 creates a receiving terminal table including information on receiving terminals that are candidates for acquiring missing packet data. Generate (update). Here, it is assumed that information of the receiving terminals 200A and 200B is included in this receiving terminal table. (4) The configuration management unit 110 of the transmission terminal 100 sends this reception terminal table to the configuration management unit 210A of the reception terminal 200A.

  (5) The configuration management unit 210A of the receiving terminal 200A updates its own receiving terminal table to the receiving terminal table sent from the configuration management unit 110 of the transmitting terminal 100. (6) Then, the configuration management unit 210A of the receiving terminal 200A sends a primary buffer release request to the configuration management unit 210B of the receiving terminal 200B based on this receiving terminal table. (7) When the primary buffer can be released in response to this request, the configuration management unit 210B of the receiving terminal 200B sends a permission response to the configuration management unit 210A of the receiving terminal 200A.

  (8) Thereafter, the configuration management unit 210A of the receiving terminal 200A sends a primary buffer connection request with connection information such as an IP address and a port number to the configuration management unit 210B of the receiving terminal 200B. (9) In response to this request, the configuration management unit 210B of the receiving terminal 200B sends a success response to the configuration management unit 210A of the receiving terminal 200A when the connection is possible.

  (10) When receiving the success response from the configuration management unit 210B of the reception terminal 200B, the configuration management unit 210A of the reception terminal 200A registers the reception terminal 200B as another reception terminal for acquiring the missing packet data. . That is, the configuration management unit 210A of the receiving terminal 200A registers the primary buffer of the receiving terminal 200B as a remote primary buffer in the data processing function unit 223A.

  (11) The configuration management unit 110 of the transmission terminal 100 also sends the reception terminal table to the configuration management unit 210B of the reception terminal 200B. The following operation of the configuration management unit 210B of the receiving terminal 200B is the same as that of the configuration management unit 210A of the receiving terminal 200A. Finally, the configuration management unit 210B of the receiving terminal 200B Register as another receiving terminal to get data. That is, the configuration management unit 210B of the receiving terminal 200B registers the primary buffer of the receiving terminal 200A as a remote primary buffer in the data processing function unit 223B.

  The flowchart in FIG. 5 illustrates an example of a reception terminal table generation (update) process periodically performed in the configuration management unit 110 of the transmission terminal 100. In step ST1, the configuration management unit 110 acquires receiving terminal information. At this time, the configuration management unit 110 of the transmission terminal 100 sends a reception terminal information request to the configuration management unit of the reception terminals (the reception terminals 200A and 200B in this embodiment) constituting the video transmission / reception system 10, Receiving terminal information is received as a response.

  Next, the configuration management unit 110 of the transmission terminal 100 determines the packet loss occurrence frequency in step ST2. That is, the configuration management unit 110 of the transmission terminal 100 determines, for each reception terminal, whether or not the packet loss occurrence frequency exceeds the threshold based on the packet loss frequency information included in the reception terminal information. For the receiving terminal whose packet occurrence frequency exceeds the threshold value, the configuration management unit 110 of the transmitting terminal 100 deletes the data of the receiving terminal from the receiving terminal table in step ST3. Note that when there is no data of the receiving terminal in the receiving terminal table, the data deleting process is not necessary.

  On the other hand, for the receiving terminal whose packet occurrence frequency does not exceed the threshold, the configuration management unit 110 of the transmitting terminal 100 moves to the process of step ST4. In step ST4, the configuration management unit 110 of the transmission terminal 100 determines whether or not the number of connections exceeds the threshold based on the information on the number of other reception terminal connections included in the reception terminal information. For the receiving terminal whose number of connections exceeds the threshold, the configuration management unit 110 of the transmitting terminal 100 deletes the data of the receiving terminal from the receiving terminal table in step ST3. Note that when there is no data of the receiving terminal in the receiving terminal table, the data deleting process is not necessary.

  On the other hand, for a receiving terminal whose number of connections does not exceed the threshold value, the configuration management unit 110 of the transmitting terminal 100 registers information on the receiving terminal in the receiving terminal table in step ST5. Note that when the data of the receiving terminal already exists in the receiving terminal table, the data registration process is unnecessary.

