JP2018129844A - Transmitter, transmission method, receiver and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily implement presentation synchronization control in broadcast and communication fusion services.SOLUTION: In a transmitter, a transmission section transmits a modulated wave. The modulated wave is obtained by individually performing transmission encoding processing on a transmission medium, a transmission stream including presentation time information according to a first time axis for each presentation unit of the transmission medium and a transmission control signal corresponding to the transmission stream, and then performing processing of time division multiplexing and modulation. Time information according to the first time axis is inserted into the transmission stream. A time information insertion section inserts another time information according to a second time axis that is different from the first time axis, into the transmission control signal.SELECTED DRAWING: Figure 9

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 a transmission stream including transmission media such as video and audio.

  An indispensable service requirement in the next generation broadcasting system is a fusion service of broadcasting and communication. Various forms of a fusion service of broadcasting and communication are assumed, but a case where basic signals such as images and sounds constituting one broadcast program are transmitted by partial broadcasting and partial communication is considered as one form. ing.

  In the current broadcasting system, MPEG2-TS (Moving Picture Experts Group-2 Transport Stream) system is widely used as a transport system for transmission media (see, for example, Patent Document 1). Also, MPEG-DASH (Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP) is known as a transmission media distribution system by communication (for example, see Non-Patent Document 1).

JP 2013-153291 A

"Realizing uninterrupted video distribution with existing Web server", Mitsuhiro Hirabayashi, NIKKEI ELECTRONICS 2012.3.19

  A technical issue in realizing the above-described integrated service of broadcasting and communication is synchronous presentation of video and audio transmitted through different paths. In order to realize the presentation synchronization control, it is required to share a base time axis (timeline).

  Generally, in broadcasting, an independent 27 MHz counter value is used as a time axis in each transmission system called STC (System Time Clock), and in communication, absolute time (UTC format as data format) called UTC (Universal Time, Coordinated) is used. Used as a time axis.

  An object of the present technology is to make it possible to satisfactorily implement presentation synchronization control in a broadcasting and communication fusion service.

The concept of this technology is
After performing transmission path encoding processing individually for each of the transmission stream and the transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium and the transmission control signal corresponding to the transmission stream A time division multiplexing and modulation process is performed to obtain a modulated wave, and a transmission unit that transmits the modulated wave is provided.
Time information according to the first time axis is inserted in the transmission stream,
The transmission apparatus further includes a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal.

  In the present technology, the transmission unit transmits a modulated wave. The modulated wave is individually encoded for each of the transmission stream and the transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium and the transmission control signal corresponding to the transmission stream. This is obtained by performing time division multiplexing and modulation processing after processing. Time information on the first time axis is inserted into the transmission stream. Then, the time information insertion unit inserts the time information on the second time axis different from the first time axis into the transmission control signal.

  For example, the transmission stream is MPEG2-TS, the time information on the first time axis is STC-based PCR, and the time information on the second time axis is time information in UTC-based NTP format. May be. Further, for example, the transmission control signal may be TMCC information, and the time information insertion unit may insert time information on the second time axis as extension information into the TMCC information.

  As described above, in the present technology, in addition to the time information on the first time axis inserted in the transmission stream, the time information on the second time axis is inserted in the transmission control signal. Therefore, on the receiving side, it is possible to satisfactorily realize the presentation synchronization control in the broadcasting and communication fusion service.

  In the present technology, for example, the transmission stream may further include an identification information insertion unit that inserts identification information indicating that the time information on the second time axis is inserted into the transmission control signal. Good. In this case, for example, the transmission stream may be MPEG2-TS, and the identification information insertion unit may insert a descriptor describing the identification information into the network information table. By inserting the identification information in this way, the receiving side can easily identify that the time information on the second time axis is inserted in the transmission control signal.

  In this case, for example, when the time information on the second time axis is time information in the UTC-based NTP format, information indicating whether the NTP format is the long format or the short format is added to the identification information. It may be made to be. Thereby, the reception side can easily recognize whether the NTP format is the long format or the short format.

  In this case, the identification information may be added with transmission delay difference information between the time information on the first time axis and the time information on the second time axis. Thereby, on the receiving side, it is possible to obtain transmission delay difference information on the transmitting side necessary for converting the presentation time information on the second time axis into the presentation time information on the first time axis.

Other concepts of this technology are
A transmission path code for each of the transmission medium and the transmission control signal corresponding to the first transmission stream and the first transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium A first receiving unit that receives a modulated wave obtained by performing time-division multiplexing and modulation processing after performing the conversion processing,
Time information according to the first time axis is inserted into the first transmission stream,
Time information based on a second time axis different from the first time axis is inserted in the transmission control signal,
An acquisition unit for acquiring time information on the first transmission stream and the second time axis from the modulated wave;
A second receiving unit that receives a second transmission stream including transmission media and presentation time information on the second time axis for each presentation unit of the transmission media;
A time information generating unit that generates time information synchronized with time information on the first time axis included in the first transmission stream acquired by the acquiring unit;
The presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. A first control unit to control;
The presentation of the transmission media included in the second transmission stream received by the second reception unit, the presentation time information included in the second transmission stream, and the second acquired by the acquisition unit The receiving apparatus further includes a second control unit that performs control based on time information based on a time axis and time information generated by the time information generation unit.

  In the present technology, a modulated wave is received by the first receiving unit. The modulated wave is transmitted to each of the transmission medium and the transmission control signal corresponding to the first transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium. This is obtained by performing time division multiplexing and modulation processing after individually performing transmission path coding processing. Here, time information based on the first time axis is inserted into the first transmission stream, and time information based on a second time axis different from the first time axis is inserted into the transmission control signal. Yes.

