JP2005217659A - Audio/video signal multiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio/video signal multiplexer capable of surely multiplexing a plurality of audio/video signals even in the case of an unstable communication state such as relaying of a program in a field. <P>SOLUTION: An MPEG 2 TS multiplexer 100 (STC generating circuit 110) again generates a system time clock (STC) on the basis of first program reference time information received first after a lapse of a prescribed time when a reception time interval of the first program clock reference information (PCR) included in a received audio video signal (MPEG-2 TS) reaches a prescribed time or over. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an audio / video signal multiplexing apparatus that receives a plurality of audio / video signals, multiplexes the plurality of audio / video signals, and outputs a multiplexed audio / video signal, and more particularly to an MPEG-2 transport stream signal. The present invention relates to an audio / video signal multiplexing apparatus for multiplexing.

  Conventionally, in places where communication conditions are stable, such as in a studio, audio / video signal multiplexing for multiplexing a plurality of MPEG-2 (Moving Picture Experts Group-2) transport stream signals (hereinafter referred to as MPEG-2 TS) An apparatus (hereinafter simply referred to as a multiplex apparatus as appropriate) has already been put into practical use (for example, Patent Document 1).

In such an MPEG-2 TS multiplexing apparatus, the transmission rate of “multiplexed MPEG-2 TS” that is multiplexed and output is higher than the transmission rate of the input MPEG-2 TS. In accordance with a system reference time (hereinafter referred to as STC (System Time Clock)) generated based on a program reference time (hereinafter referred to as PCR (Program Clock Reference)) included in the TS, “multiplexed MPEG-2 TS It is necessary to add PCR to "."
JP 2003-78913 A

  By the way, with respect to the relay of road races such as outdoor programs such as marathons, the quality of the broadcast video is required to be increased with the spread of digital HDTV broadcasting.

  For relay of outdoor programs, for example, road race relay as described above, between a mobile relay vehicle equipped with a camera for shooting runners and the like, and a base station temporarily deployed near the road race course, A wireless line is used to relay an audio / video signal (MPEG-2 TS) between the base station and a center base station arranged at a start / goal point or the like.

  Therefore, in order to relay the amount of information that increases as the quality of the outdoor program video increases, it is necessary to efficiently use the wireless line. Therefore, it is conceivable to use a conventional MPEG-2 TS multiplexing apparatus as described above for relaying outdoor programs.

  However, when the conventional MPEG-2 TS multiplexing apparatus is used for relaying outdoor programs, there are the following problems. In other words, in the relay of outdoor programs, so-called instantaneous interruption, in which the MPEG-2 TS is instantaneously disconnected, is frequently generated according to the state of the wireless line. In addition, in the relay of outdoor programs, the camera is frequently turned off and on again, and the PCR value included in the MPEG-2 TS input to the multiplexing device can vary greatly.

  In other words, in the case of relaying outdoor programs, the communication situation is unstable compared with in the studio. Therefore, when the conventional MPEG-2 TS multiplexing device is used as it is for relaying outdoor programs, it is difficult to broadcast video and audio. There is a problem that the MPEG-2 TS decoder or the multiplexing device becomes inoperable (hangs up) due to noise mixing or fluctuations in the PCR value.

  Therefore, the present invention has been made in view of the above points, and an audio / video signal multiplexing apparatus that can reliably multiplex a plurality of audio / video signals even when communication conditions are unstable, such as relaying of an outdoor program. The purpose is to provide.

  In order to solve the above-mentioned problems, the inventors investigated in detail the state of the multiplexing device when the conventional MPEG-2 TS multiplexing device was used for relaying outdoor programs. As a result, if the PCR value included in the input MPEG-2 TS fluctuates beyond the range allowable by the multiplexer, the MPEG-2 TS decoder becomes inoperable or the multiplexer is multiplexed. It was found that PCR cannot be normally added to the MPEG-2 TS ".

  In view of such a situation, the present invention has the following features. First, the first feature of the present invention is that an audio video that receives a plurality of audio video signals (for example, MPEG-2 TS), multiplexes the plurality of audio video signals, and outputs a multiplexed audio video signal. Time information used in the audio / video signal multiplexing apparatus based on first program reference time information (PCR) which is a signal multiplexing apparatus (MPEG2 TS multiplexing apparatus 100), which is time information included in the audio / video signal. A system reference time generation unit (STC generation circuits 110 and 150) for generating a system reference time (STC), and the multiplexed audio-video signal based on the system reference time generated by the system reference time generation unit A program reference time adding unit (PCR adding unit 118, 119) for adding second program reference time information (PCR) to When the reception interval of the first program reference time information is equal to or longer than a predetermined time (for example, 400 ms), the system reference time generation unit receives the first received first after the predetermined time has elapsed. Based on the program reference time information, the system reference time is regenerated.

