JP2014230154A - Transmission apparatus, transmission method, reception apparatus, and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily realize clock synchronization and presentation synchronization in a broadcast system for transmission by an IP system.SOLUTION: A transmission apparatus generates a clock of 27 MHz synchronizing with time information obtained from a time information server, generates time information including frequency information of the clock of 27 MHz, and transmits a broadcast signal of an IP system (such as an RTP system, an MMT system) including a transmission medium, presentation time information for each presentation unit of the transmission medium obtained on the basis of the generated time information, and the generated time information or the time information obtained from the time information server.

Description

  The present technology relates to a transmission device, a transmission method, a reception device, and a reception method, and more particularly, to a transmission device that transmits an IP broadcast signal including transmission media such as video and audio.

  Conventionally, digital broadcasting has been defined and operated worldwide based on the MPEG2-TS system specifications. In 10-15 years after the start of operation, video coding technology has evolved and the demand for higher resolution and higher image quality has increased. On the other hand, with the spread and speeding up of the Internet, it has become possible to receive a video signal having an image quality equivalent to that of a broadcast via a communication path.

  Under such circumstances, expectations for services that use broadcasting and communication in an integrated manner are increasing, and technically, sharing and integration of broadcasting and communication distribution specifications are required. As a result, as a broadcast system specification, a method of transmitting by the IP method similar to the communication instead of the conventional MPEG2-TS method has been studied as a new broadcast method (for example, see Non-Patent Document 1).

Study of ISO / IEC CD 23008-1 MPEG Media Transport, [online], [searched May 7, 2013], Internet <URL: http://mpeg.chiariglione.org/standards/mpeg-h/mpeg- media-transport>

  An object of the present technology is to satisfactorily realize clock synchronization and presentation synchronization in a broadcasting system that transmits by an IP system.

The concept of this technology is
A clock generator for generating a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generation unit that generates time information synchronized with the time information acquired from the time information server including the frequency information of the 27 MHz clock generated by the clock generation unit;
The transmission media, the presentation time information for each presentation unit of the transmission media obtained based on the time information generated by the time information generation unit, and the time information generated by the time information generation unit or the time information server And a transmission unit that transmits an IP broadcast signal including time information acquired from the transmission apparatus.

  In the present technology, the clock generation unit generates a 27 MHz clock synchronized with time information acquired from an NTP (Network Time Protocol) server. The time information generation unit generates time information including frequency information of the 27 MHz clock generated by the clock generation unit. This time information is synchronized with the time information acquired from the time information server.

  For example, the time information generation unit counts a 27 MHz clock generated by the clock generation unit and divides it by 300, and a 17-bit counter that counts the divided output of the 9-bit counter and divides it by 90000. And a 32-bit counter for counting the frequency-divided output of the 17-bit counter.

  For example, the clock generation unit counts the voltage-controlled oscillator that outputs a 27 MHz clock, the 9-bit counter that counts the clock output of the voltage-controlled oscillator and divides it by 300, and the divided output of the 9-bit counter. Of the 9-bit counter, the 32-bit counter that counts the divided output of the 17-bit counter, and the 9-bit counter, the 17-bit counter, and the 32-bit counter. Bit conversion for converting the bit output of the counter into a 32-bit output continuous to the lower order of the bit output of the 32-bit counter, and obtaining a 64-bit output by combining the converted 32-bit output and the bit output of the 32-bit counter And the 64-bit output obtained by this bit conversion unit. And the time information acquired from the time information server, and a comparator that provides the voltage-controlled oscillator with a control signal corresponding to the difference value. The time information generation unit includes a 9-bit counter, a 17-bit counter, and It may be configured by a 32-bit counter.

  Presentation time information for each presentation unit of the transmission media obtained by the transmission unit based on the transmission media and the time information generated by the time information generation unit, and the time information or time information server generated by the time information generation unit The IP system broadcast signal including the time information acquired from is transmitted.

  For example, the broadcast signal encapsulates the first transmission packet encapsulating the IP packet including the transmission medium and the IP packet including the time information generated by the time information generation unit or the time information acquired from the time information server. The second transmission packet may be included.

  In this case, the IP packet in the first transmission packet may further include presentation time information of the transmission medium included in the IP packet. For example, the IP packet in the first transmission packet may include an RTP packet in which the transmission medium is arranged in the payload portion.

  In this case, the broadcast signal may have a third transmission packet encapsulating the IP packet including the presentation time information of the transmission medium included in the IP packet in the first transmission packet. Good. For example, the IP packet in the first transmission packet includes an MMT packet in which transmission media is arranged in the payload portion, and the IP packet in the second transmission packet is an MMT packet in which presentation time information is arranged in the payload portion. May be included.

  As described above, in the present technology, the broadcast signal includes the time information including the frequency information of the 27 MHz clock synchronized with the time information acquired from the time information server or the time information acquired from the time information server. Therefore, the receiving side can generate a 27 MHz clock (system clock) similar to that on the transmitting side based on this time information, and clock synchronization can be realized.

  Further, in the present technology, the presentation time information for each presentation unit of the transmission medium obtained based on the time information having the frequency information of the clock of 27 MHz synchronized with the time information acquired from the time information server is further included in the broadcast signal. It is what Therefore, on the receiving side, realization of presentation synchronization is realized based on time information including frequency information of a 27 MHz clock generated based on time information included in the transmission signal and presentation time information for each presentation unit of the transmission media. It becomes possible.

  In the present technology, for example, the broadcast signal further includes identification information indicating whether the included time information is the time information generated by the time information generation unit or the time information acquired from the time information server. , May be. In this case, on the receiving side, it is possible to perform a clock generation process or the like according to the time information indicated by the identification information.

Other concepts of this technology are
A receiving unit that receives an IP broadcast signal including a transmission medium, presentation time information for each presentation unit of the transmission medium, and time information related to the time information acquired from the time information server;
Based on the time information related to the time information acquired from the time information server included in the broadcast signal, a clock for generating time information including the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information. A time information generator,
A receiving apparatus comprising: a processing unit that processes transmission media included in the broadcast signal based on presentation time information included in the broadcast signal and a clock and time information generated by the clock / time information generation unit .

  In the present technology, an IP broadcast signal including a transmission medium, presentation time information for each unit of presentation of the transmission medium, and time information related to the time information acquired from the time information server is received by the reception unit. The For example, the broadcast signal includes a first transmission packet encapsulating an IP packet including a transmission medium and a second transmission packet encapsulating an IP packet including time information related to time information acquired from a time information server. You may be allowed to have

  In this case, for example, the IP packet in the first transmission packet may further include presentation time information of the transmission medium included in the IP packet. In this case, for example, the broadcast signal has a third transmission packet that encapsulates an IP packet including presentation time information of the transmission medium included in the IP packet in the first transmission packet. May be.

  Based on the time information related to the time information acquired from the time information server included in the broadcast signal by the clock / time information generation unit, the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information are obtained. Including time information is generated. Then, the transmission unit included in the broadcast signal is processed by the processing unit based on the presentation time information included in the broadcast signal and the clock and time information generated by the clock / time information generation unit.

  For example, the time information related to the time information acquired from the time information server included in the broadcast signal is time information including 27 MHz frequency information synchronized with the time information acquired from the time information server. The information generation unit counts the voltage-controlled oscillator that outputs a 27 MHz clock, the 9-bit counter that counts the clock output of the voltage-controlled oscillator and divides it by 300, and the divided output of the 9-bit counter that counts 90000 A 17-bit counter that circulates, a 32-bit counter that counts the frequency-divided output of the 17-bit counter, a 9-bit counter, a bit output of the 17-bit counter and the 32-bit counter, and a time acquired from a time information server Compares the time information related to the information and sends a control signal to the voltage controlled oscillator And having a comparator for obtaining an error signal supplied by, it may be adapted.

  Further, for example, the time information related to the time information acquired from the time information server included in the broadcast signal is from the time information including the 27 MHz frequency information synchronized with the time information acquired from the time information server or from the time information server. The time information related to the time information acquired from the time information server included in the broadcast signal is synchronized with the time information acquired from the time information server. The clock / time information generation unit further includes identification information indicating whether the first time information includes frequency information or the same time information as the time information acquired from the time information server. A voltage-controlled oscillator to output, a 9-bit counter that counts the clock output of the voltage-controlled oscillator and divides it by 300; A 17-bit counter that counts the divided output of the 9-bit counter and divides it by 90000, a 32-bit counter that counts the divided output of the 17-bit counter, and bit outputs of the 9-bit counter, the 17-bit counter, and the 32-bit counter And the time information related to the time information acquired from the time information server included in the broadcast signal, and a comparator for obtaining an error signal to be supplied as a control signal to the voltage controlled oscillator; and the identification information includes the first time information. A selector that supplies an error signal obtained by the comparator as a control signal to the voltage-controlled oscillator when indicating, and supplies a fixed value as a control signal to the voltage-controlled oscillator when the identification information indicates the second time information. May be.

  Thus, in the present technology, the same 27 MHz clock (system clock) as that on the transmission side based on the time information related to the time information acquired from the time information server included in the broadcast signal, and the frequency of this 27 MHz clock Time information including information is generated. The transmission medium is processed based on the clock and time information and the presentation time information for each transmission media presentation unit included in the broadcast signal. Therefore, clock synchronization and presentation synchronization can be realized.

  According to the present technology, it is possible to satisfactorily realize clock synchronization and presentation synchronization in a broadcast system that transmits in the IP system. Note that the effects described in the present specification are merely examples and are not limited, and may have additional effects.

