JP7120399B2 - Sending method - Google Patents

Description

The present technology relates to a transmission method .

Convergence service of broadcasting and communication is mentioned as an essential service requirement for the next-generation broadcasting system. Although various forms of convergence services of broadcasting and communications are envisioned, one possible form is a case in which basic signals such as images and sounds that make up one broadcast program are transmitted partly by broadcasting and partly by communication. ing.

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

JP 2013-153291 A

"Uninterrupted video distribution with existing web servers", Mitsuhiro Hirabayashi, NIKKEI ELECTRONICS 2012.3.19

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

Generally, in broadcasting, an independent 27 MHz counter value called STC (System Time Clock) is used as the time axis for each transmission system, 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 make it possible to satisfactorily implement presentation synchronization control in a convergence service of broadcasting and communication.

The concept of this technology is
after individually performing transmission line coding processing on each of transmission media, transmission streams containing presentation time information on the first time axis for each presentation unit of the transmission media, and transmission control signals corresponding to the transmission streams; A transmission unit that performs time division multiplexing and modulation processing to obtain a modulated wave and transmits the modulated wave,
Time information according to the first time axis is inserted into the transmission stream,
The transmitting apparatus further includes a time information inserting unit for inserting 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 a modulated wave. This modulated wave is individually channel-coded for each of the transmission media, the transmission stream containing presentation time information on the first time axis for each presentation unit of this transmission media, and the transmission control signal corresponding to this transmission stream. It is obtained by performing time-division multiplexing and modulation after processing. Time information based on the first time axis is inserted in the transmission stream. Then, the time information inserting unit inserts time information based on a second time axis different from the first time axis into the transmission control signal.

For example, the transport 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 UTC-based NTP format time information. may Further, for example, the transmission control signal may be TMCC information, and the time information inserting unit may insert time information on the second time axis into the TMCC information as extended information.

Thus, in the present technology, in addition to inserting time information on the first time axis into the transmission stream, time information on the second time axis is inserted into the transmission control signal. Therefore, the reception side can satisfactorily implement presentation synchronization control in the convergence service of broadcasting and communication.

In addition, in the present technology, for example, an identification information inserting unit that inserts identification information indicating that time information based on the second time axis is inserted in the transmission control signal into the transmission stream may be provided. good. In this case, for example, the transmission stream is MPEG2-TS, and the identification information inserting unit inserts 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 based 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 UTC-based NTP format time information, information indicating whether the NTP format is long format or short format is added to the identification information. may be used. This allows the receiving side to easily recognize whether the NTP format is the long format or the short format.

In this case, transmission delay difference information between the time information on the first time axis and the time information on the second time axis may be added to the identification information. As a result, the receiving side can obtain transmission delay difference information on the transmitting side necessary for converting presentation time information on the second time axis into presentation time information on the first time axis.

Another concept of this technology is
A transmission line code for each of a transmission medium, a first transmission stream containing 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 A first receiving unit for receiving a modulated wave obtained by performing time-division multiplexing and modulation processing after performing conversion processing,
Time information according to the first time axis is inserted into the first transmission stream,
Time information on a second time axis different from the first time axis is inserted into the transmission control signal,
an acquisition unit that acquires 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 on the second time axis for each presentation unit of the transmission media;
a time information generator for generating time information synchronized with the time information on the first time axis included in the first transmission stream acquired by the acquisition unit;
presenting the transmission media included in the first transmission stream acquired by the acquisition unit 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 that controls
Presentation of transmission media included in the second transmission stream received by the second receiving unit is performed using presentation time information included in the second transmission stream and the second transmission stream acquired by the acquisition unit. The receiving apparatus further includes a second control section that performs control based on time information on a time axis and the time information generated by the time information generating section.

In the present technology, the modulated wave is received by the first receiving unit. This modulated wave is for each of a first transmission stream containing transmission media, presentation time information on a first time axis for each presentation unit of this transmission media, and a transmission control signal corresponding to this first transmission stream. It is obtained by performing time-division multiplexing and modulation after performing channel coding processing individually. Here, time information based on a 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. there is

The acquiring unit acquires the first transmission stream and the time information on the second time axis from the modulated wave. The second receiving unit receives the transmission media and the second transmission stream including the presentation time information on the 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, the presentation of the transmission media included in the first transmission stream acquired by the acquisition unit is generated by the first control unit and the presentation time information included in the first transmission stream by the time information generation unit. It is controlled based on time information. Further, the second control unit causes the presentation of the transmission media included in the second transmission stream received by the second reception unit to be acquired by the acquisition unit with the presentation time information included in the second transmission stream. The control is performed based on the time information generated by the second time axis and the time information generated by the time information generating section.

