JP2012015875A - Transmitter and transmission program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a transmission program with which a delay time does not increase at a transmission system when an image signal is received and reproduced so as to be transmitted through a broadcasting network and a communication network.SOLUTION: The transmitter 1 encodes an image signal and a voice signal A, and transmits broadcast waves through a broadcasting network 3. The transmitter 1 also encodes voice signals B and C to generate IP packets, and transmits them through a communication network 4 after order control/FEC processing. The transmitter 1 comprises an encoding processing unit 10 which encodes an image signal and outputs trigger when the encoding is complete. The order control/FEC processing units 15-B, 15-C perform order control/FEC processing for packets of the voice signals B and C at every trigger input. According to the above, the order control/FEC processing is performed for the voice signals B and C within encoding unit time of an image signals. Then, a frame #1 of the image signals and a sample #1 of the voice signals B and C are transmitted almost at the same time.

Description

  The present invention relates to a transmission apparatus and a transmission program for transmitting a video / audio signal using a broadcast network and a one-way communication network in which a loss of an IP (Internet Protocol) packet may occur.

  Conventionally, when an IP packet is transmitted in one direction from a transmission device to a reception device via a communication network such as the Internet, temporary congestion occurs due to buffer overflow in a network device such as a router provided in the middle of the transmission path. Occur and packets may be discarded continuously.

  As a technique for solving such a problem of IP packet loss, FEC (Forward Error Correction) processing is performed. A transmission apparatus that transmits an IP packet in one direction generates a redundant packet from a plurality of data packets by performing FEC processing, and transmits the redundant packet together with the data packet. When the receiving device detects a missing data packet, the receiving device performs FEC decoding processing using the redundant packet. As a result, the receiving apparatus can restore the lost packet.

  As another method for solving the above problem, IP packet continuous transmission processing is performed. The transmitter copies and continuously transmits data packets in preparation for data packet loss. This process of continuously transmitting data packets is called continuous transmission. The receiving device can cope with the loss of the data packet by receiving at least one of the plurality of the same data packets continuously transmitted by the transmitting device.

  Patent Document 1 proposes a technique for realizing data transmission with improved reliability by repeatedly transmitting a RTP (Real time Transport Protocol) packet by a transmitting apparatus. Further, Patent Document 2 proposes a technique in which, in video transmission using FEC processing, a transmission device interleaves video data and generates redundant packets thereon. This eliminates the need for rearrangement processing in the receiving apparatus, thereby realizing high-speed processing.

JP 2004-159101 A JP 2008-11114 A

[System for transmitting video and audio signals]
By the way, development of applications for reproducing video and audio using a broadcast network and a communication network is underway. In a transmission system for realizing this application, an IP packet storing an image signal and an IP packet storing an audio signal are transmitted as a broadcast wave via a broadcast network, and an IP packet storing another audio signal associated with the image signal is stored. Are transmitted via a communication network. The receiving device receives the IP packet storing the video signal and the IP packet storing the audio signal via the broadcast network, and receives the IP packet storing the other audio signal via the communication network. Video and audio. By applying the above-described FEC processing and / or continuous transmission processing to such a transmission system, it is possible to solve the problem of IP packet loss in a communication network.

  However, the FEC process and the continuous transmission process have the following two problems. The first problem (Problem 1) is that a delay (blocking delay) associated with blocking when generating a redundant packet occurs, and a delay (continuous transmission delay) associated with continuous transmission occurs. . The second problem (Problem 2) is that when a continuous transmission process of IP packets is performed and a predetermined number or more of IP packets are continuously discarded due to congestion, the receiving apparatus cannot receive the IP packets.

[Problem 1]
As described above, when FEC processing is used to solve the problem of IP packet loss, the transmission apparatus generates one or a plurality of redundant packets based on a plurality of data packets. Here, a unit for generating a redundant packet is called a block. That is, the transmission apparatus collects a plurality of data packets to form a block (blocking), and generates a redundant packet. However, since such blocking processing requires time for generating redundant packets from a plurality of data packets, a blocking delay occurs.

  In addition, when using continuous transmission processing to solve the problem of IP packet loss, the transmission apparatus generates IP packets for a preset number of repetitions by duplicating the IP packets, and continuously transmits the IP packets. However, since the receiving apparatus receives a plurality of duplicated IP packets, a delay associated with continuous transmission (continuous transmission delay) occurs as compared with the case of receiving one IP packet.

[Problem 2]
Furthermore, when using continuous transmission processing, when a network device such as a router provided in the communication network detects congestion, it is possible that IP packets of the repetition number or more are continuously discarded. In this case, the receiving device cannot receive the IP packet correctly.

  The influence of the problems 1 and 2 associated with the FEC process and the continuous transmission process on the transmission system for reproducing video and audio will be described. First, Problem 1 of blocking delay and continuous transmission delay causes a difference in reception timing between a video signal transmitted via a broadcast network and an audio signal transmitted via a communication network in the receiving device. I will let you. For example, when the receiving device receives an audio signal corresponding to a video signal after the video signal, in order to simultaneously reproduce the video signal and the audio signal, the video signal is temporarily stored in a buffer and the audio signal is stored. It is necessary to wait until receiving. That is, the receiving apparatus needs to wait for the received video signal until the corresponding audio signal is received, and a delay occurs in reproducing the video signal.

  Further, Problem 2 of continuous discarding makes it impossible for the receiving apparatus to receive an audio signal transmitted via a communication network, that is, to receive an audio signal corresponding to a video signal.

  Furthermore, Patent Document 1 proposes a technique for ensuring reliability by repeatedly transmitting RTP packets, and the repetition unit is a unit of data to be transmitted. This technique can also be applied to the transmission system described above. However, as in the case of Problem 1, the application to streaming distribution is not appropriate, or from the time when the video signal and the audio signal are generated in the transmission device to the transmission to the reception device until the video and the audio are reproduced. The delay time between will increase.

  Further, Patent Document 2 does not clearly describe the size of blocking, which is a unit for generating redundant packets. Therefore, as in the case of Problem 1, there is a possibility that the blocking delay becomes large, and a delay occurs in the reproduction of the video signal.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to receive a video signal and an audio signal in a transmission system that transmits the video signal and the audio signal using a broadcast network and a communication network. Thus, when reproducing, a transmission apparatus and a transmission program that do not increase the delay time from the reception of the video signal to the reproduction are presented. Another object of the present invention is to provide a transmission apparatus and a transmission program capable of ensuring tolerance to IP packet loss in a communication network in the transmission system.

