How to send

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

[Technical field]

[0001] This technology is , send Nobukata By law Regarding. [Background technology]

[0002] One of the essential service requirements for the next generation of broadcasting systems is the convergence of broadcasting and communication services. Various forms of convergence of broadcasting and communication services are envisaged, but one form is considered to be a case where the basic signals such as images and sounds that compose a single broadcast program are transmitted partly by broadcast and partly by communication.

[0003] In current broadcasting systems, the Moving Picture Experts Group-2 Transport Stream (MPEG2-TS) method is widely used as a transport method for transmission media (see, for example, Patent Document 1). Also, the Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP (MPEG-DASH) is known as a delivery system for transmission media via communication (see, for example, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-153291 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Realizing uninterrupted video distribution using existing web servers", Mitsuhiro Hirabayashi, NIKKEI ELECTRONICS, March 19, 2012 Summary of the Invention [Problem to be solved by the invention]

[0006] A technical challenge in realizing the above-mentioned integrated broadcasting and communication services is the synchronized presentation of video and audio transmitted over different paths. To achieve synchronized presentation control, a shared base timeline is required.

[0007] Generally, in broadcasting, a 27MHz counter value that is independent in each transmission system, called STC (System Time Clock), is used as the time axis, while in communications, an absolute time (NTP format as the data format) called UTC (Universal Time, Coordinated) is used as the time axis.

[0008] An object of the present technology is to enable good implementation of presentation synchronization control in integrated broadcasting and communication services. [Means for solving the problem]

[0009] The concept of this technology is as follows: a transmission unit that performs a transmission path coding process on a transmission medium, a transmission stream including presentation time information based on a first time axis for each presentation unit of the transmission medium, and a transmission control signal corresponding to the transmission stream, and then performs a time division multiplexing and modulation process to obtain a modulated wave, and transmits the modulated wave; time information based on the first time axis is inserted into the transmission stream; The time information inserting unit 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. Located in the transmitting device.

[0010] In this technology, a transmitting unit transmits a modulated wave. This modulated wave is obtained by individually performing a transmission path coding process on a transmission medium, a transmission stream including presentation time information based on 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 a time division multiplexing and modulation process. Time information based on the first time axis is inserted into the transmission stream. Then, time information based on a second time axis different from the first time axis is inserted into the transmission control signal by a time information inserting unit.

[0011] For example, the transmission stream may be MPEG2-TS, the time information according to the first time axis may be STC-based PCR, and the time information according to the second time axis may be UTC-based NTP format time information. Also, for example, the transmission control signal may be TMCC information, and the time information inserting unit may insert the time information according to the second time axis as extension information into the TMCC information.

[0012] In this way, in the present technology, in addition to inserting time information based on the first time axis into the transmission stream, time information based on the second time axis is inserted into the transmission control signal, which allows the receiving side to satisfactorily realize presentation synchronization control in integrated broadcast and communication services.

[0013] In addition, in the present technology, for example, an identification information inserting unit may be further provided that inserts identification information indicating that the time information based on the second time axis has been inserted into the transmission control signal into the transmission stream. In this case, for example, the transmission stream may be MPEG2-TS, and the identification information inserting unit may 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 based on the second time axis has been inserted into the transmission control signal.

[0014] In this case, for example, when the time information based on the second time axis is time information in the UTC-based NTP format, information indicating whether the NTP format is a long format or a short format may be added to the identification information, so that the receiving side can easily recognize whether the NTP format is a long format or a short format.

[0015] In this case, the identification information may be added with information on the transmission delay difference between the time information based on the first time axis and the time information based on the second time axis, which allows the receiving side to obtain information on the transmission delay difference at the transmitting side, which is necessary for converting the presentation time information based on the second time axis into the presentation time information based on the first time axis.

[0016] Another concept of the present technology is a first receiving unit that receives a modulated wave obtained by performing a transmission path coding process on a transmission medium, a first transmission stream including 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, and then performing a time division multiplexing and modulation process on the first transmission stream, time information based on the first time axis is inserted into the first transmission stream; time information based on a second time axis different from the first time axis is inserted into the transmission control signal; an acquisition unit that acquires the first transmission stream and time information based on the second time axis from the modulated wave; A second receiving unit that receives a second transmission stream including a transmission medium and presentation time information according to the second time axis for each presentation unit of the transmission medium; a time information generating unit that generates time information synchronized with the time information based on the first time axis included in the first transmission stream acquired by the acquiring unit; a first control unit that controls presentation of the transmission media included in the first transmission stream acquired by the acquisition unit based on presentation time information included in the first transmission stream and time information generated by the time information generation unit; a second control unit that controls presentation of the transmission media included in the second transmission stream received by the second receiving unit, based on presentation time information included in the second transmission stream, time information based on the second time axis acquired by the acquiring unit, and time information generated by the time information generating unit. in the receiving device.

