JP5092493B2 - Reception program, reception apparatus, communication system, and communication method - Google Patents

Description

  The present invention relates to communication of a video file (MPEG-2, MPEG-4, H.264 / AVC) or an audio file (MPEG-1, MPEG-2, MPEG-4, Dolby), a transport stream (TS In particular, the present invention relates to a PCR reproduction method for immediately reproducing video and audio received by a decoder in a system that performs multiplexing using IP and transmits using an IP network.

  Recently, there is an increasing demand for stream distribution for transmitting video data and the like in real time via various communication means including Internet communication.

  In particular, as video and audio data stream transmission through an IP network has become widespread in recent years, decoders are required to immediately reproduce received video and audio without discarding them.

  However, in an IP network, there is no guarantee that packets will arrive regularly in a permutation, so there is no guarantee that a signal will be input at the same timing on the receiving side. However, smooth playback synchronized with the playback time cannot be expected.

  For this reason, in MPEG2-TS, a TTS packet (TS with Time Stamp) added with a 32-MHz counter value for 32 bits for each MPEG2-TS transport stream packet (TS packet) is standardized. , The decoding / reproduction timing on the TTS packet is determined.

The TTS packet is in a format as shown in FIG. 7 , and as described above, this 32-bit field is an MPEG system for controlling the relative input time of the subsequent transport packet to the decoder. This is a clock counter value of 27 MHz synchronized with the clock.

  RTP (Real Time Transfer Protocol) is standardized as a standard for performing real-time stream transmission on a LAN.

  In this method, data is divided into packets in units of time, and the time information of the data is added to the packet and transferred. For example, even if an intermediate packet has not arrived, the time information contained in each packet is temporally transmitted. It is possible to grasp the relationship and reproduce the data at an appropriate timing.

In addition, MPEG2 playback equipment has a 27 MHz counter of STC (System Time Clock) for the purpose of synchronous playback of video and audio, and PCR (Program Clock reference) included in the MPEG2 TS packet at a predetermined interval. ) MPEG2 playback is performed while synchronizing the 27 MHz counter value (see FIG. 8 for the 48-bit format) included in the packet and the STC counter value.

When supplementing FIG. 8 , “Program_clock_reference_base” is a counter value of 90 KHz in 33 bits, and “Program_clock_reference_extension” is two types of counter values of 27 MHz in 9 bits. A counter value of a 48-bit PCR packet is generated using two (9-bit) count values . In playback side has identified the playback time based on the two time information.

  In addition, the image information in Mpeg2 is a frame called I-Picture that can reproduce the entire frame every predetermined frame, and the frame between them is only difference information from the previous or next frame called P-Picture or B-Picture. Is trying to arrange. Since such a method is adopted, only the I picture can be reproduced without the preceding and following frames.

Also, in the I-Picture, PTS (Program Time Stamp) is recorded as display time information. This is recorded as a relative value with respect to the PCR counter value, and the actual I-Picture reproduction timing is obtained by a combination of the PCR value and the PTS value.
JP 2006-0675568 A Japanese Patent No. 3466417

  The shorter the PCR packet transmission interval is, the easier it is to synchronize the reproduction data, but the efficiency of the reproduction data transfer becomes worse. Therefore, the next packet is sent within 100 ms according to the standard. It will not be sent. Further, as described above, since the time that is the reference for the reproduction time is in the counter value of the PCR packet, in order to reproduce the MPEG2 data, the head packet needs to be this PCR packet.

  However, when MPEG-2 data is sent over an IP network, data loss and data delay occur, and this leading packet may not be sent to the other party.

  After this, when the I-Picture is sent, the image information itself can be reproduced, but since the PCR information remains absent, the reproduction timing is not known, and the arrived image information is not received until the next PCR packet arrives. The maximum 100 ms cannot be reproduced.

  Due to this 100 ms non-reproducible time, the image disappears for a moment, but when used for broadcast broadcasting, for example, the viewer feels uncomfortable immediately after switching. There was a case.