  The acquisition unit acquires time information based on the first transmission stream and the second time axis from the modulated wave. The second receiving unit receives the second transmission stream including the transmission medium and the presentation time information on the second time axis for each presentation unit of the transmission medium. Further, the time information generation unit generates time information synchronized with the time information on the first time axis included in the first transmission stream acquired by the acquisition unit.

  Then, the presentation of transmission media included in the first transmission stream acquired by the acquisition unit is generated by the first control unit in the presentation time information included in the first transmission stream and the time information generation unit. Control is based on time information. The second control unit obtains the presentation of transmission media included in the second transmission stream received by the second reception unit and the presentation time information included in the second transmission stream and the acquisition unit. Control is performed based on the time information on the second time axis and the time information generated by the time information generator.

  For example, the first time axis may be an STC-based time axis, and the second time axis may be a UTC-based time axis. Also, for example, the first transmission stream is MPEG2-TS, the transmission control signal is TMCC information, and time information on the second time axis is inserted into the TMCC information as extended information. May be.

  Further, for example, the second control unit includes a correspondence relationship between the time information on the second time axis acquired by the acquisition unit and the time information generated by the time information generation unit at the time of reception of the time information, Using the transmission delay difference information between the time information on the first time axis and the time information on the second time axis, the presentation time information included in the second transmission stream is converted into presentation time information on the first time axis. The presentation of transmission media included in the second transmission stream may be controlled based on the converted presentation time information and the time information generated by the time information generation unit.

  In this case, for example, the transmission delay difference information includes transmission-side transmission delay difference information and reception-side transmission delay difference information, and the first transmission stream includes transmission-side transmission delay difference information. , May be. In this case, the second control unit may use the latest two correspondence relationships as the correspondence relationship.

  As described above, in the present technology, the transmission media included in the first transmission stream is converted into the presentation time information on the first time axis and the time information on the first time axis generated by the time information generation unit. The transmission media included in the second transmission stream is presented based on the presentation time information on the second time axis, the time information on the second time axis acquired by the acquisition unit, and the time information. It is controlled based on time information on the first time axis generated by the generator. Therefore, it is possible to satisfactorily implement presentation synchronization control in a broadcasting and communication fusion service.

  According to the present technology, it is possible to satisfactorily implement presentation synchronization control in a broadcasting and communication fusion service. 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 broadcast and communication hybrid system as embodiment. It is a figure showing roughly each system in a broadcasting and communication hybrid system. It is a system pipe model which shows the structure of a broadcast signal. It is a figure which shows the structural example of the TMCC information regarding digital broadcasting. It is a figure which shows the structural example of the extended information (time information) of TMCC information. It is a figure which shows the long format and short format of the time information which an NTP server provides. It is a figure which shows the structural example of a time information reference descriptor. It is a figure which shows the transmission delay model of PCR / NTP. It is a block diagram which shows the structural example of the broadcast transmission system which comprises a broadcast and communication hybrid system. It is a block diagram which shows the structural example of the receiver which comprises a broadcast and communication hybrid system. It is a figure for demonstrating the timeline of a transmission side and a reception side, and target time conversion.

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 / communication hybrid system configuration example]
FIG. 1 shows a configuration example of a broadcast / communication hybrid system 10. In the broadcast / communication hybrid system 10, a broadcast transmission system 110 and a distribution server 120 are arranged on the transmission side, and a receiver 200 is arranged on the reception side.

  The broadcast transmission system 110 includes a transport stream TS as a transmission stream including transmission media (components) such as video and audio, and TMCC (Transmission and Multiplexing Configuration Control) information as transmission control information corresponding to the transport stream TS. A broadcast signal composed of modulated waves obtained by performing time-division multiplexing and modulation processing is transmitted after individually performing transmission path coding processing on each of the above.

  The transport stream TS includes presentation time information (PTS: Presentation Time Stamp) for each transmission media presentation unit. This presentation time information is based on STC (System Time Clock). Also, STC-based PCR (Program Clock Reference) is inserted in this transport stream TS. In this embodiment, time information in an NTP (Network Time Protocol) format based on UTC (Universal Time, Coordinated) is inserted into the TMCC information.

  In addition, identification information indicating that time information in the NTP format is inserted into the TMCC information is inserted into the transport stream TS. In this embodiment, a time information reference descriptor (time_reference_descriptor) in which this identification information is described is inserted under a network information table (NIT). The network information table includes information about a network to be transmitted, such as a channel number, a modulation scheme, and a guard interval. Details of the time information reference descriptor will be described later.

  The distribution server 120 distributes a transmission stream including transmission media (components) such as video and audio to the reception side through the communication network 300 in response to a request from the reception side, for example. This transmission stream includes presentation time information for each transmission media presentation unit. This presentation time information is based on UTC. In this embodiment, it is assumed that a transmission medium distribution system by communication is MPEG-DASH, and the distribution server 120 is a DASH streaming server (also serving as a DASH MPD server).

  The receiver 200 receives a broadcast signal transmitted from the broadcast transmission system 110 and receives a transmission stream distributed from the distribution server 120. The receiver 200 generates time information (STC) synchronized with the PCR included in the transport stream TS. The receiver 200 controls the presentation of the transmission media included in the transport stream TS based on the time information (STC) and transmits the transmission included in the transmission stream distributed from the distribution server 120. Control media presentation.

  When the receiver 200 controls the presentation of the transmission media included in the transmission stream distributed from the distribution server 120, the receiver 200 uses time information in the UTC-based NTP format inserted in the TMCC information. That is, the receiver 200 uses the UTC-based presentation time information included in the transmission stream distributed from the distribution server 120 based on the correspondence with the time information (STC) described above when receiving the time information in the NTP format. Converted from STC base to STC base.

