JP2005269045A - Encoder unit employing a plurality of mpeg encoders and its encoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sustain continuity of STC and GOP structures in the output TS after switching when the output TS of a plurality of encoders is outputted while being switched. <P>SOLUTION: The encoder unit comprises a plurality of encoders 1-N for assigning a picture type to an input image and encoding it while reordering the picture before being outputted as TS1-TSn, a TS switch 20 for selecting one TSm from the outputs TS1-TSn, a controller 30 for distributing a GOP synchronization designating signal S2, and an STC/GOP generator 40 for distributing reference PCR data S3 and a GOP head designation signal S4. When the S2 is distributed at the picture type assignment stage, the encoders 1-N synchronize the time reference by mutual STC based on the S3 with such a GOP structure as the head position of mutual GOP is matched based on S4. The switch 20 selects one TSm at a point where the GOP head position is matched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an encoder apparatus using a plurality of MPEG (Motion Picture Expert Group) encoders and an encoding method thereof, and more particularly to a plurality of MPEGs that output a transport stream (hereinafter abbreviated as “TS”) compliant with the MPEG standard. The present invention relates to a method of synchronizing an encoder STC (System Time Clock) and a GOP (Group Of Picture) structure.

  Conventionally, a digital broadcasting system using TS employs an encoder device having a plurality of MPEG encoder devices (hereinafter abbreviated as “encoders”) and a TS switch for switching the output TS of each encoder according to the contents of the program. Things are known.

  In this encoder apparatus, each of the plurality of encoders includes a time reference based on a unique system time clock (hereinafter abbreviated as “STC (System Time Clock)”) counter of each encoder, and three types of pictures. Input based on the screen group structure (hereinafter referred to as “GOP (Group Of Picture) structure”) consisting of I picture (Intra-Pictire), P picture (Predictive-Picture), and B picture (Bidirectionally predictive-Picture) Encode the image. In this encoding, motion compensation prediction and DCT (Discrete Cosine Transform) encoding are performed, and the obtained DCT encoding coefficient is quantized, variable length encoded together with motion vector and encoding mode information, and stored in a buffer. And output as a TS composed of TS packets. The packet header of the TS packet includes a program time reference value (hereinafter abbreviated as “PCR (Program Clock Reference)”) that is transmitted based on STC.

  A TS switch is connected to the output side of each encoder. The TS switch selects and outputs one TS from the output TS from each encoder based on the switching signal supplied from the control device.

In addition, there are the following as background arts related to the present invention.
JP 2001-313936 A JP 2003-163898 A Japanese Patent Laid-Open No. 09-284771

  However, in a conventional digital broadcasting system using TS, a plurality of encoders perform encoding based on a unique STC counter and GOP structure possessed by each encoder. When one TS is selected and output from the output TS of the encoder, the output TS of the TS switcher becomes discontinuous with the PCR and GOP structures sent based on the STC across the switching point. As a result, the decoder that decodes the input image from the TS has a disadvantage that the decoded image is not switched smoothly.

  The present invention has been made in consideration of such a conventional situation, and an object of the present invention is to maintain the continuity of the STC and GOP structures in the output TS after switching when the output TS of a plurality of encoders is switched and output. And

  In order to achieve the above object, an encoder apparatus according to the present invention assigns a picture type of any one of an I picture, a P picture, and a B picture that form a GOP structure based on the MPEG standard to an input picture that forms a video, and the picture An encoder comprising a plurality of encoders that are encoded in a different order and output as a transport stream (hereinafter referred to as TS), and a TS switch that selects and outputs one TS from the TSs output from the plurality of encoders. In the apparatus, a first signal distribution unit that distributes a GOP synchronization instruction signal to the plurality of encoders, and a first signal distribution unit that distributes a standard program time reference reference value (hereinafter referred to as a standard PCR) data and a GOP head instruction signal to the plurality of encoders. 2 signal distribution means and mounted on the plurality of encoders In addition, when the GOP synchronization instruction signal is distributed in the step of assigning the picture type to the input image, synchronization of time references based on each other system time clock (hereinafter referred to as STC) based on the reference PCR data. And a synchronization means for synchronizing the GOP structure so that the GOP head positions coincide with each other based on the GOP head instruction signal, and the TS switch, and the time reference and the GOP structure are seamless. And a means for selecting one TS at a point where the GOP head positions coincide with each other from the output TSs of the plurality of encoders.