  According to such a feature, when the reception interval of the first program reference time information (PCR) included in the received audio / video signal (MPEG-2 TS) becomes equal to or longer than a predetermined time (for example, 400 ms), Since the system standard time (STC) is regenerated based on the first program reference time information received first after the elapse of time, an MPEG-2 TS decoder or an audio / video signal multiplexing device is caused by fluctuations in the PCR value. Is prevented from operating normally.

  Here, when the system reference time (STC) is regenerated, the audio / video signal is momentarily interrupted, so that the MPEG-2 TS decoder and the like are prevented from becoming inoperable, while the system reference time (STC) ) Needs to be reduced.

  According to the first feature of the present invention described above, the timing at which the system reference time (STC) is regenerated is only when the reception interval of the first program reference time information (PCR) becomes a predetermined time or more. Therefore, the occurrence of instantaneous interruption of the audio / video signal is suppressed by regenerating the STC.

  According to a second aspect of the present invention, in the first aspect of the present invention, a plurality of audio / video signals (for example, MPEG-2 TS) are received, and the plurality of audio / video signals are multiplexed to obtain multiplexed audio. An audio / video signal multiplexing device (MPEG2 signal multiplexing device 100 ′) that outputs a video signal, wherein the audio / video signal is based on first program reference time information (PCR) that is time information included in the audio / video signal. A system reference time generation unit (STC generation circuits 110 ′ and 150 ′) that generates a system reference time (STC) that is time information used in the signal multiplexer, and the system reference time generated by the system reference time generation unit Based on the program reference time adding unit (PCR) for adding second program reference time information (PCR) to the multiplexed audio-video signal And the system reference time generator has a difference between the value of the first program reference time information and the value of the system reference time equal to or greater than a predetermined threshold (for example, 10 μs). In this case, the gist is to regenerate the system reference time based on the first program reference time information received first after the predetermined threshold value is exceeded.

  According to this feature, when the difference between the value of the first program reference time information (PCR) and the value of the system standard time (STC) is equal to or greater than a predetermined threshold (for example, 10 μs), the predetermined threshold Since the system standard time (STC) is regenerated based on the first program reference time information received first after the above, the MPEG-2 TS decoder and audio / video signal are changed depending on the PCR value. It is possible to prevent the multiplexing apparatus from operating normally.

  Further, as described above, when the system reference time (STC) is regenerated, the audio video signal is momentarily interrupted, so that the MPEG-2 TS decoder and the like are prevented from becoming inoperable. Although it is necessary to reduce the number of times the standard time (STC) is regenerated, according to such a feature, the timing at which the system standard time (STC) is regenerated is the first program reference time information (PCR). Since the difference between the value and the value of the system reference time (STC) is equal to or greater than a predetermined threshold, it is possible to suppress the occurrence of instantaneous interruption of the audio-video signal due to the re-generation of the STC. Is done.

  According to a third aspect of the present invention, in the second aspect of the present invention, the number of times that the system reference time generation unit is equal to or greater than the predetermined threshold is equal to or greater than a predetermined number of times (for example, four consecutive times). In this case, the gist is to regenerate the system reference time based on the first program reference time information received first after the predetermined number of times.

  According to this feature, when the number of times that the difference between the value of the first program reference time information (PCR) and the value of the system standard time (STC) is equal to or greater than a predetermined threshold is equal to or greater than the predetermined number of times, The system reference time is regenerated based on the first program reference time information (PCR) received first after the predetermined number of times has been reached.

  Therefore, it is possible to further reduce the number of times that the system reference time (STC) is regenerated while preventing the MPEG-2 TS decoder and the like from becoming inoperable.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, when the system reference time is regenerated by the system reference time generation unit, the program is included in the audio / video signal. The gist is to further include a program correspondence table update unit (PMT version update unit 120) that updates a version of a program correspondence table (Program Map Table) indicating information.

