JP2014017607A - Video distribution device and video distribution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video distribution device capable of implementing high-quality live distribution with high reliability.SOLUTION: A video distribution device comprises: a first generation unit which generates a first data stream which synchronizes with a first clock signal and in which a plurality of packets are arranged in time series from an input data stream including video information in which a plurality of pictures are arranged in time series; a second generation unit which generates a second data stream which synchronizes with a second clock signal different from the first clock signal and in which the plurality of packets are arranged in time series from the input data stream; and a switching unit which inputs the first data stream and the second data stream, and outputs the first data stream or the second data stream in which time information is corrected on the basis of time difference, on the basis of packet contents having the time information included in the first data stream and the second data stream.

Description

  The present disclosure relates to a video distribution apparatus and a video distribution method for distributing video.

  As a technique for continuously distributing multimedia data including video included in existing contents for video-on-demand services, for example, there is a technique for duplicating a server that performs multimedia data distribution processing. It has been proposed (see Patent Document 1).

  The technique of Patent Document 1 performs the decompression process in synchronization with the compressed video data stored in the active server and the standby server being delayed for a predetermined time, and the delay of the predetermined time described above from the detection of the failure of the active server. By switching to the standby server, continuous delivery is achieved.

  In recent years, in addition to services that deliver multimedia content that has been completed in the server, live delivery services that provide immediate delivery of images from live cameras and images taken at concert venues have also been provided. ing.

  In such a live distribution service, as a technique for realizing continuous distribution, a technique for distributing using a duplexed transmission path has been proposed (see Patent Document 2).

  In the technique of Patent Document 2, a packet sequence obtained by encoding live video is branched into two systems, and the packet sequences of each system are sent to different transmission paths. Further, by selecting packets based on the sequence number on the receiving side, all packets reach the receiving-side terminal device in a normal order regardless of the occurrence of an abnormality in one of the two transmission paths.

JP 2007-60293 A JP 2008-306545 A

  By the way, the technique of Patent Document 1 is based on the premise that compressed video data having the same content is stored in each of the duplicated servers. For this reason, it cannot be applied to a live distribution service in which accumulated data does not exist sufficiently.

  On the other hand, the technology of Patent Document 2 continuously provides a user with a live distribution service by receiving a packet sequence via the other transmission path when a failure occurs in one of the duplex transmission paths. It is possible. However, in the technique of Patent Document 2, if a failure occurs in the distribution server itself that performs the encoding process of live video, the live distribution service cannot be continued. In addition, in order to receive the provision of the live distribution service using the technique of Patent Document 2, it is necessary for the user to bear the cost for maintaining the duplexed transmission path.

  An object of the present disclosure is to provide a video distribution apparatus and a video distribution method capable of realizing high-quality live distribution with high reliability.

  A video distribution apparatus according to one aspect includes a first data stream in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series And a second generation for generating a second data stream synchronized with a second clock signal different from the first clock signal, in which a plurality of packets are arranged in time series from the input data stream And the first data stream and the second data stream, and based on packet contents having time information included in the first data stream and the second data stream, respectively, the first data stream or One of the second data streams in which the time information is corrected based on a time difference is output. And a switching unit.

  According to another aspect of the video delivery method, a first packet signal in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series. Generating a data stream, generating, from the input data stream, a second data stream in which a plurality of packets are arranged in time series and synchronized with a second clock signal different from the first clock signal, and the first data stream And the second data stream is input, based on packet contents having time information included in the first data stream and the second data stream, respectively, the time information based on the first data stream or time difference One of the corrected second data streams is output.

  According to the video distribution device and the video distribution method of the present disclosure, high-quality live distribution can be realized with high reliability.

It is a figure which shows one Embodiment of a video delivery apparatus. It is a figure explaining the difference between the time by a 1st clock, and the time by a 2nd clock. It is a figure which shows one Embodiment of a detection part and a correction | amendment part. It is a figure which shows the hardware structural example of a video delivery apparatus. It is a figure explaining switching of a transport stream. It is a figure which shows another embodiment of a video delivery apparatus. It is a figure which shows the example of a failure notification packet. It is a figure which shows an example of the switching of the encoding process according to generation | occurrence | production of a failure. It is a figure which shows another example of the hardware constitutions of a video delivery apparatus. It is a figure which shows the hardware structural example of a switching unit. It is a figure which shows the example of the flowchart of the process which adjusts 2nd transport stream TS2. It is a figure which shows the example of the flowchart of switch control processing. It is a figure which shows another embodiment of a video delivery apparatus. It is a figure which shows the example of a switching of the encoding process based on a switch notice. It is a figure which shows another example of the hardware constitutions of a video delivery apparatus. It is a figure which shows an example of the flowchart of a notice switching process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment of a video distribution apparatus. The video distribution apparatus 10 illustrated in FIG. 1 is a transport that is an example of a data stream in which a plurality of packets are arranged in time series from an input data stream Sin including video information and audio information acquired by the video camera 1. Create a stream.

  Also, the video distribution device 10 sends the generated transport stream to the transmission path Rout and distributes it to the user's receiving terminal (not shown).

  The video distribution device 10 includes a first generation unit 11, a first clock generation unit 12, a second generation unit 13, a second clock generation unit 14, and a switching unit 15. The switching unit 15 includes a first buffer 151, a second buffer 152, a detection unit 153, a correction unit 154, a changeover switch 155, and a switching control unit 156.

  The first generation unit 11 and the first clock generation unit 12 illustrated in FIG. 1 are included in the first server device 20, while the second generation unit 13 and the second clock generation unit 14 are configured as described above. It is included in a second server device 30 different from the server device 20. The first clock generation unit 12 generates a first clock signal CLK1, and the second clock generation unit 14 generates a second clock signal CLK2 that is different from the first clock signal CLK1 described above. The first clock signal CLK1 is also used as a system time clock for the first server device 20, and similarly, the second clock signal CLK2 is also used as a system time clock for the second server device 30.

  In addition, the switching unit 15 may be provided as an independent device different from the first server device 20 and the second server device 30. For example, as illustrated in FIG. You may provide in the inside of the 2nd server apparatus 30. FIG. In the example of FIG. 1, among the components included in the switching unit 15, the second buffer 152, the detection unit 153, and the correction unit 154 are included in the second server device 30 described above. On the other hand, among the components included in the switching unit 15, the first buffer 151, the changeover switch 155, and the switching control unit 156 are included in the switching unit 40 independent from the first server device 20 and the second server device 30 described above. It is. Note that the switching unit 40 illustrated in FIG. 1 is connected to the second server device 30 and the first server device 20 via a transmission path.

  The first generation unit 11 illustrated in FIG. 1 performs the encoding process and the packetization process in synchronization with the first clock signal CLK1 supplied from the first clock generation unit 12, thereby the input data stream Sin described above. To generate a first transport stream TS1. Note that the video information included in the input data stream Sin is information in which a plurality of pictures are arranged in time series. The first transport stream is an example of a first data stream in which a plurality of packets are arranged in time series and synchronized with the first clock signal CLK1 described above.

  In addition, the second generation unit 13 executes the encoding process and the packetization process in synchronization with the second clock signal CLK2 supplied from the second clock generation unit 14, thereby performing the second generation from the input data stream Sin described above. A transport stream TS2 is generated. The second transport stream is an example of a second data stream in which a plurality of packets are arranged in time series and synchronized with the above-described second clock signal CLK2.

  A plurality of packets included in each of the first transport stream TS1 and the second transport stream TS2 have a fixed data length, and each include time information described later. Further, the data included in each packet is obtained by dividing the video elementary stream and the audio elementary stream obtained by encoding the video information and the audio information of the input data stream Sin for each predetermined data length.

The switching unit 15 illustrated in FIG. 1 inputs the first transport stream TS1 and the second transport stream TS2. That is, the switching unit 15 receives the first transport stream TS1 and the second transport stream TS2 from the first generation unit 11 and the second generation unit 13, respectively. Further, the switching unit 15 outputs either the first transport stream TS1 or the second transport stream whose time information is corrected as will be described later. The 2 generation unit 13 receives an input of the same input data stream Sin. Therefore, if the first generation unit 11 and the second generation unit 13 encode each picture included in the video information of the input data stream Sin as an I picture, the encoded data included in each packet is the same 2 A system transport stream can be obtained.

  However, as described above, the first generation unit 11 and the second generation unit 13 operate according to the first clock signal CLK1 and the second clock signal CLK2 which are different from each other. For this reason, time information such as a program clock reference (PCR) included in the first transport stream TS1 and corresponding time information included in the second transport stream TS2 are not synchronized with each other. That is, there is a time difference between the time information included in each packet of the first transport stream TS1 and the time information included in each packet of the second transport stream TS2.

  When two transport streams whose time information is not synchronized with each other are switched during distribution, the consistency of the time information used for reproduction and restoration on the receiving side is maintained even if the information included in the two transport streams is the same. There is a possibility that the video is interrupted due to collapse.

  That is, the time information included in the first transport stream TS1 and the second transport stream TS2 is not synchronized with each other, that is, that there is a time difference, it is possible to generate a transport stream using two server devices. It was a problem when duplexing.

  The video distribution device 10 according to the present disclosure attempts to solve the above-described problem by switching between the first transport stream TS1 and the second transport stream TS2 using the switching unit 15 as illustrated in FIG.

  The first buffer 151 included in the switching unit 15 illustrated in FIG. 1 gives a predetermined delay to the first transport stream TS1 received from the first generation unit 11, and switches the delayed first transport stream TS1 to a switch. Pass to 155.

  In addition, the second buffer 152 gives the second transport stream TS2 generated by the second generation unit 13 preferably the same delay as the first buffer 151 described above, and the second transport stream TS2 that has been delayed is given. It passes to the correction unit 154.

  Based on the time information included in the first transport stream TS1 and the time information included in the second transport stream TS2, the detection unit 153 includes the time indicated by the first clock generation unit 12 and the second clock generation unit. The time difference between the time indicated by 14 is detected.

  The correction unit 154 corrects the time information included in the second transport stream TS2 passed from the second buffer 152 based on the time difference obtained by the detection unit 153, thereby obtaining the first generation unit 11. The time information of the first transport stream TS1 is synchronized. The correcting unit 154 corrects the time information of the second transport stream TS2 as described later, thereby making the corrected time information equivalent to the time information set based on the first clock signal CLK1 described above. .

  In response to an instruction from the switching control unit 156, the changeover switch 155 transmits the delayed first transport stream TS1 to the transmission line Rout and the corrected second transport stream TS2 to the transmission line. The second state to be sent to Rout is switched.

  The switching control unit 156 sets the changeover switch 155 to the first state when the first generation unit 11 is operating normally, and the state of the changeover switch 155 when a failure occurs in the first generation unit 11. Is switched to the second state.

  As described above, the time information of the second transport stream TS2 passed from the correction unit 154 to the changeover switch 155 and the time information of the first transport stream TS1 passed from the first buffer 151 to the changeover switch 155 are synchronized with each other. doing.

  Therefore, even when the changeover switch 155 is switched from the first state to the second state according to the occurrence of a failure, the time information of the third transport stream sent to the transmission line Rout is maintained consistent. can do. As a result, when switching from the first transport stream TS1 to the second transport stream TS2, it is possible to prevent the occurrence of an instantaneous interruption of the video due to the inconsistency of the time information.

  Thus, according to the video distribution device 10 disclosed herein, the consistency of time information is maintained for the two transport streams TS1 and TS2 generated by the first generation unit 11 and the second generation unit 13, respectively. Switching can be realized. Therefore, even when a failure occurs in the first generation unit 11, the receiving terminal that receives the third transport stream via the transmission path Rout can enjoy high-quality video and audio without a break.