  In order to achieve the above object, a transmitting apparatus according to the present invention encodes a video signal, a first audio signal and a second audio signal reproduced together with the video signal, and stores the code of the video signal. An IP packet storing the packet and the code of the first audio signal is generated, and the IP packet is transmitted to a broadcast network as a broadcast wave, and an IP packet storing the code of the second audio signal is generated In the transmission device that transmits the IP packet to the communication network, a predetermined number of frames in the first audio signal and a video signal encoding processing unit that encodes a predetermined number of frames in the video signal and generates a code of the video signal A first audio signal encoding processing unit that encodes the first audio signal and generates a code of the first audio signal; and a predetermined in the second audio signal A second audio signal encoding processing unit that encodes a sample of the video signal and generates a code of the second audio signal, and stores the code generated by the video signal encoding processing unit to generate an IP packet of the video signal A video signal packetizing unit, a code generated by the first audio signal encoding processing unit, a first audio signal packetizing unit that generates an IP packet of the first audio signal, and the second A code generated by the audio signal encoding processing unit is stored, a second audio signal packetizing unit that generates an IP packet of the second audio signal, and a first audio signal packetized unit generated by the first audio signal packetizing unit A buffer for storing an IP packet of the audio signal and an IP packet of the video signal generated by the video signal packetizing unit are input, and an IP packet of the first audio signal is input from the buffer. The input video signal in accordance with the timing of the first frame of the predetermined number of frames in the video signal and the timing of the first sample of the predetermined number of samples in the first audio signal. Is generated by a transmission line encoding / modulation processing unit that performs encoding and modulation processing on the IP packet and the IP packet of the read first audio signal and transmits as a broadcast wave, and the second audio signal packetizing unit The input IP packet of the second audio signal is input, and the IP packet for the predetermined number of samples in the input second audio signal is duplicated for each encoding process for the predetermined number of frames in the video signal. And an order control unit that repeatedly transmits the duplicated IP packet.

  The transmission apparatus according to the present invention further includes an FEC (Forward Error Correction) processing unit instead of the order control unit, and the FEC processing unit generates a second audio signal generated by the second audio signal packetizing unit. Each time an encoding process is performed on a predetermined number of frames in the video signal, a redundant packet is generated using an IP packet for a predetermined number of samples in the input second audio signal, An IP packet and a redundant packet are transmitted.

  In addition, the transmission apparatus according to the present invention includes a sequence control / FEC processing unit instead of the sequence control unit, and the sequence control / FEC processing unit generates a second audio signal generated by the second audio signal packetizing unit. A signal IP packet is input, and a redundant packet is generated using an IP packet for a predetermined number of samples in the input second audio signal for each encoding process for a predetermined number of frames in the video signal, The IP packet and the redundant packet are duplicated, and the duplicated IP packet and the redundant packet are repeatedly transmitted.

  In the transmission device according to the present invention, when the video signal encoding processing unit encodes a predetermined number of frames in the video signal, generates a code of the video signal, and encoding of the predetermined number of frames is completed. A trigger is output, and the sequence control unit inputs a trigger from the video signal encoding processing unit, and each time the trigger is input, an IP packet for a predetermined number of samples in the input second audio signal is output. The copied IP packet is repeatedly transmitted, and the FEC processing unit inputs a trigger from the video signal encoding processing unit, and every time the trigger is input, a predetermined value in the input second audio signal A redundant packet is generated using IP packets for a number of samples, the IP packet and the redundant packet are transmitted, and the sequence control / FEC processing unit A trigger is input from the image signal encoding processing unit, and each time the trigger is input, a redundant packet is generated using an IP packet for a predetermined number of samples in the input second audio signal, and the IP packet and The redundant packet is duplicated, and the duplicated IP packet and redundant packet are repeatedly transmitted.

  In the transmission apparatus according to the present invention, the video signal packetizing unit stores a code of the video signal to generate a TS (Transport Stream) packet, and the first audio signal packetizing unit transmits the first audio signal. A TS packet is generated by storing a code, and the TS packet storing the code of the video signal and the TS packet storing the first audio signal are transmitted as a broadcast wave to a broadcast network.

  Furthermore, a transmission program according to the present invention causes a computer to function as the transmission device.

  According to the present invention, within the time of the encoding unit of the video signal, the packet including the second audio signal is blocked to generate a redundant packet, the packet including the second audio signal and the redundant packet are transmitted, Or / and a packet including the second audio signal is duplicated and continuously transmitted. As a result, the playback start time of the video signal and the first audio signal reproduced at the same time is delayed due to the blocking delay or / and the delay of the second audio signal generated due to continuous transmission. There is no. That is, in the receiving apparatus, the delay until reproduction output when reproducing the video signal and the first audio signal does not increase due to the generation or / and continuous transmission of redundant packets accompanied by blocking. Therefore, when the video signal and the first audio signal are received and reproduced, the delay time from the reception of the video signal and the first audio signal to the reproduction is not increased, and the above-described Problem 1 is achieved. Can be solved.

  Further, according to the present invention, packets including the second audio signal are continuously transmitted within the time of the encoding unit of the video signal. Thereby, compared with the prior art, the tolerance with respect to the packet loss in a communication network can be ensured, and the problem 2 mentioned above can be solved.

1 is a diagram for explaining the outline of a video / audio signal transmission system using a broadcast network and a communication network. FIG. It is a block diagram which shows the structure of the transmitter by embodiment of this invention. It is a timing chart which shows the process of a transmitter. It is a flowchart which shows the process with respect to the video signal and the audio | voice signal A. It is a flowchart which shows the process with respect to the audio signals B and C. (1) is a diagram illustrating the order of IP packets when continuous transmission is performed by order control. (2) is a diagram illustrating the order of IP packets when a redundant packet is generated by FEC processing. (3) is a diagram for explaining the order of IP packets when redundant packets are generated by sequential control and FEC processing and continuous transmission is performed. (1) is a figure explaining the order of an IP packet in the case of the repetition number 3 in a prior art. (2) is a diagram illustrating the order of IP packets when the number of repetitions is 3 in the embodiment of the present invention. It is a block diagram which shows the structure of a receiver.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[Transmission system, features of the present invention]
First, a transmission system including a transmission device and a reception device according to an embodiment of the present invention will be described. FIG. 1 is a diagram for explaining the outline of a video / audio signal transmission system using a broadcast network and a communication network. This transmission system includes a transmission device 1 provided by a service provider and reception devices 2-1 to 2-3 provided by users who receive the service. The transmitter 1 and the receivers 2-1 to 2-3 are connected via the broadcast network 3 and also connected via a communication network 4 such as the Internet. For example, UDP / IP is used as a transmission protocol for IP packets transmitted from the transmission apparatus 1 to the reception apparatuses 2-2 and 2-3 via the communication network 4, and unidirectional transmission is realized.