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 in the TMCC information as extended information. may

Further, for example, the second control unit determines the 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 when the time information is received, and the 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 the presentation time information on the first 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 generating unit.

In this case, for example, the transmission delay difference information consists of the transmission delay difference information on the transmitting side and the transmission delay difference information on the receiving side, and the first transmission stream includes the transmission delay difference information on the transmitting side. , may be so. Also, in this case, the second control unit may use the latest two correspondences as the correspondences.

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

Advantageous Effects of Invention According to the present technology, it is possible to satisfactorily implement presentation synchronization control in a convergence service of broadcasting and communication. Note that the effects described in this specification are merely examples and are not limited, and additional effects may be provided.

1 is a block diagram showing a configuration example of a broadcasting/communication hybrid system as an embodiment; FIG. 1 is a diagram schematically showing each system in a hybrid broadcasting/communication system; FIG. A system pipe model showing 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. FIG. 2 is a diagram showing a long format and a short format of time information provided by an NTP server; It is a figure which shows the structural example of a time information reference descriptor. FIG. 3 is a diagram showing a transmission delay model of PCR/NTP; 1 is a block diagram showing a configuration example of a broadcast transmission system that constitutes a hybrid broadcast/communication system; FIG. 1 is a block diagram showing a configuration example of a receiver that constitutes a hybrid broadcasting/communication system; FIG. FIG. 4 is a diagram for explaining timelines on the transmitting side and the receiving side and target time conversion;

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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. Modification

<1. Embodiment>
[Configuration example of broadcasting/communication hybrid system]
FIG. 1 shows a configuration example of a broadcasting/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. After performing transmission line coding processing on each of them individually, a broadcast signal composed of a modulated wave obtained by performing time division multiplexing and modulation processing is sent out.

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

Also, identification information indicating that time information in NTP format is inserted in the TMCC information is inserted in the transport stream TS. In this embodiment, a time_reference_descriptor describing this identification information is inserted under a network information table (NIT). The network information table contains information about the transmitting network, such as channel numbers, modulation schemes, and guard intervals. The details of this 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 receiving side via the communication network 300 in response to a request from the receiving side, for example. This transmission stream contains presentation time information for each presentation unit of transmission media. This presentation time information is based on UTC. In this embodiment, MPEG-DASH is used as a delivery system for transmission media through communication, and delivery server 120 is assumed to be a DASH streaming server (also serving as a DASH MPD server).

The receiver 200 receives broadcast signals sent from the broadcast transmission system 110 and also receives transmission streams distributed from the distribution server 120 . The receiver 200 generates time information (STC) synchronized with the PCR contained in the transport stream TS. Based on this time information (STC), the receiver 200 controls the presentation of the transmission media included in the transport stream TS, and also controls the presentation of the transmission media included in the transport 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 the UTC-based NTP format time information inserted in the TMCC information. That is, the receiver 200 converts the presentation time information included in the transmission stream distributed from the distribution server 120 into a UTC-based time information based on the correspondence relationship with the time information (STC) described above when the time information in the NTP format is received. Convert from to STC base and use.

FIG. 2 schematically shows each system in the hybrid broadcasting/communication 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 performing encoding processing on these image and audio data is sent from the broadcast transmission system 110 to the receiver 200 through the broadcast transmission line. Here, presentation time information (PTS) is inserted into video and audio PES packets based on an STC (System Time Clock) during encoding processing. Also, a PCR is inserted into the transport stream TS based on the STC (System Time Clock).

Sub image and audio data are input from the program material to the communication system. A transmission stream obtained by performing encoding processing on these image and audio data is sent from distribution server 120 to receiver 200 through a communication transmission line. Here, during the encoding process, 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, time information in the UTC-based NTP format is inserted into the TMCC information in the broadcasting system, and this time information is used in the receiver 200 to be included in the transmission stream distributed in the communication system. The presentation of images and sounds to be used is controlled. Therefore, even if the time axes of the presentation time information in the broadcasting system and the communication system are different, it is possible to synchronize the presentation in the integrated service of broadcasting and communication.