  That is, according to the video distribution device 10 of the present disclosure, high-quality live distribution can be realized with high reliability, and thus a high-quality service can be provided to users of the live distribution service.

  Next, the detection unit 153 illustrated in FIG. 1 detects a time difference between the time based on the first clock signal CLK1 and the time based on the second clock signal CLK2, and time information based on the detected time difference. A method for performing the correction will be described with reference to FIGS.

  FIG. 2 is a diagram for explaining the difference between the time by the first clock generation unit 12 and the time by the second clock generation unit 14. In FIG. 2, the symbol CLK1 indicates an example of the clock signal CLK1 supplied from the first clock generator 12, and the symbol CLK2 indicates an example of the clock signal CLK2 supplied from the second clock generator 14. Yes. Reference numeral NUM1 represents a count value obtained by a counting operation synchronized with the first clock generation unit 12, and reference numeral NUM2 represents a count value obtained by a counting operation synchronized with the second clock generation unit 14.

  When the first server device 20 and the second server device 30 shown in FIG. 1 have equivalent performance, the cycle τ1 of the clock signal CLK1 and the cycle τ2 of the clock signal CLK2 are substantially equal. However, even in this case, the cycle τ1 of the clock signal CLK1 and the cycle τ2 of the clock signal CLK2 do not exactly match. In many cases, the time when the first server device 20 starts operating does not coincide with the time when the second server device 30 starts operating.

  Therefore, as shown in FIG. 2, the count value NUM1 increases from the offset value Of1 by 1 after time T0, whereas the count value NUM2 is different from the offset value Of1 described above. It increases by 1 from Of2.

  The first generation unit 11 illustrated in FIG. 1 generates the first transport stream TS1 in synchronization with the first clock generation unit 12 described above, and generates the above-described count value NUM1 as a program clock every 500 milliseconds. Insert a PCR packet to include as a reference. In the following description, the program clock reference is abbreviated as PCR (Program Clock Reference). The first generation unit 13 also generates the second transport stream TS2 in synchronization with the second clock generation unit 14 described above, and similarly includes a PCR including the count value NUM2 described above at intervals of 500 milliseconds. Insert a packet. In FIG. 2, an example of a PCR packet inserted into the first transport stream TS1 is indicated by reference numeral PCR1, and an example of a PCR packet inserted into the second transport stream TS2 is indicated by reference numeral PCR2.

  For example, the detection unit 153 illustrated in FIG. 1 collates the PCR included in each of the first transport stream TS1 and the second transport stream TS2 as follows. Then, the detection unit 153 detects a time difference between the time by the first clock generation unit 12 and the time by the second clock generation unit 14 based on the collation result.

  The detection unit 153 obtains a difference τd between the time when the PCR packet (PCR1) is detected from the first transport stream TS1 and the time when the PCR packet (PCR2) is detected from the second transport stream TS2. As shown in FIG. 2, the time difference τd is equal to the time T1 when the PCR packet (PCR1) is inserted into the first transport stream TS1 and the time T2 when the PCR packet (PCR2) is inserted into the second transport stream TS2. This is equivalent to the difference.

Therefore, the count value NUM1 (T2) indicating the time T2 based on the first clock signal CLK1 is obtained by calculating the difference τd between the time T1 and the time T2 described above and the value Pcr1 set as the PCR in the PCR packet (PCR1) described above. And can be expressed as shown in Equation (1).
NUM1 (T2) = Pcr1 + τd / τ1 (1)
Then, the time difference d between the time based on the first clock signal CLK1 and the time based on the second clock signal CLK2 is represented by the value NUM1 (T2) and the PCR packet (PCR2) as shown in the equation (2). As a difference from the value Pcr2 set as.
d = Pcr2-NUM1 (T2) = Pcr2-Pcr1-τd / τ1 (2)
The monitoring unit 153 illustrated in FIG. 1 monitors the first transport stream TS1 and the second transport stream TS2, and thereby obtains information necessary for obtaining the time difference d using the above-described equation (2). Can be acquired. That is, the detection unit 153 detects the PCR packets (PCR1) and (PCR2) from the first transport stream TS1 and the second transport stream TS2, respectively, and acquires the times T1 and T2 when these are detected. Further, the detection unit 153 acquires values Pcr1 and Pcr2 set as PCR from the detected PCR packets (PCR1) and (PCR2), respectively. And the detection part 153 should just obtain | require the time difference d mentioned above by applying Formula (1), (2) mentioned above to the acquired information.

  FIG. 3 shows an embodiment of the detection unit 153 and the correction unit 154. 3 that are equivalent to the components shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  The counter CNT2 illustrated in FIG. 3 performs a counting operation in synchronization with the clock signal CLK2 from the second clock generation unit 14, and passes the count value obtained by this counting operation to the second generation unit 13 and the detection unit 153.

  The detection unit 153 illustrated in FIG. 3 includes a matching circuit 51 including two PCR detection units 52a and 52b and two registers 53a and 53b, an estimation unit 54, and a difference calculation unit 55. The PCR detection unit 52a detects a PCR packet from the first transport stream TS1, and passes the value Pcr1 set in the detected PCR packet to the estimation unit 54. Similarly, the PCR detection unit 52b detects a PCR packet from the second transport stream TS2, and passes the value Pcr2 set as the PCR to the detected PCR packet to the difference calculation unit 55. The register 53a holds the count value of the counter CNT2 described above as the first count value in response to the detection of the PCR packet by the PCR detection unit 52a. The register 53b holds the count value of the counter CNT2 described above as the second count value in response to the detection of the PCR packet by the PCR detection unit 52b.

  Here, the time when the PCR packet of the first transport stream TS1 arrives corresponds to the time T1 shown in FIG. 2, and the time when the PCR packet of the second transport stream TS2 arrives is the time shown in FIG. Corresponds to T2. That is, in FIG. 2, the first count value is a count value NUM2 (T1) indicating the time T1 based on the second clock signal CLK2, and the second count value is a total value indicating the time T2 based on the second clock signal CLK2. It is the numerical value NUM2 (T2).

  3 is based on the first count value held in the register 53a, the second count value held in the register 53b, and the value Pcr1 received from the PCR detection unit 52a. A count value NUM1 (T2) indicating a time T2 based on the signal CLK1 is estimated.

For example, the estimation unit 54 adds the difference τp between the second count value and the first count value to the above-described value Pcr1 as shown in the equation (3), so that the time T2 based on the first clock signal CLK1 is obtained. The count value NUM1 (T2) indicating
NUM1 (T2) = Pcr1 + τp (3)
The difference τp between the second count value and the first count value is an increment of the count value of the counter CNT2 between the time T1 and the time T2 shown in FIG. 2, and the time τd described above is used as the second clock signal. This corresponds to the value divided by the period τ2 of CLK2. As described above, since the cycle τ1 of the clock signal CLK1 and the cycle τ2 described above substantially coincide with each other, the value NUM1 (T2) estimated using the equation (3) and the value NUM1 ( It is equivalent to T2).

  Further, the verification circuit 51 shown in FIG. 3 may include a counter instead of the two registers 53a and 53b. The counter performs counting in synchronization with the clock signal CLK2 over the period from the detection of the PCR packet by the PCR detection unit 52a to the detection of the PCR packet by the PCR detection unit 52b, thereby allowing the second time and the first time described above to be obtained. The difference τp may be acquired.

  3 is a subtracter, for example, and subtracts the value NUM1 (T2) obtained by the estimation unit 54 from the PCR value (Pcr2) received from the PCR detection unit 52b. To do. The difference calculation unit 55 passes this subtraction result to the correction unit 154 as a time difference d between the time based on the first clock signal CLK1 and the time based on the second clock signal CLK2.

  The correction unit 154 illustrated in FIG. 3 includes a time information extraction unit 56, a subtracter 57, and a header rewriting unit 58.

  The time information extraction unit 56 extracts time information set based on the second clock signal CLK2 from the second transport stream TS2. For example, the time information extraction unit 56 may extract the value set as the PCR in the PCR packet inserted into the second transport stream TS2, together with the time stamp included in each packet of the second transport stream TS2. Note that the time stamp extracted by the time information extraction unit 56 includes a decoding time stamp indicating the restoration processing order of the encoded data and a presentation time stamp indicating the reproduction time of the restored picture.

The subtractor 57 obtains each corrected value by subtracting the time difference d obtained as described above from the time stamp and the PCR value extracted by the time information extraction unit 56. The subtractor 57 applies the correction values PTSc corresponding to the presentation time stamp (PTS), decoding time stamp (DTS), and PCR value (Pcr) by applying the following equations (4) to (6), for example. , DTSc, Pcrc.
PTSc = PTS-d (4)
DTSc = DTS-d (5)
Pcrc = Pcr−d (6)
The presentation time stamp (PTS), decoding time stamp (DTS), and PCR value (Pcr) described above are examples of time information included in the transport stream.

  Further, the header rewriting unit 58 shown in FIG. 3 rewrites the corresponding time information included in the header of each packet, using the correction values PTSc, DTSc, and Pcrc obtained as described above. That is, the header rewriting unit 58 rewrites the presentation time stamp (PTS) and decoding time stamp (DTS) set in the header of each packet to the corresponding correction values PTSc and DTSc. Similarly, the header rewriting unit 58 rewrites the PCR value (Pcr) set in the header of the PCR packet to the corresponding correction value Pcrc.

  By rewriting the correction value as described above, the time information included in the second transport stream TS2 delayed by the second buffer 152 is set to a value based on the first clock generation unit 12 shown in FIG. It can be corrected. Therefore, the time information included in the second transport stream TS2 corrected by the correction unit 154 can be handled in the same way as the time information set with reference to the first clock generation unit 12 shown in FIG. That is, the second transport stream TS2 corrected by the correcting unit 154 is synchronized with the first transport stream TS1 generated by the first generating unit 11 by the delay time by the second buffer 152.

  Here, the first buffer 151 shown in FIG. 1 and FIG. 3 gives a delay equivalent to that of the second buffer 152 to the first transport stream TS1. Therefore, the first transport stream TS1 delayed by the first buffer 151 and the second transport stream TS2 corrected by the correcting unit 154 are synchronized with each other.

  That is, the first transport stream TS1 delayed by the first buffer 151 and the second transport stream TS2 delayed by the second buffer 152 by the detection unit 153 and the correction unit 154 illustrated in FIG. Can be synchronized. Therefore, even when the third transport stream sent from the transmission path Rout is switched from the first transport stream TS1 to the second transport stream TS2 by the changeover switch 155, the consistency of time information before and after the switching is achieved. Can be maintained.

  Further, as shown in FIG. 3, both the detection unit 153 and the correction unit 154 included in the video distribution device 10 of the present disclosure can be realized by adding small-scale hardware to the second server device. is there.

  A desirable storage capacity for the first buffer 151 and the second buffer 152 is, for example, a capacity that can hold a transport stream corresponding to 15 pictures. The storage capacity corresponding to the transport stream corresponding to 15 pictures is very small compared to the storage capacity required for storing one distribution program, for example. Therefore, the first buffer 151 and the second buffer 152 can also be realized by small-scale hardware.

  In addition, the detection unit 153 illustrated in FIG. 3 does not directly acquire information indicating the time based on the first clock signal CLK1 from the first server device 20, but includes PCRs included in the two transport streams TS1 and TS2, respectively. The time difference d is detected by collating the packets. Therefore, it is necessary to provide a new signal line between the first server device 20 and the second server device 30 in order to pass information indicating the time based on the first clock signal CLK1 from the first clock generation unit 12, for example. There is no.

  Thus, according to the detection unit 153 and the correction unit 154 illustrated in FIG. 3, the time information of the second transport stream TS2 is corrected while maintaining the independence of the first server device 20 and the second server device 30. Can be realized.