  The present invention has been made in view of this point, and an object of the present invention is to provide a data transmission apparatus that can be played back when an I-Picture arrives even when the leading packet does not arrive.

In order to solve the above-described conventional problems , according to one aspect of the present invention , a digital counter that generates a count value of a reproduction time of digital data is provided, and when the digital data transport stream packet is transmitted, the digital counter Are added to the transport stream packet with a time stamp as a TTS time stamp, and the added transport stream packet with a TTS time stamp is a count value for the upper predetermined bits of the digital counter. A packet with an RTP time stamp as a header is output, and the receiving device that communicates with the transmitting device that transmits the output packet is caused to receive the packet sent from the transmitting device, and the received packet Digital data The TTS time stamp and the RTP time stamp are extracted from the received packet, and the PCR is extracted from the extracted TTS time stamp and the RTP time stamp. generates a packet, receiving program to output to a decoder for reproduction of the digital data is Ru are provided.

  As a result, even when the head packet is lost, the I-Picture playback timing can be set, and the non-recoverable time due to the head packet loss can be minimized.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a configuration diagram of an MPEG-TS transmission device 1 according to the present embodiment, and FIG. 2 is a configuration diagram of the reception device.

  The transmission device 1 and the reception device 2 transmit and receive MPEG2-TS format packets via the network 3.

In the present embodiment, in order to simplify the description, the transmission device 1 and the reception device 2 are each configured as a dedicated device, but a communication device having both the function of the transmission device 1 and the function of the reception device 2. May be configured. (Of course, the transmission and reception functions in this case are performed in the same procedure as in the present embodiment.)
In the transmission apparatus of FIG. 1, reference numeral 101 denotes an encoder / TS multiplexer, which encodes a video / audio signal in synchronization with a signal of an STC counter 102 described later to generate a TS packet.

  Reference numeral 102 denotes a 27 MHz counter of STC (System Time Clock). As described in the background art, this STC counter value is a counter value included in the PCR packet, and outputs a 42-bit 27-MHz count value.

  103 generates the TTS packet by adding the lower 32 bits of the output from the STC counter 102 as the time stamp stamp value of the TTS packet and adding the time stamp value generated in the header of the TS packet output from the encoder / TS multiplexing unit 101 to the header. A TTS packet generator.

  3 and 4 show the format of the TTS packet. Note that FIG. 3 shows a case of RAP (Random Access Point), and FIG. 4 shows a format in other cases. As can be seen from these drawings, the time stamp area of the TTS packet is 32 bits, and the TTS packet generation unit 103 defines the lower 32 bits of the counter value of the STC counter 102 in the time stamp area shown in these figures. Generate a packet.

  104 adds, to the header of the TTS packet output from the TTS packet generator 103, a header obtained by inserting a value 1/600 of the output of the STC counter 101 into the 32-bit time information of the RTP packet format, and RTP It is an RTP packet generator that generates packets.

  The upper 32 bits of the STC counter value indicate a count value of 45 KHz, which is 1/600 of 27 Mhz.

The format of the RTP packet header is shown in FIG. The RTP header is composed of 32 bits (4 bytes) × 3 = 96 bits. Among these, the time information is a 32-bit part clearly described as “time stamp”, and the RTP packet generation unit 104 As the 32-bit time information, the upper 32 bits of the STC counter 101 are inserted into the time stamp portion to generate an RTP packet.
(Additionally, with reference to FIG. 3, V (Version): 2 bits, P (Padding): 1 bit, X (eXtention): 1 bit, CC (CSRC Count: 4 Bit, M (Marker)) 1 bit (1 when the payload portion is RAP (Randam Access Point), 0 otherwise), PT (Payload Type): 7 bits (MPEG2-TS (TTS identification number assignment portion), sequence number: 16 bits (0 to 65535) ), And SSRC identification code: 32 bits (storage location of the sender identification field value), which are not different from the prior art, and will not be described. )
Reference numeral 105 denotes a communication unit that transmits the RTP packet generated by the RTP packet generation unit 104 to the network.

