CN100428798C - A digital TV decoding method and system - Google Patents

Abstract

A digital TV decoding method and system related to digital TV technology, comprising the following steps: a) extracting time information, frame header information and data information from a transport stream, b) generating a corresponding local program clock reference according to the time information , c) By comparing the data information with the frame header information, the local program clock reference or the audio speed is adjusted to control the reading of audio and video data. The system includes a demultiplexing module, an audio decoder, a video decoder, a display The module and the data memory are characterized in that: it also includes a synchronous control module, the synchronous control module generates a corresponding local program clock reference according to the time information, and the information interaction between the synchronous control module and the audio decoder controls the decoding of the audio, and is connected with the video decoding Information interaction between the device and the display module, and video display control, the present invention provides a variety of synchronous control modes, good synchronous control performance, strong practicability, and high reliability.

Description

A digital TV decoding method and system

technical field

The invention relates to digital TV technology, in particular to a digital TV decoding method and system.

Background technique

During the audio and video playback process of digital set-top boxes, the audio and video may not be played synchronously due to code stream errors and other reasons, which affects the viewing effect. Therefore, special processing is required to control the audio or video playback speed to achieve the ideal playback effect. As the system controller in a certain HDTV video decoder in the prior art, as shown in Figure 1, it includes a front unpacking unit 1, an audio-video synchronization circuit 2, an input buffer 3, an input buffer controller 4, and a table memory 5. Data splitter 6, rear unpacking unit 7 and display control circuit 8, etc., the front unpacking unit 1 receives PES data input, extracts the video frame header information related to the control of the system controller, and sends the information to The table memory 5 is temporarily stored, and the front unpacking unit 1 also generates the first frame readout signal and sends it to the input buffer controller 4; the front unpacking unit 1 sends the elementary stream data to the input buffer 3; Extract the necessary decoding parameters of the core decoder from the video data output by the device 3, and generate a fast read signal to the input buffer controller 4: the input buffer 3 receives the basic data from the front unpacking unit 1 under the control of the input buffer controller 4 stream data, and output the video data to the data splitter 6; the table memory 5 stores the relevant information of the corresponding frame in the input buffer 3, provides the necessary control information to the input buffer controller 4, and sends the information of the current display frame to Audio-video synchronous circuit 2 and display control circuit 8; Audio-video synchronous circuit 2 judges the situation of decoding end audio/video synchronism according to the PTS value of audio current playback frame and the PTS value of video current display frame, and provides to input buffer controller 4 The audio frequency lead/video lead signal indicates that it completes the adjustment of the audio/video synchronization; the display control circuit 8 realizes the video display buffer according to the type of the frame to be displayed in the table memory 5 and the overflow/underflow situation of the input buffer 3 Control to complete the reordering of the video sequence; the data splitter 6 receives the video data from the input buffer 3, and sends the video data to the core decoder after splitting. Its control mode is single and its application is not flexible enough.

Contents of the invention

The purpose of the present invention is to provide a digital TV decoding method and system to enhance the synchronization control stability of digital TV.

The digital television decoding method adopted in the present invention comprises the following steps:

A. Extract time information, frame header information and data information from the transport stream TS;

B. Generate a local program clock reference PCR according to the time information;

C. By comparing the data information with the frame header information, adjust the local program clock reference PCR or audio decoding speed to control the reading of audio and video data.

In this technical scheme:

In the step C, a calibration signal is generated when the comparison result between the data information and the frame header information is consistent, and the local program clock reference PCR or the de-audio speed is adjusted according to the trigger of the calibration signal.

Described step B comprises the following steps:

Initialize the demultiplexed program clock reference PCR;

Load it into the local counter to establish the local program clock reference PCR.

In the step A, the time information extracted from the transport stream TS includes the program clock reference PCR, the audio decoding time tag DTS and the video playback time tag PTS, and the frame header information includes the audio frame header pointer and the video frame header pointer , the data information includes elementary stream ES.

Described step C comprises the steps:

C1. According to the comparison result of the ES stream pointer and the audio frame header pointer, adjust the local program clock reference PCR or the audio solution speed;

C2, according to the comparison result of ES stream pointer and video frame head pointer, establish the corresponding relation of decoded video data and playback time label PTS;

C3. At the end of field blanking, adjust the local program clock reference PCR or control the read address signal operation according to the difference between the video playback time tag PTS and the local program clock reference PCR.