  In the encoder device according to the present invention, the synchronization means may not synchronize the GOP structure when the GOP synchronization instruction signal is canceled. Further, the second signal distribution means is configured to use the reference PCR signal and the GOP as TS data of a DVB-ASI (Digital Video Broadcast-Asynchronous Serial Interface) system or a DVB-SPI (Digital Video Broadcast-Synchronous Parallel Interface) system. The head instruction signal may be distributed to the plurality of encoders. Further, the second signal distribution means may distribute the reference PCR data and the GOP head instruction signal itself.

  The encoding method according to the present invention assigns a picture type of an I picture, a P picture, and a B picture that form a GOP structure based on the MPEG standard to an input image that constitutes a video, and changes the order of the pictures to perform encoding. In an encoding method of an encoder apparatus, comprising: a plurality of encoders that output as transport streams (hereinafter referred to as TS); and a TS switch that selects and outputs one TS from the TSs output from the plurality of encoders. A first signal distribution step of distributing a synchronization instruction signal to the plurality of encoders; and a second signal distribution of distributing a standard program time reference value (hereinafter referred to as a standard PCR) data and a GOP head instruction signal to the plurality of encoders. Step and the plurality of encoders In the step of assigning the picture type to an image, when the GOP synchronization instruction signal is distributed, the time reference is synchronized with each other based on the system PCR (STC) based on the reference PCR data, and A synchronization step for synchronizing the GOP structure so that the GOP head position coincides with each other based on the GOP head instruction signal, and the TS switching unit includes the plurality of time references and the GOP structure so that the time reference and the GOP structure can be switched seamlessly. Selecting one TS at a point at which the GOP head positions coincide with each other from the output TS of the encoder.

  In the encoding method according to the present invention, the synchronization step may not synchronize the GOP structure when the GOP synchronization instruction signal is canceled. The second signal distribution step includes the reference PCR signal and the GOP as TS data of DVB-ASI (Digital Video Broadcast-Asynchronous Serial Interface) or DVB-SPI (Digital Video Broadcast-Synchronous Parallel Interface). The head instruction signal may be distributed to the plurality of encoders. Furthermore, the second signal distribution step may distribute the reference PCR data and the GOP head instruction signal itself.

  According to the present invention, the reference PCR and GOP head instruction signal are distributed to a plurality of encoders, and the STC and GOP structure of each encoder are synchronized, so that the PCR and GOP structures in the TS after switching are discontinuous. This makes it possible to seamlessly switch TSs in the TS switcher.

  Next, the best mode for carrying out an encoder apparatus using a plurality of MPEG encoders and an encoding method thereof according to the present invention will be described in detail with reference to the drawings.

  In this embodiment, the continuity of the STC and GOP structures is maintained in the TS switch output TS by distributing the reference PCR and GOP head instruction signals to the plurality of encoders and matching the STC and GOP structures of the plurality of encoders. It is possible to be

  FIG. 1 shows the overall configuration of an encoder apparatus according to this embodiment.

  The encoder device shown in FIG. 1 includes a plurality of encoder units 10, a TS switch 20 connected to the output side of the plurality of encoder units 10, and a control device 30 connected to the input side of the plurality of encoder units 10 and the TS switch 20. And an STC (System Time Clock) / GOP (Group Of Picture) generator 40 connected to the input side of the plurality of encoder units 10.

  The multiple encoder unit 10 includes multiple encoders 1 to N. The plurality of encoders 1 to N encode the input baseband videos 1 to N, respectively, and output them as TS1 to TSn composed of TS packets.

  FIG. 2 shows an internal configuration of the plurality of encoders 1 to N. In the example of FIG. 2, the encoder 1 is illustrated, but the other encoders 2 to N are the same as this.

  The encoder 1 functionally includes a picture type assignment processing unit 11, a picture order changing processing unit 12, an encoding unit 13, and an STC counter 14.

  The picture type allocation processing unit 11 has three types of pictures that form a GOP structure in the input baseband video 1, that is, an I picture (Intra-Picture), a P picture (Predictive-Picture), and a B picture (Bidirectionally predictive-Picture). ) Is assigned. By this processing, the baseband video 1 becomes a video a having a GOP structure to which any one of I picture, P picture, and B picture is assigned.