[0017] In this technology, a first receiving unit receives a modulated wave. This modulated wave is obtained by performing a transmission path coding process individually on a transmission medium, a first transmission stream including presentation time information based on a first time axis for each presentation unit of the transmission medium, and a transmission control signal corresponding to the first transmission stream, and then performing a time division multiplexing and modulation process. Here, time information based on the first time axis is inserted into the first transmission stream, and time information based on a second time axis different from the first time axis is inserted into the transmission control signal.

[0018] The acquisition unit acquires the first transmission stream and the time information based on the second time axis from the modulated wave. The second receiving unit receives the second transmission stream including the transmission media and the presentation time information based on the second time axis for each presentation unit of the transmission media. The time information generating unit generates time information synchronized with the time information based on the first time axis included in the first transmission stream acquired by the acquisition unit.

[0019] The first control unit controls the presentation of 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. The second control unit controls the presentation of the transmission media included in the second transmission stream received by the second receiving unit based on the presentation time information included in the second transmission stream, the time information on the second time axis acquired by the acquisition unit, and the time information generated by the time information generation unit.

[0020] 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 may be MPEG2-TS, the transmission control signal may be TMCC information, and time information based on the second time axis may be inserted into the TMCC information as extended information.

[0021] Furthermore, for example, the second control unit may be configured to convert the presentation time information included in the second transmission stream into presentation time information based on the first time axis using a correspondence relationship between the time information based on the second time axis acquired by the acquisition unit and the time information generated by the time information generating unit at the time of receiving this time information, and transmission delay difference information between the time information based on the first time axis and the time information based on the second time axis, and to control the presentation of the transmission media included in the second transmission stream based on this converted presentation time information and the time information generated by the time information generating unit.

[0022] In this case, for example, the transmission delay difference information may be composed of the transmission delay difference information of the transmitting side and the transmission delay difference information of the receiving side, and the first transmission stream may include the transmission delay difference information of the transmitting side. Also, in this case, the second control unit may use the two latest correspondence relationships as the correspondence relationships.

[0023] In this way, in the present technology, the presentation of the transmission media included in the first transmission stream is controlled based on the presentation time information based on the first time axis and the time information based on the first time axis generated by the time information generating unit, and the presentation of the transmission media included in the second transmission stream is controlled based on the presentation time information based on the second time axis, the time information based on the second time axis acquired by the acquiring unit, and the time information based on the first time axis generated by the time information generating unit. Therefore, presentation synchronization control in a service that integrates broadcasting and communication can be satisfactorily realized. Effect of the Invention

[0024] According to the present technology, it is possible to satisfactorily realize presentation synchronization control in a service that integrates broadcasting and communication. Note that the effects described in this specification are merely examples and are not limiting, and additional effects may also be provided. [Brief description of the drawings]

[0025] [Figure 1] 1 is a block diagram showing an example of the configuration of a broadcasting and communication hybrid system according to an embodiment. [Diagram 2] This is a diagram showing each system in a broadcasting and communication hybrid system. [Diagram 3] This is a system pipe model showing the configuration of a broadcast signal. [Figure 4] FIG. 2 is a diagram showing an example of the configuration of TMCC information related to digital broadcasting. [Diagram 5] FIG. 11 is a diagram illustrating a configuration example of extended information (time information) of TMCC information. [Figure 6] 1A and 1B are diagrams illustrating the long and short formats of time information provided by an NTP server. [Figure 7] 13 is a diagram showing an example of the configuration of a time information reference descriptor; [Figure 8] FIG. 1 is a diagram showing a transmission delay model of PCR / NTP. [Figure 9] 1 is a block diagram showing an example of the configuration of a broadcast transmission system that constitutes a broadcasting and communication hybrid system. [Figure 10] 1 is a block diagram showing an example of the configuration of a receiver that constitutes a broadcasting and communication hybrid system. FIG. [Figure 11] FIG. 13 is a diagram for explaining the timelines on the sending and receiving sides and target time conversion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 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. Variations

[0027] <1. Preferred embodiment> [Example of a broadcasting / communication hybrid system configuration] 1 shows an example of the configuration of a broadcasting and communication hybrid system 10. In the broadcasting and communication hybrid system 10, a broadcasting transmission system 110 and a distribution server 120 are arranged on the transmitting side, and a receiver 200 is arranged on the receiving side.

[0028] The broadcast transmission system 110 performs a transmission path coding process separately on 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 this transport stream TS, and then performs time division multiplexing and modulation processes to transmit a broadcast signal consisting of a modulated wave obtained.

[0029] The transport stream TS includes presentation time information (PTS: Presentation Time Stamp) for each presentation unit of the transmission media. This presentation time information is based on the STC (System Time Clock). Furthermore, an STC-based PCR (Program Clock Reference) is inserted into the transport stream TS. In this embodiment, time information in the NTP (Network Time Protocol) format based on UTC (Universal Time Coordinated) is inserted into the TMCC information.