  In the configuration management unit 110 of the transmission terminal 100, the reception terminal table generation (update) process as described above is performed. As a result, in the receiving terminal, since it is possible to acquire the missing packet data, it is possible to register the receiving terminal having a high probability of acquiring the packet data as another receiving terminal and having a relatively low load. Acquisition will be performed more smoothly.

  An example of the operation of the video transmission / reception system 10 shown in FIG. 1 will be described. First, an example of operation when no packet loss occurs in both the receiving terminals 200A and 200B will be described using the sequence diagram of FIG.

  The operation of the receiving terminal 200A will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the reception terminal 200A. In the receiving terminal 200A, packet data of a video stream (video data) sequentially transmitted from the transmitting terminal 100 is received by the reception processing unit 221A, aligned in the primary buffer 222A, and temporarily stored.

  In the receiving terminal 200A, the data processing function unit 223A sequentially reads packet data from the primary buffer 222A and writes the packet data to the secondary buffer 224A. At this time, the data processing function unit 223A checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 6, no packet loss occurs in the receiving terminal 200A. Therefore, the data processing function unit 223A does not perform the operation of acquiring the missing packet data from the receiving terminal 200B. .

  Through the above-described writing process of the data processing function unit 223A, the secondary buffer 224A of the receiving terminal 200A accumulates packet data in which the video stream is continuous, that is, without missing. Then, in the receiving terminal 200A, the continuous packet data of the video stream stored in the secondary buffer 224A is sequentially read out by the decoder 225A and subjected to decoding processing to obtain received video data with no omission.

  Next, the operation of the receiving terminal 200B will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the reception terminal 200B. In the receiving terminal 200B, packet data of the video stream (video data) sequentially sent from the transmitting terminal 100 is received by the reception processing unit 221B, aligned in the primary buffer 222B, and temporarily stored.

  In the receiving terminal 200B, the packet data is sequentially read from the primary buffer 222B and written to the secondary buffer 224B by the data processing function unit 223B. At this time, the data processing function unit 223B checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 6, no packet loss occurs in the receiving terminal 200B. Therefore, the data processing function unit 223B does not perform the operation of acquiring the missing packet data from the receiving terminal 200A. .

  Through the above-described writing process of the data processing function unit 223B, the secondary buffer 224B of the receiving terminal 200B accumulates packet data in which video streams are continuous, that is, without missing. Then, in the receiving terminal 200B, the continuous packet data of the video stream stored in the secondary buffer 224B is sequentially read out by the decoder 225B and subjected to decoding processing, so that received video data with no omission is obtained.

  Next, with reference to the sequence diagram of FIG. 7, an example of operation when no packet loss occurs in the receiving terminal 200A but packet loss occurs in the receiving terminal 200B will be described. Although detailed description is omitted, the operation of the receiving terminal 200A is the same as that in the sequence diagram of FIG.

  The operation of receiving terminal 200B will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the reception terminal 200B. In the receiving terminal 200B, packet data of the video stream (video data) sequentially sent from the transmitting terminal 100 is received by the reception processing unit 221B, aligned in the primary buffer 222B, and temporarily stored.

  In the receiving terminal 200B, the packet data is sequentially read from the primary buffer 222B and written to the secondary buffer 224B by the data processing function unit 223B. At this time, the data processing function unit 223B checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 7, a packet loss occurs in the receiving terminal 200B. Therefore, the data processing function unit 223B obtains the missing packet data from the receiving terminal 200A and obtains the secondary buffer. An operation of writing to 224B is performed.

  That is, when the packet loss is confirmed, the data processing function unit 223B accesses the read request to the primary buffer (remote primary buffer) 222A of the receiving terminal 200A in order to acquire the missing packet data. As a result, the missing packet data is read. Then, the data processing function unit 223B checks whether the read packet data is certainly missing packet data, and then writes the packet data in the secondary buffer 224B.

  Through the above-described writing process of the data processing function unit 223B, the secondary buffer 224B of the receiving terminal 200B accumulates packet data in which video streams are continuous, that is, without missing. Then, in the receiving terminal 200B, the continuous packet data of the video stream stored in the secondary buffer 224B is sequentially read out by the decoder 225B and subjected to decoding processing, so that received video data with no omission is obtained.

  Next, referring to the sequence diagram of FIG. 8, when packet loss occurs in the receiving terminal 200B, the corresponding packet data cannot be read from the primary buffer 222A of the receiving terminal 200A, but read from other receiving terminals. An operation example when performing the above will be described. In the operation example of the sequence diagram of FIG. 8, it is assumed that there is a receiving terminal 200C in addition to the receiving terminals 200A and 200B.

