JP2020188497A - Transmission method - Google Patents

Abstract

To perform excellent presentation synchronization control in a fusion service of broadcast and communication.SOLUTION: A transmission unit transmits modulated waves. The modulated waves are obtained by individually performing transmission path encoding processing on each of a transmission stream including a transmission medium and presentation time information by a first time axis for each presentation unit of the transmission medium and a transmission control signal corresponding to the transmission stream, and then performing processing of time division multiplexing and modulation. Time information by the first time axis is inserted into the transmission stream. A time information insertion unit inserts time information by a second time axis different from the first time axis into the transmission control signal.SELECTED DRAWING: Figure 9

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 for transmitting a transmission stream including a transmission medium such as video and audio.

An indispensable service requirement for next-generation broadcasting systems is a service that integrates broadcasting and communication. Various forms of integrated broadcasting and communication services are expected, and one form is considered to be the case where basic signals such as images and sounds that make up one broadcast program are partially broadcast and partially transmitted by communication. ing.

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

Japanese Unexamined Patent Publication No. 2013-153291

"Realizing uninterrupted video distribution on existing Web servers", Mitsuhiro Hirabayashi, NIKKEI ELECTRONICS 2012.3.19

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

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

The purpose of this technology is to make it possible to satisfactorily realize the presentation synchronization control in the integrated service of broadcasting and communication.

The concept of this technology is
After performing the transmission path coding process individually for each of the transmission medium, the 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 transmission stream. A transmitter that obtains a modulated wave by performing time division multiplexing and modulation processing and transmits the modulated wave is provided.
Time information based on the first time axis is inserted in the transmission stream.
The transmission device further includes a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal.

In the present technology, the transmission unit transmits the modulated wave. This modulated wave is individually transmitted path coded for each of the transmission media, the 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 this transmission stream. It was obtained by performing time division multiplexing and modulation processing after processing. Time information on the first time axis is inserted in the transmission stream. Then, the time information insertion unit inserts the time information on the second time axis different from the first time axis into the transmission control signal.

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

As described above, in the present technology, in addition to inserting the time information on the first time axis 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 integrated service of broadcasting and communication can be satisfactorily realized.

In the present technology, for example, even if the transmission stream is further provided with 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 transmission stream may be MPEG2-TS, and the identification information insertion unit may be configured to insert a descriptor in which the identification information is described into the network information table. By inserting the identification information in this way, the receiving side can easily identify that the time information on the second time axis is inserted in the transmission control signal.

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

Further, in this case, the 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 the transmission delay difference information on the transmitting side necessary for converting the presentation time information on the second time axis into the presentation time information on the first time axis.

In addition, other concepts of this technology
A transmission path code 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. It is provided with a first receiving unit that receives the modulated wave obtained by performing the time division multiplexing and modulation processing after the conversion process.
Time information based on the first time axis is inserted in the first transmission stream.
Time information on a second time axis different from the first time axis is inserted in the transmission control signal.
An acquisition unit that acquires time information from the modulated wave according to the first transmission stream and the second time axis, and
A second receiving unit that receives the transmission medium and the second transmission stream including the 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 the time information on the first time axis included in the first transmission stream acquired by the acquisition unit, and a time information generation unit.
The presentation of the transmission medium included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. The first control unit to control and
The presentation of the transmission medium included in the second transmission stream received by the second receiving unit is presented with the presentation time information included in the second transmission stream and the second transmission acquired by the acquisition unit. The receiving device further includes a time information on a time axis and a second control unit that controls based on the 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 applied to each of the transmission media, the first transmission stream including the presentation time information by the first time axis for each presentation unit of the transmission media, and the transmission control signal corresponding to the first transmission stream. It was obtained by individually performing transmission line coding processing and then performing time division multiplexing and modulation processing. Here, the time information on the first time axis is inserted into the first transmission stream, and the time information on the second time axis different from the first time axis is inserted into the transmission control signal. There is.

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

For example, the first time axis may be an STC-based time axis and the second time axis may be a UTC-based time axis. Further, 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. You may.

