基于H.263视频码流的差错掩蔽算法

在H．263视频信号的传输过程中，由于采用了可变长编码，当发生比特错误时，很容易造成错误的扩散传播及图像质量下降。由于H．263为低速率传输模式，在进行错误恢复时不适于采用网络开销较大的前向纠错方式，所以采用了基于解码器端的差错掩蔽方法来消除错误的影响。使用的是自适应分类差错掩蔽方法，通过分析图像的运动剧烈程度，将图像分为三类进行掩蔽，既降低了运算复杂度，又取得了较好的掩蔽效果。

Error Conecalment Algorithm Used in the Transmission of H.263 Video Bit Stream

During the transmission of H.263 signal, due to the use of variable length code (VLC), a single bit error may propagate up to others. It deteriorates the quality of the picture. It is not recommended to use forward error correcting method to control the error, for H.263 bit stream is transmitted at low bit rate and that method needs much more redundancy bits. So we propose an error concealment method based on decoder to reduce the infection of the error. In this paper, we propose an adaptive classification error concealment algorithm. By analyzing the degree of the motion in a picture, we put the pictures into three classes to be concealed. This method is not only reducing the complexity of computation, but also getting a satisfied concealment result.