JP2006254298A - Device and method for moving picture reproduction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when display intervals of video data dynamically vary, reproduction quality decreases although output processing and decoding processing for the video data are performed in fixed cycles since the image data to be outputted and a PTS became discrepant before as an STC becomes discontinuous owing to PCR in a transport stream. <P>SOLUTION: An STC/PTS comparator 502 calculates the difference between the PTS and STC. When the difference is less than a certain threshold, it is judged that the STC is not discontinuous, so that the STC/PTS comparator 502 makes an output control indication in the timing where the STC and PTS match each other. When the difference is larger than the certain threshold, it is judged that the STC is discontinuous and the difference between two successive frames that a display interval calculator 504 calculates, i.e. a display interval is calculated to make an output control indication, based upon the display interval. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention provides a moving picture playback apparatus and moving picture playback suitable for playing back video and audio synchronously when playing back an MPEG2-TS stream sent by digital BS broadcasting, digital CS broadcasting, or terrestrial digital broadcasting. The present invention relates to a method, and particularly relates to a countermeasure in video reproduction when the MPEG2-TS stream or PCR continuity is interrupted.

  Japanese digital broadcasting is based on ARIB (Association of Radio Industrial and Businesses) standards. This ARIB standard was created on the basis of the European DVB (Digital Video Broadcasting) standard, and broadcasts video and audio on a MPEG (Moving Picture Coding Experts Group) 2-TS (Transport Stream) system. To do.

  In MPEG2-TS, a plurality of 188-byte fixed-length TS packets are collected to form a TS stream. The length of the 188-byte TS packet is determined in consideration of consistency with the ATM (Asynchronous Transfer Mode) cell length.

  The TS packet includes a 4-byte fixed-length packet header, a variable-length adaptation field, and a payload. In the packet header, PID (packet identifier) and various flags are defined. The type of TS packet is identified by this PID.

  A PES (Packetized Elementary Stream) packet containing individual streams such as video and audio is divided into a plurality of TS packets having the same PID number and transmitted. For encoding video, for example, MPEG4-AVC / H. The H.264 system is used. For example, AAC (MPEG2 Advanced Audio Coding) is used for audio encoding.

  Also, the PES packet in which data such as captions is stored is divided into a plurality of TS packets and transmitted, like the video and audio packets.

  In such MPEG2-TS, a PCR (Program Clock Reference) is sent every predetermined time in order to set the time of STC (System Time Clock).

  That is, some TS packets include an adaptation field. The adaptation field is used to transmit additional information related to the individual stream. Here, a 6-byte PCR is arranged in the optional field.

  On the receiver side, an STC (System Time Clock) that is a system clock is counted by an STC counter. The time of this STC counter is calibrated based on the PCR time.

  In MPEG2-TS, in order to achieve AV (audio / video) synchronization, a time stamp is added to each access unit (for example, for each picture in the case of video and for each audio frame in the case of audio). These access units are converted to PES, and a PTS (Presentation Time Stamp) for specifying a reproduction time is added to the header of the PES packet.

  The time of this PTS is described by the value of STC. On the receiver side, the STC value is advanced in synchronization with the PCR from the transmitting side. The STC count value and the PTS value are compared, and if the STC count value and the PTS value match, display processing and decoding processing are started. Thereby, synchronous reproduction with STC is performed.

  As described above, in MPEG2-TS, the STC count value advanced in synchronization with the PCR is compared with the PTS value added and transmitted to the video and audio PES packets. AV synchronized playback is realized by starting display processing and decoding processing at the timing when the count value of PTS matches the value of PTS.

  There is no problem when the TS is continuously transmitted when the encoded side and the multiplexed TS are transmitted from the transmission side, and this is decoded and reproduced on the reception side. When PCR is discontinuous, TS packet discontinuity detection or PCR discontinuity detection is performed. When the detection is detected, the STC value is calibrated, and thereafter, processing is performed using the calibrated STC. It corresponded by doing.

  However, if display or decoding is started immediately using the calibrated STC, that is, if it is immediately used as the STC of the decoder, among the data temporarily stored in the buffer, the data that should use the STC before calibration, and the STC after calibration When data that should be used are mixed, the PTS and STC of the data that should use the STC before calibration are greatly different. If the PTS and STC differ greatly, the PTS value does not match the STC counter value even if time passes, and the buffer overflows and playback stops.

  In order to deal with these problems, Patent Document 1 monitors the capacity of a buffer for storing PES packets, and when an overflow is detected, reproduction is performed asynchronously with AV. Here, AV asynchronous reproduction is a method in which audio data is subjected to output processing and decoding start processing in one audio frame cycle, and video data is subjected to output processing and decoding start processing in a predetermined fixed cycle. That is, when a buffer overflow is detected, PTS and STC are compared, output processing and decoding start processing are stopped at the same timing, and decoding processing and output processing are performed in each period of video and audio. . As a result, it is possible to avoid a situation in which although AV synchronization cannot be achieved, there is no buffer overflow and reproduction becomes impossible.

