JP2008085500A - Receiver, transmitter and synchronization control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the occurrence of a situation where each receiver cannot synchronize, when reproducing sound information and video information by not adjusting the internal reference clock, based on clock information included in an IP packet, containing sound information and the video information, when the IP packet is retransmitted. <P>SOLUTION: Receivers 30A to 30C for synchronizing with a transmitter 10 by adjusting the internal reference clock, on the basis of the clock information contained in the packet transmitted from the transmitter 10 do not adjust the internal reference clock, on the basis of the clock information contained in a received packet, when the packet is a retransmitted packet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a receiver that synchronizes with a transmitter by adjusting an internal reference clock based on clock information included in a packet transmitted from the transmitter.

  The present invention also provides a transmission for transmitting a packet including content information necessary for receiving the audio information, the video information, and the clock information together with the audio information, the video information, and the clock information to the receiver. Related to the machine.

  Furthermore, the present invention relates to a synchronization control method for synchronizing between the above transmitter and the above receiver.

  Conventionally, an audio / video information output device (transmitter) is identical to a video playback device and an audio playback device (receiver) connected by wire via an IP network, including audio information and video information, respectively. A method for distributing the IP packet is known.

  However, in the distribution method using such wired connection, since each device is connected by wire, the installation method and installation location of each device are limited, and wiring is complicated.

  Therefore, in order to increase the degree of freedom of the arrangement method and location of each device, the video and audio playback devices (reception devices) that are connected wirelessly via the IP network from the audio / video information output device (transmitter). A method of delivering the same IP packet including audio information and video information to each device.

  In such a distribution method using a wireless connection, a first distribution method that distributes the IP packet by multicast communication or unicast communication using UDP, and a unicast communication (Peer to Peer communication) using TCP. A second distribution method for distributing such IP packets is assumed.

  In such an IP packet distribution method using a wireless connection, an IP packet is lost because the transmission path between the transmitter and the receiver is unstable compared to an IP packet distribution method using a wired connection. Since it is highly possible, some measures need to be taken.

  In this regard, since the first distribution method does not have a QoS (Quality of Service) control mechanism, even when a distribution error occurs in an IP packet including audio information and video information, There has been a problem in that such IP packets cannot be retransmitted, which affects the reproduction quality of audio information and video information in the receiver.

  In order to solve such a problem, a method of adding FEC data to an IP packet including audio information and video information can be considered. However, such FEC data becomes redundant data, and traffic in the IP network increases. There was a problem.

  In contrast, the second delivery method has a QoS control mechanism, so that when a delivery error occurs in an IP packet including audio information and video information, the transmitter retransmits the IP packet. Therefore, it is possible to solve the problem of the influence on the reproduction quality of audio information and video information in the above-described receiver.

In such an IP network, the receiver is configured to synchronize with the transmitter by adjusting the internal reference clock based on the clock information included in the IP packet transmitted from the transmitter. Yes.
JP 2002-369163 A

  However, in the second delivery method described above, when the IP packet including the audio information and the video information is retransmitted, the internal reference clock is set between the receiver to which the IP packet is retransmitted and the other receiver. There is a problem that the receivers cannot synchronize when performing the reproduction process of the audio information and the video information due to the deviation.

  Further, as described above, the IP packet includes audio information and video information. However, depending on the receiver (for example, in an audio playback device such as a speaker or a video playback device such as a display) ), Not all of the information is needed.

  However, since the transmitter is configured to transmit the same IP packet including audio information and video information to each receiver, there is a problem that traffic in the IP network increases. there were.

  Therefore, the present invention has been made in view of the above points, and an object thereof is to synchronize a plurality of receivers by synchronizing between a transmitter and a receiver.

  In addition, the present invention does not adjust the internal reference clock based on the clock information included in the IP packet when the IP packet including the audio information and the video information is retransmitted. It is an object of the present invention to solve the problem that synchronization cannot be achieved in each receiver when performing information reproduction processing.

  Another object of the present invention is to prevent an increase in traffic in an IP network by transmitting only content information required by each receiver.

  A first feature of the present invention is a receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information included in a packet transmitted from the transmitter. When the packet is a retransmitted packet, the gist is that the internal reference clock is not adjusted based on clock information included in the packet.

  Here, the clock information is information serving as a reference for synchronization between the transmitter and the receiver. The internal reference clock is a reference clock (so-called system clock) inside the receiver.