Further, for example, the second control unit has a correspondence relationship between the time information acquired by the acquisition unit on the second time axis and the time information generated by the time information generation unit when the time information is received, and the second 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 generation unit.

In this case, for example, the transmission delay difference information includes transmission delay difference information on the transmitting side and transmission delay difference information on the receiving side, and the first transmission stream includes transmission delay difference information on the transmitting side. , May be done. Further, in this case, the second control unit may use the latest two correspondence relationships as the correspondence relationship.

As described above, in the present technology, the presentation of the transmission medium included in the first transmission stream is divided into the presentation time information by the first time axis and the time information by the first time axis generated by the time information generator. The presentation of the transmission medium 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. It is controlled based on the time information generated by the generation unit on the first time axis. Therefore, the presentation synchronization control in the integrated service of broadcasting and communication can be satisfactorily realized.

According to this technology, presentation synchronization control can be satisfactorily realized in the integrated service of broadcasting and communication. It should be noted that the effects described in the present specification are merely exemplary and not limited, and may have additional effects.

It is a block diagram which shows the configuration example of the broadcasting / communication hybrid system as an embodiment. It is a figure which shows each system in the broadcasting / communication hybrid system schematicly. This is a system pipe model showing the configuration of broadcast signals. It is a figure which shows the composition example of TMCC information about 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 the short format of the time information provided by the NTP server. It is a figure which shows the structure example of the 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 configuration example of the broadcasting transmission system which constitutes the broadcasting / communication hybrid system. It is a block diagram which shows the configuration example of the receiver which constitutes the broadcasting / communication hybrid system. It is a figure for demonstrating the timeline of the transmitting side / receiving side, and the target time conversion.

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

<1. Embodiment>
[Broadcasting / communication hybrid system configuration example]
FIG. 1 shows a configuration example of the 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 transmitting side, and a receiver 200 is arranged on the receiving side.

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

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

Further, in the transport stream TS, identification information indicating that the time information in the NTP format is inserted in the TMCC information is inserted. In this embodiment, a time information reference descriptor (time_reference_descriptor) in which this identification information is described is inserted under the 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 through 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 the transmission medium. This presentation time information is based on UTC. In this embodiment, it is assumed that the distribution system of the transmission medium by communication is MPEG-DASH, and the distribution server 120 is a DASH streaming server (also serving as a DASH MPD server).

The receiver 200 receives the broadcast signal transmitted 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 PCR included in the transport stream TS. Then, the receiver 200 controls the presentation of the transmission medium included in the transport stream TS based on this time information (STC), and also controls the transmission included in the transmission stream distributed from the distribution server 120. Control the presentation of media.

The receiver 200 uses the UTC-based NTP format time information inserted in the TMCC information when controlling the presentation of the transmission medium included in the transmission stream distributed from the distribution server 120. That is, the receiver 200 uses the presentation time information included in the transmission stream distributed from the distribution server 120 as a UTC base in relation to the above-mentioned time information (STC) at the time of receiving the time information in the NTP format. Is converted to STC base and used.

FIG. 2 schematically shows each system in the broadcasting / communication hybrid system 10 shown in FIG. Main image and audio data are input from the program material to the broadcasting system. The transport stream TS obtained by encoding the image and audio data is sent from the broadcast transmission system 110 to the receiver 200 through the broadcast transmission line. 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-image and audio data are input from the program material to the communication system. The transmission stream obtained by encoding the image and audio data is sent from the distribution server 120 to the receiver 200 through the communication transmission line. Here, at the time of encoding processing, presentation time information is inserted for each presentation unit of image and sound based on UTC (Universal Time, Coordinated).

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

FIG. 3 is a 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 a "TS-id". Also, there are one or more services in one transport stream. Each service is identified by "Service_id". This service is the so-called channel.