  The transmission device 1 transmits the video signal and the basic audio signal A (first audio signal) accompanying the video signal to the reception devices 2-1 to 2-3 via the broadcast network 3 as broadcast waves. At the same time, a multi-channel audio signal B and audio signal C (second audio signal), which are different from the audio signal A, accompanying the video signal are transmitted to the communication network 4 as IP packets. The audio signal B is a signal of a middle layer channel when the audio signal A is a lower layer, and the audio signal C is a signal of an upper layer channel.

  The receiving devices 2-1 to 2-3 receive broadcast waves via the broadcast network 3 and reproduce video signals and audio signals A. Thereby, the user can view video and audio. The receiving device 2-2 further receives the IP packet via the communication network 4, and reproduces the audio signal B stored in the IP packet in synchronization with the video signal and the audio signal A. The receiving device 2-3 further receives the IP packet via the communication network 4, and reproduces the audio signals B and C stored in the IP packet in synchronization with the video signal and the audio signal A. Thereby, in addition to viewing video and audio, the user can view multichannel sound with a sense of presence using the reproduced audio signal B. Further, the user can further improve the sense of reality by the reproduced audio signal C.

  Note that the audio signals B and C do not necessarily have to be multi-channel signals. For example, the audio signals B and C may be audio signals in a language different from the audio signal A, or may be audio signals that explain video. The receiving devices 2-1 to 2-3 may be switched to any one of the audio signal A, the audio signal B, and the audio signal C for reception. In the present invention, the contents of the audio signals B and C are not limited, and may be any signals accompanying the video signal.

  Here, since IP packets are transmitted to the communication network 4, when congestion occurs, the IP packets are discarded and IP packet loss (packet loss) occurs. That is, in the communication network 4, some information of the audio signals B and C may be discarded. On the other hand, since broadcast waves are transmitted to the broadcast network 3, unlike the communication network 4, the video signal and the audio signal A are not discarded. In order to solve such a problem of packet loss, as described above, the transmission apparatus 1 generates a redundant packet by FEC processing and transmits it together with the data packet, and duplicates and repeatedly transmits the data packet by continuous transmission processing. . However, in such a method, the audio signals B and C are delayed in blocking and continuous transmission, and the reproduction of the video signal and the audio signal A is delayed.

  Therefore, in the present invention, as shown in FIG. 1, in a transmission system that assumes a broadcast network 3 and a communication network 4 having different transmission quality, communication is performed after receiving a video signal and an audio signal A via the broadcast network 3. The audio signals B and C are received at substantially the same timing as the video signal and the audio signal A so that the audio signals B and C are not received via the network 4. That is, in the receiving device 2 (hereinafter, the receiving devices 2-1 to 2-3 are collectively referred to as the receiving device 2), the received video signal and audio signal A are waited for the reception of the audio signals B and C. The first frame # 1 of the video signal and the first sample # 1 of the audio signals B and C are received at the same timing so that the reproduction is not necessary. That is, the transmission apparatus 1 blocks the audio signals B and C in order to transmit the first frame # 1 of the video signal and the first sample # 1 of the audio signals B and C at substantially the same timing. The delay and the continuous transmission delay are set to the time of the encoding unit of the video signal, that is, the time for generating a plurality of frames to be subjected to one encoding process included in GOP (Group of Picture), for example, 500 milliseconds. Absorb. Specifically, the audio signals B and C are blocked and continuously transmitted within the time of the video signal encoding unit. As a result, the frame # 1 of the video signal and the sample # 1 of the audio signals B and C can be transmitted at substantially the same timing, and the video is received without waiting for the arrival of the audio signals B and C in the receiving device 2. Since the signal and the audio signal A can be reproduced, the delay time from the reception of the video signal to the reproduction is not increased.

[Transmitter]
Next, the transmission apparatus 1 shown in FIG. 1 will be described. FIG. 2 is a block diagram illustrating a configuration of the transmission device 1, and FIG. 3 is a timing chart illustrating processing of the transmission device 1. FIG. 4 is a flowchart showing processing for the video signal and the audio signal A, and FIG. 5 is a flowchart for explaining processing for the audio signals B and C. Referring to FIG. 2, this transmission apparatus 1 includes an encoding processing unit 10, 11-A to 11-C, a packetizing unit 12, 13-A to 13-C, a buffer 14, and an order control / FEC processing unit 15-. B and 15-C and a transmission path encoding / modulation processing unit 16 are provided.

  The transmission apparatus 1 generates 15 packets # 1 to # 15 as encoding units, that is, GOPs, in succession to generate an IP packet, and the encoding process is completed. 1024 samples # 1 to # 1024 as encoding units, that is, access units, are continuously encoded with respect to the audio signal A to generate IP packets, which are stored in the buffer 14. After storing and delaying, an IP packet including the codes of frame # 1 and sample # 1 is transmitted at almost the same timing as a modulation signal, and the codes of frames # 2 to # 15 and samples # 2 to # 1024 are included. IP packets are also transmitted sequentially. Further, the transmission apparatus 1 generates IP packets by continuously performing encoding processing on the audio signals B and C using 1024 samples # 1 to # 1024 as encoding units, that is, access units. When a trigger indicating that the signal encoding process is completed is generated, the sequence control / FEC process is performed. That is, the transmission apparatus 1 performs the sequence control / FEC process on the IP packet including the codes of the audio signals B and C samples # 1 to # 1024, every time the encoding process of the frames # 1 to # 15 of the video signal is completed. The IP packet including the code of the sample # 1 of the audio signals B and C is transmitted at substantially the same timing as the IP packet including the code of the frame # 1 of the video signal and the sample # 1 of the audio signal A, and the sample is transmitted. IP packets including codes # 2 to # 1024 are also transmitted sequentially. Note that the frames # 1 to # 15 of the video signal and the samples # 1 to # 1024 of the audio signals A to C correspond to signals in this encoding unit, and are reproduced at a timing synchronized with the receiving device 2. The

(Processing for video signal and audio signal A)
First, processing for the video signal and the audio signal A will be described. 3 and 4, the encoding processing unit (video signal encoding processing unit) 10 inputs frames # 1 to # 15 as 15 frames # 1 to # 15 are generated in the video signal. (Step S401), encoding is performed on the GOP using frames # 1 to # 15 as encoding units to generate a video signal code (Step S402), and output to the packetizing unit 12 (video signal packetizing unit). To do. As shown in FIG. 3, after frame # 1 is input to the encoding processing unit 10, it is retained as part of the encoding process until frame # 15 is input. When the rate of the video signal is 30 frames per second, the time for the encoding processing unit 10 to input the frames # 1 to # 15 is 500 milliseconds. That is, when the frame # 15 is input, the encoding processing unit 10 performs an encoding process on the frames # 1 to # 15 to generate a video signal code. As this encoding process, for example, an encoding method defined in ITU-T Rec. H.264 | ISO / IEC 14496-10 (MPEG-4 AVC) is used, but other encoding methods may be used. good.