It is a block diagram which shows the structural example of the transmission / reception system as embodiment. It is a figure for demonstrating the clock synchronization and presentation synchronization in a transmission / reception system. It is a figure for demonstrating the clock synchronization and presentation synchronous system in MPEG2-TS system. It is a figure which shows the structure of PCR (STC) with frequency information of 27 MHz, and the structure of PTS with frequency information of 90 KHz. It is a figure which shows the stack model which shows the example of a broadcast signal structure in a RTP system. It is a figure for demonstrating the structure of a RTP system broadcast stream (broadcast signal). It is a figure which shows the stack model which shows the example of a broadcast signal structure in a MMT system. It is a figure for demonstrating the structure of a MMT system broadcast stream (broadcast signal). It is a block diagram which shows the structural example of the broadcast transmission system by a RTP system. It is a block diagram which shows the structural example of the broadcast transmission system by a MMT system. It is a block diagram which shows the structural example of a receiver. It is a figure for demonstrating the format (NTP time stamp format) of the NTP server and the time information which this NTP server provides. It is a block diagram which shows the structural example by the side of the broadcast transmission system for demonstrating the clock synchronization and presentation synchronous system in a RTP system. It is a block diagram which shows the structural example by the side of the receiver for demonstrating the clock synchronization and presentation synchronous system in a RTP system. It is a figure which shows the structure of the NTP clock reference, and the structure of the time stamp inserted in the header of each RTP packet. It is a block diagram which shows the structural example by the side of the broadcast transmission system for demonstrating the clock synchronization and presentation synchronous system in a MMT system. It is a block diagram which shows the structural example by the side of the receiver for demonstrating the clock synchronization and presentation synchronization system in a MMT system. It is a figure which shows the structure of a NTP clock reference, and the structure of a 49-bit or a 32-bit time stamp. It is a figure which shows the structure of the time information of a 64-bit format acquired from the NTP server, and the structure of NTP_CR. It is a figure for demonstrating the other structural example of a receiver. It is a block diagram which shows the structural example by the side of the broadcast transmission system for demonstrating the other clock synchronization / presentation synchronous system in a MMT system. It is a block diagram which shows the structural example by the side of the receiver for demonstrating the other clock synchronization / presentation synchronous system in a MMT system. It is a figure which shows the structure of the time information of a 64-bit format, and the structure of a time stamp (PTS).

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

<1. Embodiment>
[Broadcast system configuration example]
FIG. 1 shows a configuration example of a transmission / reception system 10 as an embodiment. The transmission / reception system 10 includes a broadcast transmission system 100 and a receiver 200.

  The broadcast transmission system 100 transmits an IP (Internet Protocol) broadcast signal including transmission media such as video and audio. The broadcast transmission system 100 generates time information including a 27 MHz clock (system clock) synchronized with time information acquired from an NTP (Network Time Protocol) server as a time information server and frequency information of the 27 MHz clock. To do. The broadcast signal includes, together with the transmission media, presentation time information for each presentation unit of the transmission media obtained based on the generated time information, and the generated time information.

  The receiver 200 receives the above-described IP broadcast signal transmitted from the broadcast transmission system 100. Based on the time information included in the broadcast signal, the receiver 200 generates time information including a 27 MHz clock (system clock) synchronized with the time information and the frequency information of the 27 MHz clock. Then, the receiver 200 processes the transmission medium included in the broadcast signal based on the presentation time information included in the broadcast signal and the generated clock and time information.

  In the transmission / reception system 10, the broadcast transmission system 100 and the receiver 200 are configured as described above, thereby realizing clock synchronization and presentation synchronization as in the conventional MPEG2-TS system.

  The clock synchronization and presentation synchronization in the transmission / reception system will be described with reference to FIG. The transmission system and the reception system correspond to, for example, the broadcast transmission system 100 and the receiver 200 described above. The transmission system includes a clock generation unit 11 that generates a 27 MHz system clock and a clock unit (time information generation unit) 12 that generates time information. The transmission system also includes an encoding processing unit 13, a packetization / time stamp adding unit 14, and an encoding buffer 15.

  The encoding processing unit 13 encodes transmission media such as video and audio. The packetization / time stamp adding unit 14 packetizes the transmission media after encoding, and presents time information (PTS: Presentation) for each transmission media presentation unit based on the time information generated by the clock unit 12. Time Stamp) is added. The packet of the transmission medium is temporarily stored in the encode buffer 15 and transmitted at an appropriate timing.

  The reception system includes a clock generation unit 21 that generates a 27 MHz system clock and a clock unit (time information generation unit) 22 that generates time information. The receiving system also includes a decode buffer 23, a depacketization / timing adjustment unit 24, and a decode processing unit 25.

  The decode buffer 23 temporarily stores received transmission media packets. In the depacketization / timing adjustment unit 24, the packet of the transmission medium stored in the decode buffer 23 is taken out at the timing of the presentation time information added by referring to the time information generated by the clock unit 22, and depacketed. It becomes. In the decoding processing unit 25, the transmission medium obtained by depacketization is decoded to obtain a baseband transmission medium.

  In the transmission / reception system 10 shown in FIG. 1, clock synchronization and presentation synchronization are realized. Details of the clock synchronization / presentation synchronization method will be described later. Here, the clock synchronization means that the frequency of the system clock generated by the clock generation unit 11 of the transmission system and the frequency of the system clock generated by the clock generation unit 21 of the reception system become the same frequency. . If clock synchronization is not realized, corruption such as frame skipping occurs while reception is continued on the receiving side.

  The presentation synchronization means that the time information of the clock unit 12 of the transmission system and the time information of the clock unit 22 of the reception system are combined, and the presentation time information for each transmission media presentation unit is added to the packet of the transmission medium. means. Here, when the time information of the clock unit 22 of the reception system is matched with the time information of the clock unit 12 of the transmission system, a transmission delay from the transmission system to the reception system is considered. If the presentation synchronization is not realized, it is impossible to synchronize the video and audio on the receiving side and appropriately present without destroying the buffer.

  FIG. 3 shows a clock synchronization / presentation synchronization method in the conventional MPEG2-TS method. In the figure, the left side shows a configuration example on the broadcast transmission system side, and the right side shows a configuration example of a receiver.

  The broadcast transmission system includes a voltage-controlled oscillator 31 that generates a 27 MHz clock (system clock), a division period 32, a comparator 33, and a 9-bit counter 34a and a 33-bit count that constitute a clock unit (time information generation unit). 34b and a packetizing unit 35. The broadcast transmission system also includes a video encoding processing unit 36, a packetization / time stamp adding unit 37, an encoding buffer 38, and a multiplexer 39.

  The 27 MHz clock generated by the voltage controlled oscillator 31 is divided by the frequency divider 33, and a pulse is output from the frequency divider 33 with a time length of one horizontal period. The output pulse of the frequency divider 32 is supplied to the comparator 33 and compared with the phase of the reference horizontal synchronizing signal (Ref. Hsync). The comparison error signal output from the comparator 34 is supplied to the voltage controlled oscillator 31 as a control signal. The voltage controlled oscillator 31, the frequency divider 32, and the comparator 33 constitute a PLL (Phase Locked Loop) circuit. The voltage controlled oscillator 31 generates a 27 MHz clock synchronized with the reference horizontal synchronizing signal.

  The 27 MHz clock output from the voltage controlled oscillator 31 is counted by the 9-bit counter 34a and divided by 300. The 90 KHz clock obtained by the 9-bit counter 34a is counted by the 33-bit counter 34b. The bit output of (33 + 9) bits of the 9-bit counter 34a and the 33-bit counter 34b becomes a system time clock (STC) as time information.

  This system time clock is supplied to the packetizing unit 35. The packetizing unit 35 generates a TS packet having an adaptation field including a program clock reference (PCR) based on the system time clock. The TS packets are generated at predetermined intervals and sequentially supplied to the multiplexer 39. It is recommended that the PCR appear in the TS stream at 100 ms intervals. FIG. 4A shows the configuration of PCR (STC) having frequency information of 27 MHz.

  In the video encoding processor 36, video (video data) is encoded in synchronization with the 27 MHz clock obtained by the voltage controlled oscillator 31. The packetization / time stamp addition unit 37 generates a PES packet for each picture (Picture), for example, from the encoded video elementary stream, and further generates a TS packet including the encoded video in the payload. This TS packet is supplied to the multiplexer 39 through the encode buffer 38.

  The packetization / time stamp adding unit 37 is supplied with a 33-bit bit output output from the 33-bit counter 34b. This 33-bit bit output is time information with an accuracy of 90 kHz. The packetization / time stamp adding unit 37 inserts a presentation time stamp (PTS) into the header of each PES packet based on the 33-bit bit output. FIG. 4B shows the configuration of a PTS having frequency information of 90 KHz.

  As described above, the multiplexer 39 is supplied with TS packets including PCR and TS packets including encoded video. Although illustration is omitted, a TS packet including encoded audio and the like is generated in the same manner as a TS packet including encoded video and supplied to the multiplexer 39. In the multiplexer 39, each TS packet is multiplexed and a TS stream is generated. This TS stream is transmitted as a broadcast signal.

  The receiver includes a demultiplexer 41, a voltage controlled oscillator 42 that generates a 27 MHz clock (system clock), a 9-bit counter 43a and a 33-bit count 43b that constitute a clock (time information generator), and a comparator 44. Have. In addition, the receiver includes a decode buffer 45, a presentation control unit 46, and a video decode processing unit 47.

  The demultiplexer 41 is supplied with a TS stream that is a received broadcast signal. In the demultiplexer 41, the PCR is extracted from the TS packet including the PCR. At the time of channel selection or power-on, the 42-bit PCR received first is set as an initial value in a 42-bit counter comprising the counter 43a and the counter 44b. The PCR received thereafter is supplied to the comparator 44. The

  The 27 MHz clock generated by the voltage controlled oscillator 42 is counted by the 9-bit counter 43a and divided by 300. The 90 KHz clock obtained by the 9-bit counter 43a is counted by the 33-bit counter 43b. The bit output of (33 + 9) bits of the 9-bit counter 43a and the 33-bit counter 43b is a system time clock (STC) as time information.