Described step C1 comprises the following steps:

C1A, when the audio decoder reads the read pointer of the ES stream equal to the audio frame header pointer, a first calibration signal is generated;

C1B. According to the triggering of the first calibration signal, the absolute value D0 of the difference between the audio decoding time stamp DTS and the local program clock reference PCR is compared with the first fixed threshold T1, and the following operations are performed:

C1B1, if the absolute value D0 is greater than the threshold T1, load the audio decoding time stamp DTS into the local program clock reference PCR;

C1B2. Otherwise, do not perform any operation.

Described step C1 comprises the following steps:

C1a, when the audio decoder reads the read pointer of the ES stream equal to the audio frame header pointer, a first calibration signal is generated;

C1b. According to the triggering of the first calibration signal, compare the absolute value D0 of the difference between the audio decoding time stamp DTS and the local program clock reference PCR with the first fixed threshold T1, and perform the following operations:

C1b1, if the absolute value D0 is greater than the threshold T1, speed up or slow down the audio decoding speed according to the size relationship between the audio decoding time tag DTS and the local program clock reference PCR;

C1b2. Otherwise, do nothing.

Described step C2 comprises the following steps:

C21, when the video decoder reads the read pointer of the ES stream and is equal to the video frame header pointer, a second calibration signal is generated;

C22. According to the triggering of the second calibration signal, perform the following operations:

C221, if the decoded video data has a video playback time tag PTS, then generate a "yes" sign, and record the video playback time tag PTS;

C222. Otherwise, generate a "none" flag.

Described step C3 comprises the following steps:

C3A, at the end of blanking, compare the absolute value P0 of the difference between the video playback time tag PTS and the local program clock reference PCR with the second fixed threshold T2, and perform the following operations:

C3A1. If the absolute value P0 is greater than the threshold T2, control the read address signal operation to repeatedly display or skip a frame of images.

C3A2. Otherwise, display images sequentially.

Described step C3 comprises the following steps:

C3a, at the end of blanking, compare the absolute value P0 of the difference between the video playback time tag PTS and the local program clock reference PCR with the second fixed threshold T2, and perform the following operations:

C3a1. If the absolute value P0 is greater than the threshold T2, load the video playback time tag PTS into the local program clock reference PCR;

C3a2. Otherwise, do not perform any operation.

The digital TV decoding system adopted by the present invention includes a demultiplexing module, an audio decoder, a video decoder and a data storage, and the data storage is used for buffering audio and video data information, and also includes a synchronization control module, wherein,

The demultiplexing module analyzes the transport stream TS, extracts time information, frame header information and data information, and sends the data information to the data memory;

The audio decoder receives the frame header information, compares the data information and the audio frame header pointer in the frame header information, and sends the comparison result to the synchronization control module;

The video decoder receives the frame header information, compares the data information and the video frame header pointer in the frame header information, and sends the comparison result to the synchronization control module;

The synchronization control module receives the time information, generates a local program clock reference PCR, receives the comparison result, adjusts the local program clock reference PCR or the audio decoding speed, and controls the reading of audio and video data.

In this technical scheme, among them,

The time information extracted by the demultiplexing module includes program clock reference PCR, audio decoding time tag DTS and video playback time tag PTS, and is sent to the synchronization control module; the frame header information extracted includes audio frame header pointer and the video frame header pointer are sent to the audio decoder and the video decoder respectively; the extracted data information is the elementary stream ES, which is sent to the data memory for storage.

The audio decoder reads the ES read pointer and the audio frame head pointer to generate a first calibration signal and sends it to the synchronization control module, and the synchronization control module performs a local program clock reference PCR or solution according to the triggering of the first calibration signal. Audio speed is adjusted.

The video decoder reads the read pointer of the ES and the video frame head pointer to generate a second calibration signal and sends it to the synchronization control module, and the synchronization control module establishes the decoded video data and the playback time tag according to the trigger of the second calibration signal The corresponding relation of PTS adjusts the local program clock reference PCR or controls the read address signal operation of the display module according to the difference between the play time tag PTS and the local program clock reference PCR.