In addition, as a transition condition to AV asynchronous mode, STC and PTS are compared, and when the absolute value of the difference exceeds a predetermined threshold value, playback is performed in AV asynchronous mode (Patent Document 2). is there.
JP 2003-101962 A JP 2002-204404 A

  Since the AV asynchronous mode reproduction when discontinuity occurs or when PCR is discontinuous as shown in the above prior art is output continuously in a frame period in the case of audio data, STC and PTS are There is no sense of incompatibility even if they are not matched. Also, in the case of video data, when the video image display interval is fixed as in the existing digital broadcasting (BS digital broadcasting or terrestrial digital broadcasting), the video image is displayed at a fixed period during AV asynchronous mode playback. Decoding processing and display processing may be performed in accordance with the interval.

  However, in the case of video data intended for use in a mobile environment, such as 1-segment digital broadcasting that is currently scheduled to be broadcast, the display interval is dynamically changed on the transmission side in order to suppress the transfer bit rate. May change. When the display interval changes dynamically as described above, if the output process and the decode process are performed at a predetermined fixed period as in the AV asynchronous playback mode, a result of a large synchronization shift with the audio data occurs. Since the lip sync cannot be taken, the playback quality is severely degraded.

  The present invention has been made in view of such a problem, and when the TS packet in the MPEG2-TS stream is discontinuous or the PCR is discontinuous, the video data display interval dynamically changes. An object of the present invention is to provide a moving image reproducing apparatus and a moving image reproducing method that eliminates synchronization loss and realizes reproduction in accordance with the intention on the transmission side even in a difficult situation.

  The moving image reproducing apparatus of the present invention receives transmission data obtained by multiplexing video data, audio data, and time information, and the time information includes a system reference time and a reproduction time, and the reproduction time and the In a video playback device that compares the system reference time with the system reference time and plays back when the system reference time matches the playback time, the difference value between the system reference time and the playback time is calculated, and whether or not the difference value is below a certain threshold value The frame display time is calculated from the comparator that outputs the playback instruction when the difference value becomes 0, and the difference between the playback time of the previously output frame and the playback time of the next output frame, and the display time A display interval calculator that outputs a reproduction instruction when the time elapses, and when the difference value is equal to or smaller than a threshold value, reproduction is performed according to the reproduction instruction of the comparator, If the threshold value or more in the difference value is characterized in that for reproducing based on the display instruction of the display interval calculator.

  The moving image reproduction method of the present invention includes a comparison step of calculating a difference value between a system reference time and a reproduction time, determining whether the difference value is equal to or less than a certain threshold value, and outputting a reproduction instruction when the difference value becomes zero; A display interval calculation step of calculating a display time of the frame from a difference between a playback time of the frame output last time and a playback time of the frame to be output next time, and outputting a playback instruction when the display time elapses. If the difference value is equal to or greater than a certain threshold value, reproduction is performed based on the display instruction of the display interval calculation step. It is what.

  According to the moving image reproducing apparatus and the moving image reproducing method of the present invention, even when STC discontinuity occurs and the display interval of video data changes dynamically, the display is continued while accurately maintaining the display interval. Can do.

  The moving picture reproducing apparatus of the present invention calculates the difference between the program reference time and the system reference time in the transmission data, and calibrates the system reference time when the difference value is equal to or smaller than a certain threshold, The system reference time is not calibrated, and the STC calibration control unit compares the reproduction time with the system reference time or an addition value between the system reference time and the difference value, and the addition And a synchronization control unit that outputs a calibration instruction for the system reference time when the value approximates the reproduction time.

  The moving image reproduction method of the present invention calculates the difference between the program reference time and the system reference time in the transmission data, and calibrates the system reference time when the difference value is equal to or smaller than a certain threshold value. The STC calibration control step that does not calibrate the system reference time, the system reference time, or the addition value of the system reference time and the difference value, and the reproduction time are compared, and the addition value becomes the reproduction time. The approximation includes a synchronization control step of outputting a calibration instruction for the system reference time.

  According to the moving image reproducing apparatus and the moving image reproducing method of the present invention, when STC discontinuity occurs, by controlling STC calibration, the STC count value to be originally referred to can be obtained, and STC synchronization control can be performed.