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

One service includes video, audio, closed caption, etc. as transmission media (components). In other words, each service consists of components such as video, audio, and closed captioning.

Also, one transport stream includes control signals called PSI (Program Specific Information)/SI (Service Information). Furthermore, one transport stream has an STC (System Time Clock)-based PCR (Program Clock Reference).

Also, in one RF channel, TMCC information, which is a transmission control signal, is transmitted in parallel with one or more transport streams described above. In this embodiment, as described above, the TMCC information includes UTC (Universal Time, Coordinated)-based NTP (Network Time Protocol) format time 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', it returns to '00000000'. The 'transmission mode/slot information' field indicates the modulation method of the main transmission signal, the coding rate of the error correction inner coding, the satellite output backoff, and the number of allocated slots.

The "stream type/relative stream information" field indicates the correspondence relationship between the relative stream number and the stream type. The “packet format/relative stream information” field indicates the correspondence relationship between relative stream numbers and packet formats. The "pointer/slot information" field 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 "relative stream/slot information" field indicates the correspondence between slots and relative stream numbers. The "relative stream/transport stream ID correspondence table" field indicates the correspondence between relative stream numbers and transport stream identifiers. The "transmission control information" field transmits a signal and uplink control information for activation control of the receiver in emergency warning broadcasting.

At the end of the TMCC information there is a 3614-bit field of "extended information". In this embodiment, the first 80 bits of this "extended information" field are used to insert time information in UTC-based NTP format. FIG. 5 shows a configuration example of extended information (time information). A 16-bit field of "extended identifier" is set to, for example, "0x0001", indicating that the extended information is time information. Time information in UTC-based NTP format is inserted in the 64-bit field of "extension 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 an Internet standard by the ITU (International Telecommunication Union). Time information can be obtained by accessing an NTP server using the NTP protocol from a client such as a personal computer or a smart phone. The time information provided by the NTP server is represented by the cumulative number of seconds since 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, where the upper 32 bits indicate the cumulative number of seconds in UTC, and the lower 32 bits indicate less than a second. FIG. 6(b) shows a short format of time information provided by the NTP server (NTP time stamp short format). This time information is in a 32-bit format, with the upper 16 bits indicating the cumulative number of seconds in UTC and the lower 16 bits indicating 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 the descriptor type. Here, it indicates that it is a time information reference descriptor. An 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 the transmission mode of time information. A "0" indicates that only the PCR is transmitted. "1" indicates that, in addition to transmitting PCR, time information in NTP format is transmitted by PES in the TS timeline expansion method currently being standardized by MPEG. This transmission mode has a great influence on conventional broadcasting systems, and requires a band for transmission. "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 NTP format time information transmitted in addition to the PCR is long format (see FIG. 6(a)) or short format (see FIG. 6(b)). . "0" indicates the short format. "1" indicates the long format.

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

As will be described later, when the receiving side converts UTC-based presentation time information into STC-based presentation time information, a transmission delay difference between the sending side and the receiving side is required. The transmission delay difference ΔT1 on the transmitting 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 transmitting side, when the STC-based PCR and UTC-based NTP format time information are simultaneously extracted at a certain timing, the processing delay Ttss of the channel coding for the transport stream TS and the channel code for the TMCC information are detected. A transmission delay difference .DELTA.T1 is generated between the PCR and the time information in the NTP format by the difference in processing delay Ttmccs of conversion. That is, ΔT1=(Ttss−Ttmccs).

The channel-encoded transport stream TS and the channel-encoded TMCC information are multiplexed and modulated, and then transmitted to the receiving side through the broadcast transmission channel. On this broadcast transmission line, the PCR and NTP format time information are commonly delayed by a transmission line delay Tbtr. In other words, the delay difference between the PCR and NTP format time information is zero on this broadcast transmission line.

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 processing delay Ttsr for decoding the transport stream TS and the processing delay Ttmccr for decoding the TMCC information. do. That is, ΔT2=(Ttsr-Ttmccr). Therefore, the total transmission delay difference ΔT between the PCR and the NTP format time information is ΔT=ΔT1+ΔT2.