  FIG. 2 schematically shows each system in the broadcast / communication hybrid system 10 shown in FIG. Main image and audio data is input from the program material to the broadcasting system. A transport stream TS obtained by encoding these image and audio data is sent from the broadcast transmission system 110 to the receiver 200 through the broadcast transmission path. Here, at the time of encoding processing, presentation time information (PTS) is inserted into video and audio PES packets based on STC (System Time Clock). Also, PCR is inserted into the transport stream TS based on STC (System Time Clock).

  Sub image and audio data is input from the program material to the communication system. A transmission stream obtained by encoding these image and audio data is sent from the distribution server 120 to the receiver 200 through a communication transmission path. Here, at the time of encoding processing, presentation time information is inserted for each presentation unit of image and sound based on UTC (Universal Time, Coordinated).

  In this embodiment, as described above, time information in the UTC-based NTP format is inserted into the TMCC information in the broadcasting system, and is included in the transmission stream that is distributed in the communication system using this time information in the receiver 200. Presentation of images and sounds to be controlled is controlled. Therefore, even if the time axis of the presentation time information in the broadcast system and the communication system is different, the presentation synchronization in the fusion service of broadcasting and communication is possible.

  FIG. 3 is a system pipe model showing the configuration of the broadcast signal. One or a plurality of transport streams are transmitted in one RF channel. Each transport stream is identified by “TS-id”. In addition, one or more services exist in one transport stream. Each service is identified by “Service_id”. This service is a so-called channel.

  One service includes video (Audio), audio (Audio), closed caption (Closed Caption), etc. as transmission media (components). That is, each service is composed of components such as video, audio, and closed caption.

  Also, a control signal called PSI (Program Specific Information) / SI (Service Information) exists in one transport stream. Furthermore, there is a STC (System Time Clock) based PCR (Program Clock Reference) in one transport stream.

  Also, TMCC information, which is a transmission control signal, is transmitted in parallel with one or a plurality of transport streams described above in one RF channel. In this embodiment, as described above, time information in the NTP (Network Time Protocol) format based on UTC (Universal Time, Coordinated) exists in the TMCC information. This TMCC information is a physical layer control signal.

  FIG. 4 shows a configuration example of TMCC information related to digital broadcasting. The “change instruction” field is incremented by 1 each time the content of the TMCC information is changed, and when the value becomes ‘11111111’, the field returns to ‘00000000’. The fields of “transmission mode / slot information” indicate the modulation scheme of the transmission main signal, the coding rate of intra-error correction coding, the satellite output backoff, and the number of assigned slots.

  The “stream type / relative stream information” field indicates the correspondence between the relative stream number and the stream type. The “packet format / relative stream information” field indicates the correspondence between the relative stream number and the packet format. The “pointer / slot information” field indicates the start position of the first packet and the end position of the last packet stored in the slot.

  The field of “relative stream / slot information” indicates the correspondence between slots and relative stream numbers. The field of “relative stream / transmission stream ID correspondence table” indicates the correspondence between the relative stream number and the transport stream identifier. The “transmission / reception control information” field transmits a signal for starting control of the receiver in the emergency warning broadcasting and uplink control information.

  There is a 3614-bit field of “extension information” at the end of the TMCC information. In this embodiment, the first 80 bits of this “extension information” field are used to insert time information in the UTC-based NTP format. FIG. 5 shows a configuration example of the extended information (time information). The 16-bit field of “extension identifier” is set to “0x0001”, for example, and indicates that the extension information is time information. In the 64-bit field of “extended information”, time information in the UTC-based NTP format is inserted. Here, the NTP format is a 64-bit long format.

  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. 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. 6A shows a long format (NTP time stamp long format) of time information 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. Further, FIG. 6B shows a short format (NTP time stamp short format) of time information provided by the NTP server. This time information is in a 32-bit format, with the upper 16 bits indicating the number of seconds accumulated in UTC and the lower 16 bits indicating less than a second.

  FIG. 7 shows a configuration example of the time information reference descriptor (time_reference_descriptor). An 8-bit field of “descriptor_tag” indicates a descriptor type. Here, it indicates a time information reference descriptor. The 8-bit field of “descriptor_length” indicates the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor.

  A 2-bit field of “time_reference_mode” indicates a transmission mode of time information. “0” indicates that only PCR is transmitted. “1” indicates that, in addition to transmitting PCR, time information in the NTP format is transmitted by PES in the TS timeline extension method under standardization in MPEG. This transmission mode has a great influence on a conventional broadcasting system, and a band for transmission is required. “2” indicates that time information in NTP format is transmitted as TMCC information in addition to transmitting PCR.

  The 2-bit field of “time_reference_format” indicates whether the time information of the NTP format transmitted in addition to the PCR is a long format (see FIG. 6A) or a short format (see FIG. 6B). . “0” indicates a short format. “1” indicates a long format.

  A 32-bit field of “delay_adjustment” indicates a transmission delay difference ΔT1 between the PCR of the system layer and the time information of the NTP format of the physical layer. This transmission delay difference ΔT1 is in units of 1/90000 seconds. The transmission delay difference between the time information in the PCR and the NTP format occurs on both the transmission side and the reception side. The transmission delay difference ΔT1 is a transmission delay difference on the transmission side.

  As will be described later, when the UTC-based presentation time information is converted into STC-based presentation time information on the reception side, a transmission delay difference between both the transmission side and the reception side is required. The transmission delay difference ΔT1 on the transmission side is specified in the 32-bit field of “delay_adjustment” of the time information reference descriptor as described above. As for the transmission delay difference ΔT2 on the receiving side, a fixed value is set during calculation on the receiving side.

