可逆变长编码的解码器设计及VLSI实现

变长编码(VLCs，Variable Length Codes)因其高效的数据压缩能力被广泛地应用在多媒体压缩领域，但VLCs的自身性质使它对信道错误的恢复能力很弱。随着在不可靠信道，如无线信道和网络上进行视频传送需求的增加，视频通讯的错误控制和错误恢复技术变得越来越重要。可逆变长编码(RVLCs，Reversible Variable Length Codes)，当遇到传输错误时，充分利用了可用的数据，错误恢复能力强于VLCs。许多视频标准，如ITU H．263 ，ISO MPEG-4已经采用了RVLCs。本文详细描述了RVLCs解码器的解码算法和解码器的体系结构设计，给出了一个基于MPEG-4 ASP@L5的解码器VLSI实现。结果表明，该实现完全适用于MPEG-4实时编解码系统。

Reversible Variable Length Decoder Design and VLSI Implementation

Variable length codes (VLCs) are widely used for their efficient compression, but they are also very brittle to channel errors due to their nature. With the growing interest in video delivery over unreliable channels such as wireless networks or Internet, the error control and concealment in video communications become increasingly important. Reversible variable length codes (RVLCs) can make full use of available data when a transmission error occurs. Current ITU H 263+ and ISO MPEG-4 have already used RVLCs. In this paper, the algorithm and architecture of RVLCs decoder are described in detail. A VLSI implementation of RVLCs decoder for a MPEG-4 ASP@L5 is presented with the synthesized result and the layout, and the results show that it can be applied in the real time video system.