  According to such a feature, when the system reference time (STC) is regenerated, the version number of the program correspondence table (hereinafter referred to as PMT (Program Map Table)) is updated (incremented). A normal MPEG-2 TS multiplexer / demultiplexer or MPEG-2 TS decoder that receives a multiplexed audio / video signal multiplexed by the audio / video signal multiplexer reloads the program reference time information.

  This prevents the MPEG-2 TS decoder and other audio / video signal multiplexers from operating normally due to fluctuations in the PCR value.

  According to the present invention, it is possible to provide an audio / video signal multiplexing device that can reliably multiplex a plurality of audio / video signals even when the communication situation is unstable, such as relay of an outdoor program.

(Example of relay system configuration)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration example of an outdoor program relay system according to the present embodiment.

  Specifically, FIG. 1 shows a configuration example of a relay system when relaying a road race such as a marathon. As shown in the figure, a center base station BS1 is provided in the vicinity of the stadium SD that is the start / goal point of the road race.

  In the vicinity of the road race course CU, mobile relay vehicles C1 and C2 equipped with cameras for shooting runners and the like, and base stations BS2 and BS3 for relaying audio / video signals via a wireless line are arranged. Has been.

  Since such road race relay is generally live broadcasting, a radio line connecting the mobile relay vehicles C1 and C2 and the temporarily installed base stations (BS1 to BS3) is very important. Therefore, the coverage of each base station is configured to overlap with the coverage of other base stations as much as possible so that MPEG-2 TS (transport stream signal) transmitted from the mobile relay vehicles C1 and C2 can be reliably relayed. The

  As shown in the figure, the center base station BS1 has a coverage CV1. Further, the base station BS2 has coverage CV2, and the base station BS3 has coverages CV3a and CV3b. For example, the coverage CV1 and the coverage CV2 have areas that overlap each other, and in the figure, the mobile relay vehicle C1 is located in the area. Similarly, the coverage CV2 and the coverage CV3a have regions that overlap each other, and the mobile relay vehicle C2 is located in the region in the figure.

  Also, in the figure, the mobile relay vehicle C1 can be connected to the center base station BS1 via the radio line RL11 and to the base station BS2 via the radio line RL12. Furthermore, the mobile relay vehicle C2 can be connected to the base station BS3 via the radio line RL21 and to the base station BS2 via the radio line RL22.

  That is, the mobile relay vehicles C1 and C2 are connected to a plurality of base stations via a radio channel, and can transmit the same MPEG-2 TS to the plurality of base stations.

  Further, as shown in the figure, the center base station BS1 and the base station BS2 are connected via the radio line RL1, and the center base station BS1 and the base station BS3 are connected via the radio line RL2.

  Further, the center base station BS1 performs processing for switching the audio and video information included in the MPEG-2 TS according to the development of the road race for the MPEG-2 TS transmitted from the mobile relay vehicles C1 and C2, A process of inserting an impose is executed. Furthermore, the MPEG-2 TS for which the processing has been executed is relayed to the broadcasting station ST via a wireless or wired line.

  In the broadcasting station ST, the MPEG-2 TS relayed from the center base station BS1 is converted into a signal in accordance with the broadcasting system if necessary. The signal is transmitted from the transmission tower TW to the viewer as a radio signal.

(Outline block configuration of relay system)
Next, a schematic block configuration of the above-described relay system will be described with reference to FIG. As shown in the figure, the mobile relay vehicle C1 includes an MPEG2 encoder 11 that encodes a video signal or the like captured by a camera (not shown) into MPEG-2 TS, and an MPEG-2 TS, which is connected to a radio line RL11. And an OFDM transmitter 21 that transmits to the base station BS2 via the radio line RL12. Similarly, the mobile relay vehicle C2 includes an MPEG2 encoder 12 and an OFDM transmitter 22 that transmits MPEG-2 TS to the base station BS2 via a radio line RL22.

  The OFDM transmitters 21 and 22 are transmitters using an orthogonal frequency division multiplex system, and in this embodiment, an 800 MHz band is used as a frequency band to be used.

  The base station BS2 includes OFDM receivers 31 and 32, an MPEG2 TS multiplexer 100, and an FM transmitter 41.

  The OFDM receiver 31 sends the MPEG-2 TS transmitted from the mobile relay vehicle C1 via the radio line RL12 to the MPEG2 TS multiplexer 100. Similarly, the OFDM receiver 32 sends the MPEG-2 TS transmitted from the mobile relay vehicle C2 via the radio line RL22 to the MPEG2 TS multiplexer 100.