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

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

Further, in one RF channel, TMCC information which is a transmission control signal is transmitted in parallel with one or more of the above-mentioned transport streams. In this embodiment, as described above, the TMCC information includes time information in a UTC (Universal Time, Coordinated) -based NTP (Network Time Protocol) format. 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 "change instruction" field is incremented by 1 each time the content of the TMCC information is changed, and when the value becomes "11111111", the field returns to "00000000". The "Transmission mode / slot information" fields indicate the modulation method of the transmission main signal, the coding rate of the error correction internal coding, the satellite output backoff, and the number of allocated slots.

The "stream type / relative stream information" field indicates the correspondence between the relative stream number and the stream type. The "Packet format / Relative stream information" field indicates the correspondence between the relative stream number and the packet format. The "Pointer / Slot Information" field indicates the start position of the first packet and the end position of the last packet stored in the slot.

The "Relative stream / slot information" field indicates the correspondence between the slot and the relative stream number. The field of the "relative stream / transmission stream ID correspondence table" indicates the correspondence between the relative stream number and the transport stream identifier. The "Transmission / reception control information" field transmits signals and uplink control information for receiver activation control in emergency alert 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 UTC-based NTP format time information. FIG. 5 shows a configuration example of extended information (time information). The 16-bit field of the "extended identifier" is, for example, "0x0001", indicating that the extended information is time information. UTC-based NTP format time information is inserted into 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 by the ITU (International Telecommunication Union) as an Internet standard. Time information can be obtained by accessing the NTP server from a client such as a personal computer or a smartphone using the NTP protocol. The time information provided by the NTP server is represented by the total number of seconds (UTC: Coordinated Universal Time) from January 1, 1900.

FIG. 6A shows an NTP time stamp long format of time information provided by the NTP server. This time information is in a 64-bit format, with the upper 32 bits indicating the total number of seconds in UTC and the lower 32 bits indicating less than seconds. Further, FIG. 6B shows a short format (NTP time stamp short format) of time information provided by the NTP server. This time information is in a 32-bit format, with the upper 16 bits indicating the total number of seconds in UTC and the lower 16 bits indicating less than seconds.

FIG. 7 shows a configuration example of the time information reference descriptor (time_reference_descriptor). The 8-bit field of "descriptor_tag" indicates the descriptor type. Here, it is shown 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 bytes thereafter as the length of the descriptor.

The 2-bit field of "time_reference_mode" indicates the transmission mode of time information. “0” indicates that only PCR is transmitted. “1” indicates that in addition to transmitting PCR, time information in NTP format is transmitted by PES in the TS timeline extension method whose standard is being established by MPEG. It should be noted that this transmission mode has a great influence on the conventional broadcasting system, and a band for transmission is required. “2” indicates that, in addition to transmitting 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 the NTP format transmitted in addition to PCR is a long format (see FIG. 6 (a)) or a short format (see FIG. 6 (b)). .. “0” indicates that the format is short. “1” indicates that the format is long.

The 32-bit field of "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. This transmission delay difference ΔT1 is set in units of 1/90000 seconds. The transmission delay difference between the PCR and the NTP format time information occurs on both the transmitting side and the receiving side. The transmission delay difference ΔT1 is a transmission delay difference on the transmitting side.

As will be described later, when the receiving side converts the UTC-based presentation time information into the STC-based presentation time information, a transmission delay difference between both the transmitting 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 on the receiving side at the time of calculation.

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

The transmission line-encoded transport stream TS and the transmission line-encoded TMCC information are multiplexed and modulated before being sent to the receiving side through the broadcast transmission line. In this broadcast transmission line, the time information in PCR and NTP formats is commonly delayed by the transmission line delay Tbtr. That is, in this broadcast transmission line, the delay difference between the time information in the PCR and the NTP format is zero.

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

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

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

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

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

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

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

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

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

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

If the frequency of acquiring time information is sufficiently high, the configuration as it is may be used, 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 0. This setting operation is limited to once when the broadcast transmission system 110 starts operation.

The voltage controlled oscillator 133 generates a 2 ** 24 Hz clock. The 24-bit counter 134a counts the 2 ** 24 Hz clock output from the voltage controlled oscillator 133. The 32-bit counter 134b counts a 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 output of the 24-bit counter 134a and the 32-bit counter 134b becomes UTC-based time information by the counter operation from the initial value.

