MPEG-4编、解码器容错技术的研究

Study on error resilience technologies for MPEG-4codecs

在分析MPEG-4码流结构的基础上,对编码器提出了两点改进:一是对DCT系数不采用AC预测编码;二是对B帧宏块的4种编码模式全部编码。实验表明,这两点改进在基本不降低编码效率的条件下提高了对错误的抵抗力。在解码端提出了一种既能检测本数据包差错又能防止下一数据包头被错误解码的方法。针对B帧差错块的恢复,提出了一种基于运动矢量估计的方法,能有效地解决直接拷贝参考帧相应宏块所引起的图像错位问题。

Two improvements have been adopted in this paper for encoder error resilience based on the analysis of the code stream structure of MPEG-4.One is achieved by not using the AC prediction for DCT,the other is achieved by encoding all the four modes of MB of B frame.The two improvements have been proved to enhance the error resilience without decreas-ing the encode efficiency by experiments.Besides,an error detect method which can prevent the decoding error for the next video packet head is used,and a restoration measure for B frame based on the MV prediction which can improve the visual quality has been studied.[