  In this embodiment, the MPEG2 TS multiplexing apparatus 100 constitutes an “audio / video signal multiplexing apparatus”, receives a plurality of MPEG-2 TSs, multiplexes the plurality of MPEG-2 TSs, Multiplexed MPEG-2 TS "(multiplexed audio / video signal) can be output.

  The FM transmitter 41 is a digital radio transmitter using frequency modulation, and faces the FM receiver 51 provided in the center base station BS1. The FM transmitter 41 can transmit “multiplexed MPEG-2 TS” multiplexed by the MPEG2 TS multiplexer 100 to the center base station BS1 via the radio line RL1.

  Although not shown in the figure, the base station BS3 also has the same block configuration as the base station BS2.

  The center base station BS1 includes an FM receiver 51, an OFDM receiver 33, an MPEG2 TS separation / diversity combining device 200, and MPEG2 decoders 61 and 62.

  The FM receiver 51 sends “multiplexed MPEG-2 TS” transmitted from the FM transmitter 41 via the radio line RL1 to the MPEG2 TS separation / diversity combining apparatus 200.

  The OFDM receiver 33 sends the MPEG-2 TS transmitted from the mobile relay vehicle C1 via the radio line RL11 to the MPEG2 TS separation / diversity combining apparatus 200.

  The MPEG2 TS separation / diversity synthesis apparatus 200 includes an MPEG2 TS separation unit 210 and a diversity synthesis unit 250.

  The MPEG2 TS separator 210 separates “multiplexed MPEG-2 TS” multiplexed by the MPEG2 TS multiplexer 100 into MPEG-2 TS. Specifically, the MPEG2 TS separation unit 210 separates the MPEG-2 TS transmitted from the mobile relay vehicle C2 from the “multiplexed MPEG-2 TS” and sends it to the MPEG2 decoder 61. Also, the MPEG2 TS separation unit 210 sends “multiplexed MPEG-2 TS” to the diversity combining unit 250.

  The diversity combining unit 250 transmits the MPEG-2 TS transmitted from the mobile relay vehicle C1 included in the “multiplexed MPEG-2 TS” received via the FM receiver 51 and the mobile relay via the OFDM receiver 33. The MPEG-2 TS transmitted from the vehicle C1 is synthesized and one MPEG-2 TS is output to the MPEG2 decoder 62.

  The MPEG2 decoders 61 and 62 decode the MPEG-2 TS output from the MPEG2 TS separation / diversity synthesis apparatus 200 into RGB signals.

(Logic block configuration of audio / video signal multiplexer)
Next, the logical block configuration of the MPEG2 TS multiplexer 100 that constitutes the audio / video signal multiplexer according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the MPEG2 TS multiplexing apparatus 100 includes an STC generation circuit 110 and an STC generation circuit 150. Since the STC generation circuit 110 and the STC generation circuit 150 have the same configuration, the configuration of the STC generation circuit 110 will be described below.

  The STC generation circuit 110 uses time information used in the MPEG2 TS multiplexer 100 based on a PCR (Program Clock Reference) value (first program reference time information) included in MPEG-2 TS # 1 (audio / video signal). The STC (system reference time) is generated, and in this embodiment, a system reference time generation unit is configured.

  The STC generation circuit 110 includes a D / A conversion unit 111, a low-pass filter 112, a VCO 113, an STC counter 114, a PCR loader 115, and a PCR packet reception interval measurement monitoring unit 116. The STC generation circuit 110 includes a multiple conversion unit 117, PCR addition units 118 and 119, and a PMT version update unit 120.

  The D / A conversion unit 111, the low-pass filter 112, and the VCO 113 implement a PLL (Phase Locked Loop), and the PCR value included in the MPEG-2 TS # 1 received by the MPEG2 TS multiplexer 100. The oscillation frequency of the VCO 113 is adjusted by comparing with the STC (System Time Clock) generated by the STC counter 114. Specifically, the VCO 113 oscillates a frequency centered on 27 MHz and outputs a clock signal having the frequency to the STC counter 114.

  The STC counter 114 generates an STC based on the PCR value loaded from the PCR loader 115 and measures the time used in the STC generation circuit 110 (MPEG2 TS multiplexer 100).