The transport stream TS generated by the multiplexer 129 is supplied to the main signal system processing unit 141a of the transmission 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 external code coding, power diffusion, internal code coding, and mapping.

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

In this control signal system processing unit 141b, TMCC information is generated based on the transmission parameter TMCC. At this time, the time information in the NTP long format is inserted into the field of the extended information of the TMCC information (see FIG. 5). As described above, since the bit output of the 24-bit counter 134a and the 32-bit counter 134b is 56 bits, the lower 8 bits are all "0". Further, the main signal system processing unit 141b performs transmission line coding processing such as external code coding, power diffusion, internal code coding, and mapping on the generated TMCC information.

Further, in the time division multiplexing / quadrature modulation processing unit 141c of the transmission line coding device 141, the output of the main signal system processing unit 141a and the control signal system processing unit 141b is subjected to time division multiplexing and quadrature modulation processing. , Intermediate frequency modulated wave is obtained.

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

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

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

The transport stream TS obtained by the broadcast transmission line decoding unit 210 is supplied to the demultiplexer 211. In this demultiplexer 211, PCR is extracted from TS packets containing PCR. At the time of channel selection or power-on, the first 42-bit PCR received is set as an initial value in the 42-bit clock unit (time information generator) consisting of the counter 213a and the counter 213b, and then received. The PCR is fed to the comparator 214.

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

This STC-based time information is supplied to the comparator 214. In the comparator 214, for example, the STC-based time information is latched and compared with the PCR at the timing when the PCR is supplied from the demultiplexer 211. The comparison error signal output from the comparator 214 is supplied to the voltage controlled oscillator 212 as a control signal. The voltage controlled oscillator 212, counters 213a and 213b and the comparator 214 form 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 synchronize with PCR. The STC-based time information is generated.

Further, in the demultiplexer 211, TS packets including encoded video and encoded audio are extracted and temporarily stored in the decoder buffer 215. Further, the 33-bit bit output (count value of 90 KHz) of the counter 213b 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. Then, in the broadcast presentation control unit 216, the STC-based time information is referred to, and the PES packet to be decoded is sequentially fetched from the decoder buffer 215 by the broadcast AV decoder 217. In the broadcast AV decoder 217, the PES packet is depacketized, and the coded video and the coded audio are further decoded to obtain the baseband video (video data) and audio (audio data).

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

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

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

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

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

The conversion from UTC base to STC base will be further described. FIG. 11A shows the STC and UTC timelines (time axes) on the transmitting side side by side. Un-1 and Un on the UTC timeline indicate the UTC-based time inserted and transmitted in the TMCC information. Further, 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 on the transmitting side, the UTC-based presentation time UTC corresponds to the STC-based time Star.

FIG. 11B shows the STC and UTC timelines (time axes) on the receiving side side by side. The STC timeline is delayed by ΔT as compared with the UTC timeline. This ΔT is the total transmission delay difference between PCR and 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 generation unit 220, the STC-based time S'n-1 is paired with the UTC-based time Un-1. This time S'n-1 is a time before the time Sn-1 by ΔT. 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 before the time Sn by ΔT. In the relationship between the STC and the UTC timeline on the receiving side, the UTC-based presentation time Utar corresponds to the STC-based time S'tar. This time S'tar is a time before the time Star by ΔT.

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

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

In the synthesis unit 241, the AV output of the video data and audio data obtained by the broadcast AV decoder 217 is combined with the AV output of the video data and audio data obtained by the communication AV decoder 235 to obtain the final AV output. Then, the receiver 200 displays the video by the video data and outputs the audio by the audio data.

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

Further, in the broadcast / communication hybrid system 10 shown in FIG. 1, in the broadcast transmission system 110, the time information in the UTC-based NTP format is inserted into the extended information field of the TMCC information. Therefore, no new band is required to transmit the time information in the 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 the time information in the UTC-based NTP format is inserted into the TMCC information is inserted into the transport stream TS. It is a thing. That is, the time information reference descriptor is inserted into the NIT. Therefore, the receiving side can easily identify that the time information in the UTC-based NTP format is inserted in the TMCC information.

