JP6504294B2 - Transmission apparatus, transmission method, reception apparatus and reception method - Google Patents

Description

  The present technology relates to a transmitting device, a transmitting method, a receiving device, and a receiving method, and more particularly, to a transmitting device that transmits a transport stream including transmission media such as video and audio.

  One of the essential service requirements for the next-generation broadcasting system is a combination of broadcasting and communication services. There may be various forms of integrated services of broadcasting and communication, but one case is considered where the basic signals such as images and sounds that constitute one broadcast program are partially transmitted and partially transmitted as communication ing.

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

JP, 2013-153291, A

Achieving uninterrupted video delivery with existing web servers, Mitsuhiro Hirabayashi, NIKKEI ELECTRONICS 2012.3.19

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

  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, an absolute time (NTP format as a data format) called UTC (Universal Time, Coordinated) is used. Used as a time axis.

  An object of the present technology is to enable good realization of presentation synchronization control in a combined service of broadcasting and communication.

The concept of this technology is
A transmission stream including transmission time information on a transmission medium and a first time axis for each presentation unit of the transmission medium and transmission control signals corresponding to the transmission stream are individually subjected to channel coding processing A transmitter configured to perform time division multiplexing and modulation processing to obtain a modulated wave, and transmit the modulated wave;
In the transmission stream, time information on the first time axis is inserted,
The transmitting 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 transmitter transmits the modulated wave. This modulation wave is individually channel coded individually for each of the transmission media and the transmission stream including presentation time information on the first time axis for each presentation unit of the transmission media and the transmission control signal corresponding to the transmission stream. It is obtained by performing processing of time division multiplexing and modulation after processing. In the transport stream, time information on the first time axis is inserted. Then, the time information insertion unit inserts time information on a second time axis different from the first time axis into the transmission control signal.

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

  As described above, in the present technology, in addition to the time information on the first time axis being inserted into the transmission stream, the time information on the second time axis is inserted into the transmission control signal. Therefore, on the receiving side, presentation synchronization control in the combined service of broadcasting and communication can be realized well.

  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 in the transmission control signal. Good. In this case, for example, the transport stream may be MPEG2-TS, and the identification information insertion unit may be configured to insert a descriptor in which identification information is described into the network information table. By inserting the identification information in this manner, the reception 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 of 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. It may be done. Thus, the receiving side can easily recognize whether the NTP format is a long format or a short format.

  Further, in this case, transmission delay difference information between time information on the first time axis and time information on the second time axis may be added to the identification information. As a result, on the reception side, it is possible to obtain transmission delay difference information on the transmission side necessary to convert the presentation time information on the second time axis into presentation time information on the first time axis.

Also, the other concept of this technology is
A transmission line code individually for each of a first transmission stream including transmission media and presentation time information according to a first time axis for each presentation unit of the transmission media and transmission control signals corresponding to the first transmission stream And a first receiving unit for receiving a modulated wave obtained by performing time division multiplexing and modulation processing after the quantization processing.
Time information on the first time axis is inserted into the first transmission stream,
In the transmission control signal, time information on a second time axis different from the first time axis is inserted,
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 for receiving a second transmission stream including transmission media and presentation time information according to the second time axis for each presentation unit of the transmission media;
A time information generation unit that generates time information synchronized with time information on the first time axis included in the first transmission stream acquired by the acquisition unit;
The presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is performed based on presentation time information included in the first transmission stream and the time information generated by the time information generator. 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 information acquired by the acquisition unit The receiver further includes a second control unit that performs control based on time information on a time axis and time information generated by the time information generation unit.

  In the present technology, the modulated wave is received by the first receiving unit. This modulated wave is generated for each of the first transmission stream including the transmission media and the presentation time information on the first time axis for each presentation unit of the transmission media, and the transmission control signal corresponding to the first transmission stream. It is obtained by performing time division multiplexing and modulation processing after individually performing channel coding processing. Here, time information on a first time axis is inserted in the first transmission stream, and time information on a second time axis different from the first time axis is inserted in the transmission control signal. There is.