  According to such an invention, each receiver is not based on the clock information included in the retransmitted packet, but based on the clock information included in the packet that is normally received without being reproduced, Because the internal reference clock is adjusted, the internal reference clock is shifted between the receiver to which the packet has been retransmitted and the other receivers. It is possible to avoid the situation that the machine cannot synchronize.

  In the first feature of the present invention, the packet may include either one of audio information or video information and the clock information.

  According to this invention, in a receiver that does not require both audio information and video information, only necessary content information can be received, and an increase in traffic can be prevented.

  A second feature of the present invention is a receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information included in a packet transmitted from the transmitter, wherein the clock The gist is that the packet including information is transmitted by multicast communication separately from the packet including audio information or video information.

  According to this invention, each receiver includes audio information or video information in order to adjust the internal reference clock based on clock information transmitted by multicast communication, separately from packets including audio information or video information. Even when the packet is retransmitted, a difference occurs in the internal reference clock between the receiver to which the packet is retransmitted and the other receiver, and when performing reproduction processing of audio information and video information, It is possible to avoid a situation in which synchronization cannot be achieved in each receiver.

  The third feature of the present invention is necessary for receiving the first content information, the second content information, and the clock information together with the first content information, the second content information, and the clock information. A transmitter for transmitting a packet including first content configuration information to a receiver for receiving the first content configuration information, the first content information, and the first clock information. A content configuration information changing unit that changes to second content configuration information that is necessary and necessary to receive the second content information and the second clock information, the first content information, and the first content information A first packet including the first clock information and the second content configuration information is transmitted to the first receiver, and the second content information and the second content information are transmitted to the first receiver. And gist to a transmitting processing unit to transmit the second packet containing the lock information and the second content configuration information to the second receiver.

  According to this invention, the transmitter can only receive necessary content information for a receiver that does not require both the first content information (for example, video information) and the second content information (for example, audio information). Can be transmitted, and an increase in traffic can be prevented.

  According to a fourth aspect of the present invention, there is provided a synchronization control method for synchronizing between a transmitter and a receiver, wherein the transmitter includes first content information and first clock information. Transmitting a packet to the first receiver and transmitting a second packet including second content information and second clock information to the second receiver; and the first reception. A step of synchronizing with the transmitter by adjusting an internal reference clock based on the first clock information included in the first packet transmitted from the transmitter; A second receiver synchronizes with the transmitter by adjusting an internal reference clock based on the second clock information included in the second packet transmitted from the transmitter; And the first receiver is a receiver. If the first packet is a retransmitted packet, the second receiver does not adjust the internal reference clock based on the first clock information included in the first packet, and the second receiver When the received second packet is a retransmitted packet, the gist is that the internal reference clock is not adjusted based on the second clock information included in the second packet.

  According to this invention, the first receiver and the second receiver are not based on the clock information included in the retransmitted packet, but are included in the packet normally received without being retransmitted. Since the internal reference clock is adjusted based on the clock information being received, the internal reference clock is shifted between the receiver to which the packet has been retransmitted and other receivers, and the audio information and video information are reproduced. When processing is performed, it is possible to avoid a situation in which synchronization cannot be achieved in each receiver.

  Further, according to this invention, the transmitter needs necessary content for a receiver that does not require both the first content information (for example, video information) and the second content information (for example, audio information). Only information can be transmitted, and an increase in traffic can be prevented.

  According to a fifth aspect of the present invention, there is provided a synchronization control method for synchronizing between a transmitter and a receiver, wherein the transmitter receives a first packet including first content information information for a first time. Transmitting the second packet including the second content information to the second receiver, and the transmitter transmits the third packet including the clock information to the multicast communication. And the first receiver and the second receiver adjust an internal reference clock based on the clock information included in the third packet transmitted from the transmitter. And a step of synchronizing with the transmitter.

  According to this invention, each receiver receives clock information transmitted by multicast communication separately from a packet including first content information (for example, video information) or second content information (for example, audio information). In order to adjust the internal reference clock based on this, even if a packet including the first content information (for example, video information) or the second content information (for example, audio information) is retransmitted, The internal reference clock is shifted between the retransmitted receiver and the other receivers, and the reproduction process of the first content information (for example, video information) and the second content information (for example, audio information) is performed. When performing, it can avoid that the situation where it cannot synchronize in each receiver occurs.