  When MPEG2-TS is transmitted using the transmission apparatus 1 as described above, the header of the RTP packet includes information on the upper 32 bits of the output of the STC counter 102 as a time stamp, and the TTS packet in the RTP packet , The lower 32 bits of the output of the STC counter 102 are included, and packet transmission is performed.

  Next, the receiving apparatus in FIG. 2 will be described.

  In FIG. 2, 20 is a communication unit that receives a packet from the network 3, 202 is an RTP time stamp extraction unit that extracts a 32-bit time stamp from the RTP packet received by the communication unit 201, and 203 is a TTS packet from the packet. A TTS time stamp extraction unit that extracts a 32-bit time stamp in the header part, 204 a PCR packet generation that generates a PCR packet based on the time stamp information extracted by the RTP time stamp extraction unit 202 and the TTS time stamp extraction unit 203, respectively , 205 is a PCR packet extraction unit that outputs a PCR packet to a packet correction output unit 206 (to be described later) when the communication unit receives the PCR packet, and 206 is configured to reproduce an image when the PCR packet extraction unit 205 receives the PCR packet. Deco to do Outputs PCR packet received to da LSI 207, if not received, a packet modifying output unit for outputting the PCR packets generated by PCR packet generator 204.

  The operation of the receiving apparatus 2 configured as described above will be described using the flowchart of FIG.

  First, when the communication unit 201 receives RTP packet data (S1001), a time stamp (hereinafter described as an RTP time stamp) included in the RTP packet data is extracted and stored in a storage unit (not shown) ( S1002). Next, the TTS time stamp extraction unit 203 extracts the first TTS time stamp of the RTP packet and stores it in the storage unit (not shown) (S1003).

  Then, the PCR packet generation unit 204 generates a 27 MHz count value from the RTP time stamp multiplied by 600 and the TTS time stamp count value (S1004).

  In this process, since the RTP time stamp multiplied by 600 cannot obtain a value of 0 to 599 in decimal conversion, the value of 0 to 599 is acquired from the TTS time stamp, and the RTP time stamp value multiplied by 600 is obtained. A count value of 27 MHz is generated by adding values from 0 to 599 of the TTS time stamp.

  next. The generated counter value is set to 1/300 to generate a 33-bit / 90 KHz signal, and the lower 9 bits are extracted. Each of the PCR packets includes a Program_clock_reference_base counter value and a PCR packet having a “Program_clock_reference_extension” counter value. Generate (S1005).

  When the packet modification output unit 206 determines that the PCR packet is not extracted by the PCR packet extraction unit 205, the packet correction output unit 206 outputs the PCR packet generated by the PCR packet generation unit 204 to the decoder LSI 207.

  As described above, even when a PCR packet is lost at the start of MPEG2-TS data transmission, a PCR packet is generated on the receiving side using the RTP time stamp and the TTS time stamp included in the RTP packet. Since it is possible to input a PCR packet to the decoder LSI, it is possible to minimize the I-PICTURE non-reproducible time zone due to PCR packet loss.

  In this embodiment, the PCR packet generated by the PCR packet generator 204 when the PCR packet extractor 205 cannot extract the PCR packet by the packet correction output unit 206 is used. Only the PCR packet generated by the PCR packet generation unit 204 may be input to the decoder LSI 207 without using. Thereby, the configuration of the packet correction output unit 206 and the PCR packet extraction unit 205 can be omitted.