  Furthermore, it is assumed that the receiving terminal 200B registers the receiving terminal 200C in addition to the receiving terminal 200A as a receiving terminal for acquiring the missing packet data. In the sequence diagram of FIG. 8, the primary buffer 222C is a primary buffer in the receiving terminal 200C. It is assumed that the receiving terminal 200A and the receiving terminal 200C are registered in the order of registration, but the receiving terminal 200A is the first and the receiving terminal 200C is the second.

  The operation of receiving terminal 200B will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the reception terminal 200B. In the receiving terminal 200B, packet data of the video stream (video data) sequentially sent from the transmitting terminal 100 is received by the reception processing unit 221B, aligned in the primary buffer 222B, and temporarily stored.

  In the receiving terminal 200B, the packet data is sequentially read from the primary buffer 222B and written to the secondary buffer 224B by the data processing function unit 223B. At this time, the data processing function unit 223B checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 8, a packet loss occurs in the receiving terminal 200B. Therefore, the data processing function unit 223B obtains the missing packet data from the other receiving terminals and performs secondary processing. An operation of writing to the buffer 224B is performed.

  That is, when the packet loss is confirmed, the data processing function unit 223B sends a read request to the primary buffer (remote primary buffer) 222A registered first in the receiving terminal 200A in order to acquire the missing packet data. Access is made. However, since there is no corresponding packet data in the primary buffer 222A of the receiving terminal 200A, a response with no corresponding data is sent to the data function processing unit 223B.

  In response to this response, the data processing function unit 223B accesses the read request to the primary buffer (remote primary buffer) 222C of the receiving terminal 200C registered second in order to acquire the missing packet data. . Then, the missing packet data is read from the primary buffer 222C of the receiving terminal 200C. Then, the data processing function unit 223B checks whether the read packet data is certainly missing packet data, and then writes the packet data in the secondary buffer 224B.

  Through the above-described writing process of the data processing function unit 223B, the secondary buffer 224B of the receiving terminal 200B accumulates packet data in which video streams are continuous, that is, without missing. Then, in the receiving terminal 200B, the continuous packet data of the video stream stored in the secondary buffer 224B is sequentially read out by the decoder 225B and subjected to decoding processing, so that received video data with no omission is obtained.

  As described above, in the video transmission / reception system 10 shown in FIG. 1, when there is a loss in the packet data received from the transmission terminal 100, the reception terminals 200 </ b> A and 200 </ b> B receive the deletion from other reception terminals registered in advance. Packet data is acquired. That is, the receiving terminals 200A and 200B do not receive data in parallel by a plurality of reception processing units and recover packet loss, but can recover packet loss satisfactorily without unnecessarily increasing the circuit scale.

  In the video transmission / reception system 10 shown in FIG. 1, the receiving terminals 200A and 200B have a two-stage buffer structure. That is, the receiving terminals 200A and 200B are provided with primary buffers 222A and 222B that store packet data received by the reception processing units 221A and 221B and temporarily store them. The receiving terminals 200A and 200B are provided with secondary buffers 224A and 224B for temporarily storing continuous packet data that the decoders 225A and 225B perform decoding processing.

  The data processing function units 223A and 223B sequentially read out the packet data from the primary buffer and write it into the secondary buffer. When packet data read from the primary buffers 222A and 222B is missing by the data processing function units 223A and 223B, the missing packet data is acquired from other receiving terminals and stored in the secondary buffers 224A and 224B. To be written. Therefore, in the data processing function units 223A and 223B, the lost packet data can be acquired from other receiving terminals with a margin.

  In addition, in the video transmission / reception system 10 shown in FIG. 1, the transmission terminal 100 periodically acquires reception terminal information from the reception terminal and includes information on reception terminals that are candidates for acquiring missing packet data. A receiving terminal table is generated (updated). The receiving terminal table is sent to the receiving terminal. Then, in the data processing function units 223A and 223B of the receiving terminals 200A and 200B, a predetermined number of other receiving terminals for acquiring missing packet data are registered in advance based on the receiving terminal table. Therefore, the data processing function units 223A and 223B of the receiving terminals 200A and 200B can dynamically update the registration to the optimum receiving terminal for acquiring the missing packet data, and the acquisition is performed smoothly. It becomes like this.