[Broadcast transmission system configuration example]
FIG. 9 shows a configuration example of the broadcast transmission system 110. As shown in FIG. This broadcast transmission system 110 comprises a voltage controlled oscillator 121 that generates a 27 MHz clock (system clock), a frequency divider 122 that divides the frequency by 1/1716, a comparator 123, and an STC-based clock section. It has a bit counter 124 a and a 33-bit counter 124 b and a packetizer 125 . The broadcast transmission system 110 also has 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 also has a time signal interface 131 and 32-bit registers 132a and 132b. The broadcast transmission system 110 also 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 section, and a comparator 135. have. The broadcast transmission system 110 also has a transmission line coding device 141 . The channel coding device 141 includes a main signal processing unit 141a that performs channel encoding of the transport stream TS, a control signal processing unit 141b that performs channel encoding of TMCC information, time division multiplexing/ A quadrature modulation processor 141c is included.

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

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

This STC-based time information is supplied to the packetizing section 125 . The packetization 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 PCR appear in the TS stream at intervals of 100 ms.

The video/audio encoding processing unit 126 encodes video and audio in synchronization with the 27 MHz clock obtained from the voltage controlled oscillator 121 . The packetizing/time-stamping unit 127 generates a PES packet for each access unit from the encoded video and audio elementary streams, and further generates a TS packet containing encoded video and encoded audio in the payload. . This TS packet is supplied to multiplexer 129 through encoder buffer 128 .

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

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

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

If the frequency of acquiring time information is sufficiently high, the configuration may be left as is, but if it is low, the registers 132a and 132b may continue to operate as counters that automatically indicate the time 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, and the 24-bit counter 134a is set to zero. This setting operation is limited to one time when the broadcast transmission system 110 starts operation.

The voltage controlled oscillator 133 generates a 2**24 Hz clock. The 2**24 Hz clock output from the voltage controlled oscillator 133 is counted by the 24-bit counter 134a. The 32-bit counter 134b counts the 1 Hz clock, which is the carry output of the 24-bit counter 134a, and obtains the 32-bit bit output which is time information (Regenerated UTC) with second accuracy. The 56-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 section 141 a of the line coding device 141 . In the main signal system processing unit 141b, the transport stream TS is subjected to transmission line coding processing such as outer code coding, power spreading, inner code coding, and mapping.

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

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

Further, in the time division multiplexing/quadrature modulation processing section 141c of the channel coding apparatus 141, the outputs of the main signal processing section 141a and the control signal processing section 141b are subjected to time division multiplexing and quadrature modulation processing. , a modulated wave with an intermediate frequency is obtained.

[Configuration example of receiver]
FIG. 10 shows a configuration example of the receiver 200. As shown in FIG. This receiver 200 comprises a broadcast transmission path decoder 210, a demultiplexer 211, a voltage controlled oscillator 212 that generates a 27 MHz clock (system clock), and an STC-based clock (time information generator). It has a bit counter 213 a and a 33-bit count 213 b and a comparator 214 .

The receiver 200 also has a decoder buffer 215 , a broadcast presentation controller 216 and a broadcast AV decoder 217 . Further, the receiver 200 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 channel decoding unit 210 performs processing such as channel decoding on the received broadcast signal (modulated wave) to obtain a transport stream TS. Further, in the broadcast transmission path decoding unit 210, based on the time information reference descriptor (time_reference_descriptor) arranged in the NIT (Network Information Table) of the transport stream TS, the NTP format time information inserted in the TMCC information is converted to extracted.

The transport stream TS obtained by the broadcast transmission path decoding unit 210 is supplied to the demultiplexer 211 . This demultiplexer 211 extracts the PCR from the TS packet containing the PCR. When a channel is selected or the power is turned on, the first received 42-bit PCR is set as an initial value in a 42-bit clock section (time information generator) consisting of counters 213a and 213b. The PCR is provided to 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 this 9-bit counter 213a is counted by a 33-bit counter 213b. The 42-bit bit outputs of these 9-bit counter 213a and 33-bit counter 213b are STC-based time information.