  Further, according to this invention, the transmitter needs necessary content for a receiver that does not require both the first content information (for example, video information) and the second content information (for example, audio information). Only information can be transmitted, and an increase in traffic can be prevented.

  A sixth feature of the present invention is a receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information included in a packet transmitted from the transmitter, wherein the transmission A reception processing unit for extracting clock information included in a packet transmitted from a machine, and the packet received by the reception processing unit is determined to be a packet retransmitted by the transmitter; And a clock management unit configured not to adjust the internal reference clock based on the clock information extracted by the reception processing unit.

  According to such an invention, each receiver is not based on the clock information included in the retransmitted packet, but based on the clock information included in the packet that is normally received without being reproduced, Because the internal reference clock is adjusted, the internal reference clock is shifted between the receiver to which the packet has been retransmitted and the other receivers. It is possible to avoid the situation that the machine cannot synchronize.

  As described above, according to the present invention, synchronization between a plurality of receivers can be achieved by synchronization between the transmitter 10 and the receiver 30.

  According to the present invention, when an IP packet including audio information and video information is retransmitted, the audio information is not adjusted by adjusting the internal reference clock based on the clock information included in the IP packet. In addition, when performing video information reproduction processing, it is possible to avoid a situation in which synchronization cannot be achieved in each receiver.

  Further, according to the present invention, it is possible to prevent an increase in traffic in the IP network by transmitting only content information required by each receiver.

(Configuration of distribution system according to the first embodiment of the present invention)
With reference to FIG. 1 thru | or FIG. 5, the structure of the delivery system which comprises the transmitter 10 and the receiver 30 which concern on the 1st Embodiment of this invention is demonstrated.

  In the distribution system according to the present embodiment, as illustrated in FIG. 1, the transmitter 10 transmits either audio information or video information and clock information via a wireless IP network, which is a subnetwork, by unicast communication. An IP packet including (PCR: Program Clock Reference) is distributed to each of the receivers 30A to 30C.

  In the example of FIG. 1, the transmitter 10 transmits an IP packet including audio information and PCR # 2 to the receiver 30B that is the speaker # 1 and the receiver 30C that is the speaker # 2, and the video information and An IP packet including PCR # 1 is transmitted to the receiver 30A which is a display.

  PCR # 1 and PCR # 2 are clock information used by each of the receivers 30A to 30C to synchronize with the transmitter 10 by adjusting the internal reference clock.

  Here, it is assumed that the values counted by the internal reference clock in the transmitter are inserted into PCR # 1 and PCR # 2. For example, in PCR # 1 and PCR # 2, a 42-bit value STC (System Time Clock) counted by a 27 MHz clock in the transmitter is inserted.

  Further, the transmitter 10 includes first content configuration information (PSI: Program Specific Information) necessary for receiving the audio information, the video information, and the clock information together with the audio information, the video information, and the PCR (clock information). ) Is transmitted to each of the receivers 30A to 30C.

  As illustrated in FIG. 2, the transmitter 10 includes a storage unit 11, a separation processing unit 12, a PSI update unit 13, a PCR generation unit 14, a transmission processing unit 15, a buffer 16, and a retransmission request reception unit 17. It is equipped with.

  The storage unit 11 is configured to store a packet including audio information, video information, and data information, for example, a TS packet defined by MPEG-2 TS (Transport Stream).

  Specifically, in MPEG-2 TS, an ES (Elementary Stream) composed of encoded audio information, video information, and data information is packetized and divided into PES (Packetized Elementary Stream). The PES is configured to be inserted into the payload of the TS packet.

  The PES is provided with a PES header. In the PES header, the PTS (Presentation Time Stamp) for specifying the display or playback time of the audio information and video information described above, and the audio information and video information described above are specified. DTS (Decoding Time Stamp) for designating the decoding time is described.

  In addition, a PSI (first content configuration information) having the structure shown in FIG. 3A is inserted as a section in the payload of the TS packet.

  In the PSI having the structure shown in FIG. 3A, a PAT (Program Association Table) describes “PID (packet identifier) = N” of a TS packet in which a PMT (Program Mapped Table) is inserted.

  In this PSI, the PMT inserted in the TS packet of “PID = N” is “PID = VN” of the TS packet in which the video information is inserted and “TSD” of the TS packet in which the audio information is inserted. PID = AN ”and“ PID = CN ”of the TS packet in which the PCR is inserted are described.