  In the video transmission / reception system 10 shown in FIG. 1, the reception terminal information that the transmission terminal 100 periodically acquires from the reception terminal includes packet loss occurrence frequency information and connection number information of other reception terminals. In the receiving terminal table generated (updated) by the configuration management unit 110 of the transmitting terminal 100, the receiving terminal whose packet loss occurrence frequency does not exceed the threshold and the number of connections of other receiving terminals does not exceed the threshold. Information is included. Therefore, in the receiving terminals 200A and 200B, as other receiving terminals for acquiring the missing packet data, it is possible to register a receiving terminal having a high probability of acquiring the packet data and having a relatively small load. Thereby, in the receiving terminal, acquisition of the missing packet data from other receiving terminals is performed more smoothly.

<Second Embodiment>
[Video transmission / reception system]
FIG. 9 shows an example of the configuration of a video transmission / reception system 10A as the second embodiment. This video transmission / reception system 10A is a system in which video streams (video data) are simultaneously distributed from a transmission terminal to a plurality of points via a relay terminal. 9, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

  This video transmission / reception system 10A includes a transmission terminal 100, a plurality of relay terminals, two relay terminals 300A and 300B in this embodiment, a plurality of reception terminals, and four reception terminals 200C to 200F in this embodiment. It is made up of. The transmission terminal 100 is configured similarly to the transmission apparatus 100 in the video transmission / reception system 10 shown in FIG. 1 (see FIG. 2), and includes a configuration management unit 110 and a transmission processing unit 120. The configuration management unit 110 transmits / receives management data to / from the relay terminals 300A and 300B. The transmission processing unit 120 sequentially transmits packet data of a video stream (video data) to the relay terminals 300A and 300B.

  The receiving terminals 200C to 200F are configured similarly to the receiving terminals 200A and 200B in the video transmission / reception system 10 shown in FIG. 1 (see FIG. 3). That is, the receiving terminals 200 </ b> C to 200 </ b> F have a configuration management unit 210, a reception processing unit 221, a primary buffer 222, a data processing function unit 223, a secondary buffer 224, and a decoder 225.

  The configuration management unit 210 transmits / receives management data to / from the relay terminal 300 (300A, 300B). The reception processing unit 221 receives video stream packet data sequentially transmitted from the relay terminal 300 (300A, 300B). The primary buffer 222 arranges and temporarily stores the packet data received by the reception processing unit 221. The secondary buffer 224 temporarily accumulates continuous packet data that is decoded by the decoder 225. The decoder 225 decodes the continuous packet data of the video stream stored in the secondary buffer 224 to obtain received video data.

  When the packet data received by the reception processing unit 221 is missing, that is, when there is a packet loss, the data processing function unit 223 acquires the missing packet data from another receiving terminal. That is, the data processing function unit 223 reads the packet data from the primary buffer 222 and sequentially writes the packet data to the secondary buffer 224. At this time, the data processing function unit 223 checks whether or not there is any missing packet data.

  Then, when the packet data is missing, the data processing function unit 223 acquires the packet data from the other receiving terminal 200 and writes it in the secondary buffer 224. As a result, packet data having a continuous video stream, that is, no missing packet data is accumulated in the secondary buffer 224. When acquiring packet data from another receiving terminal, the data processing function unit 223 accesses a packet data storage buffer (primary buffer) in the other receiving terminal via the network.

  As shown in FIG. 10, the relay terminal 300 (300A, 300B) includes a configuration management unit 310, a reception processing unit 321, a primary buffer 322, a data processing function unit 323, a secondary buffer 324, and a transmission processing unit. 325. The reception processing unit 321 constitutes a packet data reception unit, the data processing function unit 323 constitutes a packet data acquisition unit, and the transmission processing unit 325 constitutes a packet data transmission unit.

  The configuration management unit 310 transmits and receives management data to and from the transmitting terminal 100 that is a higher-level terminal and the receiving terminal that is a lower-level terminal. The reception processing unit 321 receives video stream packet data sequentially transmitted from the transmission terminal 100. The primary buffer 322 arranges and temporarily stores the packet data received by the reception processing unit 321. The secondary buffer 324 temporarily accumulates continuous packet data that the transmission processing unit 325 sequentially transmits. The transmission processing unit 325 transmits the continuous packet data of the video stream stored in the secondary buffer 324 to the receiving terminal.