  Specifically, the STC counter 114 generates an STC based on the PCR value loaded first after the synchronization of the MPEG-2 TS # 1 received by the MPEG2 TS multiplexing apparatus 100 is established, and then is output from the VCO 113. The time used in the STC generation circuit 110 is measured according to the 27 MHz clock signal.

  Further, when the PCR value is reloaded by the PCR loader 115, the STC counter 114 regenerates the STC based on the reloaded PCR value, and then the STC counter 114 according to the 27 MHz clock signal output from the VCO 113. The time used in the generation circuit 110 is measured.

  In addition, the STC counter 114 can notify the PCR adding unit 118 of time information indicating the time measured.

  The PCR loader 115 loads the PCR value included in the MPEG-2 TS # 1 into the STC counter 114 after the synchronization of the MPEG-2 TS # 1 received by the STC generation circuit 110 is established.

  Further, the PCR loader 115 may load the PCR value included in MPEG-2 TS # 1 received by the MPEG2 TS multiplexer 100 into the STC counter 114 in accordance with an instruction from the PCR packet reception interval measurement monitoring unit 116. it can.

  The PCR packet reception interval measurement monitoring unit 116 measures a reception interval of PCR values included in MPEG-2 TS # 1 received by the MPEG2 TS multiplexing apparatus 100.

  Here, FIG. 4 shows the structure of MPEG-2 TS # 1 (and # 2) received by the MPEG2 TS multiplexer 100. FIG. 4A shows a transport packet configured in units of 188 bytes. FIG. 4B shows the structure of the transport packet. As shown in FIG. 4B, the transport packet is provided with an adaptation field. FIG. 4C shows the configuration of the adaptation field. As shown in FIG. 4C, an optional field is provided in the adaptation field.

  FIG. 4D shows the configuration of the optional field. As shown in FIG. 4D, the PCR is displayed using the PCR packet (for example, 42 bits) in the optional field.

  The PCR packet reception interval measurement monitoring unit 116 measures the reception interval of PCR packets included in MPEG-2 TS # 1 received by the MPEG2 TS multiplexing apparatus 100. In addition, when the PCR packet reception interval becomes 400 ms or more, the PCR packet reception interval measurement monitoring unit 116 first receives the PCR received from the PCR loader 115 after the PCR packet reception interval becomes 400 ms or more. Instructs the STC counter 114 to reload the PCR value indicated by the packet.

  That is, when the reception interval of the PCR value included in MPEG-2 TS # 1 received by the MPEG2 TS multiplexer 100 is equal to or longer than a predetermined time, the STC generation circuit 110 receives the signal first after the predetermined time has elapsed. STC (system reference time) can be regenerated based on the PCR value (first program reference time information) included in the MPEG-2 TS # 1.

  The multiplex conversion unit 117 multiplexes MPEG-2 TS # 1 and # 2 to generate “multiplexed MPEG-2 TS” (multiplexed audio / video signal). In this embodiment, two MPEG-2 TSs, MPEG-2 TS # 1 and # 2, are multiplexed. However, the number of multiplexed MPEG-2 TSs is other than two, for example, three. It may be. In such a case, the MPEG-2 TS multiplexer includes a plurality of STC generation circuits.

  The PCR adding unit 118 adds a PCR value (second program reference time information) to “multiplexed MPEG-2 TS” based on the STC (system standard time) generated by the STC generation circuit 110. In this embodiment, a program reference time adding unit is configured.

  Specifically, the PCR adding unit 118 stores the time information based on the STC notified from the STC counter 114 in the PCR packet of MPEG-2 TS # 1 included in the “multiplexed MPEG-2 TS”. Change the PCR value.

  The PCR adding unit 119 is connected to the STC generation circuit 150, and executes the same processing as the PCR adding unit 118. That is, the PCR adding unit 119 changes the PCR value stored in the MPEG-2 TS # 2 PCR packet included in the multiplexed MPEG-2 TS ”.

  When the STC (system reference time) is regenerated by the STC generation circuit 110, the PMT version update unit 120 is a version of a PMT (Program Map Table) indicating information related to a program (program) included in the MPEG-2 TS. In this embodiment, a program correspondence table update unit is configured.

  Specifically, the PMT version update unit 120 can increment the version number of the PMT when the STC (system reference time) is regenerated by the STC generation circuit 110. Note that the PMT version updating unit 120 may not increment the version number of the PMT even when the STC (system reference time) is regenerated by the STC generation circuit 110.

