Research On Rate Control Of MPEG-2 To AVS Video Transcoding

Along with booming digital AV and multimedia technology, video coding technology has greatly developed. Nowadays, the International Coding Standards, such as MPEG-1, MPEG-2, MPEG-4, H.26x and Chinese independently creating AVS have been established and applied to different areas. In order to adapt to heterogeneous client terminals and transmission characteristic of networks, pre-encoded video should be transcoded into another coding format. So, the resources of networks can be shared.When the compressed video sequence experiences long-distance transmission, network congestion, channel bandwidth and disposal ability of terminal should be considered. Target of rate control is to maintain the channel normal and obtain better image quality by adjusting the parameters of encoder.As the basis of the following research on rate control of transcoding, several transcoding structures and the recommended rate control methods of MPEG-2 and AVS coding standards are introduced in the thesis first. And then, the affecting factors of the bit rate and key part of rate control in transcoder are analyzed, which are theories basis of the new algorithms.On the basis of full analysis on the characteristics of two coding standards and information adopted from decoder, this thesis proposes two algorithms. One is bit allocation optimization in frame layer, namely, different bits are allocated to frames with different complexity according to decoding information. The other is the establishment of accurate relationship of quantitative parameters and bits inρ-domain. Finally, by combined rate control strategy in AVS, the new rate control scheme implements effectively control.Our lab group has developed a system which can transcode DVD stream to AVS TS stream. The second part of this thesis summarizes the software developing for AVS TS player using DirectShow framework, which consists of an AVS audio/video splitter filter and an AVS video decompressor filter.