提出一种利用ＡＴＭ网络变码率（ＶＢＲ）服务方式的两层信噪比分级视频编解码方案．编码的基本层是一个ＭＰＥＧ－２ＭＰ＠ＭＬ定码率编码器，增强层对基本层的量化误差进行细量化和变码率编码．采用以宏块为基础的帧／场自适应帧间编码技术和改进的ＴＭ５码率控制策略．无Ｂ帧的编码方式，延迟、复杂度和成本都较低，值得在ＡＴＭ网络中使用．计算机模拟实验表明，尽管存在场景切换，但此编解码器仍可获得高质量的较稳定的接收 This paper presents a two-layer signal-to-noise ratio video coding and decoding scheme using VBR service. The base layer of the encoding is an MPEG-2 MP @ ML fixed rate encoder, which enhances the quantization error of the base layer by fine quantization and variable rate encoding. Macroblock-based frame / field adaptive inter-coding technology and improved TM5 rate control strategy. No B-frame encoding, delay, complexity and cost are lower, it is worth in the ATM network. Computer simulations show that this codec can still receive high quality and stable reception despite scene switching