The beneficial effect of the present invention is: in the present invention, extract time, frame header information and data information from transport stream TS, generate corresponding local program clock benchmark PCR according to time information, compare data information and frame header information, to The local program clock reference PCR or audio speed is adjusted to control the reading of audio and video data. Specifically, the present invention uses the local program clock reference PCR as a bridge, and can adopt three reference control modes: audio-based mode, based on Video-based mode and program clock reference-based mode, the present invention provides a variety of synchronous control modes, which overcomes the shortcomings of single control mode and inflexible application in the prior art, and enhances the synchronous control performance. The clock reference PCR is used as a bridge, which enables flexible control of the system and improves the performance of application expansion. For example, it is easier to implement synchronization of subtitles.

The present invention adopts audio/video frame header address pointer to establish the link between playback time tag PTS or decoding time tag DTS and frame data (ES stream), which can ensure that playback time tag PTS or decoding time tag DTS is synchronized with frame data (ES stream), Enhanced the synchronization stability of the system. The present invention establishes a corresponding relationship by using the playback time tag PTS and the frame header address pointer. For example, for the decoded video data with the video playback time tag PTS, a "yes" flag is generated, and the video playback time tag PTS is recorded; otherwise, "no" is generated. "flag, which increases the connection between the playback time tag PTS and the address pointer of the packet data, which can solve the synchronization problem when the playback time tag PTS or the decoding time tag DTS is lost, for example, when the data error or other reasons cause the playback time tag PTS After the corresponding relationship with the data is wrong, the present invention can automatically restore the synchronization state, which further improves the practicability and reliability of the present invention.

Description of drawings

Fig. 1 is a schematic structural diagram of a prior art system;

Fig. 2 is a schematic structural diagram of a digital television decoding system of the present invention;

Fig. 3 is a schematic diagram of the basic control flow of the digital television decoding method of the present invention;

4 is a schematic flow chart of the first embodiment of the digital television decoding method of the present invention;

Fig. 5 is a schematic flow chart of the second embodiment of the digital television decoding method of the present invention;

FIG. 6 is a schematic flowchart of a third embodiment of a digital TV decoding method according to the present invention.

Detailed ways

Below according to accompanying drawing and embodiment the present invention will be described in further detail:

According to Fig. 2, the digital television decoding system among the present invention comprises demultiplexing module 10, audio frequency decoder 20, video decoder 30, data memory 40, display module 50 and synchronous control module 60, digital television decoding system in practical application Commonly used is a set-top box.

As shown in Figure 2, the demultiplexing module 10 analyzes the transport stream TS, extracts time information, frame header information and data information, and the extracted information is as follows:

Time information: program clock reference PCR, audio decoding time tag DTS and video playback time tag PTS.

Frame header information: audio frame header pointer and video frame header pointer.

Data information: elementary stream ES.

As shown in Figure 2, wherein the time information is sent to the synchronous control module 60; The audio frame header pointer and the video frame header pointer in the frame header information are sent to the audio decoder 20 and the video decoder 30 respectively; the data information is sent to the data memory 40 to save.

As shown in FIG. 2 , the audio decoder 20 reads data from the data memory 40 , parses the audio stream, and generates audio data; the video decoder 30 reads data from the data memory 40 , parses the video stream, generates video data and sends it. The display module 50 is used for displaying the video data sent by the video decoder, and the data memory 40 is used for buffering audio and video data, and buffering the data information elementary stream ES.

As shown in Figure 2, the synchronization control module 60 generates the corresponding local program clock reference PCR according to the time information, and the information interaction between the synchronization control module 60 and the audio decoder 20 controls the decoding of the audio, and communicates with the video decoder 30 and the display module Information exchange among 50, control the display of video, wherein generate calibration signal when the comparison result of data information and frame header information is consistent, synchronous control module 60 adjusts local program clock reference PCR or solution audio speed according to the triggering of calibration signal, specifically Specifically, the audio decoder 20 generates the first calibration signal according to the ES stream pointer and the audio frame header pointer and sends it to the synchronization control module 60, and the synchronization control module 60 performs the local program clock reference PCR or decodes the audio frequency according to the trigger of the first calibration signal. speed to adjust. The video decoder 30 generates a second calibration signal according to the ES stream pointer and the video frame header pointer and sends it to the synchronization control module 60, and the synchronization control module 60 establishes the correspondence between the decoded video data and the playback time label PTS according to the trigger of the second calibration signal According to the difference between the playing time tag RTS and the local program clock reference PCR, adjust the local program clock reference PCR or control the read address signal operation of the display module 50 .