[0030] Also, identification information is inserted into the transport stream TS, which indicates that NTP format time information is inserted into the TMCC information. 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 includes information about the transmitting network, such as the channel number, modulation method, and guard interval. Details of this time information reference descriptor will be described later.

[0031] The delivery server 120 delivers a transmission stream including transmission media (components) such as video and audio to a receiving side via the communication network 300, for example, in response to a request from the receiving side. This transmission stream includes presentation time information for each presentation unit of the transmission media. This presentation time information is based on UTC. In this embodiment, the delivery system for the transmission media via communication is MPEG-DASH, and the delivery server 120 is a DASH streaming server (also serving as a DASH MPD server).

[0032] The receiver 200 receives a broadcast signal sent from the broadcast transmission system 110, and also receives a transmission stream distributed from the distribution server 120. The receiver 200 generates time information (STC) synchronized with the PCR included in the transport stream TS. Then, 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 transmission stream distributed from the distribution server 120.

[0033] The receiver 200 uses UTC-based NTP formatted time information inserted in the TMCC information when controlling the presentation of the transmission media included in the transmission stream delivered from the delivery server 120. That is, the receiver 200 converts the presentation time information included in the transmission stream delivered from the delivery server 120 from UTC-based to STC-based based on the correspondence with the above-mentioned time information (STC) at the time of receiving the NTP formatted time information, and uses the converted presentation time information.

[0034] Fig. 2 shows an outline of each system in the broadcasting and communication hybrid system 10 shown in Fig. 1. Main image and audio data are input to the broadcasting system from the program material. The transport stream TS obtained by encoding the image and audio data is sent from the broadcasting transmission system 110 to the receiver 200 via the broadcast transmission path. During the encoding process, a presentation time stamp (PTS) is inserted into the video and audio PES packets based on a system time clock (STC). Also, a PCR is inserted into the transport stream TS based on the system time clock (STC).

[0035] 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 via a communication transmission path. During the encoding process, presentation time information is inserted for each presentation unit of image and audio based on UTC (Universal Time Coordinated).

[0036] In this embodiment, as described above, time information in the UTC-based NTP format is inserted into TMCC information in the broadcast system, and this time information is used in the receiver 200 to control the presentation of images and sounds contained in the transmission stream distributed in the communication system. Therefore, even if the time axes of the presentation time information in the broadcast system and the communication system are different, presentation synchronization in a broadcast and communication integrated service is possible.

[0037] Figure 3 is a System Pipe Model showing the configuration of a broadcast signal. One or more transport streams are transmitted within one RF channel. Each transport stream is identified by a "TS-id". Also, one or more services exist within one transport stream. Each service is identified by a "Service_id". This service corresponds to what is called a channel.

[0038] A single service includes video, audio, closed caption, etc. as transmission media (components). In other words, each service is made up of components such as video, audio, and closed caption.

[0039] Each transport stream also contains control signals called PSI (Program Specific Information) / SI (Service Information), and a PCR (Program Clock Reference) based on an STC (System Time Clock).

[0040] In addition, in one RF channel, TMCC information, which is a transmission control signal, is transmitted in parallel with the one or more transport streams described above. In this embodiment, as described above, the TMCC information contains time information in the NTP (Network Time Protocol) format based on UTC (Universal Time Coordinated). This TMCC information is a physical layer control signal.

[0041] Figure 4 shows an example of the structure of TMCC information related to digital broadcasting. The "change instruction" field is incremented by 1 each time a change occurs in the contents of the TMCC information, and when the value becomes '11111111', it returns to '00000000'. The "transmission mode / slot information" field indicates the modulation method of the main signal to be transmitted, the coding rate of the error correction inner coding, the satellite output backoff, and the number of assigned slots.

[0042] 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 beginning position of the first packet and the end position of the last packet stored in the slot.

[0043] 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 / reception control information" field transmits signals for receiver startup control in emergency alert broadcasts and uplink control information.

[0044] At the end of the TMCC information, there is a 3614-bit field for "extended information". In this embodiment, the first 80 bits of this "extended information" field are used to insert time information in the UTC-based NTP format. FIG. 5 shows an example of the configuration of extended information (time information). The 16-bit field for the "extended identifier" is set to, for example, "0x0001", indicating that the extended information is time information. The 64-bit field for the "extended information" is inserted with time information in the UTC-based NTP format. Here, the NTP format is a 64-bit long format.

[0045] Here, we will explain NTP (Network Time Protocol). 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 from a client such as a personal computer or smartphone using the NTP protocol. The time information provided by an NTP server is expressed as the number of seconds accumulated since January 1, 1900 (UTC: Universal Time Coordinated).