  FIG. 8 shows a transmission delay model of PCR / NTP. On the transmission side, when the time information in the STC-based PCR and the UTC-based NTP format is extracted at a certain timing at the same time, the transmission channel coding processing delay Ttss for the transport stream TS, and the transmission channel code for the TMCC information The transmission delay difference ΔT1 is generated between the PCR and the time information in the NTP format by the difference in the processing delay Ttmccs. That is, ΔT1 = (Ttss−Ttmccs).

  The transport stream TS encoded with the transmission path and the TMCC information encoded with the transmission path are multiplexed and modulated, and then sent to the receiving side through the broadcast transmission path. In this broadcast transmission path, time information in the PCR and NTP formats is delayed by the transmission path delay Tbtr in common. That is, in this broadcast transmission path, the delay difference between the time information in the PCR and NTP formats is zero.

  On the receiving side, a transmission delay difference ΔT2 is generated between the PCR and the time information in the NTP format by the difference between the transmission path decoding processing delay Ttsr for the transport stream TS and the transmission decoding processing delay Ttmccr for the TMCC information. To do. That is, ΔT2 = (Ttsr−Ttmccr). Therefore, the total transmission delay difference ΔT between the PCR and the time information in the NTP format is ΔT = ΔT1 + ΔT2.

[Broadcast transmission system configuration example]
FIG. 9 shows a configuration example of the broadcast transmission system 110. The broadcast transmission system 110 includes a voltage-controlled oscillator 121 that generates a 27 MHz clock (system clock), a frequency divider 122 that divides 1/1716, a comparator 123, and an STC-based clock unit 9 A bit counter 124a, a 33-bit counter 124b, and a packetizing unit 125 are included. The broadcast transmission system 110 includes a video / audio encoding processing unit 126, a packetization / time stamp addition unit 127, an encoder buffer 128, and a multiplexer 129.

  The broadcast transmission system 110 has a time signal interface 131 and 32-bit registers 132a and 132b. The broadcast transmission system 110 includes a voltage controlled oscillator 133 that generates a 2 ** 24 Hz clock (system clock), a 24-bit counter 134a and a 32-bit counter 134b that constitute a UTC-based clock unit, and a comparator 135. have. The broadcast transmission system 110 also includes a transmission path encoding device 141. The transmission path encoding device 141 includes a main signal processing unit 141a that performs transmission path encoding of the transport stream TS, a control signal processing unit 141b that performs transmission path encoding of TMCC information, and time division multiplexing / An orthogonal modulation processing unit 141c is included.

  The 27 MHz clock generated by the voltage controlled oscillator 121 is divided by 1/1716 by the frequency divider 122, and a pulse is output from the frequency divider 122 with a time length of one horizontal period. The output pulse of the frequency divider 122 is supplied to the comparator 123 and compared with the phase of the reference horizontal synchronization signal (Ref. Hsync). The comparison error signal output from the comparator 123 is supplied to the voltage controlled oscillator 121 as a control signal. The voltage controlled oscillator 121, the frequency divider 122, and the comparator 123 constitute a PLL (Phase Locked Loop) circuit. The voltage controlled oscillator 121 generates a 27 MHz clock synchronized with the reference horizontal synchronizing signal.

  The 27 MHz clock output from the voltage controlled oscillator 121 is counted by the 9-bit counter 124a and divided by 300. The 90 KHz clock obtained by the 9-bit counter 124a is counted by the 33-bit counter 124b. The bit output of (33 + 9) bits of these 9-bit counter 124a and 33-bit counter 124b is STC-based time information.

  This STC-based time information is supplied to the packetizing unit 125. The packetizing unit 125 generates a TS packet having an adaptation field including a program clock reference (PCR) based on this STC-based time information. The TS packets are generated at predetermined intervals and sequentially supplied to the multiplexer 129. It is recommended that the PCR appear in the TS stream at 100 ms intervals.

  In the video / audio encoding processing unit 126, video and audio are encoded in synchronization with the 27 MHz clock obtained by the voltage controlled oscillator 121. The packetization / timestamp adding unit 127 generates a PES packet for each access unit from the encoded video and audio elementary streams, and further generates a TS packet including the encoded video and encoded audio in the payload. . This TS packet is supplied to the multiplexer 129 through the encoder buffer 128.

  The packetization / time stamp adding unit 127 is supplied with a 33-bit bit output output from the 33-bit counter 124b. This 33-bit bit output is time information with an accuracy of 90 kHz. The packetization / time stamp adding unit 127 inserts a presentation time stamp (PTS) into the header of each PES packet based on the 33-bit bit output.

  As described above, the multiplexer 129 is supplied with TS packets including PCR and TS packets including encoded video and encoded audio. In the multiplexer 129, each TS packet is multiplexed to generate a transport stream TS. The transport stream TS also includes a PSI / SI control signal. In the multiplexer 129, the above-described time information reference descriptor (time_reference_descriptor) (see FIG. 7) is inserted under the NIT (Network Information Table).

  Further, the time signal interface 131 accesses, for example, an NTP server (not shown) via the Internet at a predetermined time interval, and acquires time information (see FIG. 6A) in a 64-bit format. The 32-bit registers 132a and 132b hold time information in 64-bit format acquired by the time signal 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 every time the time signal interface 131 acquires 64-bit time information.

  If the frequency of acquiring the time information is sufficiently high, this configuration may be used as it is. However, if the frequency is low, the registers 132a and 132b may continue to operate as a counter indicating the time automatically so as to reproduce the clock of the NTP server. Conceivable. Here, when the output of the register 132b indicating the lower 32 bits of the acquired time information becomes 0, 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 134b. The 24-bit counter 134a is set to zero. This setting operation is limited to one time when the broadcast transmission system 110 starts the operation.