As shown in Figure 2 and Figure 3, the basic control flow of the present invention is as follows:

a) The demultiplexing module 10 extracts time, frame header information and data information from the transport stream TS.

b) The synchronization control module 60 generates a corresponding local program clock reference PCR according to the time information.

c) By comparing the data information with the frame header information, the synchronization control module 60 adjusts the local program clock reference PCR or the de-audio speed.

d) By comparing the data information with the frame header information, the synchronization control module 60 establishes the corresponding relationship between the decoded video data and the playback time tag PTS.

e) At the end of field blanking, the synchronization control module 60 adjusts the local program clock reference PCR or controls the read address signal operation of the display module 50 according to the difference between the video playback time tag PTS and the local program clock reference PCR.

Can realize like this by the comparison of data information and frame header information: synchronous control module 60 compares data information and frame header information in rounds, when synchronous control module 60 compares the read pointer that reads ES flow and is equal to audio/video frame header pointer equal, At the same time, adjustments are made to the subsequent signal. A preferred implementation is: when the read pointer of the ES stream is equal to the audio/video frame header pointer, a calibration signal is generated and sent to the synchronization control module 60, and the subsequent signal is adjusted according to the trigger of the calibration signal.

The present invention adopts audio/video frame header address pointer to establish the link between playback time tag PTS or decoding time tag DTS and frame data (ES stream), which can ensure that playback time tag PTS or decoding time tag DTS is synchronized with frame data (ES stream), Enhanced the synchronization stability of the system.

As shown in Fig. 2 and Fig. 4, the specific control flow of the first (main mode with audio frequency) of the digital television decoding method of the present invention is as follows:

1. The demultiplexing module 10 extracts time, frame header information and data information from the transport stream TS, specifically, the time information includes the program clock reference PCR, the audio decoding time tag DTS and the video playback time tag PTS; the frame header information includes audio Frame header pointer and video frame header pointer; data information is elementary stream ES (ie, ES stream). The demultiplexing module 10 sends time information, frame header information, and data information to the synchronization control module 60, the audio decoder 20, the video decoder 30, and the data memory 40, respectively.

2. The synchronization control module 60 initializes the demultiplexed program clock reference PCR.

3. The synchronization control module 60 loads it into the local 27M counter to establish the local program clock reference PCR.

4. The audio decoder 20 reads the ES stream in the data memory 40, and when the read pointer of the ES stream is equal to the audio frame header pointer, generates a first calibration signal and sends it to the synchronization control module 60.

5. The synchronization control module 60 receives the first calibration signal, and the first calibration signal is used as a trigger pulse to trigger and compare the absolute value D0 of the difference between the audio decoding time tag DTS and the local program clock reference PCR and the first fixed threshold T1, and perform the following operations:

51. If the absolute value D0 is greater than the threshold T1, load the audio decoding time stamp DTS into the local program clock reference PCR, and proceed to step 6 as follows.

52. Otherwise, do not perform any operation and continue to step 6 below.

6. The video decoder 30 reads the ES stream, and when the read pointer is equal to the video frame header pointer, generates a second calibration signal and sends it to the synchronization control module 60 .

7. The synchronization control module 60 receives the second calibration signal, and the second calibration signal is used as a trigger pulse to trigger the following operations:

71. If the decoded video data has a video playback time tag PTS, generate a "yes" flag, and record the video playback time tag PTS, and proceed to step 8 below.

72. Otherwise, generate a "none" flag and proceed to step 8 below.

8. The display module 50 sends an end signal to the synchronous control module 60 at the end of field blanking, and the synchronous control module 60 compares the absolute value P0 of the difference between the video playback time tag PTS and the local program clock reference PCR with the second fixed threshold T2, and performs Do as follows:

81. If the absolute value P0 is greater than the threshold T2, control the display module 50 to read the address signal to make the display module 50 repeatedly display or skip a frame of images.