  The video distribution apparatus 10 including the detection unit 153 and the correction unit 154 illustrated in FIG. 3 can be realized by, for example, a hardware configuration as illustrated in FIG.

  FIG. 4 shows a hardware configuration example of the video distribution device 10. 4 that are the same as those shown in FIG. 1 and FIG. 3 are given the same reference numerals, and descriptions thereof are omitted.

  The first generation unit 11 illustrated in FIG. 4 includes a moving image encoder 111, a voice encoder 112, and a multiplexing device 113. The moving image encoder 111 generates a video elementary stream by performing the encoding process of the video information VSin included in the input data stream Sin, and passes the generated video elementary stream to the multiplexing device 113. Also, the audio encoder 112 generates an audio elementary stream by performing encoding processing of the audio information ASin included in the input data stream Sin, and passes the generated audio elementary stream to the multiplexing device 113. Also, the multiplexing device 113 generates the first transport stream TS1 by dividing the video elementary stream and the audio elementary stream into fixed-length packets, packetizing them, and multiplexing them.

  The first server device 20 shown in FIG. 4 includes a processor 21, a system time clock (STC) generation unit 22, and a transmission path interface (I / F) 23. The processor 21 controls operations of the first generation unit 11 and the transmission path interface 23. The STC generation unit 22 is an example of the first clock generation unit 12 illustrated in FIG. 1 and supplies the first clock signal CLK1 to the processor 21 and the first generation unit 11. Also, the transmission path interface 23 receives the first transport stream TS1 from the multiplexer 113 and sends it to the first buffer 151 shown in FIG. 1 via the transmission path C1.

  Similar to the first generation unit 11 described above, the second generation unit 13 illustrated in FIG. 4 includes a moving image encoder 131, a voice encoder 132, and a multiplexing device 133. The moving image encoder 131, the audio encoder 132, and the multiplexing device 133 generate the second transport stream TS2 from the input data stream Sin in the same manner as the moving image encoder 111, the audio encoder 112, and the multiplexing device 113 described above.

  The second server device 30 shown in FIG. 4 includes a processor 31, an STC generation unit 32, and two transmission path interfaces (I / F) 33a and 33b. The processor 31 controls the operations of the second generation unit 13 and the transmission path interfaces 33a and 33b. The STC generation unit 32 is an example of the second clock generation unit 14 illustrated in FIG. 1 and supplies the second clock signal CLK2 to the processor 31 and the second generation unit 13.

  In the second server device 30 shown in FIG. 4, the transmission path interface 33a passes the second transport stream TS2 generated by the second generation unit 13 to the second buffer 152 via the transmission path C2-1. In addition, the transmission path interface 33b passes the second transport TS2 whose time information is corrected by the correction unit 154 to the switching unit 40 illustrated in FIG. 1 via the transmission path C2-2.

  4 includes the matching circuit 51 and the processor 31 shown in FIG. The matching circuit 51 uses the PCR packet included in the first transport stream TS1 received via the transmission path C1 and the PCR packet included in the second transport stream TS2 received via the transmission path C2-1. The above-described collation process is performed. Based on the result of this collation processing, the processor 31 executes a process for performing the functions of the estimation unit 165 and the difference calculation unit 166 illustrated in FIG. 3, and thus functions equivalent to the detection unit 153 illustrated in FIG. 3. Can be fulfilled.

  Note that the path length from the transmission path interface 23 to the verification circuit 51 shown in FIG. 4 is desirably substantially equal to the path length from the transmission path interface 33a to the verification circuit 51. By making the two path lengths equal to each other, the difference τd between the first time T1 and the second time T2 shown in FIG. 2 can be obtained with high accuracy. Therefore, the processor 31 is based on the difference τd. However, the accuracy of the time difference d calculated using the equation (2) can be improved.

  The correction unit 154 shown in FIG. 4 includes the processor 31 and the header rewriting unit 58 shown in FIG. The processor 31 can perform the function of the time information extraction unit 56 shown in FIG. 3 by executing the process of extracting the time information of each packet output from the second buffer 152. Further, the processor 31 performs the function of the subtractor 57 shown in FIG. 3 by executing a process of subtracting the detection result obtained by the detection unit 153 from the time information extracted from each packet, and the correction is performed. Later time information can be obtained. Further, the processor 31 passes the corrected time information acquired as described above to the header rewriting unit 58 and causes the header rewriting process of each packet to be executed, so that it is equivalent to the correcting unit 154 shown in FIG. Can fulfill the function.

  The header rewriting unit 58 passes the packet for which the header rewriting process has been completed as described above to the transmission path interface 33b. Further, the transmission line interface 33b sends out to the changeover switch 155 shown in FIG. 1 via a transmission line C2-2 different from the transmission line C2-1 described above.

  Thus, the second server device 30 adds the second buffer 152, the transmission path interface 33a, the verification circuit 51, and the header rewriting unit 58 to the same configuration as the first server device 20, and also the processor 31. This can be realized by changing the software.

  Here, as described with reference to FIG. 3, the verification circuit 51 can be realized by a small-scale circuit. The header rewriting unit 58 can also be realized by changing small-scale hardware or software of the processor 31.

  Therefore, the video distribution device 10 disclosed herein is realized by adding the above-described small-scale hardware and software for the added function to one of the two server devices having the same configuration. can do. Since such a change can be realized at a relatively low cost, according to the video distribution apparatus 10 disclosed herein, a live distribution system capable of realizing high-quality live distribution with high reliability can be realized at low cost. Can be offered at.

  By the way, the working transport stream transmitted via the transmission path Rout shown in FIG. 1 is generated from the elementary stream obtained by encoding the video information VSin for each set of pictures including a predetermined number of pictures. It is desirable to do. For example, GOP (Group of Picture), which is a reproduction and editing unit in the MPEG (Moving Picture Experts Group) system, is an example of the above-described set of pictures. In addition, the encoding process of each picture in the set of pictures is combined with, for example, an intra-screen predictive encoding process, a bidirectional predictive encoding process, and a forward predictive encoding process according to the arrangement of each picture in the set of pictures. It is desirable to apply. In the following description, information indicating the type of predictive coding processing to be applied according to the arrangement of pictures belonging to the GOP is referred to as a GOP structure.

  The first transport stream TS1 generated by the first generation unit 11 shown in FIG. 1 is sent to the transmission line as a third transport stream as long as the first generation unit 11 operates normally. Accordingly, the first generation unit 11 includes, for example, a P picture to which the forward prediction encoding process is applied and a B picture to which the bidirectional prediction encoding process is applied, together with an I picture to which the intra prediction encoding process is applied. It is desirable to perform encoding processing by applying the GOP structure. An example of a desirable GOP structure is a GOP structure in which a set of two B pictures and one P picture repeats after the first I picture, such as “IBBPBBPBBPBBPBB” for 15 pictures. .

  As in the GOP structure described above, the GOP structure is maintained in the transport stream in order to successfully restore the encoded data obtained by encoding using the GOP structure including the B picture and the P picture on the receiving side. It is desirable that

  For this reason, the switching control unit 156 shown in FIG. 1 considers the GOP separation in the first transport stream TS1, and switches the first transport stream TS1 to the second transport stream TS2 by the changeover switch 155. It is desirable to do.

  Next, when switching from the first transport stream TS1 to the second transport stream TS2 in response to the occurrence of a failure in the first generation unit 11, an example suitable as a technique for executing the switching at the GOP break is shown in FIG. Will be described with reference to FIG.

  FIG. 5 is a diagram for explaining switching of transport streams. Note that among the components shown in FIG. 5, components equivalent to those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  Here, when the first generation unit 11 and the second generation unit 13 execute the encoding process to which the GOP structure is applied, respectively, the first generation unit 11 and the second generation unit 13 have the same picture. May be encoded as pictures in different orders within the GOP. In this case, the first transport stream TS1 generated by the first generation unit 11 and the second transport stream TS2 generated by the second generation unit 13 may not match the GOP delimiter.

  Therefore, hereinafter, a case will be described in which the second generation unit 13 encodes each picture included in the video information VSin as an independently decodable I picture. Thus, when each picture included in the video information VSin is encoded as an I picture, each picture can be regarded as one GOP. Therefore, the GOP delimiters between the first transport stream TS1 and the second transport stream TS2 can be matched.

  FIG. 5 illustrates a case where a failure occurs in the first generation unit 11 in the process of generating a transport stream packet corresponding to the nth picture included in the video information VSin. In the example of FIG. 5, there is a failure in the process in which the first generation unit 11 encodes / packetizes the nth picture described above as the fourth P picture from the beginning of the mth GOP (m). Indicates that it occurred.

  In the example of FIG. 5, the first buffer 151 includes packets P1 (n-15) to P1 of the transport stream TS1 corresponding to the video information VSin input to the first generation unit 11 prior to the above-described nth picture. (n-1) is held. Here, for example, the packet P1 (n-15) shown in FIG. 5 includes a part of video encoded data obtained by encoding the n-15th picture of the video information VSin by the first generation unit 11. A plurality of fixed-length packets each included is shown. Similarly, in the example of FIG. 5, a plurality of fixed-length packets are collectively shown in order to make it easy to understand the correspondence between each picture in the GOP and the packets included in the transport stream. Further, in the first transport stream TS1 and the second transport stream TS2 shown in FIG. 5, illustration of packets generated from the audio elementary stream is omitted.

  Of the packets held in the first buffer 151, the packets P1 (n-15) to P1 (n-4) are included in the (m−1) th GOP (m−1) that has been normally encoded. Corresponds to the -15th to (n-1) th pictures. On the other hand, packets P1 (n-3) to P1 (n-1) are n-3th to n- included in GOP (m) that has not been encoded by the first generation unit 11 due to the occurrence of a failure. It is a packet including encoded data corresponding to the first picture. That is, in the example of FIG. 5, the packet P1 (n-3) is a packet including the encoded data of the boundary picture that corresponds to the head of the GOP that has not been completed due to the occurrence of the above-described failure, and the first transport stream TS1. Corresponds to the GOP delimiter.

  Further, the second buffer 152 shown in FIG. 5 includes a second transport stream including encoded data obtained by encoding each of the n-15th to n−1th pictures of the video information VSin as an I picture. The packets P2 (n-15) to P2 (n-1) of TS2 are held.

  Of the packets held in the second buffer 152, packets P2 (n-3) to P2 (n-1) are packets P1 (n-3) to P1 ( Similarly to n-1), it corresponds to the (n-3) th to (n-1) th pictures included in the video information VSin.

  Further, as described above, the correction unit 154 synchronizes the time information included in each packet output from the second buffer 152 with each packet of the transport stream TS1 output from the first buffer 151.

  Therefore, the packets P2 (n-3) to P2 (n-1) whose time information has been corrected by the correction unit 154 are packets P1 (n-15) to P1 (n-4) held in the first buffer 151. Can be handled as a seamless transport stream.

  That is, after the packets P1 (n-15) to P1 (n-4) are sent to the transmission line Rout by the changeover switch 155, the packets P2 (n-3) to P2 (n-1) are sent. Thus, a transport stream maintaining the GOP structure with the consistency of time information can be obtained.

  As described above, the method of switching between the two transport streams TS1 and TS2 in consideration of the GOP delimiter can be realized by, for example, a video distribution device 10 as shown in FIG.

  FIG. 6 shows another embodiment of the video distribution device 10. 6 that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  The first server device 20 illustrated in FIG. 6 includes an insertion unit 16 in addition to the first generation unit 11 and the first clock generation unit 12 illustrated in FIG. When a failure occurs in the first generation unit 11, the insertion unit 16 inserts a failure notification packet including information for notifying the failure into the first transport stream TS1.