In the present embodiment, the transmitting apparatus 1 transmits 1/600 of the STC counter value and the lower 32 bits of the STC, and the receiving apparatus 2 reproduces the PCR packet after restoring the STC counter value. In the transmitting apparatus, the upper 32 bits of the PCR packet are put in the RTP packet time stamp and the lower order in the TTS time stamp from the output from the STC, and the receiving apparatus 2 can directly generate the PCR packet using these. good.
(Second Embodiment)
In the above-described embodiment, the RTP time stamp and the TTS time stamp are used to generate the PCR packet on the receiving side, but the PCR is generated by the decoder using the PTS in the I-Picture and the time stamp in the TTS packet. It is also possible to do.

  In the present embodiment, the PTS information itself is the same as the conventional one, and the TTS time stamp is the same as that in the above-described embodiment, so that the description of transmission from the transmission unit 1 is omitted.

  First, a TS corresponding to I-Picture is found from the received TTS. A PTS is acquired from this TS.

  As described above, in the I-Picture, a relative value with respect to a PCR counter value called PTS (Program Time Stamp) is recorded as display time information.

Using this PTS, the upper bits of the PCR that cannot be generated from the time stamp of the TTS are generated from the PTS.
A block for decoding actual video and audio such as a decoder LSI is provided with a TS packet including the PCR generated in the present invention, and then a TS packet corresponding to I-Picture.
By doing so, the decoder can recognize the display start time of the I-Picture with respect to the PTS, and reproduction from the first Picture becomes possible.

Note that this method can be realized as long as the 27 MHz counter (32 bits) does not make one round (within about 159 seconds).
Further, the counter value generated by this method can be added to the RTP time stamp of claim 1 by realizing it with an encoder.

(Supplementary Note 1) A transmitting apparatus that extracts a first time stamp and a second time stamp from a received packet, generates reproduction time information of digital data, and communicates with a receiving apparatus that reproduces the digital data. ,
A digital counter for generating a count value of the reproduction time of the digital data;
First time stamp assigning means for adding a lower predetermined bit of the digital counter as a first time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
A packet in which a transport value packet with a time stamp output by the first time stamp adding means is further provided with a count value corresponding to the upper predetermined bits of the digital counter as a second time stamp as a header is output. Two time stamping means;
Transmitting means for transmitting the packet output from the second time stamp assigning means to the receiving device;
A transmission program characterized by functioning.

(Additional remark 2) The communication of the said transmitter performs multiplexing using the transport stream (TS) of MPEG2,
The digital counter is an STC counter,
The first time stamp assigning means adds a lower 32 bit count value of the STC counter to the time stamp of the time-stamped transport stream,
The second time stamp assigning means adds the count value of the upper 32 bits of the STC counter to the time stamp of an RTP (Real Time Transfer Protocol) packet header that performs real-time stream transmission on the network. The transmission program according to appendix 1.

(Supplementary Note 3) The PTS information in the time stamp and I-Picture information is extracted from the packet received by the receiving unit, the reproduction time information of the digital data is generated from the time stamp / PTS information, and the digital data is reproduced. A transmitting device that communicates with the receiving device
A digital counter for generating a count value of the reproduction time of the digital data;
A PTS information adding unit for adding PTS information, which is a relative time count value to a PCR packet, which is a packet indicating a reproduction reference time of MPEG data by the digital time data, in I-Picture information;
Time stamp giving means for adding a lower-order predetermined bit of the digital counter as a time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
A transmission program that functions as a transmission unit that transmits a packet output from the time stamp addition unit to a reception device.

(Supplementary Note 4) A transmission apparatus that extracts a first time stamp and a second time stamp from a received packet, generates reproduction time information of digital data, and communicates with a reception apparatus that reproduces the digital data. There,
The transmitter is
A digital counter for generating a count value of the reproduction time of the digital data;
First time stamp assigning means for adding a lower predetermined bit of the digital counter as a first time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
A packet in which a transport value packet with a time stamp output by the first time stamp adding means is further provided with a count value corresponding to the upper predetermined bits of the digital counter as a second time stamp as a header is output. Two time stamping means;
Transmitting means for transmitting the packet output from the second time stamp assigning means to the receiving device;
A transmission device characterized by comprising:

(Additional remark 5) The communication of the said transmitter performs multiplexing using the transport stream (TS) of MPEG2,
The digital counter is an STC counter,
The first time stamp assigning means adds a lower 32 bit count value of the STC counter to the time stamp of the time-stamped transport stream,
The second time stamp assigning means adds the count value of the upper 32 bits of the STC counter to the time stamp of an RTP (Real Time Transfer Protocol) packet header that performs real-time stream transmission on the network. The transmission device according to appendix 4.