  The moving image playback apparatus of the present invention acquires a playback time of a frame in transmission data, calculates a playback time difference value between frames, and holds the difference value when the difference value is greater than a threshold value. When the difference between the calculation time and the reproduction time and the system reference time is equal to or less than a threshold value, the reproduction instruction is output when the difference value becomes zero, and the difference value is equal to or greater than the threshold value, A synchronization control unit that subtracts a difference value of time information between frames from a system reference time and compares the reproduction times, and outputs a reproduction instruction when the difference value becomes zero. .

  The moving image reproduction method of the present invention acquires a reproduction time of a frame in transmission data, calculates a difference value of reproduction times between frames, and retains the difference value when the difference value is larger than a certain threshold value. Calculating step, determining whether a difference value between the reproduction time and the system reference time is equal to or less than a threshold value, outputting a reproduction instruction when the difference value becomes 0, and if the difference value is equal to or greater than a certain threshold value, A synchronization control step of subtracting a difference value of time information between the frames from a system reference time to compare the reproduction times, and outputting a reproduction instruction when the difference value becomes zero.

  According to the moving image reproducing apparatus and moving image reproducing method of the present invention, when STC discontinuity occurs, the STC count value is subtracted from the STC count value and referenced to obtain the STC count value that should be referred to. Can be seamlessly reproduced without any disturbance.

  According to the present invention, the display interval of video data is dynamically changed when STC discontinuity occurs by calculating an image display interval and instructing output control based on the display interval. Even in this case, the display can be continued while accurately keeping the display interval, and the reproduction quality is improved.

  Further, by performing calibration of the STC count value and performing synchronization control, seamless reproduction can be performed with no image disturbance in the reproduction state.

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

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram showing a configuration of a moving image playback apparatus according to the first embodiment.

  In FIG. 1, an MPEG2-TS stream is supplied to an input terminal 100. The MPEG2-TS stream from the input terminal 100 is supplied to the demultiplexer 101, and the demultiplexer 101 separates a desired video PES packet and audio PES packet.

  The video PES packet separated by the demultiplexer 101 is supplied to the video buffer 103. Further, the audio PES packet separated by the demultiplexer 101 is supplied to the audio buffer 110.

  Further, the demultiplexer 101 extracts the PCR value in the adaptation field of the TS packet at every predetermined timing.

  Here, the data structure of the MPEG2-TS stream will be described with reference to FIG. In FIG. 2, reference numeral 200 denotes an MPEG2-TS stream. The MPEG2-TS stream 200 is composed of a plurality of TS packets 203 having a fixed length of 188 bytes. The MPEG2-TS packet 203 includes a header 204 and a payload 205.

  The header 204 includes a sync word 206 indicating the head of the MPEG2-TS packet 203, a PID 207 which is a data identifier in the MPEG2-TS packet 203, an adaptation field control 208 indicating whether the payload 205 is valid, an adaptation field 209, It consists of other control flags and the like (not shown).

  The PCR is added to the adaptation field 209 of the MPEG2-TS packet 203, and the PID number for PCR acquired from within the PMT (program map table) is added to the PID 207.

  PCR is added to the MPEG2-TS stream every predetermined time. The demultiplexer 101 acquires the PID 207, and extracts the PCR from the adaptation field 209 when it matches the PID number indicating that the PCR is added. The extracted PCR is supplied to the STC counter 102.

  The MPEG2-TS supplied to the input terminal 100 is formed, for example, by demodulating a reception signal of terrestrial digital broadcasting, BS digital broadcasting, or CS digital broadcasting. In addition, a recording / reproducing apparatus that directly records and reproduces an MPEG2-TS stream on a magnetic tape or HDD (Hard Disk Drive) is known. The input terminal 100 may be supplied with a TS stream reproduced from such a recording / reproducing apparatus.

  The STC counter 102 operates as a synchronization reference counter. For example, a 42-bit counter. The STC counter 102 counts, for example, in steps of 27 MHz, with the PCR value sent every predetermined time as an initial value. The output of the STC counter 102 is supplied to the video synchronization control unit 109 and the audio synchronization control unit 116.

  The video PES packet separated by the demultiplexer 101 is temporarily stored in the video buffer 103. The video PES packet stored in the video buffer 103 is supplied to the video decoder 104 when the frame buffer 105 has enough free space for one frame, that is, when a decoded image is output from the video output control unit 106.

  The video decoder 104 extracts the PTS that is the reproduction time information from the PES header in the video PES packet and the video encoded data from the PES packet data.

  Here, the data structure of the PES packet will be described with reference to FIG. The PES packet 300 includes a packet start code prefix 303 indicating the head of the PES packet, a stream ID 304 for identifying a stream included in the PES packet data 307, a PES packet length 305 indicating the length of the PES packet, and a PES header. 306 and PES packet data 307 in which stream data is stored.