  This system time clock is supplied to the comparator 44. In the comparator 44, for example, at the timing when the PCR is supplied from the demultiplexer 41, the system time clock is latched and compared with the PCR. The comparison error signal output from the comparator 44 is supplied to the voltage controlled oscillator 42 as a control signal. The voltage controlled oscillator 42, the counters 43a and 43b, and the comparator 44 constitute a PLL (Phase Locked Loop) circuit. The voltage controlled oscillator 42 generates a 27 MHz clock synchronized with the PCR, and the counters 43a and 43b synchronize with the PCR. System time clock is generated.

  In the demultiplexer 41, TS packets including the encoded video are extracted and temporarily stored in the decode buffer 45. The 33-bit bit output output from the 33-bit counter 43 b is supplied to the presentation control unit 46. In the presentation control unit 46, the PTS of each PES packet stored in the decode buffer 45 is confirmed, and the PES packet to be decoded is sequentially transmitted from the decode buffer 45 to the video decode processing unit 47 with reference to the system time clock. Capture is done.

  In the video decoding processing unit 47, the PES packet is depacketized, the encoded video is further decoded, and baseband video data is obtained. Then, in the receiver, video display based on the video data is performed. Although not shown, the demultiplexer 41 also extracts TS packets including encoded audio, and processes them in the same manner as in the case of the video described above to obtain baseband audio data. Is called.

  Returning to FIG. 1, as described above, an IP broadcast signal is transmitted from the broadcast transmission system 100 to the receiver 200. In this embodiment, the IP broadcast signal is, for example, RTP (Real-Time Transport Protocol) or MMT (MPEG Media Transport).

FIG. 5 is a stack model showing a broadcast signal configuration example in the RTP system. There is a physical layer (PHY) below. This physical layer includes a modulation scheme, an error correction scheme, and the like. On top of this physical layer, TLV (Type Length Value) or GSE (GSE (Generic
There is a transmission packet layer of Stream Encapsulation.

  An IP packet is placed on the TLV or GSE transmission packet. Further, UDP (User Datagram Protocol) is placed on the IP packet. In addition, RTP used on the Internet is placed on UDP. Then, transmission media such as video, audio, and subtitles are placed on the RTP. On the other hand, a transmission control signal as signaling information is also placed on the TLV or GSE transmission packet.

  In the case of the broadcast signal configuration example in the RTP system, the IP packet basically has the same form as the Internet streaming. As shown in the figure, NTP (Network Time Protocol) further exists on the UDP.

  FIG. 6 shows a configuration example of an RTP broadcast stream (broadcast signal). FIG. 6A shows a video elementary stream (Video ES). This elementary stream of video is divided into chunks of a predetermined size and arranged in the payload portion of an RTP packet (RTP packet) as shown in FIG. There is a time stamp field in the header portion of the RTP packet, and a PTS indicating the presentation time of each picture is inserted into this field.

  As shown in FIG. 6C, a UDP header, an IP header, and a TLV header are added to the RTP packet to generate a TLV packet (TLV packet) constituting the RTP broadcast stream. A TLV packet includes a packet including NTP time information. In addition, although illustration is abbreviate | omitted, as a TLV packet, the TLV packet containing the RTP packet of other transmission media, such as an audio and a subtitle, exists further. This RTP broadcast stream has a first transmission packet that encapsulates an IP packet that includes transmission media, and a second transmission packet that encapsulates an IP packet that includes time information.

FIG. 7 is a stack model showing an example of a broadcast signal configuration in the MMT system. There is a physical layer (PHY) below. This physical layer includes a modulation scheme, an error correction scheme, and the like. On top of this physical layer, TLV (Type Length Value) or GSE (GSE (Generic
There is a transmission packet layer of Stream Encapsulation.

  An IP packet is placed on the TLV or GSE transmission packet. Further, UDP (User Datagram Protocol) is placed on the IP packet. On the other hand, a transmission control signal as signaling information is also placed on the TLV or GSE transmission packet. An MMT packet is placed on the UDP. The payload portion of the MMT packet includes an MFU ((MMT Fragment Unit)) or a signaling message (Signaling Message). As shown in the figure, NTP (Network Time Protocol) further exists on the UDP.

  FIG. 8 shows an example of the configuration of an MMT broadcast stream (broadcast signal). FIG. 8A shows a video elementary stream (Video ES). This elementary stream of video is divided into chunks of a predetermined size and arranged in the payload portion of the MFU as shown in FIG.

  As illustrated in FIG. 8C, an MMT payload is formed by adding an MMT payload header to the MFU. Then, as shown in FIG. 8 (d), an MMT header (MMT header) is further added to the MMT payload to form an MMT packet (MMT packet). There is also an MMT packet including a signaling message such as PTS indicating the presentation time of each picture in the payload portion.

  As shown in FIG. 8E, a UDP header, an IP header, and a TLV header are added to the MMT packet to generate a TLV packet (TLV packet) that constitutes an MMT broadcast stream. A TLV packet includes a packet including NTP time information. In addition, although illustration is abbreviate | omitted, as a TLV packet, the TLV packet containing the MPU packet of other transmission media, such as an audio and a caption, exists further. This MMT broadcast stream includes a first transmission packet encapsulating an IP packet including a transmission medium, a second transmission packet encapsulating an IP packet including time information, and a first transmission packet in the first transmission packet. It has a third transmission packet that encapsulates the IP packet including the presentation time information of the transmission medium included in the IP packet.

  FIG. 9 shows a configuration example of a broadcast transmission system 100 based on the RTP method. The broadcast transmission system 100 includes a clock unit 101, a signal transmission unit 102, a video encoder 103, an audio encoder 104, a caption encoder 105, and a TLV (GSE) signaling generation unit 106. The broadcast transmission system 100 includes N IP service multiplexers 107-1 to 107-N, a TLV (GSE) multiplexer 108, and a modulation / transmission unit 109.

  The clock unit 101 generates time information synchronized with time information acquired from an NTP server (not shown), and sends an IP packet including the time information to the IP service multiplexer 107-1. The signal transmission unit 102 is, for example, a studio of a TV station or a recording / reproducing device such as a VTR, and is a system that transmits baseband signals such as video, audio, and subtitles as transmission media.

  The video encoder 103 encodes and further packetizes the video signal transmitted from the signal transmission unit 102, and sends an IP packet including a video RTP packet to the IP service multiplexer 107-1. The audio encoder 104 encodes and further packetizes the audio signal transmitted from the signal transmission unit 102, and sends an IP packet including an audio RTP packet to the IP service multiplexer 107-1.

  The caption encoder 105 encodes the caption signal transmitted from the signal transmission unit 102, further packetizes it, and sends an IP packet including the RTP packet of the caption to the IP service multiplexer 107-1. In addition, PTS is added to the header part of each RTP packet of video, audio, and subtitles based on time information generated by the clock unit 101. The IP service multiplexer 107-1 performs time division multiplexing of the IP packet sent from each encoder. At this time, the IP service multiplexer 107-1 adds a UDP header and a TLV header to each IP packet to form a TLV (GSE) packet.

  The IP service multiplexer 107-1 constitutes one channel portion included in one transponder. The IP service multiplexers 107-2 to 107-N have the same functions as the IP service multiplexer 107-1, and constitute other channel portions included in one of the transponders.

  The TLV (GSE) signaling generation unit 106 generates signaling (Signaling) information, and generates a TLV (GSE) packet in which the signaling (Signaling) information is arranged in the payload portion. The TLV (GSE) multiplexer 108 multiplexes the TLV (GSE) packets generated by the IP service multiplexers 107-1 to 107-N and the TLV (GSE) signaling generation unit 106 to generate an RTP broadcast stream (see FIG. 6 (c)). The modulation / transmission unit 109 performs RF modulation processing on the RTP broadcast stream generated by the TLV (GSE) / multiplexer 108 and transmits the result to the RF transmission line.

  The operation of the broadcast transmission system (RTP method) 100 shown in FIG. 9 will be briefly described. In the clock unit 101, time information synchronized with the time information acquired from the NTP server is generated, and an IP packet including the time information is generated. This IP packet is sent to the IP service multiplexer 107-1.

  The video signal sent from the signal sending unit 102 is supplied to the video encoder 103. In the video encoder 103, the video signal is encoded and further packetized to generate an IP packet including a video RTP packet. This IP packet is sent to the IP service multiplexer 107-1.

  The same processing is performed on the audio signal and subtitle signal transmitted from the signal transmission unit 102. The IP packet including the audio RTP packet generated by the audio encoder 104 is sent to the IP service multiplexer 107-1, and the IP packet including the caption RTP packet generated by the caption encoder 105 is transmitted to the IP service multiplexer 107. Sent to -1.

  The IP service multiplexer 107-1 performs time division multiplexing of the IP packet sent from each encoder. At this time, a UDP header and a TLV header are added to each IP packet to form a TLV (GSE) packet. In this IP service multiplexer 107-1, the processing of one channel part included in one transponder is performed, and in the IP service multiplexers 107-2 to 107-N, other parts included in the one transponder are processed. The channel portion is processed in the same manner.

  The TLV (GSE) packets obtained by the IP service multiplexers 107-1 to 107-N are sent to the TLV (GSE) multiplexer 108. The TLV (GSE) multiplexer 108 further receives a TLV (GSE) packet in which signaling information is placed in the payload portion from the TLV (GSE) signaling generation unit 106.

  The TLV (GSE) multiplexer 108 multiplexes the TLV (GSE) packets generated by the IP service multiplexers 107-1 to 107-N and the TLV (GSE) signaling generation unit 106 to generate an RTP broadcast stream. Generated. This broadcast stream is sent to the modulation / transmission unit 109. The modulation / transmission unit 109 performs RF modulation processing on the RTP broadcast stream, and sends the RF modulation signal to the RF transmission path.

  FIG. 10 shows a configuration example of a broadcast transmission system 100 based on the MMT method. The broadcast transmission system 100 includes a clock unit 111, a signal transmission unit 112, a video encoder 113, an audio encoder 114, a caption encoder 115, and a signaling generation unit 116. Further, the broadcast transmission system 100 includes a TLV (GSE) signaling generation unit 117, N IP service multiplexers 118-1 to 118-N, a TLV (GSE) multiplexer 119, and a modulation / transmission unit 120. Have.