  Also, the encoding processing unit 10 determines whether or not the encoding processing of the frames # 1 to # 15 has been completed (step S403), and determines that the encoding processing has not been completed (step S403: N) The encoding process of step S402 is performed. On the other hand, when the encoding processing unit 10 determines that the encoding process is completed (step S403: Y), the encoding processing unit 10 sets a trigger indicating that the encoding process is completed to the sequence control / FEC processing units 15-B and 15-. Output to C (step S404). Here, the trigger is the generation time of the encoding unit frames # 1 to # 15, which is the time of the encoding unit of the video signal, that is, the generation of the frames # 1 to # 15 to be subjected to one encoding process. It is output every time (500 milliseconds in the example of FIG. 3). The video signal is sequentially generated for every 15 frames # 1 to # 15, and a series of processing by the encoding processing unit 10, the packetizing unit 12, and the transmission path encoding / modulation processing unit 16 is continuously performed. is there.

  The packetizing unit 12 inputs the codes of the video signals frames # 1 to # 15 from the encoding processing unit 10, describes the sequence number and time stamp in the RTP header, and encapsulates the IP packet having the RTP header and the UDP header. The IP packet is generated (step S405) and output to the transmission path encoding / modulation processing unit 16. Encapsulation is performed according to the standard of IETF RFC3894 “RTP Payload Format for H.264”, for example. Here, the sequence number is a number assigned to each generated IP packet, and the time stamp is a presentation time at which the video signal is presented in the receiving device 2. Here, to present the video signal means to output the video signal after the code decoding process is completed in the receiving device 2, for example, to reproduce and store the video signal in a storage medium. For the audio signals A to C presented at the same time as the video signal, the same time stamp as the time stamp of the video signal described by the packetizing unit 12 is described in the packetizing units 13-A to 13-C described later. . The destination IP address is assigned a different address for each of the video signal and the audio signals A to C. This destination IP address is used in the receiving device 2 to identify the video signal and the audio signals A to C.

  The encoding processing unit (first audio signal encoding processing unit) 11-A inputs the samples # 1 to # 1024 as 1024 samples # 1 to # 1024 are generated in the audio signal A (step S406). ), An encoding process is performed on the access units using the samples # 1 to # 1024 as encoding units to generate a code of the audio signal A (step S407), and the packetizing unit 13-A (first audio signal packetizing unit) ). As illustrated in FIG. 3, the sample # 1 is retained as part of the encoding process until the sample # 1024 is input after being input to the encoding processing unit 11-A. Assuming that the audio signal is sampled at 48 KHz, the time for which the encoding processing unit 11-A inputs the samples # 1 to # 1024 is 21.3 milliseconds. That is, when the sample # 1024 is input, the encoding processing unit 11-A performs an encoding process on the samples # 1 to # 1024 to generate a code of the audio signal A. As this encoding process, for example, ISO / IEC 14496-3 MPEG-4 AAC is used, but other encoding methods may be used.

  The packetizing unit 13-A inputs the codes of the samples # 1 to # 1024 of the audio signal A from the encoding processing unit 11-A, describes the sequence number and time stamp in the RTP header, and has the RTP header and the UDP header An IP packet is generated by encapsulating the IP packet (step S408). Encapsulation is performed according to the standard of IETF RFC3640 “RTP Payload Format for Transport of MPEG-4 Elementary Stream”, for example. As for the time stamp of the audio signal A corresponding to the video signal, the time when the audio signal A is output is described as the time stamp in the same manner as the video signal.

  The packetizing unit 13-A stores the generated IP packet in the buffer 14 (step S409), and the transmission path coding / modulation processing unit 16 stores the IP packet in the buffer 14 after the packetizing unit 13-A stores the IP packet. It is determined whether or not the time has elapsed (step S410). When it is determined that the predetermined time has not elapsed (step S410: N), the process waits until the predetermined time elapses. On the other hand, when determining that the predetermined time has elapsed (step S410: Y), the transmission path encoding / modulation processing unit 16 reads the IP packet from the buffer 14 (step S411).

  Here, the IP packet including the codes of the samples # 1 to # 1024 of the audio signal A is read from the buffer 14 after a predetermined time elapses because the transmission path encoding / modulation processing unit 16 receives the video from the packetizing unit 12. This is because the timing at which the IP packet including the codes of the signal frames # 1 to # 15 is input and the timing at which the IP packet including the codes of the samples # 1 to # 1024 of the audio signal A are read from the buffer 14 are substantially the same. is there. Comparing the time of GOP (500 milliseconds) that is the encoding unit of the video signal and the time of access unit (21.3 milliseconds) that is the encoding unit of the audio signal A, the time of the video signal is better. Since it is long, the IP packet including the codes of the samples # 1 to # 1024 of the audio signal A can be transmitted earlier than the video signal generated at the same time. However, after the IP packet including the codes of the samples # 1 to # 1024 of the audio signal A is retained in the buffer 14 of the transmission device 1 for a predetermined time, the transmission path encoding / modulation processing unit 16 performs the frame # of the video signal. By reading out from the buffer 14 in accordance with the input timing of the IP packet including the codes 1 to # 15, the video signal frame # 1 and the audio signal A sample # 1 are broadcast at almost the same timing. Can be sent as Since the receiving device 2 can receive the broadcast wave in which the timing of the sample # 1 of the audio signal A and the frame # 1 of the video signal are matched, it is possible to easily perform synchronized playback of video and audio.