  The acquisition unit acquires time information on the first transmission stream and the second time axis from the modulated wave. The second reception unit receives the transmission media and a second transmission stream including presentation time information on a second time axis for each presentation unit of the transmission media. 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, by the first control unit, the presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is generated by the presentation time information included in the first transmission stream and the time information generation unit It is controlled based on time information. In addition, the second control unit acquires presentation of transmission media included in the second transmission stream received by the second reception unit by 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 generation unit.

  For example, the first time axis may be a 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 as extended information in the TMCC information. May be

  Also, for example, the second control unit may be configured to calculate the 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, The presentation time information included in the second transmission stream is converted into presentation time information based on the first time axis using transmission delay difference information between time information based on one time axis and time information based on the second time axis. The presentation of the 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 delay difference information on the transmission side and transmission delay difference information on the reception side, and the first transmission stream includes transmission delay difference information on the transmission side. , May be. Also, in this case, the second control unit may be configured to use the two latest correspondence relationships as the correspondence relationship.

  As described above, in the present technology, the presentation of the transmission media included in the first transmission stream includes 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 presentation of the transmission media included in the second transmission stream is controlled 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 The control is performed based on time information on a first time axis generated by the generation unit. Therefore, presentation synchronization control in a combination service of broadcasting and communication can be realized well.

  According to the present technology, presentation synchronization control in a combination service of broadcasting and communication can be favorably realized. The effects described in the present specification are merely examples and are not limited, and additional effects may be present.

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 broadcast and communication hybrid system. It is a system pipe model which shows composition 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 sending 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 receiving side, and target time conversion.

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

<1. Embodiment>
[Configuration example of broadcast and communication hybrid system]
FIG. 1 shows an example of the configuration of a broadcast / communication hybrid system 10. In the broadcast / communication hybrid system 10, the broadcast transmission system 110 and the distribution server 120 are disposed on the transmission side, and the receiver 200 is disposed on the reception side.

  The broadcast transmission system 110 includes a transport stream TS as a transport stream including transport 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. After performing channel coding processing individually for each of the above, processing of time division multiplexing and modulation is performed, and a broadcast signal consisting of modulated waves obtained is sent out.

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

  Further, 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 the identification information is described is inserted under the network information table (NIT: Network Information Table). The network information table contains information on the network to be transmitted, such as channel numbers, modulation schemes, and guard intervals. The details of the time information reference descriptor will be described later.

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

  The receiver 200 receives the broadcast signal sent from the broadcast transmission system 110 and also receives the transmission stream distributed from the distribution server 120. The receiver 200 generates time information (STC) synchronized with the PCR contained in the transport stream TS. Then, the receiver 200 controls the presentation of the transmission medium included in the transport stream TS based on the time information (STC), and the transmission included in the transmission stream delivered from the delivery server 120. Control media presentation.

  When controlling the presentation of the transmission media included in the transmission stream distributed from the distribution server 120, the receiver 200 uses the time information in the UTC-based NTP format inserted in the TMCC information. That is, the receiver 200 performs UTC-based presentation time information included in the transmission stream distributed from the distribution server 120 from the correspondence relationship with the above-described time information (STC) at the time of reception of the time information in the NTP format. Convert to STC base and use.

  FIG. 2 schematically shows respective systems in the broadcast / communication hybrid system 10 shown in FIG. Main image and audio data are input from the program material to the broadcasting system. A transport stream TS obtained by subjecting these image and audio data to encoding processing 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). In addition, PCR is inserted into the transport stream TS based on STC (System Time Clock).

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

  In this embodiment, as described above, UTC-based time information in the NTP format is inserted in TMCC information in the broadcast system, and the time information is used in the receiver 200 and included in the transmission stream distributed in the communication system. Control of the presentation of the image and the sound. Therefore, even if the time base of the presentation time information in the broadcasting system and the communication system is different, presentation synchronization in the combined service of broadcasting and communication becomes possible.

  FIG. 3 is a system pipe model (System Pipe Model) showing the configuration of a broadcast signal. One or more transport streams are transmitted in one RF channel. Each transport stream is identified by "TS-id". Also, one or more services exist in one transport stream. Each service is identified by "Service_id". This service corresponds to a so-called channel.

