Research And Implementation Of Audio-Video Synchronization Based On TV-Chip Platform

With the rapid development of Internet technology and broadband net as well as popularization of stream-media application, multi-media technology gets promoted continuously. Synchronization is a key technology in the multi-media domain, to which people will pay more attention in future.This paper analyses some kinds of existing synchronization method and technology. On the basis of theory analysis and deep knowledge of PLM3K platform, a specific audio-video synchronization software solution is brought forward. The solution is based on time-stamp synchronization technology, which accomplishes its function with presentation time-stamp. Also the solution takes two sources as master stream choices, of which one is audio-stream and the other is external system clock of PLM3K with 27MHz center-frequency. With different application, different master stream is choosed by the audio-video synchronization solution. However, the slave stream is always trying to keep close to the master stream. When solution takes audio stream as master, the system clock count value is initialized and updated with the PTS of audio stream. When solution takes the external clock as master, the system clock count value is initialized and updated with PCR value and clock frequency accuracy adjust is startup. By comparing time stamp of stream and system clock count value, whether audio and video is out of synchronization is judged. If it is out of synchronization, resynchronization solution of frame-repeart or frame-skip is needed to make good audio-video synchronization performance.This paper describes two arithmetics which is new and suit for PLM3K. One is about how to fetch correct PTS value from PTS RingBuffer quickly and the other is about improving the accuracy of system clock by software using averaging and approach idea. In addition, a lot of data is analysed to adjust theory value into experience value. On basis of data analysis synchronization performance is judged.The whole of audio-video synchronization solution is accomplished and is applied to business after plenty of quality-test and solution validity is proved.