  FIG. 7 shows an example of a failure notification packet. The failure notification packet illustrated in FIG. 7 includes a fixed-length payload and a header having a predetermined data length, like other packets included in the transport stream.

  In the failure notification packet header shown in FIG. 7, the symbol Sync indicates a synchronization word, and the symbol PID indicates a packet identifier. Further, as shown in FIG. 7, a predetermined value may be set in the payload header PLh provided in a part of the payload to indicate that the packet is a failure notification packet.

  The packet identifier described above is information for specifying the transport stream to which the packet belongs. Also, by setting a specific value “NULL” as the packet identifier, it can be shown that the packet does not belong to a valid transport stream. Therefore, by setting the above-mentioned specific value “NULL” as the packet identifier of the failure notification packet by the insertion unit 16, this failure notification packet is a packet that does not include the encoded data to be decoded. This may be shown to the receiving terminal.

  According to the first server device 20 having the insertion unit 16 shown in FIG. 6, it is arranged in the second server device 30 or the switching unit 40 that a failure has occurred in the first server device 20 due to the failure notification packet described above. The switching control unit 156 can be notified. Therefore, it is not necessary to provide a signal line or the like for transmitting the occurrence of a failure in the first server device 20 to the switching control unit 156.

  In the second server device 30 shown in FIG. 6, the switching control unit 156 includes a copy buffer 34, a specifying unit 157, and a switch control unit 36.

  The copy buffer 34 shown in FIG. 6 holds information equivalent to the first buffer 151 by holding a copy of the first transport stream TS1 passed from the first generation unit 11 to the first buffer 151.

  The identifying unit 157 detects the failure notification packet inserted by the inserting unit 16 of the first server device 20 from the first transport stream TS1 described above. Further, when detecting the failure notification packet, the specifying unit 157, based on the information held in the copy buffer 34 prior to the failure notification packet, defines a boundary picture corresponding to the first picture of the GOP that has not been completed due to the failure. Is identified.

  As described above, the information held in the copy buffer 34 is equivalent to the information held in the first buffer 151. Therefore, the specifying unit 157 can acquire information equivalent to the information obtained by referring to the first buffer 151 by referring to the copy buffer 34. That is, the configuration in which the copy buffer 34 is provided in the second server device 30 and the specifying unit 157 refers to the copy buffer 34 is an example of a configuration in which the specifying unit 157 refers to information in the first buffer 151. Therefore, the specifying unit 157 can acquire information for specifying the boundary picture by referring to the copy buffer 34 in response to the detection of the failure notification packet.

  For example, based on the presentation time stamp of the packet held in the copy buffer 34 immediately before the failure, the specifying unit 157 corresponds to which number of pictures from the first picture of the unfinished GOP the packet corresponds to. You may acquire the information which shows. The information acquired in this way indicates the number of pictures from the picture being processed at the time of the failure to the first picture of the incomplete GOP. That is, the number of pictures indicated by the information acquired by the specifying unit 157 based on the presentation stamp of the packet described above is an example of information for specifying the boundary picture described above.

  The specifying unit 157 specifies the boundary picture by subtracting the number of pictures described above from the number of pictures belonging to one GOP (for example, 15 pictures) instead of the number of pictures obtained as described above. Information may be passed to the switch control unit 36. The value obtained in this way indicates the number of pictures corresponding to packets that remain unsent in the first buffer 151 at the time of failure, among the pictures belonging to the GOP that has been successfully processed. ing. Hereinafter, a case will be described in which the specifying unit 157 passes the number of pictures corresponding to the untransmitted first transport stream TS1 among the pictures belonging to the GOP that has been processed normally to the switch control unit 36.

  The switch control unit 36 illustrated in FIG. 6 is a timing at which the packet of the second transport stream TS2 generated corresponding to the boundary picture based on the information passed from the specifying unit 157 is passed to the changeover switch 155. Is identified. In addition, the switch control unit 36 performs control to switch the state of the changeover switch 155 from the first state to the second state at the specified timing. Here, the first state is a state in which the changeover switch 155 sends the delayed first transport stream TS1 to the transmission line Rout. Further, the second state is a state in which the changeover switch 155 sends the corrected second transport stream TS2 to the transmission line Rout.

  For example, the switch control unit 36 monitors the packet output from the correction unit 154, and after the failure is detected, the number of pictures in which encoded data is output as a packet of the second transport stream TS2 from the correction unit 154 Count. In addition, when the count value described above matches the number of pictures indicated by the information passed from the specifying unit 157, the switch control unit 36 generates the second transport stream generated corresponding to the boundary picture. Detect as TS2 packet. In this way, at the timing when the packet of the second transport stream TS2 generated corresponding to the boundary picture is detected, the switch control unit 36 changes the state of the changeover switch 155 from the first state to the second state. Switch to.

  By performing such control by the switching control unit 156, switching from the first transport stream TS1 to the second transport stream TS2 can be realized at the GOP break regardless of the failure occurrence timing.

  In the example of FIG. 5, the switch control is performed at the timing when the packet P2 (n-3) corresponding to the boundary picture described above is output from the second buffer 152 and passed to the changeover switch 155 via the correction unit 154. The unit 36 switches the changeover switch 155 to the second state. The changeover switch 155 thus switched to the second state sends each packet passed through the second buffer 152 and the correction unit 154 to the transmission line Rout after the packet P2 (n-3) described above. Note that the state of the changeover switch 155 maintains the first state until the packet P2 (n-3) described above is output from the second buffer 152. Therefore, the packets P1 (n-15) to P1 (n-4) that remain unsent in the first buffer 151 at the time of the failure are transmitted via the changeover switch 155 before the arrival of the above-described timing. It has been sent to the transmission line Rout.

  In this manner, in the video distribution apparatus 10 having the switching control unit 156 shown in FIG. 6, the first transport stream TS1 to the second transport are separated at the GOP segment that is in the position that is temporally back from the failure occurrence timing. Switching to the stream TS2 is possible.

  Furthermore, as shown in FIG. 6, the video distribution device 10 may include a first replacement unit 158 and an encoding control unit 17.

  The first replacement unit 158 illustrated in FIG. 6 sets the packet identifier for the packet of the second transport stream TS2 generated corresponding to the picture input before the above-described boundary picture, to the specific value “ A process of replacing with “NULL” is performed. Further, the first replacement unit 158 replaces the packet identifier with a value indicating the first transport stream TS1 for the packet of the second transport stream TS2 generated corresponding to the picture input after the boundary picture. I do. Note that the first replacement unit 158 may obtain the value of the packet identifier indicating the first transport stream TS1, for example, by referring to the header of each packet held in the copy buffer 34 described above.

  By replacing the packet identifier of each packet belonging to the second transport stream TS2 with a value indicating the first transport stream TS1, the packet can be handled as a part of the first transport stream TS1.

  Referring to the example of FIG. 5, for example, the first replacement unit 158 disposed after the correction unit 154 includes the packets P2 (n-15) to P2 (n-4) output from the second buffer 152. Is replaced with the value “NULL”. By performing such replacement processing on the packet identifiers of these packets, these packets can be invalidated. Thereafter, when the packet P2 (n-3) is output from the second buffer 152, the first replacement unit 158 outputs the packet P2 (n-3) described above and the second buffer 152 after the packet. For each packet, a process of replacing the packet identifier with a value corresponding to the first transport stream TS1 is performed. By this replacement processing, each packet of the transport stream TS2 whose time information is corrected may be a packet of the first transport stream TS1 following the packet P1 (n-4) corresponding to the picture immediately before the boundary picture. it can.

  According to the video distribution apparatus 10 having the first replacement unit 158 as described above, the packet of the second transport stream TS2 corresponding to the above-described boundary picture and after is as if it were the packet of the first transport stream. It can be sent to the transmission line Rout.

  Note that according to the video distribution device 10 having the first replacement unit 158 described above, each packet of the second transport stream TS2 corresponding to a picture before the boundary picture is invalidated. That is, even if each packet of the second transport stream TS2 corresponding to the picture before the boundary picture is sent to the transmission path Rout, it is not subject to decoding processing at the receiving terminal. Therefore, the changeover switch 155 shown in FIG. 6 is realized using, for example, a path that connects the output of the first replacement unit 158 to the transmission line Rout and a switch that disconnects the output of the first buffer 151 from the transmission line Rout. May be.

  In addition, the encoding control unit 17 illustrated in FIG. 6 performs, for each picture included in the input data stream Sin, the second generation unit 13 while the first generation unit 11 is operating normally. Control is performed to apply an encoding process in units of individual pictures. For example, the encoding control unit 17 may instruct the second generation unit 13 to encode each picture as an I picture while the first generation unit 11 is operating normally. On the other hand, when the operation of the first generation unit 11 stops, the encoding control unit 17 controls the second generation unit 13 to apply the above-described encoding process in units of pictures. For example, when the operation of the first generation unit 11 is stopped, the encoding control unit 17 applies the GOP structure that has been applied to the encoding process by the first generation unit 11 to perform encoding. What is necessary is just to instruct | indicate with respect to the production | generation part 13. FIG.

  For example, the encoding control unit 17 monitors the transport stream TS1 generated by the first generation unit 11, and when the failure notification packet described above is detected, the operation of the first generation unit 11 is stopped. You may judge. In addition, the encoding control unit 17 applies the encoding process of each picture included in the input data stream Sin in the process of monitoring the transport stream TS1 generated by the first generation unit 11. Information indicating the GOP structure that has been stored may be acquired.

  In the video distribution device 10 having the encoding control unit 17 described above, the second generation unit 13 encodes each picture included in the input data stream Sin as an I picture until the above-described failure notification packet arrives. . Therefore, when a failure notification packet arrives, in response to an instruction from the encoding control unit 17, the second generation unit 13 immediately follows the GOP structure specified by the instruction from the encoding control unit 17 described above. The encoding process can be started.

  When the encoding control unit 17 performs the above-described control, the second generation unit 13 converts each picture after the picture G (n + 1) shown in FIG. 5 into a new GOP as shown in FIG. Encode as each picture to which it belongs.

  FIG. 8 shows an example of switching of encoding processing according to the occurrence of a failure. Of the elements shown in FIG. 8, the same elements as those shown in FIG. 5 are designated by the same reference numerals, and the description thereof is omitted.

  FIG. 8 shows a case where the encoding mode of the second generator 13 is switched when a failure occurs while the first P-picture of GOP (m) is being encoded by the first generator 11. Shows the case. In FIG. 8, the time at which a failure occurs in the first generation unit 11 is indicated by a symbol Ta. In addition, a boundary picture corresponding to the boundary between the last GOP (m−1) that has been encoded by the first generation unit 11 and the unfinished GOP (m) is input to the video distribution device 10 as the code Tp. Time.

  In FIG. 8, the code TS1-d indicates the first transport stream TS1 delayed by the first buffer 151. A code TS2-d indicates the second transport stream TS2 delayed by the second buffer 152. Reference sign TSout indicates a third transport stream sent to the transmission line Rout via the changeover switch 155. Note that, in the first transport stream TS1, the second transport stream TS2, and the third transport stream TSout shown in FIG. 8, illustration of packets generated from the audio elementary stream is omitted.

  In the example illustrated in FIG. 8, in response to an instruction from the encoding control unit 17 illustrated in FIG. 6, the second generation unit 13 performs the operation for each picture included in the video information VSin input after time Ta. The encoding process to which the same GOP structure as that of the 1 generation unit 11 is applied is started. In FIG. 8, the code GOP (m + 1) indicates the second transport stream TS2 for 1 GOP generated by the second generation unit 13 applying the GOP structure described above.