  The picture order changing processing unit 12 performs encoding by the encoding unit 12 at the next stage, that is, encoding using B picture, using I picture or P picture which has been temporally changed, so that the picture type is assigned in the previous process. A process of changing the picture order is performed for each picture of the video a. By this processing, the video a becomes a video b in which the I or P picture that is temporally rearward of the B picture is replaced with the front side.

  The encoding unit 13 performs encoding on each picture forming the video b whose picture order has been changed by the picture order changing processing unit 12, that is, performs motion compensation prediction and DCT (Discrete Cosine Transform) encoding, and obtains the obtained DCT code. The quantization coefficient is quantized, variable-length coding is performed together with the motion vector and coding mode information, and the coded data is stored in a buffer and then output as a TS composed of TS packets.

  The STC counter 14 always generates an STC that is a time reference for circuit operation in the encoder 1 in synchronization with reference PCR (Program Clock Reference) data S3 output from the STC / GOP generator 40.

  With the above configuration, when the encoder 1 receives the GOP synchronization instruction signal S2 from the control device 40 during encoding, the encoder 1 receives the GOP head instruction signal S4 from the STC / GOP generator 40 within the period until the cancellation. Is received, at the stage of the picture type assignment processing by the picture type assignment processing unit 11, the GOP head position of the GOP structure composed of each picture of the video a to be assigned matches the operation timing of the GOP head instruction signal S4. Is assigned a picture type.

  The TS switcher 20 selects the outputs TS1 to TSn from the plurality of encoders 1 to N based on the switching instruction signal S1 from the control device 30, and outputs TSm that is one TS.

  The control device 30 generates a switching signal S1 to be given to the TS switcher 20 and a GOP synchronization instruction signal S2 to be given to the encoders 1 to N of the multiple encoder unit 10.

  The STC / GOP generator 40 is a device that superimposes and distributes the reference PCR data S3 and the GOP head instruction signal S4 on the TS, has a packet identifier (hereinafter abbreviated as “PID”) determined by the system, and has its own STC / The reference PCR data S3 generated based on the STC in the GOP generator 40 and the GOP head instruction signal S4 are generated, and the reference generated as the DVB-ASI (Digital Video Broadcast-Asynchronous Serial Interface) TS data The PCR data S3 and the GOP head instruction signal S4 are output to the encoders 1 to N of the plurality of encoder units 10.

  Next, the operation of this embodiment will be described with reference to FIGS. 3 and 4 exemplify the case of two encoders 1 and 2 as the encoders 1 to N of the plurality of encoder units 10, but the same applies to the case of three or more encoders.

  3A shows the video timing after the picture type assignment in the normal time (when GOP synchronization is not performed), and FIG. 3B shows the video timing after the picture type assignment when the GOP synchronization is performed. 4A shows the video timing after the normal picture order change (when encoding), and FIG. 3B shows the video timing after the picture order change when encoding GOP (when encoding). Each is shown.

  First, the operation of the encoders 1 and 2 at the normal time will be described.

  First, as shown in FIG. 3 (a), the encoders 1 and 2 perform I picture, P picture, and B pictures having a GOP structure on the input baseband videos 1 and 2 by the respective picture type assignment processing units 11. By assigning any picture type of picture, videos a1 and a2 having different GOP structures are output.

  That is, the video a1 after the picture type assignment of the encoder 1 is “~, B0, B1, I2, B3, B4, P5, B6, B7, P8, B9, B10, P11, B12, B13, P14 in the order of time. , B15, B16, I17, B18, B19, P20, B21, B22, etc. (I: I picture, P: P picture, B: picture, and so on), and the video a2 after the picture type assignment of the encoder 2 is , B0, I1, B2, B3, P4, B5, B6, P7, B8, B9, P10, B11, B12, P13, B14, B15, I16, B17, B18, P19, B20, B21, P22,..., And have GOP structures with different GOP head positions.

  Thereafter, as shown in FIG. 4A, the encoders 1 and 2 output the videos b1 and b2 by switching the picture order of the videos a1 and a2 by the picture order switching processing unit 12, respectively.