  The voltage controlled oscillator 133 generates a 2 ** 24 Hz clock. The 24-bit counter 134 a counts 2 ** 24 Hz clocks output from the voltage controlled oscillator 133. The 32-bit counter 134b counts the 1 Hz clock that is the carry output of the 24-bit counter 134a, and obtains a 32-bit bit output that is time information (Regenerated UTC) with second accuracy. The 56-bit bit output of the 24-bit counter 134a and the 32-bit counter 134b becomes UTC-based time information by the counter operation from the initial value.

  The transport stream TS generated by the multiplexer 129 is supplied to the main signal system processing unit 141a of the transmission path encoding device 141. In the main signal processing unit 141b, transmission path encoding processing such as outer code encoding, power spreading, inner code encoding, and mapping is performed on the transport stream TS.

  The 56-bit bit output of the 24-bit counter 134a and the 32-bit counter 134b is supplied to the control signal system processing unit 141b of the transmission path encoding device 141 as time information in the UTC-based NTP format. Further, the transmission parameter TMCC when transmitting the transport stream TS is supplied to the control signal processing unit 141b.

  In the control signal processing unit 141b, TMCC information is generated based on the transmission parameter TMCC. At this time, time information in the NTP long format is inserted into the extended information field of the TMCC information (see FIG. 5). As described above, since the bit output of the 24-bit counter 134a and the 32-bit counter 134b is 56 bits, the lower 8 bits are all “0”. In addition, the main signal processing unit 141b performs transmission path encoding processing such as outer code encoding, power spreading, inner code encoding, and mapping on the generated TMCC information.

  In addition, in the time division multiplexing / orthogonal modulation processing unit 141c of the transmission path coding device 141, time division multiplexing and orthogonal modulation processing are performed on the outputs of the main signal system processing unit 141a and the control signal system processing unit 141b. An intermediate frequency modulated wave is obtained.

[Example of receiver configuration]
FIG. 10 shows a configuration example of the receiver 200. The receiver 200 constitutes a broadcast transmission path decoding unit 210, a demultiplexer 211, a voltage controlled oscillator 212 that generates a 27 MHz clock (system clock), and an STC-based clock unit (time information generation unit) 9 A bit counter 213a and a 33-bit count 213b and a comparator 214 are provided.

  The receiver 200 also includes a decoder buffer 215, a broadcast presentation control unit 216, and a broadcast AV decoder 217. The receiver 200 also includes a UTC / STC mapping information generation unit 220, a communication interface 231, an MPD analysis unit 232, a decoder buffer 233, a communication presentation control unit 234, a communication AV decoder 235, and a synthesis unit 241. Have.

  The broadcast transmission path decoding unit 210 performs processing such as transmission path decoding on the received broadcast signal (modulated wave) to obtain a transport stream TS. In the broadcast transmission path decoding unit 210, the time information in the NTP format inserted in the TMCC information is based on the time information reference descriptor (time_reference_descriptor) arranged in the NIT (Network Information Table) of the transport stream TS. Extracted.

  The transport stream TS obtained by the broadcast transmission path decoding unit 210 is supplied to the demultiplexer 211. In the demultiplexer 211, 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 the 42-bit clock unit (time information generating unit) composed of the counter 213a and the counter 213b. The PCR is supplied to the comparator 214.

  The 27 MHz clock generated by the voltage controlled oscillator 42 is counted by the 9-bit counter 213a and divided by 300. The 90 KHz clock obtained by the 9-bit counter 213a is counted by the 33-bit counter 213b. The 42-bit bit output of these 9-bit counter 213a and 33-bit counter 213b is STC-based time information.

  This STC-based time information is supplied to the comparator 214. In the comparator 214, for example, at the timing when the PCR is supplied from the demultiplexer 211, STC-based time information is latched and compared with the PCR. The comparison error signal output from the comparator 214 is supplied to the voltage controlled oscillator 212 as a control signal. The voltage controlled oscillator 212, the counters 213a and 213b, and the comparator 214 constitute a PLL (Phase Locked Loop) circuit. The voltage controlled oscillator 212 generates a 27 MHz clock synchronized with the PCR, and the counters 213a and 213b synchronize with the PCR. The STC-based time information is generated.

  In the demultiplexer 211, TS packets including encoded video and encoded audio are extracted and temporarily stored in the decoder buffer 215. Also, the 33-bit bit output (90 KHz count value) of the counter 213b is supplied to the broadcast presentation control unit 216 as STC-based time information.

  In the broadcast presentation control unit 216, the PTS of each PES packet stored in the decoder buffer 215 is confirmed. In the broadcast presentation control unit 216, STC-based time information is referred to, and the broadcast AV decoder 217 sequentially fetches PES packets to be decoded from the decoder buffer 215. The broadcast AV decoder 217 depackets the PES packet, further decodes the encoded video and encoded audio, and obtains baseband video (video data) and audio (audio data).

  The time information in the UTC-based NTP format extracted by the broadcast transmission path decoding unit 210 is supplied to the UTC / STC mapping information generation unit 220. The UTC / STC mapping information generation unit 220 is supplied with the 33-bit bit output (count value of 90 KHz) of the counter 213b as STC-based time information. In the UTC / STC mapping information generation unit 220, pair information (U, S) of time information in the NTP format and STC-based time information at the extraction timing is generated as mapping information.

  Time information in the UTC-based NTP format is sent from the transmission side at an appropriate cycle, but the above-described pair information is continuously generated each time it is received. The UTC / STC mapping information generation unit 220 is always in a state where the latest pair information and the previous pair information are held.

  The communication interface 231 communicates with the distribution server 120 (see FIG. 1), receives the MPD file, and receives a transmission stream including transmission media (components) such as video and audio. The MPD file is supplied to the MPD analysis unit 232, and MPD analysis information obtained by the MPD analysis unit 232 is supplied to the communication presentation control unit 234. The transmission stream received by the communication interface 231 is supplied to the communication presentation control unit 234 and also supplied to the decoder buffer 233.