[0046] Figure 6(a) shows the long format (NTP time stamp long format) of the time information provided by an NTP server. This time information is in 64-bit format, with the upper 32 bits indicating the number of seconds accumulated from UTC, and the lower 32 bits indicating fractions of a second. Figure 6(b) shows the short format (NTP time stamp short format) of the time information provided by an NTP server. This time information is in 32-bit format, with the upper 16 bits indicating the number of seconds accumulated from UTC, and the lower 16 bits indicating fractions of a second.

[0047] Figure 7 shows an example of the configuration of a time information reference descriptor (time_reference_descriptor). The 8-bit field "descriptor_tag" indicates the descriptor type. In this case, it indicates that it is a time information reference descriptor. The 8-bit field "descriptor_length" indicates the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor.

[0048] The 2-bit field "time_reference_mode" indicates the transmission mode of the time information. "0" indicates that only PCR is transmitted. "1" indicates that in addition to transmitting PCR, time information in NTP format is transmitted in PES in the TS timeline extension method currently being standardized by MPEG. Note that this transmission mode will have a significant impact on conventional broadcasting systems and will require a transmission bandwidth. "2" indicates that in addition to transmitting PCR, time information in NTP format is transmitted in TMCC information.

[0049] The 2-bit field "time_reference_format" indicates whether the NTP format time information transmitted in addition to the PCR is in long format (see Figure 6(a)) or short format (see Figure 6(b)). "0" indicates the short format. "1" indicates the long format.

[0050] The 32-bit field "delay_adjustment" indicates the transmission delay difference ΔT1 between the PCR of the system layer and the NTP format time information of the physical layer. This transmission delay difference ΔT1 is expressed in units of 1 / 90000 seconds. The transmission delay difference between the PCR and the NTP format time information occurs on both the sending side and the receiving side. The transmission delay difference ΔT1 is the transmission delay difference on the sending side.

[0051] As described later, when converting UTC-based presentation time information to STC-based presentation time information on the receiving side, the transmission delay difference on both the sending side and the receiving side is necessary. The transmission delay difference ΔT1 on the sending side is specified in the 32-bit field of "delay_adjustment" of the time information reference descriptor as described above. As for the transmission delay difference ΔT2 on the receiving side, a fixed value is set at the time of calculation on the receiving side.

[0052] Figure 8 shows the PCR / NTP transmission delay model. On the transmitting side, when STC-based PCR and UTC-based NTP formatted time information are extracted at the same time at a certain timing, a transmission delay difference ΔT1 occurs between the PCR and the NTP formatted time information, which is the difference between the processing delay Ttss of the line coding for the transport stream TS and the processing delay Ttmccs of the line coding for the TMCC information. In other words, ΔT1 = (Ttss - Ttmccs).

[0053] The line-coded transport stream TS and line-coded TMCC information are multiplexed and modulated, and then sent to the receiving side via the broadcast transmission path. In this broadcast transmission path, the PCR and NTP format time information are both delayed by the transmission path delay Tbtr. In other words, in this broadcast transmission path, the delay difference between the PCR and NTP format time information is zero.

[0054] On the receiving side, a transmission delay difference ΔT2 occurs between PCR and NTP format time information, which is the difference between the processing delay Ttsr of the transmission path decoding of the transport stream TS and the processing delay Ttmccr of the transmission decoding of the TMCC information. In other words, ΔT2 = (Ttsr - Ttmccr). Therefore, the total transmission delay difference ΔT between PCR and NTP format time information is ΔT = ΔT1 + ΔT2.

[0055] [Example of broadcast transmission system configuration] 9 shows an example of the configuration of a broadcast transmission system 110. This broadcast transmission system 110 has a voltage controlled oscillator 121 that generates a 27 MHz clock (system clock), a frequency divider 122 that performs 1 / 1716 frequency division, a comparator 123, a 9-bit counter 124a and a 33-bit counter 124b that form an STC-based clock unit, and a packetization unit 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.

[0056] 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 has 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 form a UTC-based clock unit, and a comparator 135. The broadcast transmission system 110 also has a transmission path coding device 141. The transmission path coding device 141 includes a main signal processing unit 141a that performs transmission path coding of the transport stream TS, a control signal processing unit 141b that performs transmission path coding of TMCC information, and a time division multiplexing / orthogonal modulation processing unit 141c.

[0057] A 27 MHz clock generated by a voltage controlled oscillator 121 is divided by 1716 by a frequency divider 122, and a pulse with a duration of one horizontal period is output from the frequency divider 122. The output pulse of the frequency divider 122 is supplied to a comparator 123 and compared with the phase of a reference horizontal synchronizing signal (Ref. Hsync). A 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 synchronizing signal.

[0058] 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 the 9-bit counter 124a is counted by a 33-bit counter 124b. The (33+9)-bit output of the 9-bit counter 124a and the 33-bit counter 124b becomes the STC-based time information.