  Further, the PES header 306 includes an option field 308 and other control flags (not shown). In this option field 308, PTS 309 which is reproduction time information of the stream included in the PES packet data 307 is stored.

  The video decoder 104 extracts the video data in the PES packet data 307 and the PTS 309 in the option field 308 of the PES header 306. The extracted PES packet data is, for example, MPEG4-AVC / H. H.264 or MPEG4 image decoding processing is performed and stored in the frame buffer 105 as image data. The extracted PTS is stored in the video PTS information storage unit 108.

  The video PTS information accumulation unit 108 performs accumulation while associating the PTS acquired from the video decoder 104 with the image data stored in the frame buffer 105. The accumulated PTS is deleted when the image data is output. Further, the PTS of the image data to be output next time is output to the video synchronization control unit 109.

  The video synchronization control unit 109 compares the STC and the PTS, and issues an output control instruction to the video output control unit 106 when the image output condition is satisfied. Receiving the output control instruction, the video output control unit 106 acquires the image data from the frame buffer 105 and outputs it to the monitor 107.

  The image output conditions will be described in detail later.

  On the other hand, the audio PES packet separated by the demultiplexer 101 is temporarily stored in the audio buffer 110. The audio PES packet stored in the audio buffer 110 is supplied to the audio decoder 111 when the PCM buffer 112 has a free space for one frame, that is, when the decoded PCM data is output from the audio output control 113.

  In the audio decoder 111, first, PTS which is reproduction time information from the PES header in the audio PES packet and audio encoded data from the PES packet data are acquired. The extracted PES packet data is subjected to a decoding process such as an AAC method and is stored in the PCM buffer 112 as PCM data. The extracted PTS is stored in the audio PTS information storage unit 115.

  The audio PTS information accumulation unit 115 accumulates the PTS acquired from the audio decoder 111 and the PCM data stored in the PCM buffer 112 in association with each other. The accumulated PTS is deleted when the PCM data is output. Further, the PTS of PCM data to be output next time is output to the audio synchronization control unit 116.

  The audio synchronization control unit 116 compares STC and PTS, and performs output control on the audio output control unit 113 when the output condition is satisfied. Upon receiving the output instruction, the audio output control unit 113 acquires PCM data from the PCM buffer 112 and outputs the PCM data to the speaker 114.

  Note that the PTS extracted here is different for video and audio.

  Next, STC synchronization control of the video unit in the first embodiment will be described in detail with reference to FIGS. 4, 5, and 6.

  FIG. 5 shows the configuration of the video synchronization control unit 109 in FIG. Note that this is different from the configuration (not shown) of the audio synchronization control unit 116.

  In FIG. 5, the video synchronization control unit 109 includes an STC / PTS comparator 502 that outputs an output control instruction based on an STC / PTS comparison process and a comparison result, a delay unit 503 that holds the PTS of the previously displayed frame, The PTS of the display frame and the PTS of the previously displayed frame are compared to calculate the display interval, the display interval calculator 504 that outputs the calculation result, and the calculation result from the display interval calculator 504 is the initial value, and the same clock as the PTS From the counter 506 which performs a decrement in a cycle and issues a display control instruction at the timing when the count value becomes 0, and from the display control instruction and the counter 506 from the STC / PTS comparator 502 based on the comparison result of the STC and PTS. And a selector 505 for selecting a display control instruction.

In the STC / PTS comparison process in the STC / PTS comparator 502, the absolute value of the difference value between the PTS and STC, that is,
｜ PTS-STC ｜
And the difference value is smaller than a certain threshold (Threshold), that is,
| PTS-STC | <Threshold
Determine whether or not.

  When the above inequality sign is correct, the selector 505 performs switching control so that the output control instruction of the STC / PTS comparator 502 is selected. Further, the STC count value is acquired again, and the PTS comparison is repeated until the difference value becomes zero. An output control instruction is output when the difference value becomes zero.

  When the inequality sign is incorrect, that is, larger than the threshold value, the selector 505 performs switching control so that the output control instruction from the counter 506 is selected.

  Next, the operation of the video synchronization control unit 109 will be described separately for a normal operation and a case where discontinuity occurs in the STC.

  The PTS of the frame to be displayed next time is input from the input terminal 500, and the current STC count value is input from the input terminal 501. However, it is assumed that the STC count value is converted to the same unit as PTS, for example, 90 kHz unit when input.

  In normal operation, that is, when the MPEG2-TS stream is continuous or the PCR is continuous, as shown in FIG. 4A, the STC changes continuously, and the PTS also changes following the STC. .