  When the packet data received by the reception processing unit 321 is missing, that is, when there is a packet loss, the data processing function unit 323 acquires the missing packet data from another relay terminal. That is, the data processing function unit 323 reads the packet data from the primary buffer 322 and sequentially writes the packet data to the secondary buffer 324. At this time, the data processing function unit 323 checks whether the packet data is missing.

  When the packet data is missing, the data processing function unit 323 acquires the packet data from the other relay terminal 200 and writes it in the secondary buffer 324. As a result, packet data having continuous video streams, that is, no missing packet data is accumulated in the secondary buffer 324. When acquiring packet data from another relay terminal, the data processing function unit 323 accesses a packet data storage buffer (primary buffer) in another relay terminal via the network.

  The configuration management unit 110 of the transmission terminal 100 periodically acquires relay terminal information from a plurality of relay terminals, in this embodiment, the relay terminals 300A and 300B. The relay terminal information includes connection information for enabling access to the primary buffer 322 from other relay terminals via the network, such as an IP address and a port number. The relay terminal information includes packet loss occurrence frequency information and connection number information of other relay terminals.

  Here, the configuration management unit 110 of the transmission terminal 100 periodically requests the relay terminal information from the configuration management unit 310 of the relay terminals 300A and 300B. The packet loss occurrence frequency information is information indicating the frequency of packet loss that has occurred between the previous relay terminal information request and the current relay terminal information request. The connection number information of other relay terminals is information indicating the number of accesses from other relay terminals between the previous relay terminal information request and the current relay terminal information request.

  The configuration management unit 110 of the transmission terminal 100 includes relay terminal information including information on relay terminals that are candidates for acquiring missing packet data based on the relay terminal information acquired from the configuration management unit 310 of the relay terminals 300A and 300B. Generate a table. Then, the configuration management unit 110 of the transmission terminal 100 transmits this relay terminal table to the configuration management unit 310 of the relay terminals 300A and 300B.

  Here, the configuration management unit 110 of the transmitting terminal 100, for example, creates a relay terminal table that includes information on receiving terminals whose packet loss occurrence frequency does not exceed the threshold and the number of connections of other receiving terminals does not exceed the threshold. Generate (see FIG. 5). In this embodiment, it is assumed that the relay terminal table includes information on the relay terminals 300A and 300B.

  The data processing function unit 323 of the relay terminal 300 (300A, 300B) obtains the missing packet data based on the relay terminal table received from the configuration management unit 110 of the transmission terminal 100 by the configuration management unit 310. A predetermined number of other relay terminals are registered in advance. In this embodiment, for example, the data processing function unit 323 of the relay terminal 300A registers the relay terminal 300B, and the data processing function unit 323B of the relay terminal 300B registers the relay terminal 300A.

  As described above, the transmission terminal 100 generates a relay terminal table, and the relay terminals 300A and 300B register other relay terminals for acquiring the missing packet data based on the relay terminal table. Although detailed description is omitted, the sequence at this time is the same as the relationship between the transmission terminal 100 and the reception terminals 200A and 200B shown in FIG. 1 (see the sequence diagram of FIG. 4).

  The operation of the video transmission / reception system 10A shown in FIG. 9 will be described. At the same time, packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the relay terminals 300A and 300B. Then, packet data of the video stream (video data) received from the transmission terminal 100 is further transmitted from the relay terminal 300A to the reception terminals 200C and 200D. Further, the packet data of the video stream (video data) received from the transmission terminal 100 is further transmitted from the relay terminal 300B to the reception terminals 200E and 200F.

  At this time, the relay terminals 300 </ b> A and 300 </ b> B check whether packet loss has occurred when receiving packet data from the transmission terminal 100. Then, when there is a packet loss, the relay terminals 300A and 300B perform an operation for recovering the packet loss in the same manner as the reception terminals 200A and 200B in the video transmission / reception system 10 shown in FIG.