  The clock unit 111 generates time information (NTP time information) synchronized with time information acquired from an NTP server (not shown), and sends an IP packet including this time information to the IP service multiplexer 118-1. The signal sending unit 112 is, for example, a TV station studio or a recording / playback device such as a VTR, and is a system that sends baseband signals such as video, audio, and subtitles as transmission media.

  The video encoder 113 encodes the video signal transmitted from the signal transmission unit 112, further packetizes it, and sends an IP packet including the video MMT packet to the IP service multiplexer 118-1. The audio encoder 114 encodes and further packetizes the audio signal transmitted from the signal transmission unit 112, and sends an IP packet including an audio MMT packet to the IP service multiplexer 118-1.

  The caption encoder 115 encodes the caption signal transmitted from the signal transmission unit 112, further packetizes it, and sends an IP packet including the caption MMT packet to the IP service multiplexer 118-1. The signaling generation unit 116 generates a signaling message and sends an IP packet including an MMT packet in which the signaling message is arranged in the payload part to the IP service multiplexer 118-1. This signaling message includes a PTS generated based on time information generated by the clock unit 111.

  The IP service multiplexer 118-1 performs time division multiplexing of the IP packet sent from each encoder. At this time, the IP service multiplexer 118-1 adds a UDP header and a TLV header to each IP packet to form a TLV (GSE) packet. The IP service multiplexer 118-1 constitutes one channel portion included in one transponder. The IP service multiplexers 118-2 to 118-N have the same functions as the IP service multiplexer 118-1, and constitute other channel portions included in one transponder.

  The TLV (GSE) signaling generation unit 117 generates signaling (Signaling) information, and generates a TLV (GSE) packet in which the signaling (Signaling) information is arranged in the payload portion. The TLV (GSE) multiplexer 119 multiplexes the TLV (GSE) packets generated by the IP service multiplexers 118-1 to 118 -N and the TLV (GSE) signaling generation unit 117 to generate an MMT broadcast stream (see FIG. 8 (e)). The modulation / transmission unit 120 performs RF modulation processing on the MMT broadcast stream generated by the TLV (GSE) / multiplexer 119 and sends the result to the RF transmission path.

  The operation of the broadcast transmission system (MMT system) 100 shown in FIG. 10 will be briefly described. In the clock unit 111, time information synchronized with the time information acquired from the NTP server is generated, and an IP packet including the time information is generated. This IP packet is sent to the IP service multiplexer 118-1.

  The video signal sent from the signal sending unit 112 is supplied to the video encoder 113. In this video encoder 113, the video signal is encoded and further packetized to generate an IP packet including a video MMT packet. This IP packet is sent to the IP service multiplexer 118-1.

  The same processing is also performed on the audio signal and subtitle signal transmitted from the signal transmission unit 112. The IP packet including the audio MMT packet generated by the audio encoder 114 is sent to the IP service multiplexer 118-1, and the IP packet including the caption MMT packet generated by the caption encoder 115 is transmitted to the IP service multiplexer 118. Sent to -1.

  The signaling generator 116 generates a signaling message (including PTS), and generates an IP packet including an MMT packet in which the signaling message is arranged in the payload portion. This IP packet is sent to the IP service multiplexer 118-1.

  The IP service multiplexer 118-1 performs time division multiplexing of IP packets sent from the encoders and the signaling generator 116. At this time, a UDP header and a TLV header are added to each IP packet to form a TLV (GSE) packet. In this IP service multiplexer 118-1, processing of one channel part included in one transponder is performed, and in IP service multiplexers 118-2 to 118-N, other parts included in the one transponder are processed. The channel portion is processed in the same manner.

  The TLV (GSE) packets obtained by the IP service multiplexers 118-1 to 118-N are sent to the TLV (GSE) multiplexer 119. The TLV (GSE) / multiplexer 119 also receives a TLV (GSE) packet in which signaling information is placed in the payload portion from the TLV (GSE) signaling generation unit 117.

  The TLV (GSE) multiplexer 119 multiplexes the TLV (GSE) packets generated by the IP service multiplexers 118-1 to 118 -N and the TLV (GSE) signaling generator 117, thereby generating an MMT broadcast stream. Generated. This broadcast stream is sent to the modulation / transmission unit 120. The modulation / transmission unit 120 performs RF modulation processing on the MMT broadcast stream, and sends the RF modulation signal to the RF transmission path.

  FIG. 11 shows a configuration example of the receiver 200. This receiver 200 includes a tuner / demodulator 201, a TLV (GSE) / demultiplexer 202, a clock unit 203, a video decoder 204, an audio decoder 205, a caption decoder 206, a system controller 207, Part 208.

  The tuner / demodulator 201 receives the RF modulation signal, performs demodulation processing, and obtains an RTP or MMT broadcast stream (see FIGS. 6C and 8E). The TLV (GSE) / demultiplexer 202 performs demultiplex processing and depacketization processing on this broadcast stream to generate NTP time information, PTS, signaling information, and also video, audio, and caption encoded signals. Output.

  The system control unit 207 controls each unit of the receiver 200 based on signaling information, PTS, and the like obtained by the TLV (GSE) / demultiplexer 202. The clock unit 203 generates time information synchronized with the time information based on the NTP time information obtained by the TLV (GSE) / demultiplexer 202.

  The video decoder 204 decodes the encoded video signal obtained by the TLV (GSE) / demultiplexer 202 to obtain a baseband video signal. The audio decoder 205 decodes the encoded audio signal obtained by the TLV (GSE) / demultiplexer 202 to obtain a baseband audio signal. Further, the caption decoder 206 decodes the encoded subtitle signal obtained by the TLV (GSE) / demultiplexer 202 to obtain a subtitle display signal.

  The system control unit 207 controls the decoding timing in each decoder based on PTS (presentation time information), and adjusts the presentation timing of video, audio, and subtitles. The synthesizer 208 synthesizes a subtitle display signal with the baseband video signal to obtain a video signal for video display. Note that the baseband audio signal obtained by the audio decoder 205 is an audio signal for audio output.

  The operation of the receiver 200 shown in FIG. 11 will be briefly described. The tuner / demodulator 201 receives an RF modulated signal sent through the RF transmission path, performs demodulation processing, and broadcasts the RTP system or MMT system (see FIGS. 6C and 8E). ) Is obtained. This broadcast stream is sent to the TLV (GSE) / demultiplexer 202.

  In this TLV (GSE) / demultiplexer 202, demultiplex processing and depacketization processing are performed on this broadcast stream, and NTP time information, PTS, signaling information, as well as video, audio, and caption encoded signals. Is extracted.

  The NTP time information extracted by the TLV (GSE) / demultiplexer 202 is sent to the clock unit 203. In the clock unit 203, time information synchronized with the time information is generated based on the NTP time information. That is, the clock unit 203 reproduces time information that matches the time information generated by the clock units 101 and 111 of the broadcast transmission system 100.

The encoded video signal extracted by the TLV (GSE) / demultiplexer 202 is sent to the video decoder 204 and decoded to obtain a baseband video signal. The encoded subtitle signal extracted by the TLV (GSE) / demultiplexer 202 is sent to the caption decoder 206 to be decoded to obtain a subtitle display signal. Then, the video signal and the caption display signal are synthesized by the synthesis unit 208 to obtain a video signal for video display.
Also, the encoded audio signal extracted by the TLV (GSE) / demultiplexer 202 is sent to the audio decoder 205 and decoded to obtain a baseband audio signal for audio output.

  The PTS and signaling information extracted by the TLV (GSE) / demultiplexer 202 are sent to the system control unit 207. The system control unit 207 controls each unit of the receiver 200 based on the signaling information, PTS, and the like. In this case, for example, the decoding timing in each decoder is adjusted based on the PTS and time information generated by the clock unit 203, and the presentation timing of video, audio, and subtitles is also adjusted.

  Here, NTP (Network Time Protocol) will be described. NTP is a protocol defined as an Internet standard by ITU (International Telecommunication Union). Time information can be obtained by accessing an NTP server by a NTP protocol from a client such as a personal computer or a smartphone.

  As shown in FIG. 12A, the NTP server has a hierarchy (stratum), and the smaller the number, the higher the accuracy. For example, the NTP server of stratum 1 (Stratum 1) is directly connected to the atomic clock, and the time information error is less than 1 μs. The time information provided by the NTP server is expressed as an accumulated number of seconds (UTC: Coordinated Universal Time) from January 1, 1900.

  FIG. 12B shows a time information format (NTP time stamp format) provided by the NTP server. This time information is in a 64-bit format, with the upper 32 bits indicating UTC accumulated seconds and the lower 32 bits indicating less than seconds.

  When the time information is acquired by accessing the NTP server by the NTP protocol from a client such as a personal computer or a smartphone, it is unclear which NTP server is accessed. Therefore, by synchronously accessing a plurality of NTP servers and taking an average value, variation can be suppressed and more accurate time information can be obtained.

  13 and 14 show a clock synchronization / presentation synchronization method in the RTP method. FIG. 13 shows a configuration example on the broadcast transmission system 100 side. FIG. 14 shows a configuration example on the receiver 200 side.

  Initially, with reference to FIG. 13, the structural example by the side of the broadcast transmission system 100 is demonstrated. The broadcast transmission system 100 includes an NTP / IP interface 131 and 32-bit registers 132a and 132b. The broadcast transmission system 100 also includes a voltage-controlled oscillator 133 that generates a 27 MHz clock (system clock), a 9-bit counter 134a, a 17-bit counter 134b, and a 32-bit counter 134c that form a clock unit, and a bit conversion unit 135. And a comparator 136. The broadcast transmission system 100 also includes a packetizing unit 137, a video encoding processing unit 138, a packetization / time stamp adding unit 139, an encoding buffer 140, and a multiplexer 141.