  First, the STC / PTS comparator 502 calculates the difference value | PTS−STC | between the count value of STC and the PTS. If the difference value is smaller than a certain threshold value | PTS−STC | <Threshold, the STC count value is repeatedly acquired and compared with the PTS until the STC and the PTS match, that is, until the difference value becomes 0, and the difference value At the timing when becomes 0, a display control instruction is output to the selector 505. At this time, since | PTS−STC | <Threshold is satisfied, the selector 505 selects the output control instruction of the STC / PTS comparator 502. That is, the B side is selected.

  Thereby, video output control of STC synchronous control becomes possible.

When the MPEG2-TS stream is discontinuous or the PCR is discontinuous, the STC has a discontinuous state on the way as shown in FIG. 4B when the PCR is updated. However, since the PTS follows the STC with a slight delay, a section where the PTS and the STC are largely separated, an AB section (PTS is delayed with respect to the STC in FIG. 4B) occurs. In this AB section, the difference value | PTS−STC | calculated by the STC / PTS comparator 502 is larger than the threshold, ie,
｜ PTS-STC ｜ ＞ Threshold
It is determined that control is impossible, and the selector 505 is switched to the output control instruction of the counter 506. That is, the A side is selected.

On the other hand, the display interval calculator 504 displays a difference value between the PTS of the frame output last time and the PTS output next time,
| PTS (n) -PTS (n-1) |
That is, the display time of the previously output frame is calculated, and the result is output to the counter 506. The counter 506 decrements this display time as an initial value in the same clock cycle as that of the PTS, and outputs the next frame at the timing when it becomes 0, that is, when the display period of the image being output last time is completed. Give instructions. Thereby, even when STC and PTS are not synchronized, frames can be output at an appropriate display interval.

  In the next frame after the AB period, PTS (b + 1) in FIG. 4B, the PTS starts to follow the STC, so the difference value | PTS−STC | becomes smaller than the threshold. As a result, the selector 505 is switched to the STC / PTS comparator 502 on the B side, and the output control instruction from the STC / PTS comparator 502 is performed again. That is, image output is performed in synchronization with the STC.

  A processing sequence of STC synchronization control of the video unit will be described with reference to a flowchart of FIG.

  First, in step 601, the PTS of the frame to be output next time is acquired from the video PTS information storage unit. In step 602, the current STC count value is acquired. The difference value between PTS and STC acquired in step 603 is calculated. In step 604, it is determined whether or not the difference value is greater than a certain threshold value (Threshold).

  If the difference value is smaller than Threshold, the process proceeds to step 605 and the selector 505 is set to select the output of the PTS / STC comparator 502. In step 606, the current STC count value is obtained again, and in step 607, the difference value between the PTS and the STC is calculated. If the difference value is greater than 0, the process returns to step 606. If the difference value becomes 0, the PTS and STC match, and an output control instruction is issued to the video output control unit 106 (step 608).

  If the difference value is larger than Threshold in step 604, the process proceeds to step 609, where the difference between the saved PTS of the previously output frame and the PTS of the frame to be displayed next time, PTS (n) −PTS (n− 1) is calculated and the display interval is calculated. In step 610, the calculated display interval is set in the counter as an initial value. In step 611, the counter decrements the count value by one. In step 612, it is determined whether or not the counter is 0. If not, the process returns to step 611. When the counter reaches 0, a display instruction is given at step 613.

  Finally, when the display instruction is completed, the PTS of the current frame for which the display instruction has been issued in step 614 is stored for the next display interval calculation. After the storage is completed, the process returns to step 601 again to perform processing for displaying the next frame.

  The display is continued by repeating the above.

  According to the moving image playback device and the moving image playback method configured as described above, when the MPEG2-TS stream is discontinuous or when the STC discontinuity occurs due to the discontinuous PCR, the video data display interval is changed. Display can be continued while accurately keeping the display interval even when the display changes, and the reproduction quality is improved.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS.

  FIG. 7 is a diagram showing a configuration of a moving image playback apparatus according to the second embodiment. FIG. 7 includes a PCR-STC calibration control unit 717 and a video synchronization control unit 709 that outputs an STC calibration instruction in the configuration of the moving picture reproduction apparatus of the first embodiment shown in FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The STC counter 102 operating as a synchronization reference counter calibrates the STC count value based on the PCR value sent every predetermined time. If the sent PCR is discontinuous, the STC referred to by the video synchronization control unit 709 becomes discontinuous, and STC synchronization control becomes impossible.

  Therefore, by providing the PCR-STC calibration control unit 717 and the video synchronization control unit 709 that control the timing of STC calibration, STC synchronization control can be performed even when the PCR is discontinuous.

  Next, the PCR-STC calibration control unit 717 and the video synchronization control unit 709 will be described.