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

  Further, control signals called PSI (Program Specific Information) / SI (Service Information) exist in one transport stream. Furthermore, STC (System Time Clock) -based PCR (Program Clock Reference) exists in one transport stream.

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

  FIG. 4 shows a configuration example of TMCC information related to digital broadcasting. The field "change instruction" is incremented by one each time a change is made to the contents of the TMCC information, and when the value becomes "11111111", it returns to "00000000". The fields of "transmission mode / slot information" indicate the modulation scheme of the transmission main signal, the coding rate of the error correction inner coding, the satellite output backoff, and the number of allocated slots.

  The field of “stream type / relative stream information” indicates the correspondence between relative stream numbers and stream types. The field of “packet format / relative stream information” indicates the correspondence between relative stream numbers and packet formats. The field of "pointer / slot information" indicates the position of the beginning of the first packet stored in the slot and the position of the end of the last packet.

  The field "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 relative stream numbers and transport stream identifiers. The field of "transmission / reception control information" transmits a signal for starting control of the receiver in the emergency alert broadcast and uplink control information.

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

  Here, NTP (Network Time Protocol) will be described. NTP is a protocol defined as a standard of the Internet by ITU (International Telecommunication Union). Time information can be obtained by accessing an NTP server from a client such as a personal computer or a smartphone according to the NTP protocol. The time information provided by the NTP server is expressed by the integrated number of seconds from January 1, 1900 (UTC: Coordinated Universal Time).

  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 representing the accumulated seconds of UTC and the lower 32 bits representing less than a second. 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 representing the accumulated seconds of UTC and the lower 16 bits representing less than a second.

  FIG. 7 shows a configuration example of a time information reference descriptor (time_reference_descriptor). An 8-bit field of "descriptor_tag" indicates a descriptor type. Here, it indicates that it is 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 a PCR, TS time line extension method under development of a standard in MPEG, in which time information in NTP format is transmitted in PES. Note that this transmission mode has a large effect on the conventional broadcast system, and a band for transmission is required. “2” indicates that, in addition to transmitting a PCR, time information in NTP format is transmitted as TMCC information.

  The 2-bit field of "time_reference_format" indicates whether the time information of NTP format transmitted other than PCR is long format (see FIG. 6 (a)) or short format (see FIG. 6 (b)) . "0" indicates that it is a short format. "1" indicates that the format is long.

  The 32-bit field "delay_adjustment" indicates the transmission delay difference ΔT1 between the PCR of the system layer and the time information of the NTP format of the physical layer. The transmission delay difference ΔT1 is on the basis of 1 / 90,000 seconds. The transmission delay difference between the time information of the PCR and the NTP format occurs on both the transmitting side and the receiving 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 to STC-based presentation time information on the reception side, a transmission delay difference between 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. Further, regarding the transmission delay difference ΔT2 on the receiving side, a fixed value is set at the time of calculation on the receiving side.

  FIG. 8 shows a transmission delay model of PCR / NTP. On the transmission side, when STC-based PCR and UTC-based NTP format time information are extracted simultaneously at the same time, processing delay Ttss of channel coding for transport stream TS and channel code for TMCC information A transmission delay difference .DELTA.T1 occurs 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 path coded transport stream TS and the transport path coded TMCC information are multiplexed and modulated, and then sent to the receiving side through the broadcast channel. In this broadcast transmission line, the time information of the PCR and the NTP format is commonly delayed by the transmission line delay Tbtr. That is, in this broadcast transmission line, the delay difference between time information in PCR and NTP format is zero.

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

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

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

  The 27 MHz clock generated by the voltage control oscillator 121 is divided by 1/1716 by the divider 122. The divider 122 outputs a pulse 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 control oscillator 121 as a control signal. The voltage control oscillator 121, the frequency divider 122 and the comparator 123 constitute a PLL (Phase Locked Loop) circuit, and the voltage control oscillator 121 generates a 27 MHz clock synchronized with the reference horizontal synchronization signal.

  The 27 MHz clock output from the voltage control oscillator 121 is counted by the 9-bit counter 124 a 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 outputs of (33 + 9) bits of the 9-bit counter 124 a and the 33-bit counter 124 b become STC-based time information.

