MPEG-2实时解码中的输入缓冲器控制

分析了ＭＰＥＧ２ 的时序模型,研究了理想解码器的输入缓冲器工作过程以及实际实时解码器解码开始的时刻、解码非瞬时、码流非平稳等因素对输入缓冲器的影响,指出实际解码器的输入缓冲器必须增大。在输入缓冲器容量受限制的情况下,给出了输入缓冲器控制策略。该策略已经成功地应用于作者研制的高清晰度电视功能样机中。

Input Buffer Control for Practical Real-time MPEG-2 Decoders

The time model of MPEG 2 is studied. The working status of input buffer of ideal decoders is analyzed. The influence on decoding starting time, non instant decoding and non constant rate bitstream of practical decoders is researched. To work properly, the input buffer size of practical decoders must be increased. Under the situation of constrained buffer size, the buffer control strategy is proposed. According to the buffer occupancy after the decoding of frame I and the size of frames I,P , the possible buffer underflow and overflow conditions are detected. To avoid buffer overflow, skipping a frame is used. To avoid buffer underflow, repeating a frame is performed. The strategy has been successfully implemented in the HDTV source decoder functional prototype.