[0059] This STC-based time information is supplied to a packetizer 125. The packetizer 125 generates TS packets having adaptation fields including a program clock reference (PCR) based on this STC-based time information. These TS packets are generated at predetermined intervals and sequentially supplied to a multiplexer 129. It is recommended that PCRs appear at 100 ms intervals in the TS stream.

[0060] The video / audio encoding processing unit 126 encodes the video and audio in synchronization with the 27 MHz clock obtained by the voltage controlled oscillator 121. The packetization / time stamp adding unit 127 generates a PES packet for each access unit from the encoded video and audio elementary streams, and further generates a TS packet whose payload contains encoded video and encoded audio. The TS packets are supplied to a multiplexer 129 via an encoder buffer 128.

[0061] The packetization / time stamp addition unit 127 is also supplied with a 33-bit output from the 33-bit counter 124b. This 33-bit output is time information with an accuracy of 90 kHz. Based on this 33-bit output, the packetization / time stamp addition unit 127 inserts a presentation time stamp (PTS) into the header of each PES packet.

[0062] As described above, the multiplexer 129 is supplied with TS packets including PCR, and TS packets including coded video and coded audio. The multiplexer 129 multiplexes the TS packets to generate a transport stream TS. This transport stream TS also includes a PSI / SI control signal. The multiplexer 129 inserts the above-mentioned time information reference descriptor (time_reference_descriptor) (see FIG. 7) under the NIT (Network Information Table).

[0063] Furthermore, the time signal interface 131 accesses an NTP server (not shown) via the Internet at predetermined time intervals, for example, to acquire time information in 64-bit format (see FIG. 6(a)). The 32-bit registers 132a and 132b hold the time information in 64-bit format acquired by the time signal interface 131. The 32-bit register 132a holds the most significant 32 bits of bit data, and the 32-bit register 132b holds the least significant 32 bits of bit data. The contents held in the 32-bit registers 132a and 132b are updated every time the time signal interface 131 acquires time information in 64-bit format.

[0064] If the frequency of acquiring time information is sufficiently high, this configuration may be used as is, but if the frequency is low, it is also possible that registers 132a and 132b continue to operate as counters that automatically indicate the time so as to reproduce the clock of the NTP server. Here, when the output of register 132b indicating the lower 32 bits of the acquired time information becomes all 0, the output of register 132a indicating the upper 32 bits of the time information is set as the initial value of 32-bit counter 134b, and 24-bit counter 134a is set to 0. This setting operation is limited to only one time when broadcast transmission system 110 starts operation.

[0065] 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 the 1 Hz clock, which is the carry output of the 24-bit counter 134a, to obtain a 32-bit output that 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 through the above counter operation from the initial value.

[0066] The transport stream TS generated by the multiplexer 129 is supplied to a main signal processing unit 141a of the line coding device 141. In this main signal processing unit 141b, the transport stream TS is subjected to line coding processes such as outer code coding, power spreading, inner code coding, and mapping.

[0067] The 56-bit bit outputs of the 24-bit counter 134a and the 32-bit counter 134b are supplied as UTC-based NTP format time information to a control signal processor 141b of the line coding device 141. The control signal processor 141b is also supplied with a transmission parameter TMCC for transmitting the transport stream TS.

[0068] In this control signal processor 141b, TMCC information is generated based on the transmission parameter TMCC. At this time, time information in the NTP long format is inserted into the extension information field of the TMCC information (see FIG. 5). As described above, the bit output of the 24-bit counter 134a and the 32-bit counter 134b is 56 bits, so the lowest 8 bits are all set to "0". In addition, in this main signal processor 141b, the generated TMCC information is subjected to transmission line coding processes such as outer code coding, power dispersal, inner code coding, and mapping.

[0069] Furthermore, in the time division multiplexing / orthogonal modulation processing unit 141c of the line coding device 141, the outputs of the main signal processing unit 141a and the control signal processing unit 141b are subjected to time division multiplexing and orthogonal modulation processing, thereby obtaining an intermediate frequency modulated wave.

[0070] [Receiver configuration example] 10 shows an example of the configuration of a receiver 200. This receiver 200 has a broadcast transmission path decoding unit 210, a demultiplexer 211, a voltage controlled oscillator 212 that generates a 27 MHz clock (system clock), a 9-bit counter 213a and a 33-bit counter 213b that constitute an STC-based clock unit (time information generating unit), and a comparator 214.

[0071] The receiver 200 also has a decoder buffer 215, a broadcast presentation control unit 216, and a broadcast AV decoder 217. The receiver 200 also has 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.

[0072] The broadcast transmission path decoding unit 210 performs processing such as transmission path decoding on the received broadcast signal (modulated wave) to obtain a transport stream TS. The broadcast transmission path decoding unit 210 also extracts the time information in the NTP format inserted in the TMCC information based on a time information reference descriptor (time_reference_descriptor) arranged in the NIT (Network Information Table) of the transport stream TS.

