The Realization Of Audio/video Synchronization For Mpeg-2

After 20th century, the technology in both digital television and multimedia communication has been fast moving forward. As a result, this has greatly improved people's efficiency in their work, lightened the burden of the public transportation and changed their education and entertainment mode.The digital processing and transmission of audio and video is the key of digital television and multimedia communication. ISO and IEC have established a series of international standards for sound and image compressing and coding. Among them, MPEG-2, which can effectively encode a wide range of video and audio signals, has been extensively used in cable digital TV, digital TV broadcast for satellite, and so on. Audio/video synchronization is the most difficult part of the real-time decoding in the framework of MPEG-2. The traditional way to achieve audio/video synchronize is to retrieve STC from the transport stream, which is the same as that used in the coding process. And then achieve synchronization by comparing the audio/video time stamp, PTS and DTS, with STC.On the basis of the analysis of MPEG-2, this paper designed a new audio/video synchronization algorithm without retrieving STC. With audio as the master media stream whose playing rate is unchanged, video as the attached media stream, the algorithm used the time stamp of media units which have the same time base to adjust the playing rate of the video stream in order to achieve our goal of audio/video synchronization.This paper explained the syntax of mpeg-2 system in detail, including the configuration of TS packet, PES packet and PSI section. We achieved the demultiplexing by using PAT and PMT, and get the time stamp at the same time, then adjusted the playing rate of the video stream by comparing the video PTS with the audio PTS.Experimental results showed that the method proposed in this paper is able to synchronize audio and video effectively. The synchronization ratio increased to 98.68%, critical ratio and non-synchronization ratio respectively decreased to 0.59% and 0.72%.