  The NTP / IP interface 131 accesses an NTP server (not shown) via the Internet at a predetermined time interval, and acquires time information in 64-bit format (see FIG. 12B). The 32-bit registers 132a and 132b hold 64-bit format time information acquired by the NTP / IP interface 131. The 32-bit register 132a holds upper 32 bits of bit data, and the 32-bit register 132b holds lower 32 bits of bit data. The contents held in the 32-bit registers 132a and 132b are updated each time the 64-bit format time information is acquired by the NTP / IP interface 131.

  If the frequency of acquiring the time information is sufficiently high, the configuration may remain as it is. However, if the frequency is low, the registers 132a and 132b automatically continue to operate as a counter indicating the time so as to reproduce the clock of the NTP server. It is also possible. Here, when the output of the register 132b indicating the lower 32 bits of the acquired time information becomes all 0s, the output of the register 132a indicating the upper 32 bits of the time information is set as an initial value of the 32-bit counter 134c. The 17-bit counter 134b and the 9-bit counter 134a are all set to 0. This setting operation is limited to one time when the broadcast transmission system 100 starts operation.

  The voltage controlled oscillator 133 generates a 27 MHz clock (system clock). In the 9-bit counter 134a, the 27 MHz clock output from the voltage controlled oscillator 133 is counted, divided by 300, and a 90 KHz clock is output. The 17-bit counter 134b counts the 90 KHz clock output from the 9-bit counter 134a, divides the frequency by 90000, and outputs a 1 Hz clock. In the 32-bit counter 134c, the 1-Hz clock output from the 17-bit counter 134b is counted, and a 32-bit bit output that is time information (Regenerated UTC) with second accuracy is obtained.

  The 58-bit bit output of the 9-bit counter 134a, the 17-bit counter 134b, and the 32-bit counter 134c becomes a system time clock (STC) as time information by the counter operation from the initial value. This system time clock is input to the bit conversion unit 135. In the bit conversion unit 135, for example, a conversion table is used, and the bit output of the 9-bit counter 134a and the 17-bit counter 134b is converted into a 32-bit output that is continuous with the lower bits of the bit output of the 32-bit counter 134c. The This conversion is performed to correspond to the lower 32 bits of the time information in the 64-bit format obtained from the NTP server. The bit conversion unit 135 obtains a 64-bit output that combines the 32-bit output converted in this way and the bit output of the 32-bit counter 134c.

  In the comparator 136, the 64-bit bit output from the bit conversion unit 135 is latched at the timing when the held contents of the 32-bit registers 132a and 132b are updated, and the register holding contents, that is, the 64-bit format obtained from the NTP server are latched. Compared with time information. Then, a comparison error signal is supplied from the comparator 136 to the voltage controlled oscillator 133 as a control signal.

  Here, the voltage controlled oscillator 133, the counters 134a, 134b, 134c, the bit converter 134, and the comparator 136 constitute a PLL (Phase Locked Loop) circuit. Therefore, the voltage controlled oscillator 133 generates a 27 MHz clock (system clock) synchronized with the time information in the 64-bit format acquired from the NTP server. The counters 134a, 134b, and 134c generate 58-bit time information that includes the 27-MHz clock frequency information and is synchronized with the 64-bit format time information acquired from the NTP server.

  The 58-bit time information is supplied to the packetizing unit 137. Based on the 58-bit time information, the packetizing unit 137 generates an IP packet including an NTP clock reference (NTP_CR) having frequency information of a 27 MHz clock. FIG. 15A shows the configuration of this NTP clock reference.

  In the video encoding processing unit 138, video (video data) is encoded in synchronization with the 27 MHz clock obtained by the voltage controlled oscillator 133. The packetization / time stamp addition unit 139 divides the encoded video elementary stream into chunks of a predetermined size, and generates RTP packets (RTP packets) each containing the chunks in the payload portion. The RTP packet is supplied to the multiplexer 141 through the encode buffer 140.

  The packetization / time stamp adding unit 139 is supplied with the lower 15-bit bit output of the 32-bit counter 134c and the 17-bit bit output of the 17-bit counter 134b. Based on this 32-bit output, the packetization / time stamp adding unit 139, for example, provides presentation time information (PTS) corresponding to the encoded data of each picture of video output from the video encoding processing unit 138. A 32-bit timestamp is generated.

  The time stamp value is, for example, a value obtained by adding the fixed delay amount by the encode buffer and the decode buffer to the time information of the picture output timing from the video encoding processing unit 138. The packetization / time stamp adding unit 139 inserts a time stamp (Timestamp) as the presentation time information (PTS) into the header of each RTP packet. FIG. 15B shows the structure of this time stamp.

  As described above, the multiplexer 141 is supplied with the IP packet including the NTP clock reference and the RTP packet including the encoded video. Although illustration is omitted, an RTP packet including encoded audio and the like is generated in the same manner as an RTP packet including encoded video and supplied to the multiplexer 141. The multiplexer 141 further adds a necessary header to each packet and generates an RTP broadcast stream. This RTP broadcast stream is transmitted as a broadcast signal.

  Next, a configuration example on the receiver 200 side will be described with reference to FIG. The receiver 200 includes a demultiplexer 231, a voltage controlled oscillator 232 that generates a 27 MHz clock (system clock), a 9-bit counter 233a, a 17-bit counter 233b, and a 32-bit counter 233c that constitute a clock unit, and a comparator. 234. In addition, the receiver 200 includes a decode buffer 235, a depacketization unit 236, a presentation control unit 237, and a video decode processing unit 238.

  The demultiplexer 231 is supplied with an RTP broadcast stream (see FIG. 6C) that is a received broadcast signal. The demultiplexer 231 extracts the NTP_CR from the IP packet including the NTP clock reference (NTP_CR). At the time of channel selection or power-on, the 58-bit NTP_CR received first is set as an initial value in the 58-bit counter consisting of the counter 233a, the counter 233b, and the counter 233c. 234.

  The 27 MHz clock generated by the voltage controlled oscillator 232 is counted by the 9-bit counter 233a and divided by 300. The 90 KHz clock obtained by the 9-bit counter 233a is counted by the 17-bit counter 233b and divided by 90000. The 1 Hz clock obtained by the 17-bit counter 233b is counted by the 32-bit counter 233c. The 32-bit counter 233c obtains a 32-bit bit output that is time information (Regenerated UTC) with second precision.

  The 58-bit bit output of the 9-bit counter 233a, the 17-bit counter 233b, and the 32-bit counter 233c is a system time clock (STC) as time information. This system time clock is supplied to the comparator 234. In the comparator 234, for example, at the timing when NTP_CR is supplied from the demultiplexer 231, the system time clock is latched and compared with NTP_CR.

  The comparison error signal output from the comparator 234 is supplied to the voltage controlled oscillator 232 as a control signal. Here, the voltage controlled oscillator 232, the counters 233a, 233b, 233c and the comparator 234 constitute a PLL (Phase Locked Loop) circuit. Therefore, the voltage controlled oscillator 232 generates a 27 MHz clock synchronized with NTP_CR. The frequency of the 27 MHz clock becomes equal to the frequency of the clock generated by the voltage controlled oscillator 133 of the broadcast transmission system 100 described above, and clock synchronization is realized.

  The counters 233a, 233b, and 233c generate a system time clock that is synchronized with the NTP_CR. This system time clock matches the system time clock generated by the counters 134a, 134b, 134c of the broadcast transmission system 100 described above. For this reason, as described above, in the RTP broadcast stream, presentation synchronization is realized in combination with insertion of a time stamp as presentation time information in the header of an RTP packet including transmission media such as video and audio.

  Further, in the demultiplexer 231, RTP packets including encoded video are extracted and temporarily stored in the decode buffer 235. Further, the lower 15-bit bit output of the 32-bit counter 233 c and the 17-bit bit output of the 17-bit counter 233 b are supplied to the presentation control unit 237.

  In the presentation control unit 237, a time stamp as presentation time information (PTS) inserted in the header part of each RTP packet stored in the decode buffer 235 is confirmed through the depacketization unit 236. Then, the presentation control unit 237 refers to the system time clock, and sequentially takes RTP packets to be decoded from the decoding buffer 235 into the video decoding processing unit 238 through the depacketizing unit 236.

  In the video decoding processing unit 238, the encoded video is decoded, and baseband video data is obtained. Then, the receiver 200 performs video display using the video data. Although not shown in the figure, the demultiplexer 231 also extracts RTP packets including encoded audio and processes them in the same manner as in the case of the video described above to obtain baseband audio data. Is called.

  16 and 17 show the clock synchronization / presentation synchronization method in the MMT method. FIG. 16 shows a configuration example on the broadcast transmission system 100 side. FIG. 17 illustrates a configuration example on the receiver 200 side.

  First, a configuration example on the broadcast transmission system 100 side will be described with reference to FIG. In FIG. 16, parts corresponding to those in FIG. 13 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate. The broadcast transmission system 100 includes an NTP / IP interface 131 and 32-bit registers 132a and 132b. The broadcast transmission system 100 also includes a voltage-controlled oscillator 133 that generates a 27 MHz clock (system clock), a 9-bit counter 134a, a 17-bit counter 134b, and a 32-bit counter 134c that form a clock unit, and a bit conversion unit 135. And a comparator 136. The broadcast transmission system 100 also includes a packetizing unit 137, a video encoding processing unit 138, a packetizing unit 151, a time stamp generating unit 152, a packetizing unit 153, an encoding buffer 140, and a multiplexer 141. doing.

  Similarly to the broadcast transmission system 100 shown in FIG. 13 described above, when the output of the register 132b indicating the lower 32 bits of the time information acquired by the NTP / IP interface 131 becomes all 0s, the upper 32 bits of the time information are changed. The output of the indicated register 132a is set as the initial value of the 32-bit counter 134c, and the 17-bit counter 134b and the 9-bit counter 134a are all set to 0. This setting operation is limited to one time when the broadcast transmission system 100 starts operation.