  That is, the video b1 after the picture order of the encoder 1 is changed is “˜, I2, B0, B1, P5, B3, B4, P8, B6, B7, P11, B9, B10, P14, B12, B13, I17, B15. , B16, P20, B18, B19, P23, B21, and so on, and the video b2 after changing the picture order of the encoder 2 is “˜B-1, B0, P4, B2, B3, P7, B5, B6, P10”. , B8, B9, P13, B11, B12, I16, B14, B15, P19, B17, B18, P22, B20, B21,.

  Next, the operation of encoders 1 and 2 when performing GOP synchronization will be described.

  First, as shown in FIG. 3B, when the encoders 1 and 2 receive the GOP synchronization instruction signal S2 from the control device 30 during encoding, the picture type assignment processing unit performs the period until the cancellation is performed. When the reference PCR data S3 and the GOP head instruction signal, that is, two GOP head instruction signals S4 and S4 in the example in the figure, are received from the STC / GOP generator 40 at the stage of the picture type assignment process, Using the synchronized STC as a reference, the positions (operation timing positions) of the GOP head instruction signals S4 and S4 are set to GOP head positions P1 and P2 of the GOP structure, and a new GOP is started from the GOP head positions P1 and P2. By assigning picture types, videos a3 and a4 having a GOP structure in which the GOP head positions P1 and P2 coincide with each other can be obtained. Forces.

  That is, the video a3 after the picture type assignment of the encoder 1 is “~, B0, B1, I2, B3, B4, I5 (GOP head position P1), B6, B7, P8, B9, B10, P11 in the order of time. , B12, B13, P14, B15, B16, P17, B18, B19, I20 (GOP head position P2), B21, B22,..., And the video a4 after assigning the picture type of the encoder 2 is “ B0, I1, B2, B3, P4, I5 (GOP head position P1), B6, B7, P8, B9, B10, P11, B12, B13, P14, B15, B16, P17, B18, P19, I20 ( GOP head positions P2), B21, B22, and so on, and within the period in which the GOP synchronization is instructed, the GOP head positions P1 and P2 And a match GOP structure.

  Thereafter, as shown in FIG. 4B, the encoders 1 and 2 output the videos b1 and b2 by switching the picture order of the videos a3 and a4 by the picture order switching processing unit 12, respectively.

  That is, the video b3 after changing the picture order of the encoder 1 is “˜, I2, B0, B1, I5, B3, B4, P8, B6, B7, P11, B9, B10, P14, B12, B13, P17, B15. , B16, I20 (GOP head coincidence point P3), B18, B19, P23, B21, and so on, and the video b4 after changing the picture order of the encoder 2 is “˜B-1, B0, P4, B2, B3, I5, P8, B6, B7, P11, B9, B10, P14, B12, B13, P17, B15, B16, I20 (GOP head coincidence point P3), B18, B19, P23, B21, and so on, and the GOP head position At the coincidence point P3 (operation timing), the GOP head positions of the encoders 1 and 2, that is, I20 coincide with each other.

  This makes it possible to create a switching point P4 after the GOP (between I20 and the previous picture). Therefore, at this switching point P4, the switching signal S1 is output from the TS switch 20, and the encoders 1, 2 are output. By switching the outputs TS1 and TS2, the TS switch 20 outputs one output TS in which the STC and GOP structures are seamlessly connected before and after the switching of the outputs TS1 and TS2, that is, TSm.

  Thereafter, after the GOP synchronization instruction signal S2 from the control device 30 is released, the encoders 1 and 2 return to the normal operation and operate with different GOP structures.

  Therefore, according to the present embodiment, the reference PCR data and the GOP head instruction signal are distributed to the plurality of encoders 1 to N, and the TS after switching is synchronized by synchronizing the STC and GOP structure of each encoder 1 to N. It is possible to avoid a situation in which the PCR and GOP structures inside become discontinuous, thereby enabling the TS to be switched seamlessly in the TS switcher.

  As another embodiment of the present invention, private data in the TS can be allocated to the GOP head instruction signal S4. As the STC / GOP generator 20, an encoder capable of DVB-ASI output or a compression multiplexing device can be used. Further, in FIG. 1, the TS is distributed from the STC / GOP generator 20 to the encoders 1 to N by the DVB-ASI method, but the TS is distributed from the STC / GOP generator 20 to the DVB-SPI (Digital Video Broadcast-Synchronous). It is also possible to distribute to the encoders 1 to N by the Parallel Interface method. Also, it is possible to distribute the reference PCR data and the GOP head instruction signal itself instead of the TS.