The PCR-STC calibration control unit 717 outputs the absolute value of the difference value between the PCR output from the demultiplexer 101 and the current STC, that is,
| PCR-STC |
Calculate and hold

  Further, when STC count value calibration instruction control is performed from the video synchronization control unit 709 to the PCR-STC calibration control unit 717, the STC count value is calibrated.

  The video synchronization control unit 709 determines the difference value | STC-PTS | between the STC and the PTS, and the value STC + | PCR-STC | obtained by adding the STC to the PCR-STC difference information | STC + | PCR-STC | -PTS | is compared, and if the image output condition is satisfied, output instruction control is performed on the video output control unit 106.

The operation of the PCR-STC calibration control unit 717 will be described. The absolute value of the difference value between the PCR extracted by the demultiplexer 101 and the current STC count value, ie,
| PCR-STC |
And the difference value is below a certain threshold (Threshold), that is,
｜ PCR-STC ｜ ≦ Threshold
Determine whether or not.

  If the above inequality sign is correct, the STC count value is calibrated to the PCR value.

  When the inequality sign is incorrect, that is, when it is larger than the threshold, the STC is not calibrated.

  The operation of the video synchronization control unit 709 will be described.

The difference between STC and PTS is calculated, PTS-STC difference value | PTS-STC | is extracted, and the difference between the difference value and the value obtained by adding PCR-STC difference value | PCR-STC | to STC and PTS Compare the value | STC + | PCR-STC | -PTS |
| PTS-STC | ≦ | STC + | PCR-STC | -PTS |
In this case, the control waits until the STC and the PTS match, that is, 0, and instructs the video output control unit 106 to output control.

on the other hand,
| PTS-STC |> | STC + | PCR-STC | -PTS |
Is established, the calibration instruction control for setting the value of STC + | PCR-STC | to the count value of STC is performed on the PCR-STC calibration control unit 717. After the calibration of the STC, it waits until the STC and the PTS match, and issues an output instruction to the video output control unit 106.

  Next, processing sequences of the PCR-STC calibration control unit 717 and the video synchronization control unit 709 in FIG. 7 will be described with reference to FIGS. 8, 9, and 10.

  FIG. 8 is a flowchart of STC calibration control in the PCR-STC calibration control unit 717.

  In FIG. 8, first, in step 801, the current STC count value is acquired.

  By subtracting the PCR supplied from the demultiplexer 701 and the STC acquired in step 801, the absolute value | PCR-STC | of the PCR-STC difference value is set in step 802.

  In step 803, it is determined whether the absolute value | PCR-STC | of the set PCR-STC difference value is equal to or greater than a predetermined threshold value. If it is less than the predetermined threshold value, the STC is calibrated to the PCR value in step 804, the PCR-STC difference value | PCR-STC | is cleared in step 805, and the process ends. If it is greater than or equal to the predetermined threshold value in step 803, the PCR-STC difference value | PCR-STC | is cleared in step 805 without calibrating the PCR value to STC, and the process ends.

  FIG. 9 is a flowchart of STC calibration instruction control in the PCR-STC calibration control unit 717.

  In FIG. 9, first, in step 901, the current STC count value is acquired. Next, in step 902, the absolute value | PCR-STC | of the PCR-STC difference value is added to the STC count value, and in step 903, the STC count value is calibrated.

  FIG. 10 is a flowchart showing processing in the video synchronization control unit 709.

  In FIG. 10, first, in step 1001, a PTS of a frame to be displayed next is acquired. In step 1002, the current STC counter value is acquired. In step 1003, the absolute value | PCR-STC | of the PCR-STC difference value acquired by the PCR-STC calibration control unit 717 is referred to. Further, the absolute value | PCR-STC | of the PCR-STC difference value is added to the STC count value acquired in Step 1002. The absolute value | PCR-STC | of the PCR-STC difference value here is a value extracted by the PCR-STC calibration control unit 717.

  In step 1004, the absolute value | PTS-STC | of the PTS-STC difference value is compared with the value obtained by subtracting the PTS from the value obtained by adding the absolute value | PCR-STC | of the PCR-STC difference value to the STC.

The result of the comparison in step 1004 is
| PTS-STC | ≦ STC + | PCR-STC | -PTS
In this case, the current STC is acquired again in step 1005, and the process waits until the difference value becomes 0 in step 1006. If the difference value becomes 0, since it matches, an output instruction is given to the video output control unit 106 in step 1007.

The result of the comparison in step 1004 is
| PTS-STC |> STC + | PCR-STC | -PTS
In this case, an STC calibration instruction is issued to the PCR-STC calibration control unit 717 in step 1008. After STC calibration, the steps after step 1005 are performed.

  The display is continued by repeating the above.