(Operation of audio / video signal multiplexer)
Next, the operation of the MPEG2 TS multiplexing apparatus 100 constituting the audio / video signal multiplexing apparatus according to the present embodiment will be described with reference to FIG.

  As shown in the figure, in step S110, the MPEG2 TS multiplexer 100 sets the PCR value to the STC counter based on the PCR packet received first after the synchronization of the MPEG-2 TS received by the MPEG2 TS multiplexer 100 is established. (STC counter 114).

  In step S120, the MPEG2 TS multiplexing apparatus 100 measures the reception interval of PCR packets included in the MPEG-2 TS.

  In step S130, the MPEG2 TS multiplexing apparatus 100 determines whether the reception interval of PCR packets is 400 ms or more.

  When the reception interval of the PCR packet is not 400 ms or more (No in step S130), the MPEG2 TS multiplexing apparatus 100 proceeds to the process of step S120, and the reception interval between the PCR packet received next and the PCR packet received immediately before. Continue to measure.

  On the other hand, if the reception interval of PCR packets is 400 ms or more (Yes in step S130), the MPEG2 TS multiplexing apparatus 100 proceeds to the process in step S110, and based on the next received PCR packet, the PCR value is set to the STC counter. Reload to (STC counter 114).

  Note that the MPEG2 TS multiplexing apparatus 100 may increment (update) the version of the PMT when the PCR value is reloaded into the STC counter (STC counter 114).

  In this embodiment, when the PCR packet reception interval is 400 ms or more, the PCR value is reloaded into the STC counter (STC counter 114). However, the reception interval is a value different from 400 ms. Also good. Furthermore, the MPEG2 TS multiplexing apparatus 100 may be provided with a function that allows the user to change the reception interval as appropriate according to the environment in which it is used.

(Action / Effect)
According to the MPEG2 TS multiplexing apparatus 100 that is the audio / video signal multiplexing apparatus according to the present embodiment described above, when the reception interval of the PCR packets included in the received MPEG-2 TS becomes 400 ms or more, after the elapse of 400 ms. Since the STC is regenerated based on the PCR value indicated by the first received PCR packet in FIG. 1, it is possible to prevent the MPEG2 decoder 61 and the MPEG2 TS multiplexer 100 from operating normally due to fluctuations in the PCR value. The

  That is, in a conventional audio / video signal multiplexing apparatus that is assumed to be used in a place where communication conditions are stable, such as in a studio, for example, at the time of program switching, a PMT (Program Map) included in the received MPEG-2 TS is used. When the version of (Table) is changed, only the PCR value is reloaded into the STC counter. Therefore, if the PCR value fluctuates greatly, such as in the relay of an outdoor program, the multiplexed “multiplexed MPEG-2 TS However, according to the MPEG2 TS multiplexing apparatus 100, such a problem is solved. However, the MPEG2 decoder 61 and the like cannot be operated normally.

  Furthermore, according to the MPEG2 TS multiplexing apparatus 100, the timing at which the STC is regenerated is only when the reception interval of the first PCR packet is equal to or longer than a predetermined time (400 ms), so the STC is regenerated. This suppresses the occurrence of instantaneous interruption of MPEG-2 TS.

(Other embodiments)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  For example, the present invention can be modified as follows. FIG. 6 shows a logical block configuration of an MPEG2 signal multiplexing apparatus 100 'that constitutes an audio / video signal multiplexing apparatus according to a modification of the present invention. The MPEG2 signal multiplexer 100 ′ can be used in the relay system shown in FIG. 2 instead of the MPEG2 TS multiplexer 100.

  The MPEG2 signal multiplexing apparatus 100 ′ includes an STC generation circuit 110 ′ and an STC generation circuit 150 ′ instead of the STC generation circuit 110 and the STC generation circuit 150 included in the MPEG2 TS multiplexing apparatus 100. Since the STC generation circuit 110 ′ and the STC generation circuit 150 ′ have the same configuration, the following description will mainly focus on differences in the configuration of the STC generation circuit 110 ′ from the MPEG2 TS multiplexer 100 described above. To do.

  The STC generation circuit 110 ′ is used in the MPEG2 signal multiplexing apparatus 100 ′ based on a PCR (Program Clock Reference) value (first program reference time information) included in MPEG-2 TS # 1 (audio / video signal). STC (system reference time) that is time information is generated, and in this modification, a system reference time generation unit is configured.