[0073] The transport stream TS obtained by the broadcast transmission path decoding unit 210 is supplied to a demultiplexer 211. In this demultiplexer 211, the PCR is extracted from the TS packet including the PCR. When selecting a channel or turning on the power, the first 42-bit PCR received is set as an initial value in a 42-bit clock unit (time information generating unit) consisting of counters 213a and 213b. The PCR received thereafter is supplied to a comparator 214.

[0074] Furthermore, the 27 MHz clock generated by the voltage controlled oscillator 42 is counted by a 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 output of these 9-bit counter 213a and 33-bit counter 213b becomes the STC-based time information.

[0075] This STC-based time information is supplied to a 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. A comparison error signal output from the comparator 214 is supplied as a control signal to a voltage-controlled oscillator 212. The voltage-controlled oscillator 212, counters 213a and 213b, and comparator 214 constitute a PLL (Phase Locked Loop) circuit, in which the voltage-controlled oscillator 212 generates a 27 MHz clock synchronized with the PCR, and the counters 213a and 213b generate STC-based time information synchronized with the PCR.

[0076] In addition, the demultiplexer 211 extracts TS packets including coded video and coded audio, and temporarily stores them in the decoder buffer 215. In addition, a 33-bit output (a count value of 90 KHz) of the counter 213b is supplied to the broadcast presentation control unit 216 as STC-based time information.

[0077] The broadcast presentation control unit 216 checks the PTS of each PES packet stored in the decoder buffer 215. Then, the broadcast presentation control unit 216 refers to STC-based time information, 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, and further decodes the encoded video and encoded audio to obtain baseband video (video data) and audio (audio data).

[0078] 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 33-bit output (90 KHz count value) of the counter 213b is supplied to this UTC / STC mapping information generation unit 220 as STC-based time information. In this UTC / STC mapping information generation unit 220, pair information (U, S) of the NTP format time information and the STC-based time information at the extraction timing is generated as mapping information.

[0079] The UTC-based NTP format time information is sent from the sending side at an appropriate cycle, and the above-mentioned pair information is continuously generated every time it is received. The UTC / STC mapping information generating unit 220 is always in a state where the latest pair information and the pair information immediately before that are held.

[0080] Furthermore, 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 an MPD analysis unit 232, and MPD analysis information obtained by the MPD analysis unit 232 is provided to a communication presentation control unit 234. Furthermore, the transmission stream received by the communication interface 231 is supplied to the communication presentation control unit 234, and is also supplied to a decoder buffer 233.

[0081] In MPEG-DASH, the timing information for each presentation unit of the transmission media is disclosed in the MPD file, and the 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 the transmission media based on this timing information. This presentation time information is based on UTC.

[0082] The communication presentation control unit 234 converts (timeline converts) the UTC-based presentation time information into STC-based presentation time information based on the STC-based time information, which is the 33-bit bit output (90 KHz count value) of the counter 213 b, and the latest two pairs of information (U, S) generated by the UTC / STC mapping information generation unit 220.

[0083] The conversion from UTC-based to STC-based will be further explained. FIG. 11(a) shows the STC and UTC timelines (time axes) side by side on the transmitting side. Un-1 and Un on the UTC timeline indicate the UTC-based times inserted into the TMCC information and transmitted. Also, Sn-1 and Sn on the STC timeline indicate the STC-based times corresponding to the UTC-based times Un-1 and Un, respectively. In the relationship between the STC and UTC timelines on the transmitting side, the UTC-based presented time Utar corresponds to the STC-based time Star.

[0084] Figure 11(b) shows the STC and UTC timelines (time axes) on the receiving side side by side. The STC timeline is delayed by ΔT compared to the UTC timeline. This ΔT is the total transmission delay difference between the PCR and the NTP format time information. As mentioned above, this transmission delay difference ΔT is the sum of the transmission delay difference ΔT1 on the sending side and the transmission delay difference ΔT2 on the receiving side.

[0085] In the UTC / STC mapping information generating unit 220, the UTC-based time Un-1 is paired with the STC-based time S'n-1. This time S'n-1 is ΔT earlier than the time Sn-1. In addition, in the UTC / STC mapping information generating unit 220, the UTC-based time Un is paired with the STC-based time S'n. This time S'n is ΔT earlier than the time Sn. In the relationship between the STC and UTC timelines on the receiving side, the UTC-based presented time Utar corresponds to the STC-based time S'tar. This time S'tar is ΔT earlier than the time Star.