  The separation processing unit 12 refers to the PSI (that is, PAT or PMT) inserted in the TS packet, separates audio information, video information, and data information included in the TS packet, and performs transmission processing. It is configured to transmit to the unit 15.

  The PSI updating unit 13 converts the first content configuration information (PSI having the structure of FIG. 3A) inserted in the TS packet stored in the storage unit 11 into video information and first clock information ( The second content configuration information (FIG. 3B) necessary for receiving the PCR # 1) and necessary for receiving the audio information and the second clock information (PCR # 2). Having PSI).

  In the present embodiment, the second content configuration information is realized by one PSI having the structure shown in FIG. 3B, but the video information and the first clock information (PCR # 1) are It may be realized by a plurality of PSIs such as a PSI necessary for receiving and PSI necessary for receiving audio information and second clock information (PCR # 2).

  As shown in FIG. 3B, in the PSI after the change, the PAT describes “PID = N1” of the TS packet in which PMT # 1 is inserted, and the TS packet in which PMT # 2 is inserted. “PID = N2” is described.

  In the PSI after the change, PMT # 1 inserted in the TS packet with “PID = N1” is inserted with “PID = VN” in the TS packet with video information inserted and PCR # 1. “PID = CN1” of the TS packet being described.

  In the PSI after the change, PMT # 2 inserted in the TS packet with “PID = N2” is inserted with PCR # 2 and “PID = AN” in the TS packet with voice information inserted. “PID = CN2” of the TS packet being described.

  The PCR generation unit 14 is configured to generate clock information (PCR # 1 and PCR # 2) when an IP packet including a TS packet is transmitted by the transmission processing unit 15. For example, the PCR generation unit 14 is configured to insert an STC when an IP packet including a TS packet is transmitted by the transmission processing unit 15 into the PCR.

  The PCR generation unit 14 is configured to insert the same STC into PCR # 1 and PCR # 2.

  The transmission processing unit 15 first receives a first packet including video information, first clock information (PCR # 1), and second content configuration information (PSI having the structure of FIG. 3B). Second information including the audio information, the second clock information (PCR # 2), and the second content configuration information (PSI having the structure of FIG. 3B). The packet is configured to be transmitted to the second receiver (receivers 30B and 30C).

  Specifically, as shown in FIG. 4, the transmission processing unit 15 has an IP packet in a format in which a TCP header and an IP header are added to a TS packet in which video information and PCR # 1 are inserted, that is, An IP packet including a TS packet in which video information and PCR # 1 are inserted is configured to be transmitted to the receiver 30A.

  Here, in the IP header of the IP packet, the IP address of the receiver 30A is described as the transmission destination address, and the IP address of the transmitter 10 is described as the transmission source address. In the TCP header, a transmission source port number, a transmission destination port number, a transmission sequence number (SEQ value), and the like are described.

  Further, the transmission processing unit 15 inserts the IP packet having the TCP header and the IP header into the TS packet in which the voice information and PCR # 2 are inserted, that is, the voice information and PCR # 2 are inserted. An IP packet including a TS packet is transmitted to the receivers 30B and 30C.

  Here, in the IP header of the IP packet, the IP address of the receiver 30B or 30C is described as the transmission destination address, and the IP address of the transmitter 10 is described as the transmission source address. In the TCP header, a transmission source port number, a transmission destination port number, a transmission sequence number (SEQ value), and the like are described.

  Further, the transmission processing unit 15 is configured to temporarily store the IP packet in the buffer 16 until the transmission completion response (ACK) for the IP packet is received after the IP packet is transmitted. ing.

  The transmission processing unit 15 is configured to retransmit an IP packet when receiving a notification from the retransmission request receiving unit 17 that a retransmission request for a specific IP packet has been received.

  In such a case, the transmission processing unit 15 is configured to retransmit the IP packet without changing PCR # 1 or PCR # 2 included in the IP packet.

  The retransmission request receiving unit 17 is configured to receive retransmission requests from the receivers 30A to 30C and notify the transmission processing unit 15 to that effect.

  Further, the receiver 30 (30A to 30C) adjusts the internal reference clock based on the clock information (PCR # 1 and PCR # 2) included in the IP packet transmitted from the transmitter 10, thereby transmitting the transmitter. 10 to synchronize.