  The transmission path encoding / modulation processing unit 16 receives the IP packet including the codes of the frames # 1 to # 15 of the video signal from the packetizing unit 12 and samples the audio signal A from the buffer 14 at substantially the same timing as this. An IP packet including codes # 1 to # 1024 is input, transmission path coding and modulation processing are performed (step S412), and the modulated signal is transmitted as a broadcast wave to the receiver 2 via the broadcast network 3 (step S413). ). Thereby, the transmission path encoding / modulation processing unit 16 spends the same time as the time required for the encoding processing unit 10 to input the frames # 1 to # 15 (500 milliseconds), and the frame of the video signal. An IP packet including codes # 1 to # 15 can be transmitted as a broadcast wave. In order to multiplex an IP packet into a broadcast wave, for example, when using the TLV multiplexing method defined in ARIB STD-B32 “Video coding, audio coding and multiplexing method in digital broadcasting”, this transmission path coding / As a modulation process, a method defined in ARIB STD-B44 “Transmission method of advanced broadband satellite digital broadcasting” is used, but other methods may be used. The present invention does not limit the transmission method of IP packets in broadcast waves.

(Processing for audio signals B and C)
Next, processing for the audio signals B and C will be described. Referring to FIG. 3 and FIG. 5, encoding processing units (second audio signal encoding processing units) 11-B, 11-C and packetizing units (second audio signal packetizing units) 13-B, 13- C performs the same processing as the encoding processing unit 11-A and the packetizing unit 13-A on the audio signal A transmitted as a broadcast wave. That is, the encoding processing units 11-B and 11-C input samples # 1 to # 1024 as 1024 samples # 1 to # 1024 are generated in the audio signals B and C (step S501). The access unit having # 1 to # 1024 as an encoding unit is encoded to generate codes for the audio signals B and C (step S502) and output to the packetizing units 13-B and 13-C.

  The packetizing units 13-B and 13-C input the codes of the samples # 1 to # 1024 of the audio signals B and C from the encoding processing units 11-B and 11-C, and add a sequence number and a time stamp to the RTP header. The IP packet is described and encapsulated into an IP packet having an RTP header and a UDP header (step S503), and is output to the sequence control / FEC processing units 15-B and 15-C. As for the time stamps of the audio signals B and C corresponding to the video signal, the time at which the audio signals B and C are output is described as the time stamp in the same manner as the video signal.

  The sequence control / FEC processing units 15-B and 15-C receive the IP packets including the codes of the samples # 1 to # 1024 of the audio signals B and C from the packetizing units 13-B and 13-C, and perform the encoding process. It is determined whether or not a trigger is input from the unit 10 (step S504). If it is determined that the trigger is not input (step S504: N), the sequence control / FEC processing units 15-B and 15-C wait for the trigger input. On the other hand, when it is determined that the trigger is input (step S504: Y), the order control / FEC processing units 15-B and 15-C perform order control and / or FEC processing (step S505), and the IP packet (and (Redundant packet) is transmitted to the receiving apparatus 2 via the communication network 4 (step S506).

  As shown in FIG. 3, the time from the completion of the encoding process of samples # 1 to # 1024 to the start of transmission of the IP packet storing the code is approximately 478 milliseconds (500-21.3 milliseconds). ), And seven IP packets are generated during this period. Further, in the transmission path encoding / modulation processing unit 16 that performs broadcast system output, the seven IP packets in the audio signal A are transmitted in the order of sequence numbers 1 to 7, whereas the order control that performs communication system output is performed. In the / FEC processing units 15-B and 15-C, the order control / FEC processing is performed on the seven IP packets in the audio signals B and C, and the IP packets (and redundant packets) after the order control / FEC processing are performed. Sent. Further, as indicated by α in FIG. 3, the first frame # 1 of the video signal and the first sample # 1 of the audio signal A and the first sample # 1 of the audio signals B and C are Are transmitted at almost the same timing.

[Sequence control / FEC processing section]
Next, processing performed by the sequence control / FEC processing units 15-B and 15-C will be described in detail. As described above, the sequence control / FEC processing units 15-B and 15-C store the codes of the samples # 1 to # 1024 of the audio signals B and C generated by the packetizing units 13-B and 13-C. 7 IP packets are input, and sequence control / FEC processing is performed at the timing when a trigger is input from the encoding processing unit 10. Specifically, the sequence control / FEC processing units 15-B and 15-C depend on the quality of the communication network 4 and the bit rate used for transmission of the audio signals B and C among the following three processes. , Perform a preset process. In the first process, the input seven IP packets are duplicated by a preset number of repetitions by sequential control and are continuously transmitted. In the second process, a predetermined number of redundant packets are generated from the input seven IP packets by the FEC process, and the IP packets and the redundant packets are transmitted. In the third process, the first process and the second process are performed simultaneously.

  FIG. 6 is a diagram for explaining processing of the sequence control / FEC processing units 15-B and 15-C. (1) is a diagram for explaining the order of IP packets when continuous transmission is performed by order control in the first processing, and (2) is a diagram for generating redundant packets by FEC processing in the second processing. (3) is a diagram for explaining the order of IP packets when redundant packets are generated by order control and FEC processing in the third processing and continuous transmission is performed. is there.

Referring to FIG. 6A, in the first process, the order control / FEC processing units 15-B and 15-C input IP packets in the order of sequence numbers 1 to 7, and the encoding processing unit 10 At the timing when a trigger is input from, the IP packets of sequence numbers 1 to 7 are duplicated for a preset number of repetitions, and the duplicated IP packets are output. For example, when the number of repetitions is 3, the IP packets with sequence numbers 1 to 7 are duplicated three times, and the IP packets with sequence numbers 1 to 7 are output three times in succession as follows. 1 to 7 indicate IP packets of sequence numbers 1 to 7, respectively.
7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1 → (transmission order)

  In other words, the order control / FEC processing units 15-B and 15-C collect IP packets generated during 500 milliseconds, which is a time interval for inputting a trigger, and repeatedly transmit them in that order. In this case, the sequence number and time stamp described in the RTP header of the repeated IP packet have the same values as those of the first IP packet to be transmitted, and the same IP packet is transmitted repeatedly with a time interval. Will be. Such an operation is repeated every 500 milliseconds.

Referring to FIG. 6B, in the second process, the order control / FEC processing units 15-B and 15-C input IP packets in the order of sequence numbers 1 to 7, and the encoding processing unit 10 At a timing when a trigger is input, a predetermined number of redundant packets are generated from the IP packets of sequence numbers 1 to 7, and the IP packets of sequence numbers 1 to 7 and the predetermined number of redundant packets are output. For example, when a Reed-Solomon code (n = 9, k = 7) is used, two redundant packets P1 and P2 are generated from seven IP packets and output as follows. 1 to 7 indicate IP packets of sequence numbers 1 to 7, respectively, and P1 and P2 indicate redundant packets, respectively.
P2, P1, 7, 6, 5, 4, 3, 2, 1 → (transmission order)

  That is, the order control / FEC processing units 15-B and 15-C collectively block IP packets generated during 500 milliseconds, and generate and transmit redundant packets using Reed-Solomon codes. Such an operation is repeated every 500 milliseconds.