  Here, at the time Ta described above, the second buffer 152 shown in FIG. 6 holds the second transport stream TS2 for four pictures corresponding to the unfinished GOP (m). The second buffer 152 delays the second transport stream TS2 for four pictures by 1 GOP, and outputs it from time Ts to time Tq. Note that the time Ts is the time when 1 GOP has elapsed from the time Tp described above, and the time at which the changeover switch 155 shown in FIG. 6 starts sending the delayed second transport stream TS2-d. It is. The time Tq is a time when a time corresponding to 1 GOP has elapsed since the time Ta when the failure occurred in the first generation unit 11.

  Further, following the above-described second transport stream TS2 for four pictures, the changeover switch 155 sends the second transport stream TS2 corresponding to GOP (m + 1) to the transmission path Rout as the transport stream TSout.

  As described above, when the encoding control unit 17 performs the above-described switching of the encoding mode, a failure has occurred from the boundary picture during the period in which the I pictures are continuous in the transport stream transmitted to the transmission path Rout. It can be limited to the period corresponding to the picture.

  Here, encoded data obtained by predictive encoding with each picture being an I picture is often larger than encoded data obtained by predictive encoding processing to which a GOP structure including a B picture and a P picture is applied. . For this reason, when the second generation unit 13 encodes each picture as an I picture, the second generation unit 13 often performs compression using a high compression rate on encoded data obtained by predictive encoding. Part of the information may be lost during the compression process. In other words, when the number of packets including encoded data obtained by encoding each picture as an I picture in the transport stream sent to the transmission path Rout increases, the quality of the image restored on the receiving side decreases. There is a fear. Therefore, as described above, the period in which I pictures are continuous is limited to the period corresponding to the picture from the boundary picture to the picture in which the failure has occurred, thereby suppressing deterioration in the quality of the image restored on the receiving side. be able to.

  That is, according to the video distribution device 10 of the present disclosure having the encoding control unit 17 illustrated in FIG. 6, the video quality degradation caused by switching from the first transport stream TS1 to the second transport stream TS2 is minimized. It is possible to suppress it.

  In the video distribution apparatus 10 shown in FIG. 6, the period during which the second transport stream TS2 corresponding to each picture from the boundary picture to the picture where the failure has occurred is output from the second buffer 152 is within 1 GOP. It is. Therefore, the period during which the transport stream including the encoded data obtained by encoding each picture as an I picture is sent to the transmission path Rout is about 30 milliseconds at the minimum, and 0.5 at maximum corresponds to 1 GOP. About seconds. For this reason, it is very unlikely that the user receiving the live distribution by the video distribution apparatus 10 of the present disclosure will notice a decrease in the image quality of the distributed video in the process of switching the transport stream described above.

  The video distribution apparatus 10 of the present disclosure shown in FIG. 6 can be realized by a hardware configuration as shown in FIGS. 9 and 10, for example.

  FIG. 9 shows another example of the hardware configuration of the first server device 20 and the second server device 30. Note that among the constituent elements shown in FIG. 9, the same constituent elements as those shown in FIG. 4 and FIG.

  The first server device 20 illustrated in FIG. 9 includes a packet generation unit 25. The packet generation unit 25 illustrated in FIG. 9 generates the failure notification packet illustrated in FIG. 7 in response to an instruction from the processor 21, and passes the generated failure notification packet to the transmission path interface 23. That is, for example, when a failure occurs in the first server device 20, the processor 21 instructs the packet generation unit 25 to generate a failure notification packet, thereby realizing the function of the insertion unit 16 illustrated in FIG. be able to.

  The second server device 30 shown in FIG. 9 includes a packet monitoring unit 35 along with the copy buffer 34 described above. The packet monitoring unit 35 illustrated in FIG. 9 monitors, for example, the header portion of each packet of the first transport stream TS1 sent from the first server device 20 to the transmission path C1, and the above-described specific value “ A failure notification packet in which “NULL” is set is detected.

  The processor 31 illustrated in FIG. 9 receives a notification indicating the detection result for the failure notification packet from the packet monitoring unit 35, and performs processing for adjusting the second transport stream TS2 in accordance with the received notification, as will be described later. Run. The processor 31 executes a process for adjusting the second transport stream TS2, for example, by executing a first application program stored in a memory (not shown) provided in the second server device 30.

  The first application program detects a time difference d between the time based on the first clock generation unit 12 and the time based on the second clock generation unit 14 based on the collation result by the collation circuit 51 shown in FIG. A program for processing is included. In addition, the first application program includes a program for causing the header rewriting unit 58 to execute processing for rewriting the time information included in each packet with the corrected time information.

  Further, the first application program includes a switching control program for processing to switch to the second transport stream TS2 at the GOP break in the first transport stream TS1 when a failure notification packet is detected. .

  The processor 31 realizes the function of the specifying unit 157 shown in FIG. 6 by performing the above-described process of specifying the boundary picture based on the information held in the copy buffer 34 in the course of executing the switching control program. To do. The processor 31 realizes the function of the first replacement unit 158 illustrated in FIG. 6 by causing the header rewriting unit 58 to perform the above-described packet identifier replacement processing in the course of executing the switching control program. Further, in the process of executing the switching control program, the processor 31 performs control to switch the GOP structure applied to the encoding process of the video information VSin by the second generation unit 13, thereby the encoding control unit illustrated in FIG. 6. 17 functions are realized.

  Although not shown in FIG. 9, the processor 31 executes a program for detecting the time difference d at the above-described time based on the collation result by the collation circuit 51. 1 functions as the detection unit 153 shown in FIG. Similarly, although not shown in FIG. 9, the processor 31 controls the operation of the header rewriting unit 58 according to the above-described program for rewriting time information, thereby correcting the correction shown in FIG. 1. It fulfills the function of the part 154.

  FIG. 10 shows another example of the hardware configuration of the switching unit 40. Note that, among the components shown in FIG. 10, components equivalent to those shown in FIG. 4 are denoted by the same reference numerals and description thereof is omitted.

  The switching unit 40 illustrated in FIG. 10 includes a unit control unit 41 having a packet monitoring unit 42 and a processor 43. The packet monitoring unit 42 illustrated in FIG. 10 performs the above-described failure notification packet from the first transport stream TS1 sent to the transmission path C1 by the first server device 20 in the same manner as the packet monitoring unit 35 illustrated in FIG. Is detected. When the processor 43 receives notification from the packet monitoring unit 42 that a failure notification packet has been detected, the processor 43 executes a switch control process to be described later.

  In the course of executing the switch control process, the processor 43 performs the process of specifying the boundary picture described above based on the information held in the first buffer 151, thereby enabling the function of the specifying unit 157 illustrated in FIG. Realize. Further, the processor 43 performs the process of switching the changeover switch 155 to the second state at the timing when the packet corresponding to the boundary picture is passed to the changeover switch 155 in the process of executing the switch control process, thereby performing the process illustrated in FIG. The function of the switch control unit 36 is realized.

  As shown in FIG. 10, the switching unit 40 includes a unit control unit 41 that functions as the specifying unit 157 and the switch control unit 36 shown in FIG. 6. According to this unit control unit 41, even when a signal for controlling the operation of the changeover switch 155 is not received from the second server device 30, the switching at the timing when the packet corresponding to the boundary picture is passed to the changeover switch 155 is performed. realizable.

  That is, by connecting the first server device 20 and the second server device 30 to the switching unit 40 using the transmission paths C1 and C2-2 described above, two transport streams TS1 and TS2 are separated by GOP. Switchable video distribution apparatus 10 can be realized. Thereby, since independence can be improved as each hardware of the 1st server apparatus 20, the 2nd server apparatus 30, and the switching unit 40, the maintenance and management of the video delivery apparatus 10 can be made easy.

  FIG. 11 shows an example of a flowchart of processing for adjusting the second transport stream TS2. Each process of step S301 to step S315 illustrated in FIG. 11 is an example of a process included in the first application program for the process of adjusting the second transport stream TS2. In addition, each processing of step S301 to step S315 is executed by the processor 31.

  First, the processor 31 determines whether or not a failure notification packet has been detected based on the notification from the packet monitoring unit 35 (step 301).

  For example, when the failure notification packet has not been detected as in the case where the first generation unit 11 illustrated in FIG. 9 is operating normally, the processor 31 proceeds to step 302 according to the negative determination route of step 301. .

  In step 302, as described with reference to FIG. 2, the processor 31 determines the time based on the first clock generation unit 12 and the second clock generation unit 14 based on the collation result by the collation circuit 51 illustrated in FIG. A time difference d from the time based on is calculated.

  Next, the processor 31 corrects the time information included in each packet based on the time difference d obtained in step 302 and the above-described equations (4) to (6) (step 303). In the process of step 303, the processor 31 extracts time information from the header of each packet, and corrects the time information included in each packet based on the extracted time information and the above-described equations (4) to (6). Find the value. Further, the processor 31 corrects the time information by passing the obtained time information to the header rewriting unit 58 and rewriting the time information included in the header of each packet.

  Further, the processor 31 causes the header rewriting unit 58 to execute processing for replacing the packet identifier of the second transport stream TS2 included in the header of each packet with the specific value “NULL” described above (step 304). ). The processor 31 may execute the time information correction process in step 303 and the packet identifier replacement process in step 304 at the same time, or may be executed in the reverse order.

  Next, the processor 31 determines whether or not the video distribution by the video distribution device 10 is completed (step 305). When there is an undelivered input data stream Sin, the processor 31 returns to the process of step 301 according to the negative determination route of step 305.

  Therefore, while the first generation unit 11 is operating normally, the processor 31 repeatedly executes the processing of step 301 to step 305. In the process of repeatedly executing the processing of Step 301 to Step 305, the processor 31 performs processing for invalidating the time information as well as processing for synchronizing the time information with the first transport stream TS1, as adjustment processing for the second transport stream TS2. Run. Further, in the process where the processor 31 repeats the processes of steps 301 to 305, when the video distribution is completed, the processor 31 performs a process of adjusting the second transport stream TS2 according to the affirmative determination route of step 305. finish.

  On the other hand, when a failure occurs in the first generation unit 11, the packet monitoring unit 35 illustrated in FIG. 9 notifies the processor 31 that a failure notification packet has been detected. When receiving this notification, the processor 31 proceeds to the affirmative determination route of step 301 and executes the switching control process described below. The processor 31 determines that a failure has occurred in the first server device 20 when, for example, the packet of the first transport stream TS1 is interrupted for a predetermined time or more, and the processing of the affirmative determination route in step 301 is performed. May be executed.

  First, the processor 31 switches the encoding mode by instructing the second generation unit 13 to apply the encoding mode applied in the encoding process by the first generation unit 11 (step 306). ). For example, the processor 31 applies the encoding process by the first generation unit 11 based on the information held in the copy buffer 34 illustrated in FIG. 9 while the first generation unit 11 is operating normally. Information indicating a coding mode including the GOP structure being used may be acquired. Further, the processor 31 may pass the information acquired in this way to the moving image encoder 131 (see FIG. 4) included in the second generation unit 13 and instruct the switching of the encoding mode.

  Next, the processor 31 refers to the copy buffer 34 to obtain information indicating a picture corresponding to the packet of the first transport stream TS1 generated immediately before the failure notification packet (step 307). Next, based on the information acquired in step 306, the processor 31 selects pictures that are input before the boundary picture among the pictures corresponding to the first transport stream TS1 held in the first buffer 151. Np is calculated (step 308). The number of pictures np obtained in this way is an example of information for specifying a boundary picture. Therefore, it is one of the embodiments of the specifying unit 157 illustrated in FIG. 6 that the processor 31 executes the processing of step 307 and step 308 in the affirmative determination route of step 301.

  Note that the processor 31 may execute the processing in step 306 and the processing in steps 307 and 308 in the order opposite to the order shown in FIG.