  The voltage controlled oscillator 133, the counters 134a, 134b, and 134c, the bit conversion unit 134, and the comparator 136 constitute a PLL (Phase Locked Loop) circuit. Therefore, the voltage controlled oscillator 133 generates a 27 MHz clock (system clock) synchronized with the time information in the 64-bit format acquired from the NTP server. The counters 134a, 134b, and 134c generate 58-bit time information that includes the 27-MHz clock frequency information and is synchronized with the 64-bit format time information acquired from the NTP server.

  The 58-bit time information is supplied to the packet unit 137. Based on the 58-bit time information, the packetizing unit 137 generates an IP packet including an NTP clock reference (NTP_CR) having frequency information of a 27 MHz clock. FIG. 18A shows the configuration of the NTP clock reference.

  In the video encoding processing unit 138, video (video data) is encoded in synchronization with the 27 MHz clock obtained by the voltage controlled oscillator 133. The packetizing unit 151 divides the encoded video elementary stream into chunks having a predetermined size, and generates MMT packets (MMT packets) including the chunks in the payload portion. This MMT packet is supplied to the multiplexer 141 through the encode buffer 140.

  The time stamp generator 152 is supplied with the 32-bit output of the 32-bit counter 134c and the 17-bit output of the 17-bit counter 134b, or the lower 15-bit output of the 32-bit counter 134c, and the 17-bit output of the 17-bit counter 134b. Is done.

  In the time stamp generation unit 152, for example, a 49-bit or 32-bit time stamp (Timestamp) as presentation time information (PTS) corresponding to the encoded data of each picture of the video output from the video encoding processing unit 138 is provided. Generated. FIG. 18B shows the structure of this time stamp. The time stamp value is, for example, a value obtained by adding the fixed delay amount by the encode buffer and the decode buffer to the time information of the picture output timing from the video encoding processing unit 138.

  A time stamp (Timestamp) as presentation time information (PTS) generated by the time stamp generating unit 152 is supplied to the packetizing unit 153. The packetizing unit 153 generates an MMT packet including this time stamp in the payload portion. The MMT packet is supplied to the multiplexer 141.

  As described above, the multiplexer 141 is supplied with the IP packet including the NTP / clock reference, the MMT packet including the encoded video, and the MMT packet including the time stamp. Although illustration is omitted, an MMT packet including encoded audio and the like is generated in the same manner as the MMT packet including encoded video and supplied to the multiplexer 141. The multiplexer 141 further adds a necessary header to each packet, and generates an MMT broadcast stream. This MMT broadcast stream is transmitted as a broadcast signal.

  Next, a configuration example on the receiver 200 side will be described with reference to FIG. In FIG. 17, portions corresponding to those in FIG. 14 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate. The receiver 200 includes a demultiplexer 231, a voltage-controlled oscillator 232 that generates a 27 MHz clock (system clock), a 9-bit counter 233a, a 17-bit counter 233b, and a 32-bit count 233c that form a clock, and a comparator 234. have. The receiver 200 also includes a decode buffer 235, a depacketization unit 251, a presentation control unit 237, and a video encoding processing unit 238.

  The demultiplexer 231 is supplied with an RTP broadcast stream (see FIG. 7C) that is a received broadcast signal. The demultiplexer 231 extracts the NTP_CR from the IP packet including the NTP clock reference (NTP_CR). At the time of channel selection or power-on, the 58-bit NTP_CR received first is set as an initial value in the 58-bit counter consisting of the counter 233a, the counter 233b, and the counter 233c. 234.

  Voltage controlled oscillator 232, counters 233a, 233b, 233c and comparator 234 constitute a PLL (Phase Locked Loop) circuit. Therefore, the voltage controlled oscillator 232 generates a 27 MHz clock synchronized with NTP_CR. The frequency of the 27 MHz clock becomes equal to the frequency of the clock generated by the voltage controlled oscillator 133 of the broadcast transmission system 100 described above, and clock synchronization is realized.

  The counters 233a, 233b, and 233c generate a system time clock that is synchronized with the NTP_CR. This system time clock matches the system time clock generated by the counters 134a, 134b, 134c of the broadcast transmission system 100 described above. Therefore, as described above, in the MMT broadcast stream, the presentation synchronization is coupled with the insertion of the MMT packet including the time stamp (Timestamp) as the presentation time information (PTS) of transmission media such as video and audio. Realized.

  The MMT packet including the encoded video extracted by the demultiplexer 231 is temporarily stored in the decode buffer 235. The 32-bit output of the 32-bit counter 134c and the 17-bit output of the 17-bit counter 134b, or the lower-order 15-bit output of the 32-bit counter 134c, and the 17-bit output of the 17-bit counter 134b are used as a system time clock. It is supplied to the presentation control unit 237.

  In the presentation control unit 237, through the depacketization unit 251, based on the MMT packet including the time stamp (Timestamp) as the presentation time information (PTS) accumulated in the decode buffer 235, each MMT packet including the encoded video is transmitted. The presentation time is confirmed. The presentation control unit 237 refers to the system time clock and sequentially takes MMT packets to be decoded from the decoding buffer 235 through the depacketization unit 251 into the video decoding processing unit 238.

  In the video decoding processing unit 238, the encoded video is decoded, and baseband video data is obtained. Then, the receiver 200 performs video display using the video data. Although not shown, the demultiplexer 231 also extracts MMT packets including encoded audio, and processes them in the same manner as in the case of the video described above to obtain baseband audio data. Is called.

  As described above, in the transmission / reception system 10 shown in FIG. 1, the 27 MHz signal synchronized with the time information acquired from the NTP server in the IP broadcast signal (for example, RTP broadcast stream, MMT broadcast stream, etc.). Time information (NTP_CR) including clock frequency information is included. Therefore, on the receiving side, a 27 MHz clock (system clock) similar to that on the transmitting side can be generated based on this time information, and clock synchronization can be realized.

  Further, in the transmission / reception system 10 shown in FIG. 1, a transmission media presentation unit obtained based on time information (system time clock) synchronized with time information acquired from an NTP server in addition to an IP broadcast signal. Each presentation time information (PTS) is included. Therefore, on the receiving side, time information (system time clock) including the frequency information of the 27 MHz clock generated in synchronization with the time information included in the transmission signal, and presentation time information for each transmission media presentation unit ( Presentation synchronization can be realized based on (PTS).

  In the transmission / reception system 10 shown in FIG. 1, the system time clock (STC) of the broadcast transmission system 100 and the receiver 200 matches the time information of NTP. Therefore, for example, on the receiving side, one screen can be easily configured using videos obtained through a plurality of paths.

<2. Modification>
In the above embodiment, the IP system broadcast signal received by the receiver 200 is not the time information itself acquired from the NTP server, but the time information including the frequency information of the 27 MHz clock synchronized with the time information. It has been described as having (NTP_CR). However, there may be a case where the time information itself acquired from the NTP server is included as an IP broadcast signal received by the receiver 200.

  FIG. 19A shows a structure of time information in a 64-bit format acquired from the NTP server. FIG. 19B shows the configuration of NTP_CR. In this NTP_CR configuration, 6-bit all-zero data is added to the lower order of the 9-bit output, and the 64-bit format is formed as a whole. Thus, the 64-bit format time information acquired from the NTP server has a bit configuration different from that of the NTP_CR.

  Therefore, when the time information in the 64-bit format acquired from the NTP server is included as time information in the IP broadcast signal, the PLL circuit of the above-described receiver 200 (see FIGS. 14 and 17) does not operate normally. . Therefore, for example, in the case of the MMT system, as the signaling information, identification information for identifying whether the time information included in the broadcast signal is the time information in the 64-bit format acquired from the NTP server or NTP_CR ( Flag information). On the receiving side, based on this identification information, the operation of the PLL circuit portion can be switched to prevent malfunction.

  FIG. 20 shows a configuration example of the receiver 200 in that case. In FIG. 20, portions corresponding to those in FIG. 17 are denoted by the same reference numerals. When the identification information indicates that the identification information is NTP_CR, the selector 261 sends the comparison error signal output from the comparator 234 to the voltage controlled oscillator 232 as a control signal. In this case, the configuration is the same as that in FIG. 17, and the voltage controlled oscillator 232 generates a 27 MHz clock synchronized with NTP_CR by the PLL circuit. On the other hand, when the identification information indicates that the time information is in 64-bit format acquired from the NTP server, the selector 261 sends a fixed value to the voltage controlled oscillator 232 as a control signal. In this case, the voltage controlled oscillator 232 is in a free run state.

  Further, when the identification information indicates that the identification information is NTP_CR, among the counters operated by the voltage controlled oscillator 232, the selector 263 sends the 49 bits output of the counters 233 c and 233 b to the presentation control unit 237. On the other hand, when the identification information indicates that the identification information is time information in 64-bit format acquired from the NTP server, the selector 263 latches the received 64-bit register 261a. The upper 49 bits of the output of 261b are sent to the presentation control unit 237.

  In this modification, when the initial values of the counter 233a, the counter 233b, and 233c are given, at the time of channel selection and power-on, the lower 32 bits of the 64-bit NTP data shown in FIGS. 19A and 19B are received. When the bit output becomes all 0s, the upper 32 bits output of the time information is set as the initial value of the 32-bit counter 233c, and the 17-bit counter 233b and the 9-bit counter 233a are all set to 0, respectively.

  In the above embodiment, the time information (NTP_CR) includes the frequency information of the 27 MHz clock synchronized with the time information in the IP broadcast signal, not the time information itself in the 64-bit format acquired from the NTP server. ) Is included. However, the receiving side includes the time information in the 64-bit format acquired from the NTP server in the IP broadcast signal, and the receiving side generates a 27 MHz clock having the same frequency as the transmitting side based on the time information. It is also conceivable to generate a system time clock that matches the system time clock.

  21 and 22 show an example of the clock synchronization / presentation synchronization method in that case. FIG. 21 shows a configuration example on the broadcast transmission system 100 side. FIG. 22 shows a configuration example on the receiver 200 side. Here, the MMT method will be described. Although the description is omitted, the same applies to the RTP method.