[0086] In the communication presentation control unit 234, the UTC-based presentation time Utar is converted to the STC-based time Star (target time conversion) by the following formula (1). (Star-Sn) / (Sn-Sn-1)=(Utar-Un) / (Un-Un-1) Star=((Utar-Un)(Sn-Sn-1) / (Un-Un-1))+Sn =((Utar-Un)(S´nS´n-1) / (Un-Un-1))+S´n+ΔT1+ΔT2 (1)

[0087] Returning to Fig. 10, the communication presentation control unit 234 confirms the presentation time converted to the STC base as described above for each presentation unit stored in the decoder buffer 233. Then, the communication presentation control unit 234 refers to the STC-based time information from the counter 213b, 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 coded video and coded audio of each presentation unit, and obtains baseband video (video data) and audio (audio data).

[0088] In the synthesis unit 241, the AV output of the video data and audio data obtained in the broadcast AV decoder 217 is synthesized with the AV output of the video data and audio data obtained in the communication AV decoder 235 to produce a final AV output. Then, in the receiver 200, images are displayed based on this video data, and sound is output based on the audio data.

[0089] As described above, in the broadcasting / communication hybrid system 10 shown in Fig. 1, in addition to inserting STC-based PCR into the transport stream TS, the broadcasting transmission system 110 inserts UTC-based NTP format time information into the TMCC information. Therefore, on the receiving side, presentation synchronization control in a broadcasting / communication integrated service can be satisfactorily realized.

[0090] In addition, in the broadcasting / communication hybrid system 10 shown in Fig. 1, the time information in the UTC-based NTP format is inserted into the extended information field of the TMCC information in the broadcasting transmission system 110. Therefore, no additional band is required to transmit the time information in the UTC-based NTP format.

[0091] In addition, in the broadcasting / communication hybrid system 10 shown in Fig. 1, in the broadcasting transmission system 110, identification information indicating that time information in the UTC-based NTP format has been inserted into the TMCC information is inserted into the transport stream TS. In other words, a time information reference descriptor is inserted into the NIT. Therefore, the receiving side can easily identify that time information in the UTC-based NTP format has been inserted into the TMCC information.

[0092] 1, the time information reference descriptor inserted into the transport stream TS by the broadcast transmission system 110 describes the transmission delay difference ΔT1 between the PCR in the system layer on the transmitting side and the NTP format time information in the physical layer. Therefore, even if UTC-based NTP format time information is inserted into the TMCC information and sent, the receiving side can use this transmission delay difference ΔT1 to satisfactorily convert the UTC-based presentation time information into STC-based presentation time information.

[0093] <2. Modifications> In the above embodiment, an example has been shown in which the transmission stream is a transport stream TS (MPEG2-TS), the time information based on the first time axis is STC-based PCR, and the time information based on the second time axis is UTC-based NTP format time information. Although detailed explanations are omitted, the present technology can of course be similarly applied to other cases in which similar transmission streams are handled.