  As illustrated in FIG. 5, the receiver 30 includes a reception processing unit 31, a buffer 32, a decoding processing unit 33, a reproduction processing unit 34, a clock management unit 35, and a retransmission request transmission unit 36. Yes.

  The reception processing unit 31 is configured to perform reception processing on the IP packet transmitted from the transmitter 10 or the IP packet retransmitted from the transmitter 10.

  Specifically, the reception processing unit 31 is configured to extract the PES and store it in the buffer 32 with reference to the PSI inserted in the TS packet included in the received IP packet.

  Note that such an IP packet includes either video information or audio information and clock information (PCR # 1 or PCR # 2).

  In addition, the reception processing unit 31 extracts the PCR # 1 or the PCR # 2 by referring to the PSI inserted in the TS packet included in the IP packet normally received without being retransmitted and clocked. It is configured to transmit to the management unit 35.

  The reception processing unit 31 may be configured not to extract the PCR # 1 or PCR # 2 included in the retransmitted IP packet and transmit it to the clock management unit 35.

  Here, the reception processing unit 31 is configured to determine whether or not the received IP packet is a retransmitted IP packet based on the transmission sequence number included in the TCP header in the received IP packet. ing.

  The decoding processing unit 33 refers to the DTS in the PES header assigned to the PES accumulated in the buffer 32 and the STC (internal reference clock) managed by the clock management unit 35, and stores the PTS in the payload of the PES. Decoding processing is performed on the inserted video information or audio information.

  Specifically, when the STC managed by the clock management unit 35 becomes equal to the DTS in the PES header assigned to the specific PES, the decoding processing unit 33 performs the decoding process on the PES. It is configured as follows.

  The reproduction processing unit 34 refers to the PTS in the PES header assigned to the PES accumulated in the buffer 32 and the STC managed by the clock management unit 35, and the video inserted in the payload of the PES. Reproduction processing (display processing) is performed on information or audio information.

  Specifically, the reproduction processing unit 34 performs reproduction processing on the PES when the STC managed by the clock management unit 35 is equal to the PTS in the PES header assigned to the specific PES. It is configured as follows.

  The clock management unit 35 is configured to synchronize with the transmitter 10 by adjusting the STC based on PCR # 1 or PCR # 2 transmitted from the reception processing unit 31. As a result, synchronization between the receivers 30A to 30C is also established.

  For example, the clock management unit 35 is configured to set the STC included in the PCR # 1 or PCR # 2 transmitted from the reception processing unit 31 as the STC in the receiver.

  When the IP packet received by the reception processing unit 31 is a retransmitted packet, the clock management unit 35 performs internal processing based on the clock information (PCR # 1 or PCR # 2) included in the IP packet. The reference clock (STC) is not adjusted.

  Here, the clock management unit 35 is configured to determine whether or not the received IP packet is a retransmitted IP packet based on the transmission sequence number included in the TCP header in the received IP packet. ing.

  The retransmission request transmission unit 36 is configured to transmit a retransmission request for requesting retransmission of the IP packet to the transmitter 10 when the reception processing of the IP packet by the reception processing unit 31 fails. .

(Operation of the distribution system according to the first embodiment of the present invention)
With reference to FIG.6 and FIG.7, operation | movement of the delivery system which concerns on the 1st Embodiment of this invention is demonstrated.

  First, with reference to FIG. 6, a method for distributing IP packets between the transmitter 10 and the receiver 30 according to the present embodiment will be described.

  As shown in FIG. 6, in step S1001, the receiver 30 transmits a device search request for searching for a device existing on the wireless IP network by multicast communication using SSDP (Simple Service Discovery Protocol). .

  In step S1002, the transmitter 10 existing on the wireless IP network returns a response to the device search request to the receiver 30 by unicast communication.

  In step S1003, the receiver 30 transmits a device information acquisition request for acquiring device information of the transmitter 10 to the transmitter 10 by unicast communication. In step S1004, the transmitter 10 In response to the device information acquisition request, the device information of the transmitter 10 is returned to the receiver 30 by unicast communication.

  In step S1005, the receiver 30 transmits a service information acquisition request for acquiring the service information of the transmitter 10 to the transmitter 10 by unicast communication. In step S1006, the transmitter 10 In response to the service information acquisition request, the service information of the transmitter 10 is returned to the receiver 30 by unicast communication.