  In MPEG-DASH, timing information for each presentation unit of transmission media is disclosed in the MPD file, and there is also timing information for each presentation unit in the transmission media body. The communication presentation control unit 234 acquires presentation time information for each transmission media presentation unit based on the timing information. This presentation time information is based on UTC.

  The communication presentation control unit 234 includes STC-based time information, which is a 33-bit bit output (count value of 90 KHz) of the counter 213b, and the latest two pair information (UU) generated by the UTC / STC mapping information generation unit 220. , S), the UTC-based presentation time information is converted into STC-based presentation time information (timeline conversion).

  The conversion from UTC base to STC base will be further described. FIG. 11A shows the timeline (time axis) of STC and UTC on the transmission side. Un-1 and Un on the UTC timeline indicate UTC-based times that are transmitted by being inserted into the TMCC information. Also, Sn-1 and Sn on the STC timeline indicate STC-based times corresponding to UTC-based times Un-1 and Un, respectively. In the relationship between STC and UTC timelines on the transmission side, the UTC-based presentation time Utar corresponds to the STC-based time Star.

  FIG. 11B shows the timeline (time axis) of STC and UTC on the receiving side. The STC timeline is delayed by ΔT compared to the UTC timeline. ΔT is a total transmission delay difference between the PCR and time information in the NTP format. As described above, the transmission delay difference ΔT is obtained by adding the transmission delay difference ΔT1 on the transmission side and the transmission delay difference ΔT2 on the reception side.

  In the UTC / STC mapping information generation unit 220, the STC-based time S′n−1 is paired with the UTC-based time Un−1. This time S′n−1 is a time before ΔT by the time Sn−1. In addition, in the UTC / STC mapping information generation unit 220, the STC-based time S′n is paired with the UTC-based time Un. This time S′n is a time that is ΔT before the time Sn. In the relationship between STC and UTC timelines on the receiving side, the UTC-based presentation time Utar corresponds to the STC-based time S′tar. This time S′tar is a time before ΔT by the time Star.

In the communication presentation control unit 234, the UTC-based presentation time Utar is converted into an STC-based time Star (converted to a target time) by the following formula (1).
(Star−Sn) / (Sn−Sn−1) = (Utar−Un) / (Un−Un−1)
Star = ((Utar-Un) (Sn-Sn-1) / (Un-Un-1)) + Sn
= ((Utar−Un) (S´n−S´n-1) / (Un−Un-1)) + S´n + ΔT1 + ΔT2
... (1)

  Returning to FIG. 10, the communication presentation control unit 234 confirms the presentation time of each presentation unit stored in the decoder buffer 233 and converted into the STC base as described above. In the communication presentation control unit 234, the STC-based time information from the counter 213b is referred to, and the communication AV decoder 235 sequentially fetches the video and audio presentation units to be decoded from the decoder buffer 233. . In the communication AV decoder 235, the encoded video and encoded audio of each presentation unit are decoded, and baseband video (video data) and audio (audio data) are obtained.

  The synthesizer 241 synthesizes the AV output of the video data and audio data obtained by the communication AV decoder 235 with the AV output of the video data and audio data obtained by the broadcast AV decoder 217 to obtain a final AV output. In the receiver 200, video display using the video data is performed, and audio output using the audio data is performed.

  As described above, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, in addition to inserting the STC-based PCR into the transport stream TS, the time information in the UTC-based NTP format is added to the TMCC information. Is inserted. Therefore, on the receiving side, it is possible to satisfactorily realize the presentation synchronization control in the broadcasting and communication fusion service.

  Also, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, time information in the UTC-based NTP format is inserted into the extended information field of the TMCC information. Therefore, a new band for transmitting time information in the UTC-based NTP format is not required.

  In the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, identification information indicating that time information in the UTC-based NTP format is inserted in the TMCC information is inserted in the transport stream TS. Is. That is, the time information reference descriptor is inserted into the NIT. Therefore, the receiving side can easily identify that time information in the UTC-based NTP format is inserted in the TMCC information.

  In the broadcast / communication hybrid system 10 shown in FIG. 1, the time information reference descriptor inserted in the transport stream TS by the broadcast transmission system 110 includes the time of the system layer PCR and the physical layer NTP format on the transmission side. A transmission delay difference ΔT1 with the information is described. For this reason, even if time information in the UTC-based NTP format is inserted into the TMCC information and transmitted, the reception side uses the transmission delay difference ΔT1 to convert the UTC-based presentation time information into STC-based presentation time information. It becomes possible to convert well.

<2. Modification>
In the above-described embodiment, the transport stream is the transport stream TS (MPEG2-TS), the time information on the first time axis is STC-based PCR, and the time information on the second time axis is UTC-based. An example of time information in the NTP format is shown. Although detailed description is omitted, it is needless to say that the present technology can be similarly applied to other cases in which the same transmission stream is handled.