  According to the moving image playback apparatus and the moving image playback method configured as described above, even when the MPEG2-TS stream is discontinuous or the STC discontinuity due to the PCR is discontinuous, the STC calibration is controlled, so that the original reference is made. STC count value to be obtained, and STC synchronization control can be performed.

(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIGS.

  FIG. 11 is a diagram showing a configuration of a moving image playback apparatus according to the third embodiment. FIG. 11 includes a PTS offset calculation unit 1117 in the configuration of the moving image playback apparatus of the first embodiment shown in FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The PTS offset calculation unit 1117 watches the PTS of the video data sent from the demultiplexer 101 to the video buffer 103, detects a change point, and calculates the PTS offset.

FIG. 12 shows the relationship between the PTS values indicating the time when video data is reproduced, with the horizontal axis indicating elapsed time and the vertical axis indicating PTS. The PTS offset calculation unit 1117 watches the value of the PTS 309 (FIG. 3), and the absolute value of the difference value between the PTS in the current frame and the PTS in the previous frame, that is,
| PTS (r) −PTS (r−1) | (where r is the current frame number)
And the difference value is greater than a certain threshold (Threshold1), ie
| PTS (r) -PTS (r-1) |> Threshold1
If this is the case, the change point.
Here, the holding means of the PTS is realized using a delay device. In FIG. 12, point A is the change point. The absolute value of the difference between the PTS of the current frame and the PTS of the previous frame at the change point A, that is,
| PTS (r) -PTS (r-1) |
Is a PTS offset.

The video synchronization control unit 109 calculates the absolute value of the difference value between STC and PTS, that is,
｜ PTS-STC ｜
And the difference value is less than a certain threshold (Threshold2), ie
| PTS-STC | <Threshold2
Determine whether or not. Here, the threshold Threshold1 and the threshold Threshold2 are the same.

  If the inequality sign is correct, the STC count value is acquired and the PTS comparison is repeated until the difference value becomes zero. A display control instruction is output at the timing when the difference value becomes zero.

When the inequality sign is incorrect, that is, larger than the threshold, the PTS offset is obtained from the STC count value and the PTS offset calculation unit 1117, and the STC count value is the absolute value of the difference value of the PTS offset, that is,
｜ STC count value−PTS offset |
And the comparison between this value and PTS is repeated until it becomes zero. A display control instruction is output at the timing when the difference value becomes zero.

  A processing sequence of STC synchronization control of the video unit will be described with reference to a flowchart of FIG.

  First, in step 1301, the PTS sent from the demultiplexer 101 to the video buffer 103 is watched to detect a change point, and the absolute value of the difference value between the PTS in the current frame and the PTS in the previous frame, PTS offset | PTS ( r) -PTS (r-1) | In step 1302, the current STC count value is acquired. The difference value between the PTS and STC acquired in step 1303 is calculated. In step 1304, it is determined whether or not the difference value is greater than a threshold value (Threshold).

  If the difference value is smaller than Threshold, the process proceeds to step 1305 to obtain the current STC count value, and in step 1306, the difference value between the PTS and the STC is calculated. If the difference value is greater than 0, the process returns to step 1305. If the difference value becomes 0, the PTS and STC match, and an output control instruction is issued to the video output control unit 106 (step 1307).

  If the difference value is larger than Threshold in step 1304, the process proceeds to step 1308, where the PTS offset calculated by the PTS offset calculation unit is acquired, and the STC count value is calculated as the difference value between the PTS offset and the PTS (step 1309). . If the difference value is larger than 0 in step 1310, the process returns to step 1309. If the difference value becomes 0, the PTS and STC match, and an output control instruction is issued to the video output control unit 106 (step 1307).

  According to the moving image reproducing apparatus and moving image reproducing method configured as described above, when the MPEG2-TS stream is discontinuous or the STC discontinuity occurs due to the PCR discontinuity, the PTS offset is subtracted from the STC count value. Thus, the STC count value that should be originally referred to is obtained, and seamless reproduction can be performed without image distortion in the reproduction state.

  The moving image reproducing apparatus and the moving image reproducing method according to the present invention are useful when reproducing an MPEG2-TS stream transmitted by digital BS broadcasting, digital CS broadcasting, or terrestrial digital broadcasting.