  In step S <b> 1007, the receiver 30 transmits a data request to the transmitter 10.

  In step S1008, the transmitter 10 considers the device information and service information of the receiver 30, and the first IP packet including the video information and PCR # 1 (first clock information) or the audio information. A second IP packet including PCR # 2 (second clock information) is generated, and the first IP packet or the second IP packet is transmitted to the receiver 30 in step S1009.

  In step S1010, the receiver 30 reproduces the video information or the audio information included in the received first packet or the second IP packet, and includes it in the received first packet or the second IP packet. Based on PCR # 1 or PCR # 2, the STC is adjusted to synchronize with the transmitter 10.

  Secondly, with reference to FIG. 7, the operation of adjusting the STC (internal reference clock) in the receiver 30 according to the present embodiment will be described.

  As illustrated in FIG. 7, in step S101, the reception processing unit 31 of the receiver 30 refers to the PSI inserted in the TS packet included in the received IP packet, and performs PCR # 1 or PCR # 2 To extract.

  In step S102, the reception processing unit 31 determines whether or not the received IP packet is a retransmitted IP packet based on the transmission sequence number inserted in the TCP header in the received IP packet.

  If it is not a retransmitted IP packet, this operation proceeds to step S103. If it is not a retransmitted IP packet, this operation ends.

  In step S103, the reception processing unit 31 transmits the extracted PCR # 1 or PCR # 2 to the clock management unit 35, and the clock management unit 35 adjusts the STC based on the received PCR # 1 or PCR # 2. By doing so, the transmitter 10 is synchronized.

(Operation and effect of distribution system according to the present embodiment)
According to the distribution system according to the present embodiment, each of the receivers 30A to 30C is retransmitted rather than based on the clock information (PCR # 1 or PCR # 2) included in the retransmitted IP packet. In order to adjust the internal reference clock (STC) based on the clock information (PCR # 1 or PCR # 2) included in the normally received IP packet, the receiver 30A to which the IP packet has been retransmitted And the other receivers 30B and 30C have a difference in the internal reference clock (STC), and when performing reproduction processing of audio information and video information, the receivers 30A to 30C cannot be synchronized. Can be avoided.

  Further, according to the distribution system according to the present embodiment, the transmitter 10 can transmit only necessary information to the receivers 30A to 30C that do not require both audio information and video information. In the receivers 30A to 30C that do not require both audio information and video information, only necessary information (for example, audio information or video information) can be received, and an increase in traffic can be prevented.

(Distribution system according to the second embodiment of the present invention)
Next, a distribution system according to a second embodiment of the present invention will be described with reference to FIGS. Hereinafter, the distribution system according to the present embodiment will be described mainly with respect to differences from the distribution system according to the first embodiment described above.

  As shown in FIG. 8, in the distribution system according to the present embodiment, the transmitter 10 transmits a first packet including video information (first content information) by unicast communication via a wireless IP network. So as to transmit to the first receiver (receiver 30A) and transmit the second packet including the audio information (second content information) to the second receiver (receivers 30B and 30C). It is configured.

  In the distribution system according to the present embodiment, the transmitter 10 transmits the third packet including the clock information (PCR) to the receivers 30A to 30C by multicast communication via the wireless IP network. It is configured as follows. The PSI updating unit 13 in the transmitter 10 according to the present embodiment stores the first content configuration information (PSI having the structure of FIG. 9A) inserted in the TS packet stored in the storage unit 11. Structure of second content configuration information (FIG. 9B) that is necessary for receiving video information (first content information) and that is necessary for receiving audio information (second content information) To PSI).

  In the present embodiment, the second content configuration information is realized by one PSI having the structure shown in FIG. 9B, but the PSI and audio information necessary for receiving the video information are received. It may be realized by a plurality of PSIs such as a PSI necessary for the purpose.

  As shown in FIG. 9B, in the PSI after the change, the PAT describes “PID = N1” of the TS packet in which PMT # 1 is inserted, and the TS packet in which PMT # 2 is inserted. “PID = N2” is described.

  In the PSI after the change, PMT # 1 inserted in the TS packet of “PID = N1” describes only “PID = VN” of the TS packet in which the video information is inserted.