  Note that a redundant packet generation method using Reed-Solomon codes is already known, and thus description thereof is omitted. For more information, see “Efficient Reliable Multicast Using FEC and Limited Retransmission for HDTV IP Broadcasting” (S.Aoki, et al., IEEE Consumer Communications & Network Conference (CCNC) 2008, FP1-S5-1, January 2008), Also, please refer to "A Study on a Transmission Method that Ensures Reliability in IP Multicast Broadcasting" (Shuichi Aoki et al., IEICE Technical Report CQ2006-35, September 2006). In addition, redundant packets may be generated by Exclusive OR according to “Unidirectional Transport of Constant Bit Rate MPEG-2 Transport Streams on IP Networks” (SMPTE 2022-2-2007) without using Reed-Solomon codes.

Referring to FIG. 6 (3), in the third process, the sequence control / FEC processing units 15-B and 15-C input IP packets in the order of sequence numbers 1 to 7, and the encoding processing unit 10 At a timing when a trigger is input from the IP packets of sequence numbers 1 to 7, a predetermined number of redundant packets are generated, and the IP packets of sequence numbers 1 to 7 and the predetermined number of redundant packets are set for a preset number of repetitions. Duplicate and output duplicated IP packet and redundant packet. For example, when a Reed-Solomon code (n = 9, k = 7) is used, two redundant packets P1 and P2 are generated from seven IP packets. When the repetition number is 3, 7 IP packets and 2 redundant packets are duplicated 3 times, and 7 IP packets and 2 redundant packets are output 3 times in succession as follows: .
P2, P1, 7, 6, 5, 4, 3, 2, 1, P2, P1, 7, 6, 5, 4, 3, 2, 1, P2, P1, 7, 6, 5, 4, 3, 2, 1 → (Sending order)

  In other words, the order control / FEC processing units 15-B and 15-C collectively block IP packets generated during 500 milliseconds, generate redundant packets using Reed-Solomon codes, and repeat this unit. Send. Such an operation is repeated every 500 milliseconds.

  As described above, according to the transmission device 1 according to the embodiment of the present invention, the sequence control / FEC processing units 15-B and 15-C each time a trigger is input from the encoding processing unit 10, that is, a video signal. The generation time of encoding units frames # 1 to # 15, which is the encoding unit time, that is, the generation time of frames # 1 to # 15 to be subjected to one encoding process (in the example of FIG. 3, 500 mm The sequence control / FEC processing is performed within a second). Therefore, the first frame # 1 of the video signal and the first sample # 1 of the audio signals B and C are transmitted at substantially the same timing (see α in FIG. 3), and the receiving device 2, since the video signal and the audio signal A can be reproduced without waiting for the arrival of the audio signals B and C, the delay time from the reception of the video signal to the reproduction is not increased. That is, it is possible to solve the problem 1 that a delay occurs in reproducing the video signal in the receiving device 2 due to the delay caused by blocking or / and continuous transmission of the audio signals B and C.

  In addition, when performing order control, the order control / FEC processing units 15-B and 15-C perform order control within 500 milliseconds each time a trigger is input from the encoding processing unit 10. The duplicated IP packet is sent repeatedly. For example, when the number of repetitions is 3, the IP packets with sequence numbers 1 to 7 are duplicated three times within 500 milliseconds, and the IP packets with sequence numbers 1 to 7 are output three times in succession. As a result, compared to the prior art, resistance against packet loss in the communication network 4 can be ensured, and the problem 2 that the voice signals B and C cannot be received due to continuous discard of IP packets due to congestion can be solved. Details will be described below.

FIG. 7 is a diagram for explaining the order of IP packets in the related art and the embodiment of the present invention when 3 is set as the number of repetitions. FIG. 7A shows the case of the prior art. 7 (2) shows the case of the embodiment of the present invention. In the case of the prior art shown in FIG. 7A, the IP packets with sequence numbers 1 to 7 are repeatedly transmitted for each IP packet with the same sequence number as shown below by order control.
7, 7, 7, ..., 3, 3, 3, 2, 2, 2, 1, 1, 1 → (transmission order)
On the other hand, in the case of the transmitting apparatus 1 according to the embodiment of the present invention shown in FIG. 7B, the IP packets with sequence numbers 1 to 7 are obtained by the order control in the order control / FEC processing units 15-B and 15-C. As shown below, IP packets with sequence numbers 1 to 7 are collectively transmitted repeatedly. This is the same as in the case of the first process shown in FIG.
7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1 → (transmission order)

  In the case of the prior art, when congestion occurs in the communication network 4 and packet loss continues for three IP packets having the same sequence number, the IP packet may not be restored. On the other hand, in the case of the transmission apparatus 1 according to the embodiment of the present invention, when the packet loss continues 14 times or more, the IP packet may not be restored. That is, in the case of the prior art, the IP packet can be restored only when the packet loss is continuously two times. However, in the case of the transmission device 1 according to the embodiment of the present invention, the packet loss is continuously 13 times or less. If so, the IP packet can be restored. Therefore, according to the transmission device 1 according to the embodiment of the present invention, it is possible to ensure resistance to packet loss in the communication network 4 as compared with the prior art, and reliability of transmission of the audio signals B and C corresponding to the video signal. Can be secured.

[Receiver]
Next, the receiving apparatus 2 (2-1 to 2-3) illustrated in FIG. 1 will be described. FIG. 8 is a block diagram illustrating a configuration of the receiving device 2. The receiving apparatus 2 includes a demodulation / transmission path decoding processing unit 20, reception buffers 21-B and 21-C, FEC processing units 22-B and 22-C, depacketizing units 23 and 24-A to 24-C, a transport Buffers 25, 26-A to 26-C and decoding processors 27, 28-A to 28-C are provided.

  The receiving device 2 receives the modulation signal of the video signal and the audio signal A as a broadcast wave via the broadcast network 3 and receives IP packets of the audio signals B and C via the communication network 4. In this case, the frame # 1 of the video signal and the sample # 1 of the audio signal A and the samples # 1 of the audio signals B and C are received at substantially the same timing. Then, the receiving device 2 identifies the IP packet of the video signal and the audio signal A, decodes and reproduces it. In addition, the receiving device 2 rearranges the IP packets of the audio signals B and C by order control corresponding to the order control / FEC processing units 15-B and 15-C of the transmitting device 1, and / or recovery processing by FEC. To decrypt and play.