  The 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: Program Clock Reference) based on the STC-based time information. The TS packets are generated at predetermined intervals and sequentially supplied to the multiplexer 129. In addition, it is recommended that PCR appears at intervals of 100 ms in the TS stream.

  The video / audio encoding processing unit 126 encodes video and audio in synchronization with the 27 MHz clock obtained by the voltage control oscillator 121. The packetization / time stamp addition unit 127 generates a PES packet for each access unit from the encoded elementary stream of video and audio, and further generates a TS packet including encoded video and encoded audio in the payload. . The TS packet is supplied to the multiplexer 129 through the encoder buffer 128.

  Further, the packetization / time stamp addition unit 127 is supplied with the 33-bit bit output output from the 33-bit counter 124 b. The 33-bit bit output is time information with an accuracy of 90 kHz. The packetization / time stamp addition 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 the TS packet including the PCR, and the TS packet including the encoded video and the encoded audio. The multiplexer 129 multiplexes each TS packet to generate a transport stream TS. The transport stream TS also includes PSI / SI control signals. The multiplexer 129 inserts the above-described time information reference descriptor (time_reference_descriptor) (see FIG. 7) under the NIT (Network Information Table).

  Further, for example, an NTP server (not shown) is accessed via the Internet at a predetermined time interval by the time signal interface 131, and time information in a 64-bit format (see FIG. 6A) is acquired. The 32-bit registers 132 a and 132 b hold the time information in the 64-bit format acquired by the time signal interface 131. The upper 32 bits of bit data are held in the 32 bit register 132a, and the lower 32 bits of bit data are held in the 32 bit register 132b. The contents held by the 32-bit registers 132a and 132b are updated each time the time signal interface 131 acquires time information in a 64-bit format.

  If the frequency of acquiring time information is sufficiently high, the configuration may be the same as this, but if low, the registers 132a and 132b may be continuously operated as a counter indicating 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 all 0, the output of the register 132a indicating the upper 32 bits of the time information is set as the initial value of the 32-bit counter 134b. The 24-bit counter 134a is set to 0. This setting operation is limited to only one time the broadcast transmission system 110 starts operation.

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

  The transport stream TS generated by the multiplexer 129 is supplied to the main signal processing unit 141 a of the transmission path coding device 141. The main signal processing unit 141 b performs transmission path coding processing such as outer code coding, power spreading, inner code coding, and mapping 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 processor 141b of the transmission path encoding device 141 as time information of a NTP-based NTP format. The control signal processor 141 b is also supplied with a transmission parameter TMCC when transmitting the transport stream TS.

  The control signal processor 141 b generates TMCC information based on the transmission parameter TMCC. At this time, time information in the NTP long format is inserted in the field of the extension information of the TMCC information (see FIG. 5). As described above, since the bit outputs of the 24-bit counter 134a and the 32-bit counter 134b are 56 bits, the lower 8 bits are all "0". Further, in the main signal processing unit 141 b, transmission path coding processing such as outer code coding, power spreading, inner code coding, and mapping is performed on the generated TMCC information.

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

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

  The receiver 200 further includes a decoder buffer 215, a broadcast presentation control unit 216, and a broadcast AV decoder 217. The receiver 200 further 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 combining unit 241. Have.

  In the broadcast channel decoding unit 210, processing such as channel decoding is performed on the received broadcast signal (modulated wave) to obtain the transport stream TS. Also, in the broadcast transmission path decoding unit 210, based on the time information reference descriptor (time_reference_descriptor) disposed in the NIT (Network Information Table) of the transport stream TS, the time information of the NTP format inserted in the TMCC information is It is extracted.

  The transport stream TS obtained by the broadcast transmission path decoding unit 210 is supplied to the demultiplexer 211. The demultiplexer 211 extracts the PCR from the TS packet including the PCR. At the time of tuning 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) consisting of the counter 213a and the counter 213b, and then received The PCR is supplied to the comparator 214.

  Further, the 27 MHz clock generated by the voltage control 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 outputs of the 9-bit counter 213a and the 33-bit counter 213b become STC-based time information.

  The 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 control 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 PCR, and the counters 213a and 213b synchronizes with PCR. STC-based time information is generated.