  Here, using the sequence diagram of FIG. 11, an operation example in the case where no packet loss occurs in the relay terminal 300A but a packet loss occurs in the relay terminal 300B will be described. In the sequence diagram of FIG. 11, a primary buffer 322A, a data processing function unit 323A, a secondary buffer 324A, and a transmission processing unit 325A are respectively a primary buffer, a data processing function unit, a secondary buffer, and a transmission processing unit in the relay terminal 300A. Is shown. In the sequence diagram of FIG. 11, the primary buffer 322B, the data processing function unit 323B, the secondary buffer 324B, and the transmission processing unit 325B are respectively a primary buffer, a data processing function unit, a secondary buffer, and a transmission in the relay terminal 300B. A processing unit is shown.

  The operation of relay terminal 300A will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the relay terminal 300A. In the relay terminal 300A, packet data of a video stream (video data) sequentially sent from the transmission terminal 100 is received by the reception processing unit 321A, aligned in the primary buffer 322A, and temporarily stored.

  In relay terminal 300A, packet data is sequentially read from primary buffer 322A and written to secondary buffer 324A by data processing function unit 323A. At this time, the data processing function unit 323A checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 11, no packet loss occurs in the relay terminal 300A. Therefore, the data processing function unit 323A does not perform the operation of acquiring the missing packet data from the relay terminal 300B. .

  Through the above-described writing process of the data processing function unit 323A, packet data having a continuous video stream, that is, no missing data is accumulated in the secondary buffer 324A of the relay terminal 300A. In the receiving terminal 300A, the continuous packet data of the video stream stored in the secondary buffer 324A is sequentially read out by the transmission processing unit 325A and transmitted to the receiving terminals 200C and 200D.

  The operation of relay terminal 300B will be described. Packet data of a video stream (video data) is sequentially transmitted from the transmission terminal 100 to the relay terminal 300B. In the relay terminal 300B, the packet data of the video stream (video data) sequentially sent from the transmission terminal 100 is received by the reception processing unit 321B, aligned in the primary buffer 322B, and temporarily accumulated.

  In the relay terminal 300B, the packet data is sequentially read from the primary buffer 322B and written to the secondary buffer 324B by the data processing function unit 323B. At this time, the data processing function unit 323B checks whether or not there is a packet loss in the received packet data. As described above, in the operation example of the sequence diagram of FIG. 11, a packet loss occurs in the relay terminal 300B. Therefore, the data processing function unit 323B obtains the missing packet data from the relay terminal 300A and obtains the secondary buffer. An operation of writing to 324B is performed.

  That is, when the packet loss is confirmed, the data processing function unit 323B accesses the read request to the primary buffer (remote primary buffer) 322A of the relay terminal 300A in order to acquire the missing packet data. As a result, the missing packet data is read. Then, the data processing function unit 323B checks whether the read packet data is certainly missing packet data, and then writes the packet data in the secondary buffer 324B.

  Through the above-described writing process of the data processing function unit 323B, packet data having a continuous video stream, that is, no missing data is accumulated in the secondary buffer 324B of the relay terminal 300B. In the relay terminal 300B, the continuous packet data of the video stream stored in the secondary buffer 324B is sequentially read out by the transmission processing unit 325B and transmitted to the receiving terminals 200E and 200F.

  As described above, in the video transmission / reception system 10A shown in FIG. 9, when the relay terminals 300A and 300B are missing in the packet data received from the transmission terminal 100, they are dropped from other relay terminals registered in advance. Packet data is acquired. That is, the relay terminals 300A and 300B do not receive data in parallel by a plurality of reception processing units and recover packet loss, but can recover packet loss satisfactorily without unnecessarily increasing the circuit scale. Further, since the packet loss can be recovered at the stage of the relay terminals 300A and 300B before reaching the receiving terminals 200C to 200F, it is possible to improve the data distribution quality such as video.

<3. Modification>
In the above embodiment, in the receiving terminal 200 or the relay terminal 300, the data processing function units 223 and 323 sequentially read packet data from the primary buffer and write them in the secondary buffers 224 and 324. At this time, when detecting packet loss, the data processing units 223 and 323 acquire packet data missing from other terminals and write the data to the secondary buffers 224 and 324. As a result, continuous packet data is stored in the secondary buffers 224 and 324 without any loss of the video stream (video data).

  As described above, when the data processing units 223 and 323 acquire the missing packet data from other terminals, the packet data is read from the primary buffers (remote primary buffers) 222 and 223 of the other terminals. For this reason, when the target packet data does not exist in the primary buffers 222 and 223 of the other terminals, it is not possible to acquire the missing packet data from the other terminals.