  In the PSI after the change, PMT # 2 inserted in the TS packet of “PID = N2” describes only “PID = AN” of the TS packet in which the voice information is inserted.

  The transmission processing unit 15 transmits a first packet including video information and second content configuration information (PSI having the structure of FIG. 9B) to the first receiver (receiver 30A). The second packet including the audio information and the second content configuration information (PSI having the structure of FIG. 3B) is transmitted to the second receiver (receivers 30B and 30C). Has been.

  Specifically, as illustrated in FIG. 10A, the transmission processing unit 15 is configured to send an IP packet in a format in which a TCP header and an IP header are added to a TS packet in which video information or audio information is inserted. That is, an IP packet including a TS packet in which video information or audio information is inserted is transmitted to the receiver 30A or the receivers 30B and 30C.

  The transmission processing unit 15 is configured to generate a third packet including clock information (PCR) and transmit the third packet to the receivers 30A to 30C by multicast communication.

  Specifically, as illustrated in FIG. 10B, the transmission processing unit 15 adds a TCP header and an IP header to the TS packet in which the clock information (PCR) generated by the PCR generation unit is inserted. An IP packet having the format described above, that is, an IP packet including a TS packet in which video information or audio information is inserted, is transmitted to the receivers 30A to 30C by multicast communication.

  The PCR generation unit 14 is configured to generate clock information (PCR) when an IP packet including clock information is transmitted by the transmission processing unit 15. For example, the PCR generation unit 14 is configured to insert an STC when an IP packet including clock information is transmitted by the transmission processing unit 15 into the PCR.

  In addition, the clock management unit 35 of the receiver 30 according to the present embodiment is included in an IP packet transmitted by multicast communication, separately from an IP packet including audio information or video information transmitted by unicast communication. It is configured to synchronize with the transmitter 10 by adjusting the STC based on the clock information (PCR).

  In the transmitter 10 according to the present embodiment, the first video information may be used as the first content information, and the second video information may be used as the second content information.

  According to the distribution system according to the present embodiment, each of the receivers 30A to 30C has an internal reference clock based on clock information (PCR) transmitted by multicast communication, separately from IP packets including audio information or video information. In order to adjust (STC), even when a packet including audio information or video information is retransmitted, an internal reference is set between the receiver 30A to which the packet is retransmitted and the other receivers 30B and 30C. It is possible to avoid occurrence of a situation in which synchronization is not achieved in each of the receivers 30A to 30C when a clock (STC) shift occurs and audio information and video information are reproduced.

  Further, according to the distribution system according to the present embodiment, the transmitter 10 can transmit only necessary information to the receivers 30A to 30C that do not require both audio information and video information. In the receivers 30A to 30C that do not require both audio information and video information, only necessary information (for example, audio information or video information) can be received, and an increase in traffic can be prevented.

(Distribution system according to the third embodiment of the present invention)
Next, with reference to FIG.11 and FIG.12, the delivery system which concerns on the 3rd Embodiment of this invention is demonstrated. Hereinafter, the distribution system according to the present embodiment will be described mainly with respect to differences from the distribution system according to the first embodiment described above.

  As shown in FIG. 11, in the distribution system according to the present embodiment, the transmitter 10 transmits an IP packet including video information and PCR # 1 to the receiver 30A that is a display, and is decoded. An IP packet including information (Liner PCM # 1 and Liner PCM # 2) and PCR # 2 is configured to be transmitted to receiver 30B as speaker # 1 and receiver 30C as speaker # 2. Yes.

  The transmitter 10 according to the present embodiment includes a voice separation unit 12A in addition to the configuration of the transmitter 10 according to the first embodiment described above.

  The voice separation unit 12A is configured to perform decoding processing on the voice information output from the separation processing unit 12 and generate Liner PCM # 1 to #n.

  Note that the PSI update unit 13 may be configured to prepare the number of PMTs corresponding to each of the liner PCMs # 1 to #n in the PSI having the configuration of FIG. The PMT may be configured to describe the PID of the TS packet in which each of the Liner PCMs # 1 to #n is inserted.