(Processing for video signal and audio signal A)
First, processing for the video signal and the audio signal A will be described. The demodulation / transmission path decoding processing unit 20 receives the video signal and the modulation signal of the audio signal A received via the broadcast network 3, performs a demodulation process and a transmission path decoding process, and extracts a multiplexed IP packet. The demodulation / transmission path decoding processing unit 20 identifies the IP packet of the video signal and the IP packet of the audio signal A based on the destination address of the IP packet, and outputs the IP packet of the video signal to the depacketizing unit 23. The IP packet of the audio signal A is output to the depacketizing unit 24-A.

  The depacketizing unit 23 receives the IP packet of the video signal from the demodulation / transmission path decoding processing unit 20, removes the IP header, UDP header, and RTP header from the IP packet, and acquires the code of the video signal stored in the IP packet. . In addition, the depacketizing unit 23 acquires a time stamp from the RTP header, and stores the time stamp and a video signal code corresponding to the time stamp in the transport buffer 25. As described above, the time stamp indicates the time when the video signal is presented.

  The depacketizing unit 24-A receives the IP packet of the audio signal A from the demodulation / transmission path decoding processing unit 20, performs the same processing as the depacketizing unit 23, and performs a time stamp and a code of the audio signal A corresponding to the time stamp. Is stored in the transport buffer 26-A. As described above, the time stamp indicates the time when the audio signal A is presented.

  The decoding processing unit 27 reads the time stamp from the transport buffer 25, compares the time indicated by the time stamp with the time of a timer (not shown), and the time of the timer is a time that is a predetermined time before the time indicated by the time stamp. Sometimes, the code of the video signal corresponding to the time stamp is read from the transport buffer 25. Then, the decoding processing unit 27 performs a decoding process on the code of the read video signal, and outputs the video signal when the time of the timer reaches the time indicated by the time stamp. Such processing by the demodulation / transmission path decoding processing unit 20, the depacketizing unit 23, the transport buffer 25, and the decoding processing unit 27 is performed for each frame # 1 to # 15 of the video signal, and the video signal is reproduced.

  The decoding processor 28-A performs the same processing as the decoding processor 27, and when the time of the timer is a predetermined time before the time indicated by the time stamp stored in the transport buffer 26-A, The code of the audio signal A corresponding to the time stamp is read from the transport buffer 26-A. Then, the decoding processing unit 28-A performs a decoding process on the read code of the audio signal A, and outputs the audio signal A when the time of the timer reaches the time indicated by the time stamp. Such processing by the demodulation / transmission path decoding processing unit 20, the depacketizing unit 24-A, the transport buffer 26-A, and the decoding processing unit 28-A is performed by the audio signal A corresponding to the frames # 1 to # 15 of the video signal. The audio signal A is reproduced every sample # 1 to # 1024.

(Processing for audio signals B and C)
Next, processing for the audio signals B and C will be described. When receiving the IP packet of the audio signal A via the communication network 4, the receiving device 2 stores it in the reception buffer 21-B. The reception buffer 21-B extracts the sequence number from the RTP header of the IP packet, deletes the IP packet having the same sequence number, and rearranges the IP packets in the order of the sequence numbers.

  When the FEC processing unit 22-B reads the IP packets rearranged in the sequence number order from the reception buffer 21-B, determines whether or not the sequence numbers are discontinuous, and determines that they are discontinuous If a missing IP packet is detected, FEC decoding processing is performed using redundant packets, and IP packet recovery processing is performed. The FEC processing unit 22-B outputs the IP packet of the audio signal B, which is rearranged in the order of the sequence numbers and after the FEC decoding process, to the depacketizing unit 24-B. Note that when there is no redundant packet (when it is not transmitted or lost), the FEC decoding process is not performed.

  The reception buffer 21-C and the FEC processing unit 22-C perform the same processing as the reception buffer 21-B and the FEC processing unit 22-B on the IP packet of the audio signal C received via the communication network 4.

  The depacketizing units 24-B and 24-C perform the same processing as the depacketizing units 23 and 24-A, and transfer the time stamps and the codes of the audio signals B and C corresponding to the time stamps to the transport buffers 26-B and 26. Store in -C. As described above, the time stamp indicates the time at which the audio signals B and C are presented.

The decoding processing units 28-B and 28-C perform the same processing as the decoding processing units 27 and 28-A,
When the time of the timer is a predetermined time before the time indicated by the time stamp stored in the transport buffers 26-B and 26-C, the time stamp is transferred from the transport buffer 26-B and 26-C to the time stamp. The codes of the corresponding audio signals B and C are read out and decoded, and the audio signals B and C are output when the time of the timer reaches the time indicated by the time stamp. Such reception buffers 21-B and 21-C, FEC processing units 22-B and 22-C, depacketizing units 24-B and 24-C, transport buffers 26-B and 26-C, and a decoding processing unit 28- The processing by B and 28-C is performed for each sample # 1 to # 1024 of the audio signals B and C corresponding to the frames # 1 to # 15 of the video signal, and the audio signals B and C are reproduced.

  As described above, according to the receiving device 2 according to the embodiment of the present invention, the first frame # 1 of the video signal and the audio signal A of the video signal and the audio signals A to C transmitted from the transmitting device 1 are used. Since the first sample # 1 and the first sample # 1 of the audio signals B and C are received at substantially the same timing, the video signal and the audio signal A can be received without waiting for the arrival of the audio signals B and C. Can be played. Accordingly, there is no increase in the delay time from the reception of the video signal to the reproduction. That is, it is possible to solve the problem 1 that a delay occurs in reproducing the video signal in the receiving device 2 due to the delay caused by blocking or / and continuous transmission of the audio signals B and C.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the technical idea thereof. In the above embodiment, the encoding processing unit 10 of the transmission apparatus 1 sets the encoding unit of the video signal to 15 frames, so that the generation time of the encoding unit frames # 1 to # 15 is 500 milliseconds. Therefore, a trigger is output to the sequence control / FEC processing units 15-B and 15-C every 500 milliseconds. In addition, the encoding processing units 11-A to 11-C set the time for inputting the samples # 1 to # 1024 of the audio signals A to C to 21.3 milliseconds, and the sequence control / FEC processing units 15-B and 15 -C performs the sequence control / FEC process at the trigger timing input every 500 milliseconds. In general, the encoding unit time of the video signal is longer than the encoding unit time of the audio signals A to C. Accordingly, the present invention is not limited to the specific values and methods described above.