  In this case, there is a possibility that the other terminal acquires packet data missing from another terminal. However, even in that case, as described above, the packet data read from the primary buffers 222 and 223 of the other terminals is only written to the secondary buffers 224 and 324, and the packets lost by the other terminals are lost. It cannot be used when acquiring data.

  Therefore, as shown in FIG. 12, when the receiving terminal 200 or the relay terminal 300 acquires the missing packet data from the other terminals, the remote access primary buffer 226 for temporarily storing the packet data. 326 may be provided. In this case, the other terminal first accesses the reception primary buffers 222 and 322 in order to obtain the missing packet data. When the target packet data does not exist at that time, the remote access primary buffer 226 is further provided. , 326 is accessed. As a result, the packet data already acquired from the other terminal at the receiving terminal 200 or the relay terminal 300 can be effectively used by the other terminal.

  The operation in the configuration of FIG. 12 will be briefly described. (1) The packet data of the received video stream (video data) is aligned and temporarily stored in the receiving primary buffers 222 and 322. (2) The data processing function units 223 and 323 sequentially read the packet data from the reception primary buffers 222 and 322, and (3) write them to the secondary buffers 224 and 324 (not shown in FIG. 12).

  (2 ′) At this time, the data processing function units 223 and 323 check whether or not the received packet data has a packet loss. When the packet loss occurs, the lost packet data is transferred to the remote primary buffer of another terminal. 222, 322. The packet data is written into the secondary buffers 224 and 324. (3 ′) Further, the data processing function units 223 and 323 write the packet data into the remote access primary buffers 226 and 326 to perform primary data storage.

  As the configuration of FIG. 12, the receiving terminal 200 or the relay terminal 300 includes the remote access primary buffers 226 and 326, so that when packet data missing from other terminals is acquired, the packet data is temporarily stored. Can accumulate. As a result, the packet data already acquired from the other terminal at the receiving terminal 200 or the relay terminal 300 can be effectively used by the other terminal.

  Further, in the above-described embodiment, the number of receiving terminals and relay terminals is an example, and is not limited to the number of embodiments. Further, in the video transmission / reception system 10A shown in FIG. 9, only one relay terminal is inserted between the transmission terminal and the reception terminal. However, for example, when the relay terminal has a configuration of two or more stages. , This technology can be applied as well,

  In the above embodiment, the packet data of the video stream (video data) is sequentially transmitted from the transmission terminal. However, the data transmitted from the transmission terminal is not limited to the video data. For example, as data distributed from the transmission terminal, other data such as voice data, text data, and a program can be considered.

  Further, in the above-described embodiment, it has been described that the secondary buffer and the decoder are separately provided in the receiving terminal, and the secondary buffer and the transmission processing unit are separately provided in the relay terminal. . However, the secondary buffers may be included in the decoder and the transmission processing unit, respectively.

  The present technology can be applied to a video transmission / reception system that simultaneously distributes data from a transmission terminal to a plurality of points.

DESCRIPTION OF SYMBOLS 10,10A ... Video transmission / reception system 100 ... Transmission terminal 110 ... Configuration management part 120 ... Transmission processing part 130 ... Encoder 200, 200A-200F ... Reception terminal 210A, 210B ... Configuration management unit 221A, 221B ... reception processing unit 222A, 222B ... primary buffer 223A, 223B ... data processing function unit 224A, 224B ... secondary buffer 225A, 225B ... decoder 300, 300A, 300B ... Relay terminal 310 ... Configuration management unit 321 ... Reception processing unit 322 ... Primary buffer 323 ... Data processing function unit 324 ... Secondary buffer 325 ... Transmission processing unit

Claims (13)