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

Also, the demultiplexer 211 extracts TS packets containing encoded video and encoded audio, and temporarily stores them 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 section 216 as STC-based time information.

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

Also, the UTC-based NTP format time information 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 generator 220 is supplied with the 33-bit bit output (count value of 90 KHz) of the counter 213b as STC-based time information. The UTC/STC mapping information generation unit 220 generates pair information (U, S) of NTP format time information and STC-based time information at the extraction timing as mapping information.

Time information in the UTC-based NTP format is sent from the transmitting side at appropriate intervals, and the pair information described above is continuously generated each time it is received. The UTC/STC mapping information generator 220 always holds the latest pair information and the previous pair information.

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

The communication presentation control unit 234 generates the STC-based time information, which is the 33-bit bit output (count value of 90 kHz) of the counter 213b, and the latest two pairs of pair information (U , S), UTC-based presentation time information is converted into STC-based presentation time information (timeline conversion).

Conversion from UTC-based to STC-based is further described. FIG. 11(a) shows the timelines (time axes) of STC and UTC on the transmitting side side by side. Un-1 and Un on the UTC timeline indicate the UTC-based time inserted into the TMCC information and transmitted. Sn-1 and Sn on the STC timeline indicate STC-based times corresponding to UTC-based times Un-1 and Un, respectively. In relation to the STC and UTC timelines at the sender, the UTC-based presentation time Utar corresponds to the STC-based time Star.

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

In the UTC/STC mapping information generator 220, the STC-based time S'n-1 is paired with the UTC-based time Un-1. This time S'n-1 is the time ΔT before the time Sn-1. Also, in the UTC/STC mapping information generating section 220, the STC-based time S'n is paired with the UTC-based time Un. This time S'n is the time ΔT before the time Sn. In the relationship of the STC and UTC timelines at the receiving end, the UTC-based presentation time Utar corresponds to the STC-based time S'tar. This time S'tar is the time ΔT before the time Star.

The communication presentation control unit 234 converts the UTC-based presentation time Utar into the STC-based time Star (target time conversion) using 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 converted into the STC base as described above for each presentation unit accumulated in the decoder buffer 233 . 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 takes in 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 broadcast AV decoder 217 with the AV output of the video data and audio data obtained by the communication AV decoder 235 to obtain a final AV output. Then, in the receiver 200, image display is performed based on this video data, and sound output is performed based on audio data.

As described above, in the broadcast/communication hybrid system 10 shown in FIG. 1, the broadcast transmission system 110 inserts STC-based PCR into the transport stream TS, and also inserts UTC-based NTP format time information into the TMCC information. is inserted. Therefore, the reception side can satisfactorily implement presentation synchronization control in the convergence service of broadcasting and communication.

In the broadcasting/communication hybrid system 10 shown in FIG. 1, the broadcasting transmission system 110 inserts the time information in the UTC-based NTP format into the extension information field of the TMCC information. Therefore, no new bandwidth is required for transmitting time information in the UTC-based NTP format.

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

In the broadcasting/communication hybrid system 10 shown in FIG. 1, the time information reference descriptor inserted into the transport stream TS by the broadcasting transmission system 110 contains the system layer PCR and physical layer NTP format time on the transmitting side. A transmission delay difference ΔT1 from information is described. Therefore, on the receiving side, even if time information in the UTC-based NTP format is inserted into the TMCC information and sent, the transmission delay difference ΔT1 is used to convert the UTC-based presentation time information into STC-based presentation time information. Good conversion is possible.

<2. Variation>
In the above embodiment, the transport stream is a 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. NTP format time information. Although detailed explanation is omitted, it goes without saying that the present technology can be similarly applied to other cases in which similar transmission streams are handled.