  Also, 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 213 b is supplied to the broadcast presentation control unit 216 as STC-based time information.

  The broadcast presentation control unit 216 confirms the PTS of each PES packet stored in the decoder buffer 215. The broadcast presentation control unit 216 refers to STC-based time information, and the broadcast AV decoder 217 sequentially fetches PES packets to be decoded from the decoder buffer 215. The broadcast AV decoder 217 depacketizes the PES packet and decodes the encoded video and the encoded audio to obtain baseband video (video data) and audio (audio data).

  Further, the time information in the UTC format in the 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 (90 KHz count value) of the counter 213 b as STC-based time information. The UTC / STC mapping information generation unit 220 generates, as mapping information, time information in an NTP format and STC-based time information pair information (U, S) at the extraction timing.

  The time information in the UTC-based NTP format is sent from the transmitting side at an appropriate cycle, but the above-mentioned pair information is continuously generated each time it is received. The UTC / STC mapping information generation unit 220 always holds the latest pair information and the pair information immediately before that.

  The communication interface 231 communicates with the distribution server 120 (see FIG. 1) to receive the MPD file and receive a transmission stream including transmission media (components) such as video and audio. The MPD file is supplied to the MPD analysis unit 232, and the MPD analysis information obtained by the MPD analysis unit 232 is provided to the communication presentation control unit 234. Also, the transport 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 the MPEG-DASH, timing information for each presentation unit of transmission media is disclosed in the MPD file, and timing information for each presentation unit is also present in the transmission media body. The communication presentation control unit 234 acquires presentation time information for each presentation unit of the transmission media based on the timing information. This presentation time information is UTC based.

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

  The conversion from UTC base to STC base is further described. FIG. 11 (a) shows the timeline (time axis) of STC and UTC on the transmission side. Un-1 and Un on the UTC timeline indicate the UTC-based time to be inserted and transmitted in 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 context of the STC and UTC timeline at the sender, the UTC based presentation time Utar corresponds to the STC based time Star.

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

  In UTC / STC mapping information generation unit 220, STC-based time S 'n-1 is paired with UTC-based time Un-1. This time S ′ n−1 is a time that is ΔT earlier than time Sn−1. Further, 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 earlier than time Sn. In the relationship between STC and UTC timelines at the receiver, the UTC based presentation time Utar corresponds to the STC based time S'tar. This time S'tar is a time that is ΔT earlier than time Star.

In the communication presentation control unit 234, the UTC-based presentation time Utar is converted into STC-based time Star (target time conversion) according to the following equation (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 + .DELTA.T1 + .DELTA.T2
... (1)

  Returning to FIG. 10, in the communication presentation control unit 234, the presentation time of each presentation unit stored in the decoder buffer 233 converted into the STC base as described above is confirmed. Then, 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 each presentation unit of video and audio to be decoded from the decoder buffer 233. . The communication AV decoder 235 decodes the encoded video and encoded audio of each presentation unit to obtain baseband video (video data) and audio (audio data).

  The synthesizing unit 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 the final AV output. Then, in the receiver 200, video display is performed by the video data, and audio output is performed by the audio data.

  As described above, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, in addition to the STC-based PCR being inserted in the transport stream TS, time information in NTP format in UTC format in TMCC information. Is to be inserted. Therefore, on the receiving side, presentation synchronization control in the combined service of broadcasting and communication can be realized well.

  Further, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, time information in UTC format in NTP format is inserted in the extended information field of TMCC information. Therefore, no new bandwidth is required to transmit time information in UTC-based NTP format.

  Further, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, identification information indicating that time information in UTC format in NTP format is inserted in TMCC information is inserted in the transport stream TS. It is That is, the time information reference descriptor is inserted into the NIT. Therefore, on the receiving side, it can be easily identified that time information in UTC format in NTP format is inserted in 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 PCR of the system layer on the transmission side and time of the NTP format of the physical layer. A transmission delay difference ΔT1 with information is described. Therefore, even if time information in the UTC format is inserted into TMCC information and sent on the receiving side, this transmission delay difference ΔT1 is used to convert UTC-based presentation time information into STC-based presentation time information. It becomes possible to convert well.