  Next, the processor 31 counts the number ns of pictures corresponding to the second transport stream TS2 output from the second buffer 152 after the failure has occurred in the first generation unit 11 (step 309). For example, the processor 31 monitors a packet output from the second buffer 152, and each time a packet corresponding to one picture is output from the second buffer 152, a numerical value “1” is added to the number of pictures ns described above. The counting process may be performed by performing the adding process.

  Next, the processor 31 compares the number of pictures ns obtained in step 309 with the number of pictures np obtained in step 308 (step 310). When the picture number ns is smaller than the picture number np indicating the position of the border picture, the processor 31 determines that the packet corresponding to the border picture has not been output from the second buffer 152, and the result of step 310 is affirmative. Execute the judgment route process.

  In the affirmative determination route of step 310, the processor 31 performs processing for replacing the packet identifier included in the header of the packet output from the second buffer 152 with a specific value “NULL” in the same manner as in step 304 described above. Perform (step 311). Next, the processor 31 performs a process of correcting time information included in the packet output from the second buffer 152 in the same manner as in step 303 (step 312). In the process of step 312, the processor 31 may obtain a correction value corresponding to each time information based on the value of the time difference d obtained when the process of step 302 was executed last. Next, in step 313, the processor 31 determines whether or not the video distribution processing is completed. If there is an undistributed input data stream Sin, the processor 31 returns to the processing in step 309 according to the negative determination route in step 313. .

  Therefore, during a period in which the packet corresponding to the picture is output from the second buffer 152 before the boundary picture described above, the processor 31 repeatedly executes the processes of Steps 309 to 313 described above. In this way, the processor 31 performs a process of synchronizing the time information with the first transport stream TS1 and a process of invalidating the second transport stream TS2 corresponding to the picture preceding the boundary picture. Execute the adjustment process including.

  After that, when the number of pictures ns obtained in step 309 is equal to or greater than the number of pictures np indicating the position of the boundary picture described above (negative determination in step 310), the processor 31 corresponds to the boundary picture from the second buffer 152. It is determined that the packet to be output has been output.

  In the negative determination route of step 310, the processor 31 causes the header rewriting unit 58 to execute a process of replacing the packet identifier included in the header of each packet with the packet identifier of the first transport stream TS1 (step 314). ). For example, the processor 31 may acquire the packet identifier of the first transport stream TS1 based on the information held in the copy buffer 34 described above while the first generation unit 11 is operating normally. Good. The processor 31 may pass the packet identifier acquired in this way to the header rewriting unit 58 and instruct the header rewriting unit 58 to rewrite the packet identifier. By performing such a packet identifier rewriting process, the packet after the rewriting process can be a packet belonging to the first transport stream TS1.

  Next, the processor 31 corrects the time information included in each packet by executing the process of step 312 described above. Next, in step 313, the processor 31 determines whether or not the video distribution processing is completed. If there is an undistributed input data stream Sin, the processor 31 returns to the processing in step 309 according to the negative determination route in step 313. Then, processing for each subsequent packet is performed.

  In this way, the processor 31 repeatedly executes the processing of step 309, step 310, step 314, step 312 and step 313 described above for the packet corresponding to each picture after the boundary picture output from the second buffer 152. To do. In the course of this processing, the processor 31 performs processing for converting each packet corresponding to a picture after the boundary picture into a packet of the first transport stream TS1, and processing for synchronizing time information with the first transport stream TS1. The adjustment process including is executed.

  Thereafter, when the distribution of the input data stream Sin is finished, the processor 31 finishes the adjustment process of the second transport stream TS2 according to the affirmative determination route of Step 313.

  In the flowchart shown in FIG. 11, the processor 31 executes the process of step 311 or step 314 according to the determination result of step 310. In this way, the processor 31 performs switching between the process of invalidating each packet after header rewriting and the process of making each packet a part of the first transport stream TS1 before and after the boundary picture. FIG. 6 is one embodiment of the first replacement unit 158 shown in FIG. 6. In addition, the processor 31 executes steps 303 and 312 as processes for correcting time information in the affirmative determination route and the negative determination route in step 301, respectively, in the embodiment of the correction unit 154 shown in FIG. One. Note that, in the negative determination route of step 301, the process of correcting the time information of step 312 is executed before the process of step 310, for example, thereby switching the order of the time information correction process and the packet identifier replacement process. May be executed.

  When the processor 31 executes such processing, a part of the second transport stream TS2 corresponding to each picture after the boundary picture is passed to the switching unit 40 as a part of the first transport stream TS1. Can do.

  FIG. 12 shows an example of a flowchart of the switch control process. Each process of step S321 to step S326 illustrated in FIG. 12 is an example of a switch control process. In addition, each processing of step S321 to step S326 is executed by the processor 43 shown in FIG.

  First, the processor 43 determines whether or not a failure notification packet is detected from the first transport stream TS1 based on the notification from the packet monitoring unit 42 shown in FIG. 10 (step 321).

  For example, when the failure notification packet has not been detected as in the case where the first generation unit 11 illustrated in FIG. 9 is operating normally, the processor 43 follows the negative determination route of step 321 to Repeat the process. On the other hand, when it is notified from the packet monitoring unit 42 that the failure notification packet has been detected, the processor 43 proceeds to the affirmative determination route of step 321 and executes a process of switching the state of the changeover switch 155.

  In the affirmative determination route of step 321, the processor 43 first refers to the first buffer 151 illustrated in FIG. 10 and indicates a picture corresponding to the packet of the first transport stream TS 1 generated immediately before the failure notification packet. Information is acquired (step 322).

  Next, the processor 43 selects, based on the information acquired in the process of step 322, the picture input before the boundary picture among the pictures corresponding to the first transport stream TS1 held in the first buffer 151. The number np is calculated (step 323).

  Next, the processor 43 counts the number ns of pictures corresponding to the first transport stream TS1 output from the first buffer 151 after the failure has occurred in the first generation unit 11 (step 324). For example, the processor 43 monitors a packet output from the first buffer 151, and each time a packet corresponding to one picture is output from the first buffer 151, a numerical value “1” is added to the number of pictures ns described above. The counting process may be performed by performing the adding process.

  Next, the processor 31 compares the number of pictures ns obtained in step 324 with the number of pictures np obtained in step 323 (step 325). When the picture number ns is smaller than the picture number np indicating the position of the boundary picture, the processor 43 returns to the process of step 324 according to the negative determination route of step 325 and repeats the processes of step 324 and step 325.

  Thereafter, when the number of pictures ns output from the first buffer 151 has reached the number of pictures np indicating the position of the boundary picture (affirmative determination in step 325), the processor 43 proceeds to the process of step 326.

  In step 326, the processor 43 selects the second transport stream TS2 via the transmission line C2-2 shown in FIG. 10 from the first state where the selector 155 selects the output of the first buffer 151. Switch to the state and end the switching control process.

  When the processor 43 executes such switching control processing, switching to the second transport stream TS2 to which the adjustment processing described with reference to FIG. 11 is performed at the GOP break in the first transport stream TS1. Can be realized. That is, the function of the switching control unit 157 shown in FIG. 6 can be realized by the processor 43 shown in FIG. 10 executing the processing of step 321 to step 326.

  In addition, after this switching process, the selector switch 155 maintains the second state in which the second transport stream TS2 via the transmission line C2-2 is selected, and the second transport stream TS2 subjected to the adjustment process described above. Are sent to the transmission line Rout.

  Thus, each packet of the second transport stream TS2 sent to the transmission path Rout includes time information synchronized with the first transport stream TS1 and the same packet identifier as that of the first transport stream TS1. Therefore, the receiving terminal that receives these packets can be restored and reproduced as a part of the first transport stream TS1 sent before the switching described above, so that a delay or dropout of the video occurs. Never do.

  As described above, according to the video distribution device 10 having the hardware configuration illustrated in FIGS. 9 and 10, even when a failure occurs in the first server device 20 including the first generation unit 11, the switching process described above is performed. High-quality live video distribution service can be continued with high reliability.

  By the way, in order to continuously provide a live video distribution service, it is desirable to periodically check the states of the first server device 20 and the second server device 30 included in the video distribution device 10. In addition, both the inspection of the second server device 30 operating as the standby system and the inspection of the first server device 20 operating as the active system can be performed while continuing the live video distribution service. desirable.

  Next, a method for enabling periodic inspection of the first server device 20 while continuing the live video distribution service will be described.

  FIG. 13 shows another embodiment of the video distribution apparatus 10. Note that among the constituent elements shown in FIG. 13, the same constituent elements as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  The first server device 20 shown in FIG. 13 gives a switching notice including information specifying the first timing for executing the switching prior to switching the working system from the first generating unit 11 to the second generating unit 13. A notice unit 18 for notifying the switching unit 15 is included. For example, the notice unit 18 generates a switching notice based on schedule information indicating the time to stop the first server device 20 by periodic inspection, and the generated switching notice is generated before the first timing corresponding to the above-described time. May be notified to the switching unit 15.

  For example, the notification unit 18 may generate a control packet including the number of pictures included in one GOP in the encoding mode employed by the first generation unit 11 as the switching notification. Further, the notifying unit 18 inserts the control packet generated as described above immediately before the packet corresponding to the head of the GOP encoded last by the first generating unit 11, and the first transport stream TS1. A change notice may be notified by sending it as a part. In addition, when the notification part 18 produces | generates the control packet mentioned above, it is desirable to set specific value "NULL" to a packet identifier similarly to the failure notification packet shown in FIG.

  Further, the second server device 30 illustrated in FIG. 13 includes a notice control unit 159 and a second replacement unit 160 as components belonging to the switching unit 15. As in the example shown in FIG. 13, the notice control unit 159 and the second replacement unit 160 are arranged in the switching unit 40 instead of arranging the notice control unit 159 and the second substitution unit 160 in the second server device 30. May be.

  The notice control unit 159 shown in FIG. 13 changes the state of the changeover switch 155 at the second timing after the time corresponding to the delay by the first buffer 151 from the first timing designated by the notice of switching. Control to switch from the first state to the second state is performed.

  The second timing described above corresponds to the timing at which the delayed first transport stream TS1 passed from the first buffer 151 to the changeover switch 155 is interrupted. In addition, the second timing is switched by a packet generated by the second generation unit 13 from the input data stream Sin after the first timing described above after the delay by the second buffer 152 and the correction of time information by the correction unit 154. It is also the timing to reach 155.

  Therefore, the advancement control unit 159 performs the above-described control to switch from the first transport stream TS1 generated before the arrival of the first timing to the second transport stream TS2 generated after the arrival of the first timing. Can be realized.

  The second replacement unit 160 replaces the packet identifier of each packet output from the second buffer 152 or the correction unit 154 with the specific value “NULL” until the second timing described above. By performing such replacement processing, the second replacement unit 160 can invalidate the second transport stream TS2 passed to the changeover switch 155 before the arrival of the second timing.

  Further, the second replacement unit 160 replaces the packet identifier of each packet output from the second buffer 151 or the correction unit 154 after the second timing described above with a value indicating the first transport stream TS1. When the second replacement unit 160 performs such replacement processing, each packet generated by the second generation unit 13 after the arrival of the first timing is sent to the changeover switch 155 as a packet of the first transport stream TS1. Can pass.

  Further, as illustrated in FIG. 13, the second server device 30 may include an encoding control unit 17. Note that the encoding control unit 17 illustrated in FIG. 13 determines that the operation of the first generation unit 11 has stopped when the packet of the first transport stream TS1 output from the first server device 20 is lost. May be. In addition, after detecting the control packet described above, the encoding control unit 17 outputs the first transport stream TS1 for the number of pictures included in the control packet when the first server device 20 outputs the first transport stream TS1. An operation stop of the generation unit 11 may be detected.