82. Otherwise, no special operation is performed, and the display module 50 displays images sequentially.

This embodiment establishes a corresponding relationship by using the playback time tag PTS and the frame header address pointer. For example, for the decoded video data with the video playback time tag PTS, a "yes" flag is generated, and the video playback time tag PTS is recorded; otherwise, a "" is generated. "None" mark, increase the connection between the playback time tag PTS and the address pointer of the packet data, which can solve the synchronization problem when the playback time tag PTS or decoding time tag DTS is lost, for example, when the data error or other reasons cause the playback time tag After the corresponding relationship between PTS and data is wrong, this embodiment can automatically restore the synchronization state, which further improves the practicability and reliability of the present invention.

As shown in Fig. 2 and Fig. 5, the specific control flow of the second (based on video mode) of the digital television decoding method of the present invention is as follows:

1) The demultiplexing module 10 extracts time, frame header information and data information from the transport stream TS, specifically, the time information includes the program clock reference PCR, the audio decoding time tag DTS and the video playback time tag PTS; the frame header information includes audio Frame header pointer and video frame header pointer; data information is elementary stream ES (ie, ES stream). The demultiplexing module 10 sends time information, frame header information, and data information to the synchronization control module 60, the audio decoder 20, the video decoder 30, and the data memory 40, respectively.

2) The synchronization control module 60 initializes the demultiplexed program clock reference PCR.

3) The synchronization control module 60 loads it into the local 27M counter to establish the local program clock reference PCR.

4) The audio decoder 20 reads the ES stream in the data memory 40, and when the read pointer of the ES stream is equal to the audio frame header pointer, generates a first calibration signal and sends it to the synchronization control module 60.

5) The synchronization control module 60 receives the first calibration signal, and the first calibration signal is used as a trigger pulse to trigger and compare the absolute value D0 of the difference between the audio decoding time stamp DTS and the local program clock reference PCR and the first fixed threshold T1, and perform the following operations :

51) If the absolute value D0 is greater than the threshold T1, speed up or slow down the audio decoding speed according to the size relationship between the audio decoding time tag DTS and the local program clock reference PCR, that is, when DTS>PCR, slow down the audio decoding speed, and when DTS<PCR , speed up the audio solution, and continue to the following step 6).

52) Otherwise, do not perform any operation, and continue to the following step 6).

6) The video decoder 30 reads the ES stream, and when the read pointer is equal to the video frame header pointer, generates a second calibration signal and sends it to the synchronization control module 60 .

7) The synchronization control module 60 receives the second calibration signal, and the second calibration signal is used as a trigger pulse to trigger the following operations:

71) If the decoded video data has a video playback time tag PTS, then generate a "yes" flag, and record the video playback time tag PTS, continue to the following step 8).

72) Otherwise, generate a "none" flag and proceed to step 8) below.

8) The display module 50 sends an end signal to the synchronous control module 60 at the end of field blanking, and the synchronous control module 60 compares the absolute value P0 of the difference between the video playback time tag PTS and the local program clock reference PCR with the second fixed threshold T2, and performs Do as follows:

81) If the absolute value P0 is greater than the threshold T2, load the video playback time tag PTS into the local program clock reference PCR.

82) Otherwise, do nothing.

As shown in Fig. 2 and Fig. 6, the third (based on the program clock reference mode) specific control flow of the digital television decoding method of the present invention is as follows:

I. The demultiplexing module 10 extracts time, frame header information and data information from the transport stream TS, specifically, the time information includes the program clock reference PCR, the audio decoding time tag DTS and the video playback time tag PTS; the frame header information includes audio Frame header pointer and video frame header pointer; data information is elementary stream ES (ie, ES stream). The demultiplexing module 10 sends time information, frame header information, and data information to the synchronization control module 60, the audio decoder 20, the video decoder 30, and the data memory 40, respectively.

II. The synchronization control module 60 initializes the demultiplexed program clock reference PCR.

III. The synchronization control module 60 loads it into the local 27M counter to establish the local program clock reference PCR.

IV. The audio decoder 20 reads the ES stream in the data memory 40 , and when the read pointer of the ES stream is equal to the audio frame header pointer, generates a first calibration signal and sends it to the synchronization control module 60 .