(Additional remark 6) From the packet which the said receiving part received, PTS information in time stamp and I-Picture information is extracted, the reproduction time information of digital data is produced | generated from time stamp and PTS information, and reproduction of digital data is performed. A transmitting device that communicates with a receiving device that performs:
The transmitter is
A digital counter for generating a count value of the reproduction time of the digital data;
A PTS information adding unit for adding PTS information, which is a relative time count value to a PCR packet, which is a packet indicating a reproduction reference time of MPEG data by the digital time data, in I-Picture information;
Time stamp giving means for adding a lower-order predetermined bit of the digital counter as a time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
And a transmission unit that transmits the packet output from the time stamp assigning unit to the reception device.

(Supplementary note 7) A communication system comprising a transmitting device and a receiving device, and performing network transfer of digital data by a transport stream packet with a time stamp to which a counter value of a predetermined period is added for each transport stream packet,
The transmitter is
A digital counter for generating a count value of the reproduction time of the digital data;
First time stamp assigning means for adding a lower predetermined bit of the digital counter as a first time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
A packet in which a transport value packet with a time stamp output by the first time stamp adding means is further provided with a count value corresponding to the upper predetermined bits of the digital counter as a second time stamp as a header is output. Two time stamping means;
Transmitting means for transmitting the packet output from the second time stamp assigning means to a receiving device;
The receiving device is:
A receiver for receiving a packet sent from the transmitter;
An extraction unit for extracting a first time stamp and a second time stamp from the packet received by the reception unit;
A digital data reproduction time generation unit that generates digital data reproduction time information from the first time stamp and the second time stamp extracted by the extraction unit and outputs the digital data to a decoder that reproduces the digital data;
The communication system characterized by having.

(Supplementary Note 8) The communication of the communication system is to perform multiplexing using a transport stream (TS) of MPEG2.
The digital counter is an STC counter,
The first time stamp assigning means adds a lower 32 bit count value of the STC counter to the time stamp of the time-stamped transport stream,
The second time stamp assigning means adds a count value of upper 32 bits of the STC counter to a time stamp of an RTP (Real Time Transfer Protocol) packet header that performs real-time stream transmission on the network.
The communication system according to appendix 7, wherein the digital data reproduction time generation unit is configured to generate a PCR packet that is a packet indicating a reproduction reference time of MPEG data.

(Supplementary Note 9) A communication system that includes a transmission device and a reception device, and performs network transfer of digital data in Mpeg format using a transport stream packet with a time stamp to which a counter value of a predetermined period is added for each transport stream packet. ,
The transmitter is
A digital counter for generating a count value of the reproduction time of the digital data;
A PTS information adding unit for adding PTS information, which is a relative time count value to a PCR packet, which is a packet indicating a reproduction reference time of MPEG data by the digital time data, in I-Picture information;
Time stamp giving means for adding a lower-order predetermined bit of the digital counter as a time stamp to a transport stream packet with a time stamp when sending a transport stream packet of digital data;
Transmitting means for transmitting the packet output from the time stamp assigning means to a receiving device,
The receiving device is:
A receiver for receiving a packet sent from the transmitter;
An extraction unit for extracting PTS information in the time stamp and I-Picture information from the packet received by the reception unit;
A digital data reproduction time generation unit that generates digital data reproduction time information from the time stamp / PTS information extracted by the extraction unit, and outputs the digital data reproduction time to a decoder;
The communication system characterized by having.