Moreover, this technique can also take the following structures.
(1) Transmission channel coding processing is performed individually for transmission media, transmission streams containing presentation time information on the first time axis for each presentation unit of the transmission media, and transmission control signals corresponding to the transmission streams. After performing time division multiplexing and modulation processing to obtain a modulated wave, a transmission unit for transmitting the modulated wave,
Time information according to the first time axis is inserted into the transmission stream,
The transmitting device further includes a time information inserting unit that inserts time information based on a second time axis different from the first time axis into the transmission control signal.
(2) the transport stream is MPEG2-TS;
The time information on the first time axis is STC-based PCR,
The transmitting device according to (1), wherein the time information on the second time axis is UTC-based NTP format time information.
(3) the transmission control signal is TMCC information;
The transmitting device according to (1) or (2), wherein the time information inserting unit inserts time information according to the second time axis as extended information into the TMCC information.
(4) further comprising an identification information inserting unit that inserts, into the transmission stream, identification information indicating that the time information on the second time axis is inserted into the transmission control signal. The transmitting device according to any one of 1.
(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 long format or short format is added to the identification information. The transmission device according to (4) above.
(6) Transmission according to (4) or (5), 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. Device.
(7) the transport stream is MPEG2-TS;
The transmission device according to any one of (4) to (6), wherein the identification information inserting unit inserts a descriptor describing the identification information into a network information table.
(8) The transmitting unit individually transmits transmission paths for transmission media, transmission streams containing presentation time information on the first time axis for each presentation unit of the transmission media, and transmission control signals corresponding to the transmission streams. Having a transmission step of performing time division multiplexing and modulation processing after performing encoding processing to obtain a modulated wave, and transmitting the modulated wave;
Time information according to the first time axis is inserted into the transmission stream,
A transmission method further comprising a time information inserting step of inserting time information according to a second time axis different from the first time axis into the transmission control signal.
(9) Separately for each of the transmission media, the first transmission stream including 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 that receives a modulated wave obtained by performing time division multiplexing and modulation processing after performing channel coding processing,
Time information according to the first time axis is inserted into the first transmission stream,
Time information on a second time axis different from the first time axis is inserted into the transmission control signal,
an acquisition unit that acquires 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 on the second time axis for each presentation unit of the transmission media;
a time information generator for generating time information synchronized with the time information on the first time axis included in the first transmission stream acquired by the acquisition unit;
presenting the transmission media included in the first transmission stream acquired by the acquisition unit 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 that controls
Presentation of transmission media included in the second transmission stream received by the second receiving unit is performed using presentation time information included in the second transmission stream and the second transmission stream acquired by the acquisition unit. A receiving device further comprising a second control section that performs control based on time information on a time axis and the time information generated by the time information generating section.
(10) The second control unit
Correspondence relationship 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 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, and the converted The receiving device according to (9) above, which controls presentation of the transmission media included in the second transmission stream based on the presentation time information and the time information generated by the time information generating section.
(11) The transmission delay difference information consists of transmission delay difference information on the transmitting side and transmission delay difference information on the receiving side,
The receiving device 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 two latest correspondences are used as the correspondences.
(13) The receiver 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 receiving device according to any one of (9) to (13), wherein time information on the second time axis is inserted in the TMCC information as extended 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, and a transmission control signal corresponding to the first transmission streams, generated by the first receiving unit. A first receiving step of receiving a modulated wave obtained by performing time division multiplexing and modulation processing after individually performing transmission line coding processing on each of
Time information according to the first time axis is inserted into the first transmission stream,
Time information on a second time axis different from the first time axis is inserted into 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, by a second receiving unit, 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 step for generating time information synchronized with the time information on the first time axis included in the first transmission stream acquired in the acquiring step;
presenting the transmission media included in the first transmission stream acquired in the acquisition step 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 of controlling;
presentation of the transmission media included in the second transmission stream received in the second receiving step, the presentation time information included in the second transmission stream and the second transmission stream acquired in the acquisition step; A reception method further comprising a second control step of performing control based on time information on a time axis and the time information generated in the time information generating step.

The main feature of this technology is that in addition to inserting STC-based PCR into the transport stream TS, UTC-based NTP format time information is also inserted into the TMCC information. The advantage is that presentation synchronization control can be satisfactorily realized (see FIG. 9).

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 section 126... Video/audio encoding processing section 127... Packetization/time stamp addition section 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 line coding device 141a... Main signal system processor 141b... Control signal system processor 141c... - Time division multiplexing/quadrature modulation processing unit 200 Receiver 201 Broadcast transmission path 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 (1)

The transmission unit has a transmission step of transmitting transmission media and time information on the first time axis,
In the transmitting step, reference time information including information for making time information on the second time axis correspond to time information on the first time axis and information on delay in signal encoding processing is further transmitted .
Send method.

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