A packet data receiving unit for receiving packet data sequentially sent from the transmitting terminal;
A packet data obtaining unit that obtains the missing packet data from another receiving terminal when the packet data received by the packet data receiving unit is missing;
A receiving terminal comprising: the packet data receiving unit, or a decoding processing unit that performs decoding processing on continuous packet data obtained by the packet data receiving unit and the packet data obtaining unit to obtain received data. A primary buffer for aligning and temporarily storing packet data received by the packet data receiver;
A secondary buffer for temporarily storing continuous packet data for which the decoding processing unit performs decoding processing;
The packet data acquisition unit
The packet data is sequentially read from the primary buffer and written to the secondary buffer, and when the packet data read from the primary buffer is missing, the missing packet data is obtained from another receiving terminal to obtain the secondary data. The receiving terminal according to claim 1, wherein the receiving terminal writes in a buffer. The receiving terminal according to claim 2, further comprising a remote access buffer for temporarily storing packet data acquired by the packet data acquiring unit from the other receiving terminal. The packet data acquisition unit
The receiving terminal according to claim 1, wherein a predetermined number of the other receiving terminals for acquiring the missing packet data are registered in advance based on a receiving terminal table periodically supplied from the transmitting terminal. The packet data acquisition unit
The receiving terminal according to claim 1, wherein when acquiring the missing packet data from the other receiving terminal, the packet data storage buffer in the other receiving terminal is accessed. A packet data receiving step for receiving packet data sequentially sent from the transmitting terminal;
When there is a missing packet data received in the packet data receiving step, a packet data obtaining step for obtaining the missing packet data from another receiving terminal;
A packet data receiving method comprising: the packet data receiving step, or a decoding processing step of performing decoding processing on the continuous packet data obtained in the packet data receiving step and the packet data acquisition step to obtain received data. A packet data transmitter that transmits packet data to a plurality of receiving terminals simultaneously;
Receiving terminal information is periodically obtained from the plurality of receiving terminals, and a receiving terminal table including information on receiving terminals that are candidates for obtaining missing packet data is generated based on the obtained receiving terminal information. And a configuration management unit that supplies the information of the generated reception terminal table to the plurality of reception terminals. The receiving terminal information acquired from the plurality of receiving terminals includes packet loss occurrence frequency information and connection number information of other receiving terminals,
The said structure management part produces | generates the said receiving terminal table containing the information of the receiving terminal whose packet loss occurrence frequency does not exceed the threshold value, and the number of connections of other receiving terminals does not exceed the threshold value. Sending terminal. A transmission / reception system comprising a transmitting terminal and a plurality of receiving terminals,
The sending terminal
A packet data transmission unit for simultaneously transmitting packet data to the plurality of receiving terminals,
The receiving terminal is
A packet data receiving unit for receiving packet data sequentially sent from the transmitting terminal;
A packet data obtaining unit that obtains the missing packet data from another receiving terminal when the packet data received by the packet data receiving unit is missing;
A transmission / reception system comprising: the packet data receiving unit, or a decoding processing unit that performs decoding processing on continuous packet data obtained by the packet data receiving unit and the packet data acquiring unit to obtain received data. The sending terminal
Receiving terminal information is periodically obtained from the plurality of receiving terminals, and a receiving terminal table including information on receiving terminals that are candidates for obtaining missing packet data is generated based on the obtained receiving terminal information. And a configuration management unit that supplies the generated reception terminal table information to the plurality of reception terminals,
The packet data acquisition unit of the receiving terminal previously stores a predetermined number of the other receiving terminals for acquiring the missing packet data based on a receiving terminal table periodically supplied from the transmitting terminal. The transmission / reception system according to claim 9 to be registered. A packet data receiving unit for receiving packet data sequentially sent from the host terminal;
A packet data acquisition unit that acquires the missing packet data from another relay terminal when the packet data received by the packet data reception unit is missing;
A relay terminal comprising: the packet data receiving unit, or a packet data transmitting unit that sequentially transmits continuous packet data obtained by the packet data receiving unit and the packet data acquiring unit to a lower terminal. A primary buffer for aligning and temporarily storing packet data received by the packet data receiver;
A secondary buffer that temporarily accumulates continuous packet data that the packet data transmitter sequentially transmits, and
The packet data acquisition unit
The packet data is sequentially read from the primary buffer and written to the secondary buffer, and when the packet data read from the primary buffer is missing, the missing packet data is obtained from another relay terminal to obtain the secondary data. The relay terminal according to claim 11, wherein the relay terminal writes in a buffer. A packet data receiving step for receiving packet data sequentially sent from the host terminal;
A packet data acquisition step of acquiring the missing packet data from another relay terminal when the packet data received in the packet data reception step is missing;
A packet data relay method comprising: the packet data receiving step, or a packet data transmitting step of sequentially transmitting the continuous packet data obtained in the packet data receiving step and the packet data acquiring step to a lower terminal.

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