Further, in the broadcast / communication hybrid system 10 shown in FIG. 1, the time information reference descriptor inserted into the transport stream TS by the broadcast transmission system 110 includes the PCR of the system layer on the transmission side and the time in the NTP format of the physical layer. The transmission delay difference ΔT1 with the information is described. Therefore, on the receiving side, even if the time information in the UTC-based NTP format is inserted into the TMCC information and sent, the UTC-based presentation time information is converted into the STC-based presentation time information by using this transmission delay difference ΔT1. It can be converted well.

<2. Modification example>
In the above-described embodiment, the transmission stream is the transport stream TS (MPEG2-TS), the time information on the first time axis is STC-based PCR, and the time information on the second time axis is UTC-based. An example of time information in the NTP format of is shown. Although detailed description is omitted, it goes without saying that the present technology can be similarly applied to other cases of handling similar transmission streams.

In addition, the present technology can also have the following configurations.
(1) Transmission path coding processing is individually performed for each of the transmission media, the 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 transmission stream. After that, time division multiplexing and modulation processing are performed to obtain a modulated wave, and a transmission unit for transmitting the modulated wave is provided.
Time information based on the first time axis is inserted in the transmission stream.
A transmission device further comprising a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal.
(2) The transmission stream is MPEG2-TS.
The time information based on the first time axis is STC-based PCR.
The transmission device according to (1) above, wherein the time information on the second time axis is UTC-based NTP format time information.
(3) The transmission control signal is TMCC information and is
The transmission device according to (1) or (2), wherein the time information insertion unit inserts time information according to the second time axis into the TMCC information as extended information.
(4) The transmission stream further includes an identification information insertion unit for inserting identification information indicating that the time information according to the second time axis is inserted in the transmission control signal (1) to (3). The transmitter according to any of the above.
(5) When the time information on the second time axis is the time information in the UTC-based NTP format, information indicating whether the NTP format is a long format or a short format is added to the identification information. The transmitter according to (4) above.
(6) The transmission according to (4) or (5) above, wherein transmission delay difference information between the time information on the first time axis and the time information on the second time axis is added to the identification information. apparatus.
(7) The transmission stream is MPEG2-TS.
The transmission device according to any one of (4) to (6) above, wherein the identification information insertion unit inserts a descriptor in which the identification information is described into a network information table.
(8) The transmission unit individually transmits the transmission path for each of the transmission media, the 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 transmission stream. It has a transmission step of obtaining a modulated wave by performing time division multiplexing and modulation processing after performing the coding process and transmitting the modulated wave.
Time information based on the first time axis is inserted in the transmission stream.
A transmission method further comprising a time information insertion step of inserting time information on a second time axis different from the first time axis into the transmission control signal.
(9) Individually for each of the transmission 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. It is provided with a first receiving unit that receives the modulated wave obtained by performing the time division multiplexing and modulation processing after performing the transmission path coding process.
Time information based on the first time axis is inserted in the first transmission stream.
Time information on a second time axis different from the first time axis is inserted in the transmission control signal.
An acquisition unit that acquires time information from the modulated wave according to the first transmission stream and the second time axis, and
A second receiving unit that receives the transmission medium and the second transmission stream including the 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 the time information on the first time axis included in the first transmission stream acquired by the acquisition unit, and a time information generation unit.
The presentation of the transmission medium included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. The first control unit to control and
