MPEG-1/2 To MPEG-4 Multimedia Stream Transcoding

Due to the huge volume in data size of the digitized video and audio information, the difficulties for the store and delivery of these information have been a bottleneck that handicap people to access and use them effectively. The optimum way is to compress them by some effective data compression, and then handle them. But, nowadays a number of international video compression standards have been established for various video applications. The video data follows different stream formats, bit rate, frame rate and spatial resolution. Multimedia stream transcoding technology can convert a compressed video stream from one format to another, it is fit to the given application constrains.The second chapter concentrates on the MPEG serial video compression standards. The data structure and encode/decode architectures of MPEG-2 and MPEG-4 are introduced in detail. For different applications, transcoding speed and transcoding quality are different, the key techniques of a non real-time and a real-time transcoder are discussed. In the third chapter, aim at the non real-time transcoding, the developing method with DirectShow for multimedia is investigated. A multimedia stream transcoding structure and it's software system are given. Based on comparison of MPEG-2 and MPEG-4, the fourth chapter presents compressed domain transcoder, which can skip the motion estimation , motion compensation and DCT/IDCT transformation processes, so as to reduce the complexity greatly. The transcoder can work effectively and in real-time.