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

Furthermore, the present technology can also be configured as follows.
(1) Transmission path coding processing individually for each of the transmission stream including the transmission media and the presentation time information according to the first time axis for each presentation unit of the transmission media and the transmission control signal corresponding to the transmission stream And a transmitter configured to obtain a modulated wave by performing time division multiplexing and modulation processing, and transmitting the modulated wave.
In the transmission stream, time information on the first time axis is inserted,
A transmission apparatus further comprising: a time information insertion unit which 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 STC-based PCR,
The transmitting apparatus according to (1), wherein the time information according to the second time axis is time information in a UTC-based NTP format.
(3) The transmission control signal is TMCC information,
The transmission apparatus according to (1) or (2), wherein the time information insertion unit inserts time information on the second time axis as the extension information into the TMCC information.
(4) The transmission stream further includes an identification information insertion unit that inserts identification information indicating that the time information on the second time axis is inserted in the transmission control signal. (1) to (3) The transmitter according to any one of the above.
(5) When the time information based on the second time axis is time information based on UTC format NTP format, information indicating whether the NTP format is long format or short format is added to the identification information The transmitting device according to (4).
(6) Transmission delay difference information of 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 unit according to any one of (4) to (6), wherein the identification information insertion unit inserts a descriptor in which the identification information is described in a network information table.
(8) The transmission unit individually transmits a transmission stream including transmission time information on the transmission medium and the presentation time information on the first time axis for each presentation unit of the transmission medium and transmission control signals corresponding to the transmission stream. After the encoding process is performed, time-division multiplexing and modulation processes are performed to obtain a modulated wave, and a transmitting step of transmitting the modulated wave is included,
In the transmission stream, time information on the first time axis is inserted,
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) For each of the first transmission stream including the transmission media and the presentation time information on the first time axis for each presentation unit of the transmission media and the transmission control signal corresponding to the first transmission stream A first receiving unit for receiving a modulated wave obtained by performing time division multiplexing and modulation after performing channel coding processing;
Time information on the first time axis is inserted into the first transmission stream,
In the transmission control signal, time information on a second time axis different from the first time axis is inserted,
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 for receiving a second transmission stream including transmission media and presentation time information according to the second time axis for each presentation unit of the transmission media;
A time information generation unit that generates time information synchronized with time information on the first time axis included in the first transmission stream acquired by the acquisition unit;
The presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is performed based on presentation time information included in the first transmission stream and the time information generated by the time information generator. 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 information acquired by the acquisition unit A second control unit configured to control based on time information on a time axis and time information generated by the time information generation unit.
(10) The second control unit
Correspondence between time information on the second time axis acquired by the acquisition unit and time information generated by the time information generation unit when the time information is received, and time information on the first time axis And presentation time information included in the second transmission stream is converted into presentation time information based on the first time axis using the transmission delay difference information between the time information on the second time axis and the second time axis. The receiver according to (9), which controls presentation of a transmission medium included in the second transmission stream based on the presentation time information and the time information generated by the time information generation unit.
(11) The transmission delay difference information includes transmission delay difference information on the transmission side and transmission delay difference information on the reception side.
The reception apparatus according to (10), wherein the first transmission stream includes transmission delay difference information on the transmission side.
(12) The second control unit
The reception device according to (10) or (11), wherein the latest two correspondence relationships are used as the correspondence relationship.
(13) The reception device 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 transport stream is MPEG2-TS,
The transmission control signal is TMCC information,
The reception device according to any one of (9) to (13), wherein time information on the second time axis is inserted as extended information in the TMCC information.
(15) A first transmission stream including transmission media and presentation time information on a first time axis for each presentation unit of the transmission media by a first reception unit, and a transmission control signal corresponding to the first transmission stream After individually performing channel coding processing for each of the above, and performing a processing of time division multiplexing and modulation, and receiving a modulated wave obtained by the processing;
Time information on the first time axis is inserted into the first transmission stream,
In the transmission control signal, time information on a second time axis different from the first time axis is inserted,
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, by the second receiving unit, a second transmission stream including transmission media and presentation time information according to the second time axis for each presentation unit of the transmission media;
A time information generation step for generating time information synchronized with 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 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 information acquired in the acquisition step A second control step of controlling based on time information on a time axis and time information generated in the time information generation step.