The presentation of the transmission medium included in the second transmission stream received by the second receiving unit is presented with the presentation time information included in the second transmission stream and the second transmission acquired by the acquisition unit. A receiving device further comprising a time information on a time axis and a second control unit that controls based on the time information generated by the time information generating unit.
(10) The second control unit is
Correspondence between the time information acquired by the acquisition unit on the second time axis and the time information generated by the time information generation unit when the time information is received, and the time information on the first time axis. Using the transmission delay difference information between the information 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 conversion is performed. The receiving device according to (9), which controls the presentation of the transmission media included in the second transmission stream based on the presented time information and the time information generated by the time information generating unit.
(11) The transmission delay difference information is composed 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 transmitting side.
(12) The second control unit is
The receiving device according to (10) or (11) above, which uses the latest two correspondences as the correspondence.
(13) The receiving device according to any one of (9) to (12) above, wherein the first time axis is an STC-based time axis, and the second time axis is a UTC-based time axis.
(14) The first transmission stream is MPEG2-TS.
The transmission control signal is TMCC information and is
The receiving device according to any one of (9) to (13), wherein the time information on the second time axis is inserted into the TMCC information as extended information.
(15) The transmission control signal corresponding to the transmission medium and the first transmission stream including the presentation time information by the first time axis for each presentation unit of the transmission media and the first transmission stream by the first receiving unit. It has a first reception step of receiving a modulated wave obtained by performing time division multiplexing and modulation processing after individually performing transmission path coding processing for each of the above.
Time information based on the first time axis is inserted in the first transmission stream.
Time information on a second time axis different from the first time axis is inserted in the transmission control signal.
An acquisition step of acquiring time information according to the first transmission stream and the second time axis from the modulated wave, and
A second receiving step of receiving the transmission medium and the second transmission stream including the presentation time information according to the second time axis for each presentation unit of the transmission media by the second receiving unit.
A time information generation step that generates time information synchronized with the time information according to the first time axis included in the first transmission stream acquired in the acquisition step, and a time information generation step.
The presentation of the transmission media included in the first transmission stream acquired in the acquisition step is based on the presentation time information included in the first transmission stream and the time information generated in the time information generation step. The first control step to control and
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 acquisition in the acquisition step. A receiving method further comprising a time information on a time axis and a second control step for controlling based on the 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 the transport stream TS, it also inserts UTC-based NTP format time information into TMCC information, in a service that integrates broadcasting and communication on the receiving side. This is because the 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 (27MHz)
122 ... Divider (1/1716)
123 ・ ・ ・ Comparator 124a ・ ・ ・ 9-bit counter 124b ・ ・ ・ 33-bit counter 125 ・ ・ ・ Packetization unit 126 ・ ・ ・ Video / audio encoding processing unit 127 ・ ・ ・ Packetization / time stamp addition unit 128 ・・ ・ Encoder buffer 129 ・ ・ ・ Comparator 131 ・ ・ ・ Time signal interface 132a, 132b ・ ・ ・ 32-bit counter 133 ・ ・ ・ Voltage controlled oscillator (2 ** 24Hz)
134a ... 24-bit counter 134b ... 32-bit counter 135 ... Comparer 141 ... Transmission line coding device 141a ... Main signal system processing unit 141b ... Control signal system processing unit 141c ...・ Time division multiplexing / orthogonal modulation processing unit 200 ・ ・ ・ Receiver 201 ・ ・ ・ Broadcast transmission line decoding unit 211 ・ ・ ・ Demultiplexer 212 ・ ・ ・ Voltage controlled oscillator (27MHz)
213a ... 9-bit counter 213b ... 33-bit counter 214 ... Comparator 215 ... Decoder buffer 216 ... Broadcast presentation 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

This technology, related to transmit method.

Claims (15)