Moreover, this technique can also take the following structures.
(1) A transmission path encoding process is individually performed for each of a transmission stream and a transmission stream including presentation time information on the first time axis for each presentation unit of the transmission medium and a transmission control signal corresponding to the transmission stream. After performing the time division multiplexing and modulation processing to obtain a modulated wave, comprising a transmitter for transmitting the modulated wave,
Time information according to the first time axis is inserted in the transmission stream,
A transmission device further comprising a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal.
(2) The transmission stream is MPEG2-TS,
The time information on the first time axis is an STC-based PCR,
The transmission device according to (1), wherein the time information on the second time axis is time information in a UTC-based NTP format.
(3) The transmission control signal is TMCC information,
The transmission device according to (1) or (2), wherein the time information insertion unit inserts time information on the second time axis as extension information into the TMCC information.
(4) The transmission stream further includes an identification information insertion unit that inserts identification information indicating that time information on the second time axis is inserted into the transmission control signal. (1) to (3) The transmission apparatus in any one of.
(5) When the time information on the second time axis is time information in UTC-based NTP format, information indicating whether the NTP format is a long format or a short format is added to the identification information The transmitting apparatus according to (4).
(6) Transmission delay difference information between time information on the first time axis and time information on the second time axis is added to the identification information. Transmission according to (4) or (5) apparatus.
(7) The transmission stream is MPEG2-TS,
The transmission device according to any one of (4) to (6), wherein the identification information insertion unit inserts a descriptor in which the identification information is described into a network information table.
(8) The transmission unit individually transmits the transmission medium and the transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium and the transmission control signal corresponding to the transmission stream. After performing the encoding process, a time division multiplexing and modulation process is performed to obtain a modulated wave, and a transmission step for transmitting the modulated wave is included.
Time information according to the first time axis is inserted in the transmission stream,
A transmission method further comprising a time information insertion step of inserting time information on a second time axis different from the first time axis into the transmission control signal.
(9) Individually for each of the transmission medium and the transmission control signal corresponding to the first transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium A first receiving unit that receives a modulated wave obtained by performing time division multiplexing and modulation after performing transmission path encoding processing;
Time information according to the first time axis is inserted into the first transmission stream,
Time information based on a second time axis different from the first time axis is inserted in the transmission control signal,
An acquisition unit for acquiring time information on the first transmission stream and the second time axis from the modulated wave;
A second receiving unit that receives a second transmission stream including transmission media and presentation time information on the second time axis for each presentation unit of the transmission media;
A time information generating unit that generates time information synchronized with time information on the first time axis included in the first transmission stream acquired by the acquiring unit;
The presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. A first control unit to control;
The presentation of the transmission media included in the second transmission stream received by the second reception unit, the presentation time information included in the second transmission stream, and the second acquired by the acquisition unit A receiving apparatus, further comprising: a second control unit that performs control based on time information based on a time axis and time information generated by the time information generation unit.
(10) The second control unit
Correspondence between the time information on the second time axis acquired by the acquisition unit and the time information generated by the time information generation unit when the time information is received, and the time information on the first time axis Using the transmission delay difference information between the second time stream and the time information on the second time axis, the presentation time information included in the second transmission stream is converted into the presentation time information on the first time axis. The receiving device according to (9), wherein the presentation of transmission media included in the second transmission stream is controlled based on the presented time information and the time information generated by the time information generation unit.
(11) The transmission delay difference information includes transmission-side transmission delay difference information and reception-side transmission delay difference information.
The receiving apparatus according to (10), wherein the first transmission stream includes transmission delay difference information on the transmission side.
(12) The second control unit
The receiving device according to (10) or (11), wherein the latest two correspondence relationships are used as the correspondence relationship.
(13) The receiving apparatus according to any one of (9) to (12), wherein the first time axis is an STC-based time axis, and the second time axis is a UTC-based time axis.
(14) The first transmission stream is MPEG2-TS,
The transmission control signal is TMCC information,
The receiving device according to any one of (9) to (13), wherein time information based on the second time axis is inserted as extension information into the TMCC information.
(15) A first transmission stream including a transmission medium and presentation time information on a first time axis for each presentation unit of the transmission medium and a transmission control signal corresponding to the first transmission stream by the first receiver A first reception step of receiving a modulated wave obtained by performing time-division multiplexing and modulation processing after individually performing transmission path encoding processing on each of the
Time information according to the first time axis is inserted into the first transmission stream,
Time information based on a second time axis different from the first time axis is inserted in the transmission control signal,
An acquisition step of acquiring time information on the first transmission stream and the second time axis from the modulated wave;
A second receiving step of receiving a second transmission stream including transmission media and presentation time information on the second time axis for each presentation unit of the transmission media by a second reception unit;
A time information generation step for generating time information synchronized with the time information on the first time axis included in the first transmission stream acquired in the acquisition step;
The presentation of the transmission media included in the first transmission stream acquired in the acquisition step is based on the presentation time information included in the first transmission stream and the time information generated in the time information generation step. A first control step to control;
The presentation of the transmission media included in the second transmission stream received in the second reception step, the presentation time information included in the second transmission stream, and the second time acquired in the acquisition step A receiving method further comprising a second control step of controlling based on time information on a time axis and time information generated in the time information generating step.

  The main feature of this technology is that in addition to inserting the STC-based PCR into the transport stream TS, the time information in the UTC-based NTP format is inserted into the TMCC information. This is to make it possible to realize the presentation synchronization control satisfactorily (see FIG. 9).

DESCRIPTION OF SYMBOLS 10 ... Broadcast / communication hybrid system 110 ... Broadcast transmission system 120 ... Distribution server 121 ... Voltage controlled oscillator (27 MHz)
122 ... Frequency divider (1/1716)
123 ... Comparator 124a ... 9-bit counter 124b ... 33-bit counter 125 ... Packetization unit 126 ... Video / audio encoding processing unit 127 ... Packetization / time stamp addition unit 128 ..Encoder buffer 129 ... Multiplexer 131 ... Time signal interface 132a, 132b ... 32-bit counter 133 ... Voltage controlled oscillator (2 ** 24Hz)
134a ... 24-bit counter 134b ... 32-bit counter 135 ... Comparator 141 ... Transmission path encoding device 141a ... Main signal system processing unit 141b ... Control signal system processing unit 141c ... Time division multiplexing / orthogonal modulation processing unit 200: Receiver 201 ... Broadcast transmission path decoding unit 211 ... Demultiplexer 212 ... Voltage controlled oscillator (27MHz)
213a ... 9-bit counter 213b ... 33-bit counter 214 ... Comparator 215 ... Decoder buffer 216 ... Broadcast presentation controller 217 ... Broadcast AV decoder 220 ... UTC / STC mapping information Generation unit 231 ... Communication interface 232 ... MPD analysis unit 233 ... Decoder buffer 234 ... Communication presentation control unit 235 ... Communication AV decoder 241 ... Composition unit 300 ... Communication network