  First, a configuration example on the broadcast transmission system 100 side will be described with reference to FIG. In FIG. 21, portions corresponding to those in FIG. 16 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate. In this broadcast transmission system 100, the packetizing unit 137 is supplied with time information in 64-bit format acquired from the NTP server from the registers 132a and 132b. In the packetizing unit 137, an IP packet including the time information in the 64-bit format is generated and sent to the multiplexer 141.

  As a result, the MMT broadcast stream generated by the multiplexer 141 includes time information in 64-bit format acquired from the NTP server. FIG. 23A shows the structure of time information in a 64-bit format. FIG. 23B shows a structure of a time stamp generated by the time stamp generating unit 152. 21 is configured in the same manner as in FIG.

  Next, a configuration example on the receiver 200 side will be described with reference to FIG. In FIG. 22, parts corresponding to those in FIG. 17 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate. The 64-bit format time information (see FIG. 12B) extracted by the demultiplexer 231 is held in the 32-bit registers 261a and 261b. The 32-bit register 261a holds upper 32-bit bit data, and the 32-bit register 261b holds lower 32-bit bit data. The contents held in the 32-bit registers 261a and 262b are updated each time 64-bit format time information is extracted by the demultiplexer 231.

  The 58-bit bit output of the 9-bit counter 233a, the 17-bit counter 233b, and the 32-bit counter 233c is a system time clock (STC) as time information. This system time clock is input to the bit conversion unit 262. In the bit conversion unit 262, for example, a conversion table is used, and the bit output of the 9-bit counter 233a and the 17-bit counter 233b is converted into a 32-bit output continuous to the lower order of the bit output of the 32-bit counter 233c. The This conversion is performed to correspond to the lower 32 bits of the time information in the 64-bit format obtained from the NTP server. The bit conversion unit 262 obtains a 64-bit output that combines the 32-bit output converted in this way and the bit output of the 32-bit counter 233c.

  The comparator 234 latches the 64-bit bit output from the bit conversion unit 262 at the timing when the contents held in the 32-bit registers 261a and 261b are updated, and the 64-bit format extracted from the contents held in the register, that is, the MTT broadcast stream. Is compared with the time information. Then, a comparison error signal is supplied from the comparator 234 to the voltage controlled oscillator 232 as a control signal.

  Here, the voltage controlled oscillator 232, the counters 233a, 233b, and 233c, the bit conversion unit 262, and the comparator 234 form a PLL (Phase Locked Loop) circuit similar to that on the transmission side. Therefore, the voltage controlled oscillator 232 generates a 27 MHz clock (system clock) synchronized with the time information in the 64-bit format extracted from the MTT broadcast stream.

  In this modification, when the initial values of the counter 233a, the counter 233b, and the counter 233c are given, the lower 32 bits of the received 64-bit NTP data in FIG. When the output of the register 261b becomes all 0s, the output of the register 261a indicating the upper 32 bits of the time information is set as the initial value of the 32-bit counter 233c, and the 17-bit counter 233b and the 9-bit counter 233a are all set. Set to 0.

  The counters 233a, 233b, and 233c include 58-bit time information (system time clock) that includes the 27-MHz clock frequency information and is synchronized with the 64-bit format time information extracted from the MTT broadcast stream. Generated. The other parts in FIG. 22 are configured in the same manner as in FIG.

  Even in the clock synchronization / presentation synchronization method (MMT method) shown in FIGS. 21 and 22, clock synchronization and presentation synchronization can be realized in the same manner as the clock synchronization / presentation synchronization method (MMT method) in FIGS. .

Moreover, this technique can also take the following structures.
(1) a clock generation unit that generates a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generation unit that generates time information synchronized with the time information acquired from the time information server including the frequency information of the 27 MHz clock generated by the clock generation unit;
The transmission media, the presentation time information for each presentation unit of the transmission media obtained based on the time information generated by the time information generation unit, and the time information generated by the time information generation unit or the time information server A transmission unit that transmits an IP broadcast signal including time information acquired from the transmission device.
(2) The broadcast signal is
A first transmission packet encapsulating the IP packet including the transmission medium, and a second encapsulating the IP packet including the time information generated by the time information generation unit or the time information acquired from the time information server. The transmission device according to (1), including:
(3) The transmission device according to (2), wherein the IP packet in the first transmission packet further includes the presentation time information of the transmission medium included in the IP packet.
(4) The transmission device according to (3), wherein the IP packet in the first transmission packet includes an RTP packet in which the transmission medium is arranged in a payload portion.
(5) The broadcast signal is
The transmission device according to (2), including a third transmission packet encapsulating an IP packet including the presentation time information of the transmission medium included in the IP packet in the first transmission packet.
(6) The IP packet in the first transmission packet includes an MMT packet in which the transmission medium is arranged in a payload portion,
The transmission device according to (5), wherein the IP packet in the second transmission packet includes an MMT packet in which the presentation time information is arranged in a payload portion.
(7) The time information generation unit
A 9-bit counter that counts the frequency of 27 MHz generated by the clock generation unit and divides it by 300, a 17-bit counter that counts the divided output of the 9-bit counter and divides it by 90000, The transmission device according to any one of (1) to (6), further including a 32-bit counter that counts the divided output.
(8) The clock generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
Of the bit outputs of the 9-bit counter, the 17-bit counter, and the 32-bit counter, the bit outputs of the 9-bit counter and the 17-bit counter are converted into 32-bit outputs that are consecutively lower than the bit outputs of the 32-bit counter. A bit conversion unit for converting and obtaining a 64-bit output by combining the converted 32-bit output and the bit output of the 32-bit counter;
A comparator that compares the 64-bit output obtained by the bit conversion unit with the time information acquired from the time information server, and provides a control signal corresponding to the difference value to the voltage controlled oscillator;
The time information generator is
The transmission device according to any one of (1) to (7), including the 9-bit counter, the 17-bit counter, and the 32-bit counter.
(9) The broadcast signal is
Any one of (1) to (8) further including identification information indicating whether the time information included is the time information generated by the time information generation unit or the time information acquired from the time information server A transmitting device according to claim 1.
(10) a clock generation step of generating a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generating step for generating time information synchronized with the time information acquired from the time information server including the frequency information of the generated 27 MHz clock;
IP including transmission media, presentation time information for each presentation unit of the transmission media obtained based on the generated time information, and the generated time information or time information acquired from the time information server A transmission method comprising: a transmission step of transmitting a broadcast signal of a format.
(11) A receiving unit that receives an IP broadcast signal including a transmission medium, presentation time information for each presentation unit of the transmission medium, and time information related to the time information acquired from the time information server;
Based on the time information related to the time information acquired from the time information server included in the broadcast signal, a clock for generating time information including the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information. A time information generator,
A receiving apparatus comprising: a processing unit that processes transmission media included in the broadcast signal based on presentation time information included in the broadcast signal and a clock and time information generated by the clock / time information generation unit.
(12) The time information related to the time information acquired from the time information server included in the broadcast signal is time information including 27 MHz frequency information synchronized with the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
The bit output of the 9-bit counter, the 17-bit counter, and the 32-bit counter is compared with the time information related to the time information acquired from the time information server included in the broadcast signal, and as a control signal to the voltage-controlled oscillator The receiving device according to (11), further including a comparator that obtains an error signal to be supplied.
(13) The time information related to the time information acquired from the time information server included in the broadcast signal is time information including 27 MHz frequency information synchronized with the time information acquired from the time information server or the time information. It is the same time information as the time information obtained from the server,
The broadcast signal is first time information in which time information related to the time information acquired from the time information server includes 27 MHz frequency information synchronized with the time information acquired from the time information server, It further has identification information indicating whether the time information is the same as the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
The bit output of the 9-bit counter, the 17-bit counter, and the 32-bit counter is compared with the time information related to the time information acquired from the time information server included in the broadcast signal, and as a control signal to the voltage-controlled oscillator A comparator for obtaining an error signal to be supplied;
When the identification information indicates the first time information, an error signal obtained by the comparator is supplied as a control signal to the voltage controlled oscillator, and when the identification information indicates the second time information, a fixed value is set. The receiving device according to (11), further including a selector that supplies a voltage-controlled oscillator as a control signal.
(14) The time information related to the time information acquired from the time information server included in the broadcast signal is the same time information as the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter for counting the divided output of the 9-bit counter and dividing it by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
Of the bit outputs of the 9-bit counter, the 17-bit counter, and the 32-bit counter, the bit outputs of the 9-bit counter and the 17-bit counter are converted into 32-bit outputs that are consecutively lower than the bit outputs of the 32-bit counter. A bit conversion unit for converting and obtaining a 64-bit output by combining the converted 32-bit output and the bit output of the 32-bit counter;
A comparator that compares the 64-bit output obtained by the bit conversion unit with the time information obtained from the time information server and obtains an error signal to be supplied as a control signal to the voltage controlled oscillator; The transmitting device according to 1.
(15) The broadcast signal is
A first transmission packet encapsulating an IP packet including the transmission medium; and a second transmission packet encapsulating an IP packet including time information related to time information acquired from the time information server. (11) The transmission device according to any one of (14).
(16) The transmission device according to (15), wherein the IP packet in the first transmission packet further includes the presentation time information of the transmission medium included in the IP packet.
(17) The broadcast signal is
The transmission device according to (15), including a third transmission packet encapsulating the IP packet including the presentation time information of the transmission medium included in the IP packet in the first transmission packet.
(18) A reception step of receiving an IP broadcast signal including a transmission medium, presentation time information for each presentation unit of the transmission medium, and time information related to the time information acquired from the time information server;
Based on the time information related to the time information acquired from the time information server included in the broadcast signal, a clock for generating time information including the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information.・ Time information generation step,
A receiving method comprising: processing the transmission medium included in the broadcast signal based on the presentation time information included in the broadcast signal and the generated clock and time information.
(19) It consists of a transmitting device and a receiving device,
The transmitter is
A clock generator for generating a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generation unit that generates time information synchronized with the time information acquired from the time information server including the frequency information of the 27 MHz clock generated by the clock generation unit;
The transmission media, the presentation time information for each presentation unit of the transmission media obtained based on the time information generated by the time information generation unit, and the time information generated by the time information generation unit or the time information server A transmission unit that transmits an IP broadcast signal including time information acquired from
The receiving device
A receiving unit for receiving the IP system broadcast signal;
A clock / time information generating unit that generates time information including a 27 MHz clock and frequency information of the 27 MHz clock synchronized with the time information based on the time information included in the broadcast signal;
A transmission / reception system comprising: a transmission medium included in the broadcast signal; and a processing unit that processes presentation time information included in the broadcast signal and a clock and time information generated by the clock / time information generation unit.