V. The synchronization control module 60 receives the first calibration signal, and the first calibration signal is used as a trigger pulse to trigger and compare the absolute value D0 of the difference between the audio decoding time tag DTS and the local program clock reference PCR and the first fixed threshold T1, and perform the following operations :

V1. If the absolute value D0 is greater than the threshold T1, speed up or slow down the audio decoding speed according to the size relationship between the audio decoding time tag DTS and the local program clock reference PCR, and continue with the following step VI.

V2. Otherwise, do not perform any operation and continue to the following step VI.

VI. The video decoder 30 reads the ES stream, and when the read pointer is equal to the video frame header pointer, generates a second calibration signal and sends it to the synchronization control module 60 .

VII. The synchronous control module 60 receives the second calibration signal, and the second calibration signal is used as a trigger pulse to trigger the following operations:

VII1. If the decoded video data has a video playback time tag PTS, then generate a "yes" flag, and record the video playback time tag PTS, continue to the following step VIII.

VII2. Otherwise, generate a "none" flag and proceed to step VIII below.

VIII. The display module 50 sends an end signal to the synchronous control module 60 at the end of field blanking, and the synchronous control module 60 compares the absolute value P0 of the difference between the video playback time tag PTS and the local program clock reference PCR with the second fixed threshold T2, and performs Do as follows:

VIII1. If the absolute value P0 is greater than the threshold T2, control the display module 50 to read the address signal, so that the display module 50 repeatedly displays or skips a frame of images.

VIII2. Otherwise, no special operation is performed, and the display module 50 displays images sequentially.

Through the above control process, the present invention extracts time, frame header information and data information from the transport stream TS, generates the corresponding local program clock reference PCR according to the time information therein, and compares the local program clock by comparing the data information with the frame header information. Baseline PCR or solution audio speed is adjusted to control audio and video data reading. Specifically, the present invention takes the local program clock reference PCR as a bridge, and can adopt three reference control modes: audio-based mode, video-based mode, and program clock reference-based mode. The present invention provides a variety of synchronous The control mode overcomes the shortcomings of single control mode and inflexible application in the prior art, and uses the local program clock reference PCR as a bridge to make the system flexible control and improve the application expansion performance. Subtitle synchronization, etc.

Claims (14)

1. digital TV decoding method, it is characterized in that: it comprises the steps:

A, from transport stream TS extracting time information, frame head information and data message;

B, according to described time information generating local program clock reference PCR;

C, by to the comparison of described data message and described frame head information, to local program clock reference PCR or separate audio speed adjustment, the reading of control audio and video data.

2. digital TV decoding method according to claim 1, it is characterized in that: among the described step C, produce calibrating signal when data message is consistent with the comparative result of frame head information, according to the triggering of calibrating signal to local program clock reference PCR or separate audio speed adjustment.

3. digital TV decoding method according to claim 1 is characterized in that: described step B comprises the steps:

Timer reference of programs PCR initialization to demultiplexing;

It is loaded into the timer reference of programs PCR that sets up this locality in the local counter.

4. digital TV decoding method according to claim 1, it is characterized in that: in the described steps A, comprise timer reference of programs PCR, audio decoder time tag DTS and video playback time tag PTS by the temporal information of extracting in the transport stream TS, described frame head information comprises audio frame head pointer and video frame header pointer, and described data message comprises basic stream ES.

5. digital TV decoding method according to claim 4 is characterized in that: described step C comprises the steps:

C1, according to the comparative result of ES flow index and audio frame head pointer, to local program clock reference PCR or separate audio speed adjustment;

C2, according to the comparative result of ES flow index and video frame header pointer, set up the corresponding relation of decode video data and reproduction time label PTS;

C3, in field blanking finish time, according to the difference of video playback time tag PTS and local program clock reference PCR, local program clock reference PCR adjusted or controls read the address signal operation.

6. digital TV decoding method according to claim 5 is characterized in that: described step C1 comprises the steps:

C1A, when the read pointer that reads ES stream when audio decoder equals the audio frame head pointer, produce first calibrating signal;

C1B, according to the triggering of described first calibrating signal, with the absolute value D0 of the difference of audio decoder time tag DTS and local program clock reference PCR and the first fixed threshold T1 relatively, carry out following operation:

C1B1, if absolute value D0 greater than this threshold value T1, is loaded into the Decoding Time Stamp DTS of audio frequency among the local program clock reference PCR;

C1B2 otherwise, do not carry out any operation.