  The encoding control unit 17 switches the encoding mode of the second generation unit 13 in accordance with the operation state of the first generation unit 11, thereby causing the second generation unit 13 to respond to the arrival of the first timing described above. An encoding process to which the same GOP structure as that of the first generation unit 11 is applied can be started.

  As a result, as shown in FIG. 14, the second transport stream TS2 generated by applying the above-described GOP structure by the second generation unit 13 is transferred to the changeover switch 155 in accordance with the above-described second timing. it can.

  FIG. 14 shows an example of coding mode switching based on the switching notice. Of the elements shown in FIG. 14, elements equivalent to those shown in FIG. 8 are denoted by the same reference numerals, and description thereof is omitted.

  The example of FIG. 14 shows a case where the control packet P1 (CTL) described above is inserted at the boundary between the m−1th GOP and the mth GOP by the notice unit 18 shown in FIG. In this case, the first generation unit 11 stops the operation at time Tc1 when the generation of the first transport stream TS1 for 1 GOP indicated by the code GOP (m) is completed. That is, in the example of FIG. 14, the time Tc1 corresponds to the first timing at which switching from the first server device 20 to the second server device 30 is executed. In addition, at the first timing, the second generation unit 13 starts an encoding process using the same GOP structure as the GOP (m−1) of the first transport stream TS1. In FIG. 14, the code GOP (m + 1) indicates the second transport stream TS2 generated by the second generation unit 13 corresponding to each picture for 1 GOP after time Tc1.

  In the example of FIG. 14, the time Tc2 when the delay time of 1 GOP has elapsed from the time Tc1 described above corresponds to the second timing after the time of 1 GOP has elapsed from the first timing. At this second timing, the second transport stream TS2 indicated by the symbol GOP (m + 1) in FIG. 14 is part of the transport stream TSout following the first transport stream TS1 indicated by the symbol GOP (m). Is sent out as

  As described above, according to the video distribution apparatus 10 shown in FIG. 13, the GOP structure capable of transmitting high-quality video with a small amount of information even in the transport stream immediately after switching by performing the above-described notice switching control. Can be applied.

  Note that the first generation unit 11 desirably uses the GOP (m) to be generated last as a closed GOP having a GOP structure that can be restored without depending on information included in the subsequent GOP. An example of the structure of the closed GOP is a structure in which the last picture is encoded as a P picture, as shown in FIG. In this way, by setting the last GOP before switching as a closed GOP, the receiving terminal restores the last GOP of the first transport stream TS1 without using the information of the subsequent second transport stream TS2. It becomes possible. Thereby, it is possible to prevent the image from being disturbed with the switching of the transport stream with higher accuracy.

  The video distribution apparatus 10 illustrated in FIG. 13 can be realized with a hardware configuration as illustrated in FIG.

  FIG. 15 shows another example of the hardware configuration of the video distribution device 10. 15 that are the same as those shown in FIGS. 4 and 9 are given the same reference numerals, and descriptions thereof are omitted.

  In the first server device 20 shown in FIG. 15, the packet generator 25 generates a control packet for the above-described notice switching in response to an instruction from the processor 21, and generates it in response to an instruction from the processor 21. The control packet is passed to the transmission path interface 23.

  Further, for example, the processor 21 causes the packet generation unit 25 to generate a control packet and output the control packet based on schedule information set in a memory (not shown) provided in the first server device 20. Control timing.

  Thus, the processor 21 realizes the function of the notice unit 18 shown in FIG. 13 by controlling the control packet generation operation and output operation by the packet generation unit 25 based on preset schedule information. Can do.

  In the second server device 30 shown in FIG. 15, the packet monitoring unit 35 detects the control packet described above from the first transport stream TS1 sent from the first server device 20 to the transmission path C1.

  The processor 31 illustrated in FIG. 15 executes a notice switching process for operating the second generation unit 13 as an active system, as will be described later, when a control packet is detected by the packet monitoring unit 35. For example, the processor 31 executes the notice switching process by executing a second application program stored in a memory (not shown) provided in the second server device 30.

  The second application program detects a time difference d between the time based on the first clock generation unit 12 and the time based on the second clock generation unit 14 based on the collation result by the collation circuit 51 shown in FIG. A program for processing is included. The processor 31 performs the function of the detection unit 153 illustrated in FIG. 13 by executing a program for the above-described processing for detecting the time difference d based on the collation result by the collation circuit 51. In addition, in FIG. 15, illustration of the detection part 153 is abbreviate | omitted.

  Further, the second application program includes a program for causing the header rewriting unit 58 to execute a process of rewriting the time information included in each packet with the corrected time information. The processor 31 performs the function of the correction unit 154 shown in FIG. 1 by controlling the operation of the header rewriting unit 58 in accordance with the above-described program for rewriting time information. In FIG. 15, the correction unit 154 is not shown.

  Further, the second application program includes a program for processing for controlling switching of the selector switch 155 based on information included in the detected control packet. The processor 31 realizes the function of the notice control unit 159 shown in FIG. 13 by performing processing for controlling switching of the changeover switch 155 based on the information received from the packet monitoring unit 35.

  In addition, the second application program includes a program for processing for controlling the packet identifier rewriting operation by the header rewriting unit 58 based on the information included in the detected control packet. The processor 31 realizes the function of the second replacement unit 160 illustrated in FIG. 13 by performing processing for controlling the packet identifier rewriting operation by the header rewriting unit 58 based on the information received from the packet monitoring unit 35. .

  That is, when the processor 31 included in the hardware configuration example illustrated in FIG. 15 is notified from the packet monitoring unit 35 that the control packet described above has been detected, the prediction switching process illustrated in FIG. 16 is performed. The video distribution apparatus 10 shown in FIG. 13 can be realized.

  FIG. 16 shows an example of a flowchart of the notice switching process. Of the steps shown in FIG. 16, the same steps as those shown in FIG. 11 are denoted by the same reference numerals and description thereof is omitted.

  The process of each step shown in FIG. 16 is an example of a process included in the second application program for the prediction switching process. Further, the processing of each step is executed by the processor 31.

  First, the processor 31 receives a notification of the information included in the control packet described above from the packet monitoring unit 35, and acquires the number of pictures np belonging to the last GOP encoded before switching from the received information (step S31). 331).

  Next, the processor 31 determines whether or not the first generation unit 11 is operating (step 332). For example, the processor 31 may receive information indicating the detection status by the packet monitoring unit 35 and execute the determination process in step 332 based on the information indicating the detection status.

  When it is notified from the packet monitoring unit 35 that the state of detecting the packet of the first transport stream TS1 is continuing, the processor 31 determines that the first generation unit 11 is operating. Then, the process proceeds to the affirmative determination route in step 332.

  In the affirmative determination route of step 332, the processor 31 executes processing for correcting and invalidating the time difference d for each packet of the second transport stream TS2, as in steps 302 to 304 shown in FIG. . Thereafter, the processor 31 returns to the process of step 332.

  Here, during the period in which the determination that the first generation unit 11 is operating in step 332 continues, the first transport stream corresponding to the last GOP before switching is generated by the first generation unit 11. It corresponds to the period. That is, the processor 31 repeatedly executes the processing in step 332 and the processing in steps 302 to 304 over the period in which the first transport stream corresponding to the last GOP before switching is generated. In the example shown in FIG. 14, this period is a period from the timing when the control packet P1 (CTL) is inserted into the first transport stream TS1 to the time Tc1 corresponding to the first timing.

  When the first generation unit 11 completes the generation of the first transport stream TS1 corresponding to the last GOP, the packet monitoring unit 35 notifies the processor 31 that the packet of the first transport stream TS1 can no longer be detected. Notice. In response to this notification, the processor 31 determines that the operation of the first generation unit 11 has stopped, and starts processing of a negative determination route in step 332.

  In the negative determination route of step 332, the processor 31 first switches the encoding mode of the second generation unit 13 in the same manner as in step 306 shown in FIG. As described above, the processor 31 executes the process of step 306 in the negative determination route of step 332, thereby realizing the function of the encoding control unit 17 illustrated in FIG. As a result, as shown in FIG. 14, the first generation unit 11 causes the second generation unit 13 to generate the first generation at the timing when the generation of the first transport stream TS1 corresponding to the last GOP (m) is completed. An encoding process to which the same GOP structure as that of the unit 11 is applied can be started.

  Next, the processor 31 counts the number of pictures ns corresponding to the second transport stream TS2 output from the second buffer 152 after switching the encoding mode in step 306 described above (step 333).

  Next, the processor 31 compares the number of pictures np belonging to the last GOP of the first transport stream TS1 with the number of pictures ns obtained in the process of step 333 (step 334).

  When the picture number ns is smaller than the picture number np (Yes in step 334), the processor 31 has yet to output the second transport stream TS2 corresponding to the last GOP of the first transport stream TS1. Judge that there is no. In this case, the processor 31 executes the processing of step 311 to step 313 as the processing of the affirmative determination route of step 334 as in the flowchart shown in FIG. That is, while the second buffer 152 outputs each packet of the second transport stream TS2 corresponding to the last GOP before switching, the processor 31 performs steps 333 and 334 and steps 311 to 313 described above. Repeat the process. In this way, the processor 31 performs the process of synchronizing the time information with the first transport stream TS1 and the process of invalidating the second transport stream TS2 corresponding to the last GOP before switching. .

  Thereafter, when the number of pictures ns obtained in step 333 becomes equal to or greater than the number of pictures np belonging to the last GOP (negative determination in step 334), the processor 31 determines that the packet generated after switching the coding mode is the first one. It is determined that the data is output from the second buffer 152.

  In the negative determination route of step 334, the processor 31 first determines whether or not the number of pictures ns obtained in step 333 is equal to the number of pictures np belonging to the last GOP (step 335). If the determination in step 335 is affirmative, the processor 31 instructs the changeover switch 155 shown in FIG. 15 to change to the second state described above, and thereby sends the second transport stream TS2 to the changeover switch 155. The data is sent to the transmission line Rout (step 336). Note that the timing at which the determination in step 335 is affirmative is the second timing corresponding to the time Tc2 shown in FIG. That is, in the course of the negative determination route processing of step 334, the processor 31 executes the processing of step 336 according to the positive determination of step 335, thereby realizing the function of the notice control unit 159 shown in FIG. can do.

  In addition, in the negative determination route processing of step 334, including after execution of the processing of step 336 described above, the processor 31 performs the same packet identifier replacement processing as that of step 314 shown in FIG. Thereby, after switching the encoding mode described above, the packet of the second transport stream TS2 generated by the second generation unit 13 can be sent to the transmission path Rout as a packet belonging to the first transport stream TS1. It becomes.

  Thus, each packet of the second transport stream TS2 sent to the transmission path Rout includes time information synchronized with the first transport stream TS1 and the same packet identifier as that of the first transport stream TS1. Therefore, the receiving terminal that receives these packets can be restored and reproduced as a part of the first transport stream TS1 sent before the switching described above, so that a delay or dropout of the video occurs. Never do.

  As described above, when the processor 31 executes the second application program for the notice switching process, the second server apparatus 30 includes the notice control unit 159 and the second replacement unit 160 illustrated in FIG. The function of the switching unit 15 can be realized.

  The second application program for the notice switching process can be realized by changing a part of the application program for causing the second server device 30 to operate as a standby video distribution device. The increase in hardware due to the provision of the packet monitoring unit 35 and the header rewriting unit 58 is also small.

  As described above, according to the video distribution device 10 of the present disclosure, by adding small-scale functions to the hardware and software of the second server device 30, the first server device 20 performs the first distribution while continuing the video distribution. Switching to one server device 30 can be realized. As a result, it is possible to carry out periodic inspections and the like of the first server device 20 while continuing the live video distribution service, so that the reliability of the video distribution device 10 can be further improved.