  In the above embodiment, an example in which an IP packet storing a code of a video signal and an audio signal A is described as a broadcast signal has been described. However, a TS (Transport Stream) packet defined in MPEG-2 Systems These codes may be stored and multiplexed. Specifically, the packetizing unit 12, 13 -A of the transmission device 1 is a method stipulated in a report “Technical Conditions for Multimedia Broadcasting for Mobile Terminals” reported by the Information and Communication Council dated October 16, 2009, for example. Is used to encapsulate the generated IP packet into a TS packet and output the TS packet.

  Note that a normal computer can be used as the hardware configuration of the transmission device 1 and the reception device 2 according to the embodiment of the present invention. The transmission device 1 and the reception device 2 are configured by a computer including a CPU, a volatile storage medium such as a RAM, a non-volatile storage medium such as a ROM, an interface, and the like. Encoding processing unit 10, encoding processing units 11-A to 11-C, packetizing units 12, 13-A to 13-C, buffer 14, sequence control / FEC processing units 15-B and 15 provided in the transmission apparatus 1 Each function of -C and the transmission path encoding / modulation processing unit 16 is realized by causing the CPU to execute a program describing these functions. Also, the demodulation / transmission path decoding processing unit 20, the reception buffers 21-B and 21-C, the FEC processing units 22-B and 22-C, the depacketizing units 23 and 24-A to 24-C, which are included in the receiving device 2, The functions of the transport buffers 25, 26-A to 26-C and the decoding processing units 27, 28-A to 28-C are realized by causing the CPU to execute programs describing these functions. These programs can be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like.

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 2 Reception apparatus 3 Broadcast network 4 Communication network 10,11 Encoding process part 12,13 Packetizing part 14 Buffer 15 Order control / FEC process part 16 Transmission path encoding / modulation process part 20 Demodulation / Transmission path decoding process part 21 receiving buffer 22 FEC processing unit 23, 24 depacketizing unit 25, 26 transport buffer 27, 28 decoding processing unit

Claims (6)

A video signal, a first audio signal and a second audio signal reproduced together with the video signal are encoded, and an IP packet storing the code of the video signal and an IP packet storing the code of the first audio signal And transmitting the IP packet as a broadcast wave to a broadcast network, generating an IP packet storing the code of the second audio signal, and transmitting the IP packet to a communication network.
A video signal encoding processing unit that encodes a predetermined number of frames in the video signal and generates a code of the video signal;
A first audio signal encoding processor that encodes a predetermined number of samples in the first audio signal and generates a code of the first audio signal;
A second audio signal encoding processing unit that encodes a predetermined number of samples in the second audio signal and generates a code of the second audio signal;
A video signal packetizing unit that stores the code generated by the video signal encoding processing unit and generates an IP packet of the video signal;
A first audio signal packetizing unit for storing the code generated by the first audio signal encoding processing unit and generating an IP packet of the first audio signal;
A second audio signal packetizing unit that stores the code generated by the second audio signal encoding processing unit and generates an IP packet of the second audio signal;
A buffer for storing an IP packet of the first audio signal generated by the first audio signal packetizing unit;
The IP packet of the video signal generated by the video signal packetizing unit is input, and the IP packet of the first audio signal is read from the buffer after a predetermined time, and the first frame of a predetermined number of frames in the video signal Encoding and modulating the IP packet of the input video signal and the IP packet of the read first audio signal in synchronization with the timing of the first sample of the predetermined number of samples in the first audio signal A transmission path encoding / modulation processing unit that performs processing and transmits the broadcast wave;
An IP packet of the second audio signal generated by the second audio signal packetizing unit is input, and a predetermined value in the input second audio signal is input every time encoding processing is performed on a predetermined number of frames in the video signal. A transmission device comprising: an order control unit that duplicates IP packets for a number of samples and repeatedly transmits the duplicated IP packets. The transmission apparatus according to claim 1,
An FEC (Forward Error Correction) processing unit is provided instead of the sequence control unit,
The FEC processing unit inputs the IP packet of the second audio signal generated by the second audio signal packetizing unit, and inputs the input first packet every time encoding processing is performed on a predetermined number of frames in the video signal. A transmission apparatus, comprising: generating a redundant packet using an IP packet for a predetermined number of samples in two audio signals, and transmitting the IP packet and the redundant packet. The transmission apparatus according to claim 1,
A sequence control / FEC processing unit instead of the sequence control unit;
The sequence control / FEC processing unit receives the IP packet of the second audio signal generated by the second audio signal packetizing unit, and performs the encoding process for a predetermined number of frames in the video signal for each of the encoding processes. Generating redundant packets using IP packets for a predetermined number of samples in the input second voice signal, replicating the IP packets and redundant packets, and repeatedly transmitting the copied IP packets and redundant packets. A transmission device characterized. In the transmission device according to any one of claims 1 to 3,
The video signal encoding processing unit encodes a predetermined number of frames in the video signal, generates a code of the video signal, and outputs a trigger when the encoding of the predetermined number of frames is completed,
The sequence control unit according to claim 1 receives a trigger from the video signal encoding processing unit, and duplicates an IP packet for a predetermined number of samples in the input second audio signal each time the trigger is input. , Repeatedly sending the duplicated IP packet,
The FEC processing unit according to claim 2 inputs a trigger from the video signal encoding processing unit, and uses an IP packet for a predetermined number of samples in the input second audio signal each time the trigger is input. Generating a redundant packet, transmitting the IP packet and the redundant packet;
The sequence control / FEC processing unit according to claim 3 receives a trigger from the video signal encoding processing unit, and each time the trigger is input, an IP packet for a predetermined number of samples in the input second audio signal A transmission apparatus, comprising: generating a redundant packet using a packet, replicating the IP packet and the redundant packet, and repeatedly transmitting the copied IP packet and redundant packet. In the transmission device according to any one of claims 1 to 4,
The video signal packetizing unit stores a code of the video signal to generate a TS (Transport Stream) packet,
The first audio signal packetizing unit stores a code of the first audio signal to generate a TS packet,
A transmission apparatus characterized by transmitting a TS packet storing a code of the video signal and a TS packet storing a first audio signal as a broadcast wave to a broadcast network.   The transmission program for functioning a computer as a transmission device as described in any one of Claim 1-5.

Images