  The transmission processing unit 15 generates an IP packet including each of the Liner PCMs # 1 to #n and the clock information (PCR # 2), and sends it to the receivers 30B and 30C corresponding to the Liner PCMs # 1 to #n The IP packet is transmitted. Note that, in the transmitter 10 according to the present embodiment, audio information for the first channel (for example, Liner PCM # 1) is used as the first content information, and the second channel information is used for the second channel. Audio information (eg, Liner PCM # 2) may be used.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Accordingly, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

1 is an overall configuration diagram of a distribution system including a transmitter and a receiver according to a first embodiment of the present invention. It is a functional block diagram of the transmitter which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the update method of PSI by the PSI update part of the transmitter which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the format of the IP packet produced | generated by the transmission process part of the transmitter which concerns on the 1st Embodiment of this invention. It is a functional block diagram of the receiver which concerns on the 1st Embodiment of this invention. It is a sequence diagram which shows the delivery method of the IP packet between the transmitter and receiver which concerns on the 1st Embodiment of this invention. 4 is a flowchart illustrating an operation of adjusting an internal reference clock in the receiver according to the first embodiment of the present invention. It is a whole block diagram of the delivery system which comprises the transmitter and receiver which concern on the 2nd Embodiment of this invention. It is a figure for demonstrating the update method of PSI by the PSI update part of the transmitter which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the format of the IP packet produced | generated by the transmission process part of the transmitter which concerns on the 2nd Embodiment of this invention. It is a whole block diagram of the delivery system which comprises the transmitter and receiver which concern on the 3rd Embodiment of this invention. It is a functional block diagram of the transmitter which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Transmitter 11 ... Memory | storage part 12 ... Separation processing part 12A ... Voice separation part 13 ... PSI update part 14 ... PCR generation part 15 ... Transmission processing part 16 ... Buffer 17 ... Retransmission request | requirement receiving parts 30A, 30B, 30C ... 31 ... Reception processing unit 32 ... Buffer 33 ... Decoding processing unit 34 ... Reproduction processing unit 35 ... Clock management unit 36 ... Retransmission request transmission unit

Claims (7)

A receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information contained in a packet transmitted from the transmitter,
When the received packet is a retransmitted packet, the receiver does not adjust the internal reference clock based on clock information included in the packet.   2. The receiver according to claim 1, wherein either one of audio information or video information and the clock information are included in the packet. A receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information contained in a packet transmitted from the transmitter,
The receiver including the clock information is transmitted by multicast communication separately from the packet including audio information or video information. A packet containing first content information necessary for receiving the first content information, the second content information, and the clock information together with the first content information, the second content information, and the clock information. A transmitter for transmitting to the receiver,
The first content configuration information is necessary for receiving the first content information and the first clock information, and is necessary for receiving the second content information and the second clock information. A content configuration information changing unit for changing to the second content configuration information;
A first packet including the first content information, the first clock information, and the second content configuration information is transmitted to a first receiver, and the second content information and the second content information are transmitted to the first receiver. And a transmission processing unit that transmits a second packet including the clock information and the second content configuration information to the second receiver. A synchronization control method for synchronizing between a transmitter and a receiver,
The transmitter transmits a first packet including first content information and first clock information to the first receiver, and includes a second packet including second content information and second clock information. Transmitting two packets to a second receiver;
The first receiver synchronizes with the transmitter by adjusting an internal reference clock based on the first clock information included in the first packet transmitted from the transmitter. Process,
The second receiver synchronizes with the transmitter by adjusting an internal reference clock based on the second clock information included in the second packet transmitted from the transmitter. A process,
When the received first packet is a retransmitted packet, the first receiver adjusts the internal reference clock based on the first clock information included in the first packet. Without
The second receiver does not adjust the internal reference clock based on the second clock information included in the second packet when the received second packet is a retransmitted packet. A synchronization control method characterized by the above. A synchronization control method for synchronizing between a transmitter and a receiver,
The transmitter transmits a first packet including first content information to the first receiver, and transmits a second packet including second content information to the second receiver. Process,
The transmitter transmitting a third packet including the clock information by multicast communication;
The first receiver and the second receiver adjust the internal reference clock based on the clock information included in the third packet transmitted from the transmitter; A synchronization control method comprising the steps of: A receiver that synchronizes with the transmitter by adjusting an internal reference clock based on clock information contained in a packet transmitted from the transmitter,
A reception processing unit for extracting clock information included in a packet transmitted from the transmitter;
When it is determined that the packet received by the reception processing unit is a packet retransmitted by the transmitter, the internal reference clock is not adjusted based on the clock information extracted by the reception processing unit. And a clock management unit configured as described above.

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