[0094] The present technology can also be configured as follows. (1) A transmission unit that performs a transmission path coding process on a transmission medium, a transmission stream including presentation time information based on a first time axis for each presentation unit of the transmission medium, and a transmission control signal corresponding to the transmission stream, and then performs a time division multiplexing and modulation process to obtain a modulated wave and transmits the modulated wave; time information based on the first time axis is inserted into the transmission stream; The time information inserting unit 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. Transmitting device. (2) The transmission stream is MPEG2-TS, The time information based on the first time axis is an STC-based PCR, The time information based on the second time axis is UTC-based NTP format time information. The transmitting device according to (1) above. (3) The transmission control signal is TMCC information, The time information insertion unit inserts the time information based on the second time axis as extension information into the TMCC information. The transmitting device according to (1) or (2). (4) The apparatus further includes an identification information inserting unit that inserts, into the transmission stream, identification information indicating that the time information based on the second time axis is inserted into the transmission control signal. A transmitting device according to any one of (1) to (3). (5) When the time information based on the second time axis is time information in a UTC-based NTP format, information indicating whether the NTP format is a long format or a short format is added to the identification information. The transmitting device according to (4) above. (6) The identification information includes information about a transmission delay difference between the time information based on the first time axis and the time information based on the second time axis. The transmitting device according to (4) or (5). (7) The transmission stream is MPEG2-TS, The identification information insertion unit inserts a descriptor in which the identification information is described into a network information table. A transmitting device according to any one of (4) to (6). (8) A transmission step of performing a transmission path coding process on each of a transmission medium and a transmission stream including presentation time information based on 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 a time division multiplexing and modulation process to obtain a modulated wave and transmitting the modulated wave by the transmission unit; time information based on the first time axis is inserted into the transmission stream; The method further includes a time information inserting step of inserting time information based on a second time axis different from the first time axis into the transmission control signal. Transmission method. (9) A first receiving unit is provided for receiving a modulated wave obtained by performing a transmission path coding process on a transmission medium, a first transmission stream including presentation time information based on a first time axis for each presentation unit of the transmission medium, and a transmission control signal corresponding to the first transmission stream, and then performing a time division multiplexing and modulation process on the first transmission stream, time information based on the first time axis is inserted into the first transmission stream; time information based on a second time axis different from the first time axis is inserted into the transmission control signal; an acquisition unit that acquires the first transmission stream and time information based on the second time axis from the modulated wave; A second receiving unit that receives a second transmission stream including a transmission medium and presentation time information according to the second time axis for each presentation unit of the transmission medium; a time information generating unit that generates time information synchronized with the time information based on the first time axis included in the first transmission stream acquired by the acquiring unit; a first control unit that controls presentation of the transmission media included in the first transmission stream acquired by the acquisition unit based on presentation time information included in the first transmission stream and time information generated by the time information generation unit; a second control unit that controls presentation of the transmission media included in the second transmission stream received by the second receiving unit, based on presentation time information included in the second transmission stream, time information based on the second time axis acquired by the acquiring unit, and time information generated by the time information generating unit. Receiving device. (10) The second control unit includes: Using a correspondence relationship between the time information based on the second time axis acquired by the acquisition unit and the time information generated by the time information generation unit at the time of receiving the time information, and transmission delay difference information between the time information based on the first time axis and the time information based on the second time axis, presentation time information included in the second transmission stream is converted into presentation time information based on the first time axis, and presentation of a transmission media included in the second transmission stream is controlled based on the converted presentation time information and the time information generated by the time information generation unit. The receiving device according to (9) above. (11) The transmission delay difference information includes transmission delay difference information on a sending side and transmission delay difference information on a receiving side, The first transmission stream includes the transmission delay difference information of the transmitting side. The receiving device according to (10) above. (12) The second control unit includes: The two most recent correspondences are used as the above correspondences. The receiving device according to (10) or (11) above. (13) The first time axis is an STC-based time axis, and the second time axis is a UTC-based time axis. A receiving device according to any one of (9) to (12). (14) The first transmission stream is an MPEG2-TS, The transmission control signal is TMCC information, The time information based on the second time axis is inserted into the TMCC information as extended information. A receiving device according to any one of (9) to (13). (15) A first receiving step is provided for receiving a modulated wave obtained by performing a transmission path coding process on a first transmission stream including a transmission medium and presentation time information on a first time axis for each presentation unit of the transmission medium and a transmission control signal corresponding to the first transmission stream, and then performing a time division multiplexing and modulation process on the first transmission stream, by a first receiving unit; time information based on the first time axis is inserted into the first transmission stream; time information based on a second time axis different from the first time axis is inserted into the transmission control signal; an acquisition step of acquiring the first transmission stream and time information based on the second time axis from the modulated wave; A second receiving step of receiving a second transmission stream including a transmission medium and presentation time information according to the second time axis for each presentation unit of the transmission medium by a second receiving unit; a time information generating step of generating time information synchronized with the time information based on the first time axis included in the first transmission stream acquired in the acquiring step; a first control step of controlling presentation of the transmission media included in the first transmission stream acquired in the acquisition step based on presentation time information included in the first transmission stream and time information generated in the time information generating step; The method further includes a second control step of controlling presentation of the transmission media included in the second transmission stream received in the second receiving step, based on presentation time information included in the second transmission stream, time information based on the second time axis acquired in the acquiring step, and time information generated in the time information generating step. Receiving method.

[0095] The main feature of this technology is that it enables effective presentation synchronization control in integrated broadcasting and communication services on the receiving side by inserting STC-based PCR into the transport stream TS and UTC-based NTP format time information into the TMCC information (see Figure 9). [Explanation of symbols]

[0096] 10. Broadcasting and communication hybrid system 110 Broadcast transmission system 120 Distribution Server 121···Voltage controlled oscillator (27MHz) 122...Frequency divider (1 / 1716) 123...Comparator 124a 9-bit counter 124b...33-bit counter 125 Packetizer 126 Video / audio encoding processing unit 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 processing section 141b... Control signal processing unit 141c Time division multiplexing / orthogonal modulation processing section 200···Receiver 201 Broadcast transmission path decoding unit 211 Demultiplexer 212···Voltage controlled oscillator (27MHz) 213a 9-bit counter 213b...33-bit counter 214...Comparator 215 Decoder buffer 216 Broadcast presentation control unit 217 Broadcast AV Decoder 220 UTC / STC mapping information generator 231 Communication interface 232...MPD analysis department 233 Decoder Buffer 234 Communication presentation control unit 235···Communication AV decoder 241... Synthesis section 300 Communication network

Claims

[Claim 1] A transmitting step of a transmitting unit transmitting a transmission stream including a transmission medium and time information based on a first time axis, The transmitting step further includes transmitting reference time information including information for making the time information based on the second time axis correspond to the time information based on the first time axis in relation to a delay in the signal encoding process; The reference time information is information arranged in a table included in the transmission stream. Transmission method.

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