(Supplementary Note 10) A transmission device having a digital counter that generates a count value of a reproduction time of digital data and a reception device, and using a transport stream packet with a time stamp with a counter value of a predetermined period added to each transport stream packet A communication method performed by a communication system that performs network transfer of digital data,
The transmitting device is
A first time stamp assigning step of adding the lower predetermined bits of the digital counter to the transport stream packet with a time stamp as a first time stamp when sending the transport stream packet of digital data;
A packet in which the count value for the upper predetermined bits of the digital counter is added as a second time stamp as a header to the transport stream packet with the time stamp output in the first time stamp adding step is output. A second time stamping step;
A transmitter step of transmitting the packet output in the second time stamp assigning step to the receiving device;
The receiving device is
A receiving step of receiving a packet sent from the transmitting device;
An extraction step of extracting the first time stamp and the second time stamp from the packet received in the reception step;
A digital data reproduction time generation step of generating digital data reproduction time information from the first time stamp and the second time stamp extracted in the extraction step, and outputting the digital data reproduction time to a decoder;
A communication method characterized by executing

(Additional remark 11) The communication of the said communication system performs multiplexing using the transport stream (TS) of MPEG2,
The digital counter is an STC counter,
In the first time stamp assigning step, the count value of the lower 32 bits of the STC counter is added to the time stamp of the transport stream with time stamp,
In the second time stamp addition step, the count value of the upper 32 bits of the STC counter is added to the time stamp of an RTP (Real Time Transfer Protocol) packet header that performs real-time stream transmission on the network.
11. The communication method according to appendix 10, wherein the digital data reproduction time generation step generates a PCR packet that is a packet indicating a reproduction reference time of MPEG data.

(Supplementary Note 12) A transmission device having a digital counter that generates a count value of a reproduction time of digital data and a reception device, and a transport stream packet with a time stamp in which a counter value of a predetermined period is added to each transport stream packet A communication method in a communication system for performing network transfer of digital data in Mpeg format,
The transmitting device is
A PTS information addition step of adding PTS information, which is a relative time count value with a PCR packet, which is a packet indicating a reproduction reference time of MPEG data based on the digital time data, to the I-Picture information;
A time stamp assigning step of adding the lower predetermined bits of the digital counter to the transport stream packet with a time stamp as a time stamp when sending the transport stream packet of digital data;
A transmission step of transmitting a packet output from the time stamp assigning means to a receiving device;
Run
The receiving device is
A receiving step of receiving a packet sent from the transmitting device;
An extraction step of extracting PTS information in the time stamp and I-Picture information from the packet received in the reception step;
A digital data reproduction time generation step for generating digital data reproduction time information from the time stamp / PTS information extracted in the extraction step, and outputting the digital data reproduction time to a decoder;
Communication method to execute.

Configuration diagram of transmitting apparatus 1 in an embodiment of the present invention Configuration diagram of receiving apparatus 2 in an embodiment of the present invention The figure which shows the format of the TTS packet The figure which shows the format of the TTS packet The figure which shows the format of the header of a RTP packet The figure which shows the operation | movement flowchart of the receiver 2 in one Example of this invention. The figure which shows the format of the header of a TTS packet The figure which shows the format of the header of a PCR packet

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 101 Encoder / TS multiplexing part 102 TTS packet generation part 103 STC counter 104 RTP packet generation part 105 Communication part 2 Reception apparatus 201 Communication part 202 RTP time stamp extraction part 203 TTS time stamp extraction part 204 PCR packet generation part 205 PCR packet extraction unit 206 Packet correction output unit 207 Decoder LSI

Claims (4)