It is a schematic block diagram which shows the whole structure of the encoder apparatus based on the Example of this invention. It is a schematic block diagram which shows the internal structure of a some encoder. It is a figure which shows the video timing after picture type allocation. It is a figure which shows the video timing after a picture order change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Multiple encoder part 11 Picture type allocation process part 12 Picture order change process part 13 Encoding part 14 STC counter 20 TS switch 30 Controller 40 STC / GOP generator S1 Switching instruction signal S2 GOP synchronization instruction signal S3 Reference PCR data S4 GOP head instruction signal

Claims (8)

A transport stream (hereinafter referred to as TS) is encoded by assigning any picture type of an I picture, P picture, and B picture having a GOP structure based on the MPEG standard to an input picture that forms a video, and changing the picture order. Multiple encoders that output as
An encoder device comprising a TS switch for selecting and outputting one TS from TS output from the plurality of encoders;
First signal distribution means for distributing a GOP synchronization instruction signal to the plurality of encoders;
Second signal distribution means for distributing reference program time reference value (hereinafter referred to as reference PCR) data and GOP head instruction signal to the plurality of encoders;
When the GOP synchronization instruction signal is distributed in the step of assigning the picture type to the input image and mounted in the plurality of encoders, a mutual system time clock (hereinafter referred to as a system time clock) based on the reference PCR data. , STC) and a synchronization means for synchronizing the GOP structure so as to synchronize the GOP head positions with each other based on the GOP head instruction signal.
Means for selecting one TS at the point where the GOP head positions coincide with each other from the output TSs of the plurality of encoders so as to be seamlessly switched between the time base and the GOP structure; An encoder device comprising:   The encoder apparatus according to claim 1, wherein the synchronization means does not synchronize the GOP structure when the GOP synchronization instruction signal is canceled.   The second signal distribution means includes the reference PCR signal and the GOP head indication as TSB data of DVB-ASI (Digital Video Broadcast-Asynchronous Serial Interface) or DVB-SPI (Digital Video Broadcast-Synchronous Parallel Interface). 3. The encoder device according to claim 1, wherein a signal is distributed to the plurality of encoders.   The encoder apparatus according to claim 1 or 2, wherein the second signal distribution unit distributes the reference PCR data and the GOP head instruction signal itself. A transport stream (hereinafter referred to as TS) is encoded by assigning any picture type of an I picture, P picture, and B picture having a GOP structure based on the MPEG standard to an input picture that forms a video, and changing the picture order. Multiple encoders that output as
In an encoding method of an encoder device comprising a TS switch for selecting and outputting one TS from TS output from the plurality of encoders,
A first signal distribution step of distributing a GOP synchronization instruction signal to the plurality of encoders;
A second signal distribution step of distributing reference program time reference reference value (hereinafter referred to as reference PCR) data and GOP head instruction signal to the plurality of encoders;
When the plurality of encoders assigns the picture type to the input image and the GOP synchronization instruction signal is distributed, a mutual system time clock (hereinafter referred to as STC) is based on the reference PCR data. A synchronization step of synchronizing the GOP structure so as to synchronize the time base according to GOP and to match the GOP head position with each other based on the GOP head instruction signal;
The TS switcher has a step of selecting one TS at a point where the GOP head positions coincide with each other from the output TSs of the plurality of encoders so that the time reference and the GOP structure are switched seamlessly. Characteristic encoding method.   6. The encoding method according to claim 5, wherein the synchronization step does not synchronize the GOP structure when the GOP synchronization instruction signal is released.   In the second signal distribution step, the reference PCR signal and the GOP head instruction are provided as TS data of DVB-ASI (Digital Video Broadcast-Asynchronous Serial Interface) or DVB-SPI (Digital Video Broadcast-Synchronous Parallel Interface). 7. The encoding method according to claim 5, wherein a signal is distributed to the plurality of encoders.   7. The encoding method according to claim 5, wherein the second signal distribution step distributes the reference PCR data and the GOP head instruction signal itself.

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