  The STC generation circuit 110 ′ includes a PCR / STC measurement monitoring unit 116 ′ instead of the PCR packet reception interval measurement monitoring unit 116 (see FIG. 3) provided in the STC generation circuit 110.

  The PCR / STC measurement monitoring unit 116 ′ measures the difference between the PCR value included in MPEG-2 TS # 1 and the time value counted by the STC counter 114 (hereinafter referred to as “PCR / STC difference”). Is. In addition, when the “PCR / STC difference” becomes 10 μs or more, the PCR / STC measurement monitoring unit 116 ′ first starts after the “PCR / STC difference” becomes 10 μs or more with respect to the PCR loader 115. The STC counter 114 is instructed to reload the PCR value indicated by the received PCR packet.

  That is, when the “PCR / STC difference” becomes equal to or greater than a predetermined threshold, the STC generation circuit 110 ′ determines the PCR value included in the MPEG-2 TS # 1 received first after the predetermined threshold is exceeded. Based on (first program reference time information), STC (system reference time) can be regenerated.

  In addition, when the number of times that the “PCR / STC difference” becomes 10 μs or more is continuously 4 times or more, the STC generation circuit 110 ′ first receives the MPEG− received after the 4 times or more. 2 STC (system reference time) can be regenerated based on the PCR value (first program reference time information) included in TS # 1.

  Specifically, the PCR / STC measurement monitoring unit 116 ′ determines that the “PCR / STC measurement” 116 “ The STC counter 114 is instructed to reload the PCR value indicated by the PCR packet received first after the number of times that the “STC difference” becomes 10 μs or more continuously becomes 4 or more.

  Next, the operation of the above-described MPEG2 signal multiplexing apparatus 100 'will be described with reference to FIG.

  As shown in the figure, in step S210, the MPEG2 signal multiplexing apparatus 100 ′ determines the PCR value based on the PCR packet received first after the synchronization of the MPEG-2 TS received by the MPEG2 signal multiplexing apparatus 100 ′ is established. The data is loaded into the STC counter (STC counter 114).

  In step S220, the MPEG2 signal multiplexing apparatus 100 'acquires the PCR value indicated by the PCR packet included in the MPEG-2 TS and the time value counted by the STC counter 114.

  In step S230, the difference between the acquired PCR value and the time value counted by the STC counter 114, that is, the “PCR / STC difference” is measured.

  In step S240, the MPEG2 signal multiplexing apparatus 100 'determines whether or not the "PCR / STC difference" is 10 μs or more.

  When the “PCR / STC difference” is not 10 μs or more (No in step S240), the MPEG2 signal multiplexing apparatus 100 ′ proceeds to the process in step S220, and receives the next PCR packet and the time measured by the STC counter 114. Continue to get the value of.

  On the other hand, if the “PCR / STC difference” is 10 μs or more (Yes in step S240), in step S250, the MPEG2 signal multiplexing apparatus 100 ′ determines that the “PCR / STC difference” is 10 μs or more four times in succession. Determine whether or not.

  If the “PCR / STC difference” is 4 μs or more in succession four times (Yes in step S250), the MPEG2 signal multiplexing apparatus 100 ′ proceeds to the process in step S210 and, based on the next received PCR packet, The PCR value is reloaded into the STC counter (STC counter 114).

  On the other hand, when the number of times when the “PCR / STC difference” is 10 μs or more is less than 4 consecutive times (No in step S250), the MPEG2 signal multiplexing apparatus 100 ′ proceeds to the process in step S220 and receives the next PCR received. The packet and the time value counted by the STC counter 114 are continuously acquired.

  Note that the MPEG2 TS multiplexing apparatus 100 may increment (update) the version of the PMT when the PCR value is reloaded into the STC counter (STC counter 114).

  In this modified example, the PCR value is reloaded into the STC counter (STC counter 114) when the “PCR / STC difference” is 10 μs or more continuously four times. The value of “” may be a value different from 10 μs. Further, the number of times that the “PCR / STC difference” is 10 μs or more counted before the PCR value is reloaded into the STC counter may be a value different from four times. Further, the MPEG2 signal multiplexing apparatus 100 ′ may include a function that allows the user to appropriately change the “PCR / STC difference” value and the number of times in accordance with the environment in which the MPEG2 signal multiplexing apparatus 100 ′ is used.