7. digital TV decoding method according to claim 5 is characterized in that: described step C1 comprises the steps:

C1a, when the read pointer that reads ES stream when audio decoder equals the audio frame head pointer, produce first calibrating signal;

C1b, according to the triggering of described first calibrating signal, with the absolute value D0 of the difference of audio decoder time tag DTS and local program clock reference PCR and the first fixed threshold T1 relatively, carry out following operation:

C1b1, if absolute value D0 greater than this threshold value T1, according to the quickening of the magnitude relationship of audio decoder time tag DTS and local program clock reference PCR or slow down and separate audio speed;

C1b2 otherwise, do not carry out any operation.

8. digital TV decoding method according to claim 5 is characterized in that: described step C2 comprises the steps:

C21, when the read pointer that reads ES stream when Video Decoder equals the video frame header pointer, produce second calibrating signal;

C22, according to the triggering of described second calibrating signal, carry out following operation:

C221, if decode video data has video playback time tag PTS, then produce " having " sign, and write down this video playback time tag PTS;

C222 otherwise, produce " nothings " and indicate.

9. digital TV decoding method according to claim 5 is characterized in that: described step C3 comprises the steps:

C3A, in field blanking finish time, with the absolute value P0 of the difference of video playback time tag PTS and local program clock reference PCR and the second fixed threshold T2 relatively, carry out following operation:

C3A1, if absolute value P0 greater than this threshold value T2, address signal operation is read in control, repeats to show or skip a two field picture;

C3A2 otherwise, the order display image.

10. digital TV decoding method according to claim 5 is characterized in that: described step C3 comprises the steps:

C3a, in field blanking finish time, with the absolute value P0 of the difference of video playback time tag PTS and local program clock reference PCR and the second fixed threshold T2 relatively, carry out following operation:

C3a1, if absolute value P0 greater than this threshold value T2, video playback time tag PTS is loaded among the local program clock reference PCR;

C3a2 otherwise, do not carry out any operation.

11. a digital TV decoding system comprises demultiplexing module, audio decoder, Video Decoder and data storage, described data storage is used for buffer memory sound, video data information, it is characterized in that: also comprise synchronization control module, wherein,

Described demultiplexing module analyzing atransmission stream TS, extracting time information, frame head information and data message, described data message sends to described data storage;

Described audio decoder receives described frame head information, and the audio frame head pointer in comparing data information and the frame head information sends to described synchronization control module with comparative result;

Described Video Decoder receives described frame head information, and the video frame header pointer in comparing data information and the frame head information sends to described synchronization control module with comparative result;

Described synchronization control module receives described temporal information, produces local program clock reference PCR, receives described comparative result, and to local program clock reference PCR or separate audio speed adjustment, control audio and video data read.

12. digital TV decoding according to claim 11 system, it is characterized in that: the described temporal information that described demultiplexing module is extracted comprises timer reference of programs PCR, audio decoder time tag DTS and video playback time tag PTS, and is sent to synchronization control module; The described frame head information of extracting comprises audio frame head pointer and video frame header pointer, is sent to audio decoder and Video Decoder respectively; The described data message that extracts is basic stream ES, is sent to data storage and preserves.

13. according to claim 11 or 12 described digital TV decoding systems, it is characterized in that: read pointer and audio frame head pointer that described audio decoder reads ES produce first calibrating signal and send it to synchronization control module, synchronization control module according to the triggering of described first calibrating signal to local program clock reference PCR or separate audio speed adjustment.

14. according to claim 11 or 12 described digital TV decoding systems, it is characterized in that: read pointer and video frame header pointer that described Video Decoder reads ES produce second calibrating signal and send it to synchronization control module, synchronization control module is set up the corresponding relation of decode video data and reproduction time label PTS according to the triggering of described second calibrating signal, according to reproduction time label PTS and local program clock reference PCR difference, local program clock reference PCR is adjusted or controls the address signal of reading of display module and operate.

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