1 is a block diagram showing a configuration of a video playback device according to Embodiment 1 of the present invention. Data structure diagram of MPEG2-TS stream according to Embodiment 1 of the present invention Data structure diagram of PES packet according to Embodiment 1 of the present invention Relationship diagram between PTS and STC according to Embodiment 1 of the present invention The block diagram which shows the structure of the video synchronization control part which concerns on Embodiment 1 of this invention. The flowchart in the synchronous control which concerns on Embodiment 1 of this invention FIG. 3 is a block diagram showing a configuration of a video playback device according to Embodiment 2 of the present invention. Flowchart in STC calibration control according to Embodiment 2 of the present invention Flowchart in STC calibration instruction control according to Embodiment 2 of the present invention The flowchart in the synchronous control which concerns on Embodiment 2 of this invention FIG. 3 is a block diagram showing a configuration of a video playback device according to Embodiment 3 of the present invention. PTS and time relationship diagram according to Embodiment 3 of the present invention The flowchart in the synchronous control which concerns on Embodiment 3 of this invention

Explanation of symbols

100, 500, 501 Input terminal 101 Demultiplexer 102 STC
103 video buffer 104 video decoder 105 frame buffer 106 video output control unit 107 monitor 108 video PTS information storage unit 109, 709 video synchronization control unit 110 audio buffer 111 audio decoder 112 PCM buffer 113 audio output control unit 114 speaker 115 audio PTS information storage Unit 116 audio synchronization control unit 502 STC / PTS comparator 503 delay unit 504 display interval calculator 505 selector 506 counter 717 PCR-STC calibration control unit 1117 PTS offset calculation unit

Claims (6)

Input transmission data in which video data and audio data and time information are multiplexed, the time information includes a system reference time and a reproduction time, and compares the reproduction time with the system reference time, In the video playback device that plays back when the system reference time matches the playback time,
A comparator that calculates a difference value between the system reference time and the reproduction time, determines whether the difference value is equal to or less than a threshold value, and outputs a reproduction instruction when the difference value becomes 0;
A display interval calculator that calculates the display time of the frame from the difference between the playback time of the frame that was output last time and the playback time of the frame that is output next time, and that outputs a playback instruction when the display time has elapsed,
If the difference value is less than or equal to a threshold value, playback is performed according to the playback instruction of the comparator. If the difference value is greater than or equal to a threshold value, playback is performed based on the display instruction of the display interval calculator. A moving image reproducing apparatus for performing the operation. The difference between the program reference time and the system reference time in the transmission data is calculated, and when the difference value is less than or equal to a threshold value, the system reference time is calibrated, and when the difference value is greater than a certain threshold value, the system reference time is calibrated. An STC calibration control unit characterized by not performing
The system reference time or an addition value between the system reference time and the difference value is compared with the reproduction time, and if the addition value approximates the reproduction time, a synchronization instruction for outputting a calibration instruction for the system reference time is output. A moving image reproducing apparatus comprising: a control unit. Obtaining a reproduction time of a frame in transmission data, calculating a difference value of the reproduction time between frames, and when the difference value is larger than a certain threshold, a reproduction time offset calculating unit that holds the difference value;
It is determined whether or not the difference value between the reproduction time and the system reference time is equal to or less than a certain threshold value. If the difference value becomes 0, a reproduction instruction is output, and if the difference value is equal to or greater than a certain threshold value, A moving picture reproducing apparatus comprising: a synchronization control unit that subtracts a difference value of time information between frames and compares the reproduction times, and outputs a reproduction instruction when the difference value becomes zero. A comparison step of calculating a difference value between the system reference time and the reproduction time, determining whether the difference value is a certain threshold value or less, and outputting a reproduction instruction when the difference value becomes 0;
A display interval calculation step of calculating the display time of the frame from the difference between the playback time of the frame output last time and the playback time of the frame to be output next time, and outputting a playback instruction when the display time has elapsed,
If the difference value is less than or equal to a threshold value, playback is performed according to the playback instruction of the comparison step. If the difference value is greater than or equal to a threshold value, playback is performed based on the display instruction of the display interval calculation step. A method for reproducing a moving image characterized by comprising: The difference between the program reference time and the system reference time in the transmission data is calculated, and when the difference value is less than or equal to a threshold value, the system reference time is calibrated, and when the difference value is greater than a certain threshold value, the system reference time is calibrated. STC calibration control step not performing
Synchronous control that compares a system reference time or an addition value between the system reference time and the difference value with a reproduction time, and outputs a calibration instruction for the system reference time when the addition value approximates the reproduction time A method for reproducing a moving image. Obtaining a reproduction time of a frame in transmission data, calculating a difference value of the reproduction time between frames, and when the difference value is larger than a certain threshold value, a reproduction time offset calculating step of holding the difference value;
It is determined whether or not the difference value between the reproduction time and the system reference time is equal to or less than a certain threshold value. If the difference value becomes 0, a reproduction instruction is output, and if the difference value is equal to or greater than a certain threshold value, And a synchronization control step of subtracting a difference value of time information between the frames to compare the reproduction times and outputting a reproduction instruction when the difference value becomes zero.

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