It has a digital counter that generates a count value for the playback time of digital data, and when the digital data transport stream packet is sent, the lower-order predetermined bits of the digital counter are added to the transport stream packet with a time stamp as a TTS time stamp. and, in the TTS time stamped transport stream packet-added, further, outputs a packet grant RTP timestamp is the count value of the predetermined upper bits of the digital counter as a header, the packet output To the receiving device that communicates with the transmitting device that transmits,
If the sent from the transmitting device to receive the packet going that it does not include a PCR packet indicating the playback reference time of the digital data in the received packet,
Extracting the TTS timestamp and the RTP timestamp from the received packet;
A receiving program characterized in that the PCR packet is generated from the extracted TTS time stamp and RTP time stamp and output to a decoder for reproducing digital data. It has a digital counter that generates a count value for the playback time of digital data, and when the digital data transport stream packet is sent, the lower-order predetermined bits of the digital counter are added to the transport stream packet with a time stamp as a TTS time stamp. and, in the TTS time stamped transport stream packet-added, further, outputs a packet grant RTP timestamp is the count value of the predetermined upper bits of the digital counter as a header, the packet output A receiving device for communicating with a transmitting device for transmitting,
A reception section that receives the packet that will be sent from the transmitting device,
When the PCR packet indicating the playback reference time of the digital data in the received packet is not included, from the packets before Symbol receiving unit receives an extracting unit for extracting the TTS time stamps and the RTP time stamp ,
A digital data reproduction time generation unit that generates the PCR packet from the TTS time stamp and the RTP time stamp extracted by the extraction unit and outputs the PCR packet to a decoder that reproduces the digital data;
A receiving device characterized by comprising: A communication system comprising a transmitting device and a receiving device, and performing network transfer of digital data by a transport stream packet with a time stamp to which a counter value of a predetermined period is added for each transport stream packet,
The transmitter is
A digital counter for generating a count value of the reproduction time of the digital data;
When transmission of the transport stream packet of digital data, and TTS time stamping unit for adding a TTS timestamp lower predetermined bits in the time-stamped transport stream packet of the digital counter,
The TTS time stamping the output transport stream packet with a time stamp by means further, RTP time stamping for outputting a packet grant RTP timestamp is the count value of the predetermined upper bits of the digital counter as a header Means,
Transmitting means for transmitting the packet output from the RTP time stamp assigning means to a receiving device,
The receiving device is:
A reception section that receives the packet that will be sent from the transmitting device,
When the PCR packet indicating the playback reference time of the digital data in the received packet is not included, from a packet prior Symbol receiving unit receives an extracting unit for extracting the TTS time stamps and the RTP time stamp,
A digital data reproduction time generation unit that generates the PCR packet from the TTS time stamp and the RTP time stamp extracted by the extraction unit and outputs the PCR packet to a decoder that reproduces the digital data;
The communication system characterized by having. A network of digital data by transport stream packets with time stamps, each comprising a transmission device and a reception device having a digital counter for generating a count value of the reproduction time of digital data, and adding a counter value of a predetermined period for each transport stream packet A communication method performed by a communication system that performs transfer,
The transmitting device is
When transmission of the transport stream packet of digital data, and TTS time stamping step of adding a TTS timestamp lower predetermined bits in the transport stream packet with the time stamp of the digital counter,
An RTP time stamp for outputting a packet in which an RTP time stamp, which is a count value corresponding to upper predetermined bits of the digital counter , is added to the transport stream packet with a time stamp output in the TTS time stamp adding step. Granting step;
Run a transmission hand step of transmitting the packets outputted by the RTP time stamp adding step to a receiving device,
The receiving device is
A receiving step of receiving the packets that will be sent from the transmitting device,
When the PCR packet indicating the playback reference time of the digital data in the received packet is not included, from the packets received in the previous SL reception step, an extraction step of extracting the TTS time stamps and the RTP time stamp,
A digital data reproduction time generation step of generating the PCR packet from the TTS time stamp and the RTP time stamp extracted in the extraction step, and outputting them to a decoder for reproducing the digital data;
A communication method characterized by executing

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