MPEG-2 解码中的音视频同步及其实时实现

Audio Video Synchronisation for MPEG 2 Decoding and Its Real Time Implementation

音视频同步是ＭＰＥＧ－２实时解码实现的难点．讨论了ＭＰＥＧ－２的音视频同步模型，提出了一种适于实时解码的ＭＰＥＧ－２音视频同步算法，给出了同步的判断准则和实际的处理过程．对于不同的失步类型，采取跳帧或重复一帧的纠正措施．采用中断方式实现解码芯片与主控芯片的通信，主控芯片建立ＰＴＳ表并判断是否同步，在失步时控制解码芯片采取纠正措施．这种音视频同步算法已经成功地应用于作者研制的高清晰度电视（ＨＤＴＶ）信源解码功能样机中．实验表明，它能够准确、可靠地实现音视频同步．

An MPEG 2 audio video synchronisation model is discussed and its difficulties of real time implementation are pointed out.A new algorithm which is suitable for real time implementation is suggested,the judge rule of synchronisation is provided and the processing steps are given.According to the type of loss sync,a skip frame or repeat frame process is taken. An interrupt performs communication media between the micro controller and decoder ASIC.The micro controller maintains a PTS table,judges synchronisation status and controls the ASIC to perform the correct process.This audio video synchronisation algorithm is successfully adopted in the HDTV source decoder functional prototype.The experimental results show that the algorithm can realise an accurate and credible synchronisation.