  In this modified example, the PCR value is reloaded into the STC counter when the “PCR / STC difference” is 10 μs or more four times in succession. When the “/ STC difference” is 10 μs or more, the PCR value may be reloaded into the STC counter.

  According to the MPEG2 signal multiplexing apparatus 100 ′ described above, when the number of times the “PCR / STC difference” is 10 μs or more is continuously 4 times or more, the first reception is made after the number of times becomes 4 or more. An STC is regenerated based on the PCR value indicated by the PCR packet.

  Therefore, compared with the above-described MPEG2 TS multiplexer 100, the number of times that the STC is regenerated can be further reduced while preventing the MPEG2 signal multiplexer 100 'from being disabled.

  Furthermore, in the above-described embodiment of the present invention, MPEG-2 has been described as an example. However, the scope of the present invention should not be construed as being limited to MPEG-2. That is, the present invention can be applied to a multiplexing device that operates based on program reference time information that is time information included in an audio-video signal and system reference time information that is time information used in the multiplexing device.

It is a figure which shows the structural example of the relay system of the outdoor program which concerns on embodiment of this invention. It is a figure which shows schematic block structure of the relay system of the outdoor program which concerns on embodiment of this invention. It is a figure which shows the logic block structure of the audio video signal multiplexing apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the audio video signal multiplexed in the audio video signal multiplexing apparatus which concerns on embodiment of this invention. It is a figure which shows the operation | movement flow of the audio video signal multiplexing apparatus which concerns on embodiment of this invention. It is a figure which shows the logic block structure of the audio video signal multiplexing apparatus which concerns on the example of a change of this invention. It is a figure which shows the operation | movement flow of the audio video signal multiplexing apparatus which concerns on the example of a change of this invention.

Explanation of symbols

100, 100 '... MPEG2 TS multiplexer, 11, 12 ... MPEG2 encoder, 21, 22 ... OFDM transmitter, 31, 32, 33 ... OFDM receiver, 41 ... FM transmitter, 51 ... FM receiver, 61 62 ... MPEG2 decoder, 110, 110 '... STC generation circuit, 111 ... D / A converter, 112 ... low pass filter, 113 ... VCO, 114 ... STC counter, 115 ... PCR loader, 116 ... PCR packet reception interval measurement Monitoring unit 116 ′... PCR / STC measurement monitoring unit 117. Multiple conversion unit 118 and 119 PCR addition unit 150 and 150 ′ STC generation circuit 200 MPEG2 TS separation / diversity synthesis device 210 MPEG2 TS Separation unit, 250 ... diversity combining unit, BS1 ... center base station, BS2, BS3 ... base station, 1, C2 ... mobile relay car CU ... course, CV1, CV2, CV3a, CV3b ... coverage, RL1, RL2, RL11, RL12, RL21, RL22 ... radio channel, SD ... Stadium, ST ... broadcasting stations, TW ... transmission tower

Claims (4)

An audio / video signal multiplexing device that receives a plurality of audio / video signals, multiplexes the plurality of audio / video signals, and outputs a multiplexed audio / video signal,
A system reference time generation unit that generates a system reference time that is time information used in the audio and video signal multiplexing device based on first program reference time information that is time information included in the audio and video signal;
A program reference time adding unit for adding second program reference time information to the multiplexed audio-video signal based on the system reference time generated by the system reference time generating unit;
When the reception interval of the first program reference time information is equal to or longer than a predetermined time, the system reference time generation unit is based on the first program reference time information received first after the predetermined time has elapsed. And generating the system reference time again.   When the difference between the value of the first program reference time information and the value of the system reference time is equal to or greater than a predetermined threshold, the system reference time generation unit first starts after the difference exceeds the predetermined threshold. 2. The audio / video signal multiplexing apparatus according to claim 1, wherein the system reference time is regenerated based on the received first program reference time information.   When the number of times the system reference time generation unit is equal to or greater than the predetermined threshold value is equal to or greater than the predetermined number of times, the system reference time generation unit is 3. The audio / video signal multiplexing apparatus according to claim 2, wherein the system reference time is regenerated based on the audio signal. When the system reference time is regenerated by the system reference time generation unit, the system further includes a program correspondence table update unit that updates a version of a program correspondence table indicating information related to a program included in the audio / video signal. The audio / video signal multiplexer according to any one of claims 1 to 3.

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