After performing the transmission path coding process individually for each of the transmission medium, the 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 transmission stream. A transmitter that obtains a modulated wave by performing time division multiplexing and modulation processing and transmits the modulated wave is provided.
Time information based on the first time axis is inserted in the transmission stream.
A transmission device further comprising a time information insertion unit that inserts time information on a second time axis different from the first time axis into the transmission control signal. The transmission stream is MPEG2-TS.
The time information based on the first time axis is STC-based PCR.
The transmission device according to claim 1, wherein the time information based on the second time axis is UTC-based NTP format time information. The transmission control signal is TMCC information and is
The transmission device according to claim 1, wherein the time information insertion unit inserts time information according to the second time axis into the TMCC information as extended information. The transmission device according to claim 1, further comprising an identification information insertion unit for inserting identification information indicating that time information according to the second time axis is inserted into the transmission control signal in the transmission stream. When the time information on the second time axis is the time information in the UTC-based NTP format, the identification information is added with information indicating whether the NTP format is a long format or a short format. Item 4. The transmitting device according to item 4. The transmission device according to claim 4, wherein transmission delay difference information between the time information on the first time axis and the time information on the second time axis is added to the identification information. The transmission stream is MPEG2-TS.
The transmission device according to claim 4, wherein the identification information insertion unit inserts a descriptor in which the identification information is described into a network information table. The transmission unit individually performs transmission path coding processing for each of the transmission media, the 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 transmission stream. It has a transmission step of obtaining a modulated wave by performing time division multiplexing and modulation processing after performing the above, and transmitting the modulated wave.
Time information based on the first time axis is inserted in the transmission stream.
A transmission method further comprising a time information insertion step of inserting time information on a second time axis different from the first time axis into the transmission control signal. A transmission path code for each of the transmission 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. It is provided with a first receiving unit that receives the modulated wave obtained by performing the time division multiplexing and modulation processing after the conversion process.
Time information based on the first time axis is inserted in the first transmission stream.
Time information on a second time axis different from the first time axis is inserted in the transmission control signal.
An acquisition unit that acquires time information from the modulated wave according to the first transmission stream and the second time axis, and
A second receiving unit that receives the transmission medium and the second transmission stream including the 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 the time information on the first time axis included in the first transmission stream acquired by the acquisition unit, and a time information generation unit.
The presentation of the transmission medium included in the first transmission stream acquired by the acquisition unit is based on the presentation time information included in the first transmission stream and the time information generated by the time information generation unit. The first control unit to control and
The presentation of the transmission medium included in the second transmission stream received by the second receiving unit is presented with the presentation time information included in the second transmission stream and the second transmission acquired by the acquisition unit. A receiving device further comprising a time information on a time axis and a second control unit that controls based on the time information generated by the time information generating unit. The second control unit is
Correspondence between the time information acquired by the acquisition unit on the second time axis and the time information generated by the time information generation unit when the time information is received, and the time information on the first time axis. Using the transmission delay difference information between the information 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 conversion is performed. The receiving device according to claim 9, which controls the presentation of the transmission media included in the second transmission stream based on the presented time information and the time information generated by the time information generating unit. The transmission delay difference information is composed of transmission delay difference information on the transmitting side and transmission delay difference information on the receiving side.
The receiving device according to claim 10, wherein the first transmission stream includes transmission delay difference information on the transmitting side. The second control unit is
The receiving device according to claim 10, wherein the latest two correspondences are used as the correspondences. The receiving device according to claim 9, wherein the first time axis is an STC-based time axis, and the second time axis is a UTC-based time axis. The first transmission stream is MPEG2-TS.
The transmission control signal is TMCC information and is
The receiving device according to claim 9, wherein time information based on the second time axis is inserted into the TMCC information as extended information. By the first receiving unit, the transmission media, the first transmission stream including the presentation time information by the first time axis for each presentation unit of the transmission media, and the transmission control signal corresponding to the first transmission stream are respectively. On the other hand, it has a first reception step of receiving a modulated wave obtained by individually performing transmission line coding processing and then performing time division multiplexing and modulation processing.
Time information based on the first time axis is inserted in the first transmission stream.
Time information on a second time axis different from the first time axis is inserted in the transmission control signal.
An acquisition step of acquiring time information according to the first transmission stream and the second time axis from the modulated wave, and
A second receiving step of receiving the transmission medium and the second transmission stream including the presentation time information according to the second time axis for each presentation unit of the transmission media by the second receiving unit.
A time information generation step that generates time information synchronized with the time information on the first time axis included in the first transmission stream acquired in the acquisition step, and a time information generation step.
The presentation of the transmission media included in the first transmission stream acquired in the acquisition step is based on the presentation time information included in the first transmission stream and the time information generated in the time information generation step. The first control step to control and
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 acquisition in the acquisition step. A receiving method further comprising a time information on a time axis and a second control step for controlling based on the time information generated in the time information generation step.

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