  The main feature of this technology is that it is synchronized with the time information in 64-bit format acquired from the time information related to the time information acquired from the NTP server (time information server) in the IP broadcast signal or the time information. The clock synchronization can be realized by including the time information including the frequency information of the 27 MHz clock (see FIGS. 5 and 7).

DESCRIPTION OF SYMBOLS 10 ... Transmission / reception system 11 ... Clock generation part 12 ... Clock part (time information generation part)
DESCRIPTION OF SYMBOLS 13 ... Encoding process part 14 ... Packetization / time stamp addition part 15 ... Encoding buffer 21 ... Clock generation part 22 ... Clock part (Time information generation part)
DESCRIPTION OF SYMBOLS 23 ... Decoding buffer 24 ... Depacketization / timing adjustment part 25 ... Decoding processing part 100 ... Broadcast transmission system 101 ... Clock part 102 ... Signal transmission part 103 ... Video encoder 104 ... Audio encoder 105 ... Caption encoder 106 ... TLV (GSE) signaling generator 107-1 to 107-N ... IP service multiplexer 108 ... TLV (GSE) multiplexer 109 ... Modulation / transmission unit 111 ... clock unit 112 ... signal transmission unit 113 ... video encoder 114 ... audio encoder 115 ... caption encoder 116 ... signaling generation unit 117 ... TLV (GSE) Signaling generator 118-1 to 118-N ... IP server Screw multiplexer 119 ... Multiplexer 120 ... Modulation / transmission unit 131 ... NTP / IP interface 132a, 132b ... 32 bit register 133 ... Voltage controlled oscillator 134a ... 9 bit counter 134b ... 17-bit counter 134c ... 32-bit counter 135 ... bit converter 136 ... comparator 137 ... packetizer 138 ... video encode processor 139 ... packetization / timestamp adder 140 ... Encode buffer 141 ... Multiplexer 151 ... Packetization unit 152 ... Time stamp generation unit 153 ... Packetization unit 200 ... Receiver 201 ... Tuner / demodulation unit 202 ... · TLV (GSE) · Demultiplexer 203 · · · Total unit 204 ... Video decoder 205 ... Audio decoder 206 ... Caption decoder 207 ... System control unit 208 ... Synthesis unit 231 ... Demultiplexer 232 ... Voltage controlled oscillator 233a ... 9-bit counter 233b ... 17-bit counter 233c ... 32-bit counter 234 ... comparator 235 ... decode buffer 236 ... depacketizer 237 ... presentation controller 238 ... video decode processing Unit 251 ... depacketization unit 261 ... selector 262 ... bit conversion unit 263 ... selector

Claims (18)

A clock generator for generating a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generation unit that generates time information synchronized with the time information acquired from the time information server including the frequency information of the 27 MHz clock generated by the clock generation unit;
The transmission media, the presentation time information for each presentation unit of the transmission media obtained based on the time information generated by the time information generation unit, and the time information generated by the time information generation unit or the time information server A transmission unit that transmits an IP broadcast signal including time information acquired from the transmission device. The broadcast signal is
A first transmission packet encapsulating the IP packet including the transmission medium, and a second encapsulating the IP packet including the time information generated by the time information generation unit or the time information acquired from the time information server. The transmission apparatus according to claim 1, further comprising: The transmission device according to claim 2, wherein an IP packet in the first transmission packet further includes the presentation time information of a transmission medium included in the IP packet. The transmission device according to claim 3, wherein the IP packet in the first transmission packet includes an RTP packet in which the transmission medium is arranged in a payload portion. The broadcast signal is
The transmission apparatus according to claim 2, further comprising: a third transmission packet encapsulating the IP packet including the presentation time information of the transmission medium included in the IP packet in the first transmission packet. The IP packet in the first transmission packet includes an MMT packet in which the transmission medium is arranged in a payload portion,
The transmission device according to claim 5, wherein the IP packet in the second transmission packet includes an MMT packet in which the presentation time information is arranged in a payload portion. The time information generator is
A 9-bit counter that counts the frequency of 27 MHz generated by the clock generation unit and divides it by 300, a 17-bit counter that counts the divided output of the 9-bit counter and divides it by 90000, The transmission device according to claim 1, further comprising a 32-bit counter that counts the divided output. The clock generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
Of the bit outputs of the 9-bit counter, the 17-bit counter, and the 32-bit counter, the bit outputs of the 9-bit counter and the 17-bit counter are converted into 32-bit outputs that are consecutively lower than the bit outputs of the 32-bit counter. A bit conversion unit for converting and obtaining a 64-bit output by combining the converted 32-bit output and the bit output of the 32-bit counter;
A comparator that compares the 64-bit output obtained by the bit conversion unit with the time information acquired from the time information server, and provides a control signal corresponding to the difference value to the voltage controlled oscillator;
The time information generator is
The transmission device according to claim 1, comprising the 9-bit counter, the 17-bit counter, and the 32-bit counter. The broadcast signal is
The transmission device according to claim 1, further comprising identification information indicating whether the time information included is time information generated by the time information generation unit or time information acquired from the time information server. A clock generation step of generating a 27 MHz clock synchronized with the time information acquired from the time information server;
A time information generating step for generating time information synchronized with the time information acquired from the time information server including the frequency information of the generated 27 MHz clock;
IP including transmission media, presentation time information for each presentation unit of the transmission media obtained based on the generated time information, and the generated time information or time information acquired from the time information server A transmission method comprising: a transmission step of transmitting a broadcast signal of a format. A receiving unit that receives an IP broadcast signal including a transmission medium, presentation time information for each presentation unit of the transmission medium, and time information related to the time information acquired from the time information server;
Based on the time information related to the time information acquired from the time information server included in the broadcast signal, a clock for generating time information including the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information. A time information generator,
A receiving apparatus comprising: a processing unit that processes transmission media included in the broadcast signal based on presentation time information included in the broadcast signal and a clock and time information generated by the clock / time information generation unit. The time information related to the time information acquired from the time information server included in the broadcast signal is time information including 27 MHz frequency information synchronized with the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
The bit output of the 9-bit counter, the 17-bit counter, and the 32-bit counter is compared with the time information related to the time information acquired from the time information server included in the broadcast signal, and as a control signal to the voltage-controlled oscillator The receiving device according to claim 11, further comprising a comparator that obtains an error signal to be supplied. The time information related to the time information acquired from the time information server included in the broadcast signal is acquired from the time information including the 27 MHz frequency information synchronized with the time information acquired from the time information server or from the time information server. Is the same time information as
The broadcast signal is first time information in which time information related to the time information acquired from the time information server includes 27 MHz frequency information synchronized with the time information acquired from the time information server, It further has identification information indicating whether the time information is the same as the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
The bit output of the 9-bit counter, the 17-bit counter, and the 32-bit counter is compared with the time information related to the time information acquired from the time information server included in the broadcast signal, and as a control signal to the voltage-controlled oscillator A comparator for obtaining an error signal to be supplied;
When the identification information indicates the first time information, an error signal obtained by the comparator is supplied as a control signal to the voltage controlled oscillator, and when the identification information indicates the second time information, a fixed value is set. The receiving device according to claim 11, further comprising a selector that supplies the voltage controlled oscillator as a control signal. The time information related to the time information acquired from the time information server included in the broadcast signal is the same time information as the time information acquired from the time information server,
The clock / time information generator
A voltage controlled oscillator that outputs a 27 MHz clock;
A 9-bit counter that counts and divides the clock output of the voltage controlled oscillator by 300;
A 17-bit counter that counts the divided output of the 9-bit counter and divides the frequency by 90000;
A 32-bit counter that counts the divided output of the 17-bit counter;
Of the bit outputs of the 9-bit counter, the 17-bit counter, and the 32-bit counter, the bit outputs of the 9-bit counter and the 17-bit counter are converted into 32-bit outputs that are consecutively lower than the bit outputs of the 32-bit counter. A bit conversion unit for converting and obtaining a 64-bit output by combining the converted 32-bit output and the bit output of the 32-bit counter;
A comparator that compares the 64-bit output obtained by the bit conversion unit with time information acquired from the time information server and obtains an error signal to be supplied as a control signal to the voltage controlled oscillator. The transmitting device described. The broadcast signal is
A first transmission packet encapsulating the IP packet including the transmission medium, and a second transmission packet encapsulating the IP packet including time information related to the time information acquired from the time information server. Item 12. The transmission device according to Item 11. The transmission device according to claim 15, wherein the IP packet in the first transmission packet further includes the presentation time information of a transmission medium included in the IP packet. The broadcast signal is
The transmission device according to claim 15, further comprising a third transmission packet encapsulating the IP packet including the presentation time information of the transmission medium included in the IP packet in the first transmission packet. A reception step of receiving an IP broadcast signal including a transmission medium, presentation time information for each presentation unit of the transmission medium, and time information related to the time information acquired from the time information server;
Based on the time information related to the time information acquired from the time information server included in the broadcast signal, a clock for generating time information including the 27 MHz clock and the frequency information of the 27 MHz clock synchronized with the time information.・ Time information generation step,
A receiving method comprising: processing the transmission medium included in the broadcast signal based on the presentation time information included in the broadcast signal and the generated clock and time information.

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