适应调频同步广播的MPEG-2再复用器PCR修正算法

 节目参考时钟（PCR）是MPEG-2系统中音视频解码的时间基准，MPEG-2解码器利用PCR时间信息控制MPEG-2视频解码、显示时间及音视频同步。PCR修正是MPEG-2再复用器设计的关键技术之一。对目前再复用器实现中的PCR修正算法及MPEG-2标准传输流中PCR进行分析研究，提出了一种新的MPEG-2再复用器PCR修正算法。采用该修正方法，可以避免再复用器在再复用过程中对MPEG-2信号进行缓冲后PCR包中标识的PCR值和解码器实际接收到PCR包时的时间值不一致情况的发生；解决了MPEG-2解码时由于不一致引起的PCR抖动和缓冲区溢出问题；使解码器可以利用该PCR信息恢复出编码端的时钟，保持编、解码器时钟同步。采用该修正算法修正的再复用器的音频信号可满足对时间要求更苛刻的调频同步音频广播的要求。

A PCR Correction Method of MPEG-2 Re-multiplexer Adapted for FM Synchronous Broadcast

The Program Clock Reference (PCR) is the time base of decoding video and audio in MPEG-2 system. A MPEG-2 decoder uses the PCR to control the decode time and the present time of video and to realize the synchronization of video and audio. The PCR correction is one of the key technique for the MPEG-2 remultiplexer design. This paper proposes an improved and practical method of the PCR correction for the design of MPEG-2 remultiplexer through analysis of problems in the PCR correction method currently used in MPEG-2 remultiplexer． With the correction method, the re-multiplexer can solve the problem that the timing of the PCR value described in the PCR field is not in accord with the timing of the decoder received in the PCR field in the packet, due to the buffering of the MPEG-2 signal in the processing of remultiplexing, therefore, it can solve the problems of PCR jitter and buffer overflow in the processing of MPEG-2 decode, which would happen with a wrong PCR correction method. A decoder can reconstruct the clock signal of the encoder from the PCR value, and keep the clock in synchronization between decoder and encoder. Furthermore the audio signal after re-multiplexer with the new PCR correction method can meet FM synchronous broadcast requirements for a more accurate time.