  As shown in FIG. 10, the switching unit 40 may be provided with a unit control unit 41 including a packet monitoring unit 42 and a processor 43, and the function of the notice control unit 159 may be realized by the unit control unit 41. .

  Also, the notice switching process shown in FIG. 16 may be incorporated as part of the process for adjusting the second transport stream TS2 shown in FIG. For example, in the flowchart of FIG. 11, as the first process in the negative determination route in step 301, the processor 31 is caused to execute a process of determining whether or not the control packet described above is detected by the packet monitoring unit 35. One application program may be changed. And what is necessary is just to make the processor 31 perform the notice switching process shown in FIG. 16 as a process of the affirmation determination route of the determination process mentioned above.

Regarding the above description, the following items are further disclosed.
(Appendix 1)
A first generator for generating a first data stream in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series;
A second generation unit configured to generate a second data stream synchronized with a second clock signal different from the first clock signal in which a plurality of packets are arranged in time series from the input data stream;
The first data stream and the second data stream are input, and based on packet contents having time information included in the first data stream and the second data stream, respectively, the first data stream or the time difference is obtained. And a switching unit that outputs one of the second data streams in which the time information is corrected.
(Appendix 2)
In the video distribution device according to attachment 1,
The switching unit is
A first buffer for providing a predetermined delay to the first data stream;
A second buffer for providing the predetermined delay to the second data stream;
Based on the time information included in the first data stream and the time information included in the second data stream, the difference between the time based on the first clock signal and the time based on the second clock signal is A detection unit that detects the time difference;
A correction unit configured to correct the time information included in the second data stream delayed by the second buffer based on the time difference so as to be synchronized with the time information included in the first data stream;
A changeover switch for switching between a first state in which the delayed first data stream is sent to the transmission line and a second state in which the corrected second data stream is sent to the transmission line;
When the first generation unit is operating normally, the changeover switch is set to the first state, and when a failure occurs in the first generation unit, the changeover switch is set to the second state. And a switching control unit.
(Appendix 3)
In the video distribution device according to attachment 2,
The time information of the first data stream includes a first program clock reference indicating a first count value obtained by a counting operation synchronized with a first clock signal,
The time information of the second data stream includes a second program clock reference indicating a second count value obtained by a counting operation synchronized with the second clock signal,
The detector is
The first program clock reference included in the first data stream, a first time when the first program clock reference is detected, and a second time when the second program clock reference is detected from the second data stream. Based on the estimation unit for estimating the first count value at the second time,
A difference calculation unit that calculates a difference between the estimation result obtained by the estimation unit and the second program clock reference detected from the second data stream at the second time, and outputs the calculation result as the time difference; A video distribution apparatus comprising:
(Appendix 4)
In the video distribution device according to attachment 2,
The first generation unit performs an encoding process in units of a set of pictures including a predetermined number of pictures,
The first buffer and the second buffer give a delay corresponding to a time when the predetermined number of pictures are input as the video information to the first data stream and the second data stream, respectively.
The switching control unit
When a failure is detected in the first generation unit, based on the information held in the first buffer, the first picture of the picture set in which encoding processing and packetization processing are incomplete due to the failure Has a specific part that identifies the border picture that corresponds to
At the timing when the packet of the second data stream generated corresponding to the boundary picture is passed to the changeover switch, the state of the changeover switch is sent and the delayed first data stream is sent to the transmission line. The video distribution apparatus according to claim 1, wherein the video distribution device is switched from a first state to a second state in which the corrected second data stream is sent to the transmission path.
(Appendix 5)
In the video distribution device according to attachment 4,
Among the packets included in the second data stream, a packet identifier indicating a data stream to which the packet belongs is included in a packet corresponding to a picture input before the boundary picture, and data in which the packet is invalid A first replacement unit that replaces the packet identifier included in a packet corresponding to a picture input after the boundary picture with a value indicating the first data stream, replacing the specific value indicating that it belongs to the stream; A video distribution apparatus characterized by that.
(Appendix 6)
In the video distribution device according to attachment 4,
In response to the occurrence of a failure in the first generation unit, a failure notification packet including the specific value as the packet identifier together with information indicating the occurrence of the failure is generated, and the generated failure notification packet is generated in the first data stream. Having an insertion part to be inserted,
The said specific | specification part detects the failure in a said 1st production | generation part based on the said failure notification packet. The video delivery apparatus characterized by the above-mentioned.
(Appendix 7)
In the video distribution device according to attachment 4,
While the first generation unit is operating normally, the second generation unit is made to apply an encoding process in units of individual pictures to each picture included in the data stream, and A video control unit that controls the second generation unit to apply an encoding process in units of the set of pictures when the operation of the first generation unit is stopped; Distribution device.
(Appendix 8)
In the video distribution device according to attachment 1,
Furthermore,
A video delivery apparatus comprising: a notice section that notifies the switch section of a notice of switching including information specifying a first timing for executing the switch prior to output switching by the switch section.
(Appendix 9)
In the video distribution device according to attachment 8,
The switching unit is
A first buffer for providing a predetermined delay to the first data stream;
A second buffer for providing the predetermined delay to the second data stream;
Based on the time information included in the first data stream and the time information included in the second data stream, a difference between the time based on the first clock signal and the time based on the second clock signal is calculated as the time. A detection unit that detects the difference;
A correction unit configured to correct the time information included in the second data stream delayed by the second buffer based on the time difference so as to be synchronized with the time information included in the first data stream;
A changeover switch for switching between a first state in which the delayed first data stream is sent to the transmission line and a second state in which the corrected second data stream is sent to the transmission line;
Control is performed to switch the state of the changeover switch from the first state to the second state at a second timing after the time corresponding to the predetermined delay has elapsed from the first timing specified in the change notice. A video distribution device comprising a notice control unit.
(Appendix 10)
In the video distribution device according to attachment 8,
The first generation unit performs an encoding process in units of a set of pictures including a predetermined number of pictures,
The first buffer and the second buffer give a delay corresponding to a time when the predetermined number of pictures are input as the video information to the first data stream and the second data stream, respectively.
The notice unit inserts a control packet including the number of pictures included in the set of pictures immediately before a packet corresponding to the head of the set of pictures encoded last by the first generation unit,
The video notice device, wherein the notice control unit specifies the second timing based on the number of pictures included in the control packet.
(Appendix 11)
In the video distribution device according to attachment 8,
The switching unit is
Until the second timing, the packet identifier of each packet output from the second buffer or the correction unit is replaced with the specific value, and output from the second buffer or the correction unit after the second timing. And a second replacement unit that replaces a packet identifier of each packet with a value indicating the first data stream.
(Appendix 12)
Generating a first data stream in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series;
Generating a second data stream synchronized with a second clock signal different from the first clock signal in which a plurality of packets are arranged in time series from the input data stream;
The first data stream and the second data stream are input, and based on packet contents having time information included in the first data stream and the second data stream, respectively, the first data stream or the time difference is obtained. One of the second data streams in which the time information is corrected is output based on the video distribution method.

DESCRIPTION OF SYMBOLS 10 ... Video delivery apparatus; 11 ... 1st production | generation part; 12 ... 1st clock production | generation part; 13 ... 2nd production | generation part; 14 ... 2nd clock production | generation part; 15 ... Switching part; 16 ... Insertion part; Control unit; 18 ... notice unit; 20 ... first server device; 21, 31, 43 ... processor; 22, 32 ... system time clock (STC) generation unit; 23, 33a, 33b ... transmission line interface (I / F) 34 ... Copy buffer; 35, 42 ... Packet monitoring unit; 36 ... Switch control unit; 41 ... Unit control unit; 51 ... Verification unit; 52a, 52b ... PCR detection unit; 53a, 53b ... Register; 55 ... Difference calculation unit; 56 ... Time information extraction unit; 57 ... Subtractor; 58 ... Header rewriting unit; 111, 131 ... Video encoder; 112, 132 ... Audio encoder; 113, 133 ... Multiplexer 151 ... 1st buffer; 152 ... 2nd buffer; 153 ... detection part; 154 ... correction | amendment part; 155 ... changeover switch; 156 ... switching control part; 157 ... specific | specification part; 158 ... 1st replacement part; Control unit; 160 ... second replacement unit

Claims (7)

A first generator for generating a first data stream in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series;
A second generation unit configured to generate a second data stream synchronized with a second clock signal different from the first clock signal in which a plurality of packets are arranged in time series from the input data stream;
The first data stream and the second data stream are input, and based on packet contents having time information included in the first data stream and the second data stream, respectively, the first data stream or the time difference is obtained. And a switching unit that outputs one of the second data streams in which the time information is corrected. The video distribution device according to claim 1,
The switching unit is
A first buffer for providing a predetermined delay to the first data stream;
A second buffer for providing the predetermined delay to the second data stream;
Based on the time information included in the first data stream and the time information included in the second data stream, a difference between the time based on the first clock signal and the time based on the second clock signal is calculated as the time. A detection unit that detects the difference;
A correction unit configured to correct the time information included in the second data stream delayed by the second buffer based on the time difference so as to be synchronized with the time information included in the first data stream;
A changeover switch for switching between a first state in which the delayed first data stream is sent to the transmission line and a second state in which the corrected second data stream is sent to the transmission line;
When the first generation unit is operating normally, the changeover switch is set to the first state, and when a failure occurs in the first generation unit, the changeover switch is set to the second state. And a switching control unit. The video distribution device according to claim 2,
The first generation unit performs an encoding process in units of a set of pictures including a predetermined number of pictures,
The first buffer and the second buffer give a delay corresponding to a time when the predetermined number of pictures are input as the video information to the first data stream and the second data stream, respectively.
The switching control unit
When a failure is detected in the first generation unit, based on the information held in the first buffer, the first picture of the picture set in which encoding processing and packetization processing are incomplete due to the failure Has a specific part that identifies the border picture that corresponds to
At the timing when the packet of the second data stream generated corresponding to the boundary picture is passed to the changeover switch, the state of the changeover switch is sent and the delayed first data stream is sent to the transmission line. The video distribution apparatus according to claim 1, wherein the video distribution device is switched from a first state to a second state in which the corrected second data stream is sent to the transmission path. The video distribution device according to claim 3,
The switching unit is
Among the packets included in the second data stream, a packet identifier indicating a data stream to which the packet belongs is included in a packet corresponding to a picture input before the boundary picture, and data in which the packet is invalid A first replacement unit that replaces the packet identifier included in a packet corresponding to a picture input after the boundary picture with a value indicating the first data stream, replacing the specific value indicating that it belongs to the stream; A video distribution apparatus characterized by that. The video distribution device according to claim 3,
While the first generation unit is operating normally, the second generation unit is made to apply an encoding process in units of individual pictures to each picture included in the data stream, and A video control unit that controls the second generation unit to apply an encoding process in units of the set of pictures when the operation of the first generation unit is stopped; Distribution device. The video distribution device according to claim 1,
Furthermore,
Prior to switching of output by the switching unit, a video distribution apparatus including a notification unit that notifies the switching unit of a switching notification including information specifying a first timing for executing the switching. Generating a first data stream in which a plurality of packets are arranged in time series and synchronized with a first clock signal from an input data stream including video information in which a plurality of pictures are arranged in time series;
Generating a second data stream synchronized with a second clock signal different from the first clock signal in which a plurality of packets are arranged in time series from the input data stream;
The first data stream and the second data stream are input, and based on packet contents having time information included in the first data stream and the second data stream, respectively, the first data stream or the time difference is obtained. One of the second data streams in which the time information is corrected is output based on the video distribution method.

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