压缩域MPEG-2到MPEG-4视频转码中不匹配宏块的复原算法

Robust Mode Mismatch Macroblock Retrieval Algorithm for Transcoding MPEG-2 to MPEG-4 in Compression Domain

作为一种最有应用前景的先进的压缩编码标准，MPEG-4将会很快在视频传输、存储和剪辑等许多领域中得到应用。不过，MPEG-2和MPEG-4这两种优秀的视频系统肯定会在很长一段时间内共存。本文提出了一种基于MC-DCT域的转码方法。重点解决了两种标准视频流中宏块编码模式不匹配的一些关键问题。仿真结果表明，本算法不仅能有效地实现MPEG-2到MPEG-4的转码，满足实时性和低处迟的需求，而且能隐藏或复原编码模式不匹配宏块，明显地改变视觉质量。

MPEG-4,as one of the most promising and advanced compression standard,will be leading the video transmission, storage,and edition applications in the coming future. But two excellent standard-compliant streams,MPEG-2 and MPEG-4 video, will be coexisting in different systems for a long time. This paper addresses the issues of transcoding MPEG-2 video to MPEG-4 compliant bitstream in compression domain to meet low complexity and low latency real-time application. The key issue about macroblock coding mode mismatch in transcoding processing will be discussed in detail. The reported simulation results testified that the proposed transcoding algorithm could not only convert MPEG-2 stream to MPEG-4 steam effectively, but also retrieve or conceal the mismatched macroblock robustly,which will improve the perceptual quality greatly.