  The main feature of this technology is that, in addition to inserting STC-based PCR into transport stream TS, by inserting time information in NTP format NTP-based into TMCC information, in the broadcast and communication fusion service on the receiving side It is that the presentation synchronous control can be realized well (see FIG. 9).

10 ··· Hybrid broadcast and communication system 110 ··· Broadcast transmission system 120 ··· Distribution server 121 ··· Voltage controlled oscillator (27 MHz)
122 ・ ・ ・ Divider (1/1716)
123: Comparator 124a: 9-bit counter 124b: 33-bit counter 125: packetizing unit 126: video / audio encoding processor 127: packetizing / time stamp adding unit 128 · · Encoder buffer 129 · · · Multiplexer 131 · · · Time signal interface 132a, 132b · · · 32-bit counter 133 · · · voltage controlled oscillator (2 ** 24 Hz)
134a: 24-bit counter 134b: 32-bit counter 135: comparator 141: transmission line coding device 141a: main signal processing unit 141b: control signal processing unit 141c.・ Time division multiplexing / quadrature modulation processing unit 200 ・ ・ ・ Receiver 201 ・ ・ ・ Broadcast channel decoding unit 211 ・ ・ ・ Demultiplexer 212 ・ ・ ・ Voltage controlled oscillator (27 MHz)
213a ... 9 bit counter 213b ... 33 bit counter 214 ... comparator 215 ... decoder buffer 216 ... broadcast presentation control unit 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: Synthesis unit 300: Communication network

Claims (6)

A transmission unit that transmits a transmission stream including transmission media and time information according to a first time axis, and description information related to time information according to the first time axis;
The description information includes time correction information for correcting a correspondence between a time indicated by time information on the first time axis and a time indicated by time information on a second time axis different from the first time axis. seen including,
The time information on the first time axis is STC-based PCR,
The time information according to the second time axis is time information in UTC format in NTP format,
The description information, the NTP format including transmitting device information indicating which short-format or a long format. The transport stream is MPEG2-TS,
The transmitter according to claim 1, wherein a descriptor in which the description information is described is inserted in a network information table. A transmission stream including transmission media and time information according to a first time axis, and a procedure for transmitting description information related to time information according to the first time axis;
The description information includes time correction information for correcting a correspondence between a time indicated by time information on the first time axis and a time indicated by time information on a second time axis different from the first time axis. seen including,
The time information on the first time axis is STC-based PCR,
The time information according to the second time axis is time information in UTC format in NTP format,
The description information, the information method including transmitting indicating whether the NTP format is short-format or a long format. In order to correct the correspondence between the time information indicated by the first time axis, the time indicated by the time information indicated by the first time axis, and the time indicated by the time information indicated by the second time axis different from the first time axis comprising of the description information including the time correction information, and transmission media, the reception unit that receives the presentation time information according to the second time base for each presentation unit of said transmission media,
The time information on the first time axis is STC-based PCR,
The time information according to the second time axis is time information in UTC format in NTP format,
The description information includes information indicating whether the NTP format is a long format or a short format ,
A receiver further comprising: a control unit configured to control the presentation of the transmission medium based on the presentation time information, the time correction information, and time information generated in synchronization with the time information on the first time axis. The control unit
The presentation time information is converted into presentation time information on the first time axis using the time correction information, and is generated in synchronization with the converted presentation time information and time information on the first time axis The reception apparatus according to claim 4 , wherein presentation of the transmission medium is controlled based on time information. In order to correct the correspondence between the time information indicated by the first time axis, the time indicated by the time information indicated by the first time axis, and the time indicated by the time information indicated by the second time axis different from the first time axis (D) description information including time correction information, a transmission medium, and a procedure for receiving presentation time information according to the second time axis for each presentation unit of the transmission medium,
The time information on the first time axis is STC-based PCR,
The time information according to the second time axis is time information in UTC format in NTP format,
The description information includes information indicating whether the NTP format is a long format or a short format ,
A reception method, further comprising : a procedure of controlling presentation of the transmission medium based on time information generated in synchronization with the presentation time information, the time correction information, and time information on the first time axis.

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