Claims (15)

After performing transmission path encoding processing individually for each of the transmission stream and the transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium and the transmission control signal corresponding to the transmission stream A time division multiplexing and modulation process is performed to obtain a modulated wave, and a transmission unit that transmits the modulated wave is provided.
Time information according to the first time axis is inserted in the transmission stream,
A transmission device further comprising a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal. The transport stream is MPEG2-TS,
The time information on the first time axis is an STC-based PCR,
The transmission apparatus according to claim 1, wherein the time information on the second time axis is time information in a UTC-based NTP format. The transmission control signal is TMCC information,
The transmission device according to claim 1, wherein the time information insertion unit inserts time information on the second time axis as extension information into the TMCC information. The transmission apparatus according to claim 1, further comprising: an identification information insertion unit that inserts identification information indicating that time information on the second time axis is inserted into the transmission control signal in the transmission stream. When the time information based on the second time axis is time information in a UTC-based NTP format, information indicating whether the NTP format is a long format or a short format is added to the identification information. Item 5. The transmission device according to Item 4. The transmission apparatus according to claim 4, wherein transmission delay difference information between time information on the first time axis and time information on the second time axis is added to the identification information. The transport stream is MPEG2-TS,
The transmission device according to claim 4, wherein the identification information insertion unit inserts a descriptor in which the identification information is described into a network information table. The transmission unit individually performs transmission path coding processing on the transmission stream including the transmission medium and the presentation time information on the first time axis for each presentation unit of the transmission medium and the transmission control signal corresponding to the transmission stream. And performing a time division multiplexing and modulation process to obtain a modulated wave, and transmitting the modulated wave,
Time information according to the first time axis is inserted in the transmission stream,
A transmission method further comprising a time information insertion step of inserting time information on a second time axis different from the first time axis into the transmission control signal. A transmission path code for each of the transmission medium and the transmission control signal corresponding to the first transmission stream and the first transmission stream including the presentation time information on the first time axis for each presentation unit of the transmission medium A first receiving unit that receives a modulated wave obtained by performing time-division multiplexing and modulation processing after performing the conversion processing,
Time information according to the first time axis is inserted into the first transmission stream,
Time information based on a second time axis different from the first time axis is inserted in the transmission control signal,
An acquisition unit for acquiring time information on the first transmission stream and the second time axis from the modulated wave;
A second receiving unit that receives a second transmission stream including transmission media and presentation time information on the second time axis for each presentation unit of the transmission media;
A time information generating unit that generates time information synchronized with time information on the first time axis included in the first transmission stream acquired by the acquiring unit;
The presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. A first control unit to control;
The presentation of the transmission media included in the second transmission stream received by the second reception unit, the presentation time information included in the second transmission stream, and the second acquired by the acquisition unit A receiving apparatus, further comprising: a second control unit that performs control based on time information based on a time axis and time information generated by the time information generation unit. The second controller is
Correspondence between the time information on the second time axis acquired by the acquisition unit and the time information generated by the time information generation unit when the time information is received, and the time information on the first time axis Using the transmission delay difference information between the second time stream and the time information on the second time axis, the presentation time information included in the second transmission stream is converted into the presentation time information on the first time axis. The receiving device according to claim 9, wherein presentation of transmission media included in the second transmission stream is controlled based on the presented presentation time information and the time information generated by the time information generation unit. The transmission delay difference information consists of transmission delay difference information on the transmission side and transmission delay difference information on the reception side,
The receiving device according to claim 10, wherein the first transmission stream includes transmission delay difference information on the transmission side. The second controller is
The receiving device according to claim 10, wherein the latest two correspondence relationships are used as the correspondence relationship. The receiving device according to claim 9, wherein the first time axis is an STC-based time axis, and the second time axis is a UTC-based time axis. The first transport stream is MPEG2-TS,
The transmission control signal is TMCC information,
The receiving apparatus according to claim 9, wherein time information based on the second time axis is inserted as extension information in the TMCC information. By the first receiving unit, each of the transmission medium and the transmission control signal corresponding to the first transmission stream including the transmission medium and the presentation time information on the first time axis for each presentation unit of the transmission medium. A first reception step of receiving a modulated wave obtained by performing time division multiplexing and modulation after individually performing transmission path coding processing;
Time information according to the first time axis is inserted into the first transmission stream,
Time information based on a second time axis different from the first time axis is inserted in the transmission control signal,
An acquisition step of acquiring time information on the first transmission stream and the second time axis from the modulated wave;
A second receiving step of receiving a second transmission stream including transmission media and presentation time information on the second time axis for each presentation unit of the transmission media by a second reception unit;
A time information generation step for generating time information synchronized with the time information on the first time axis included in the first transmission stream acquired in the acquisition step;
The presentation of the transmission media included in the first transmission stream acquired in the acquisition step is based on the presentation time information included in the first transmission stream and the time information generated in the time information generation step. A first control step to control;
The presentation of the transmission media included in the second transmission stream received in the second reception step, the presentation time information included in the second transmission stream, and the second time acquired in the acquisition step A receiving method further comprising a second control step of controlling based on time information on a time axis and time information generated in the time information generating step.

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