MPEG transcoding for DVD recording
In this paper a system level MPEG transcoding scheme is proposed. The MPEG-2 system standard specifies two kinds of streams: transport stream (TS) and program stream (PS). Each is optimized for a different set of applications. The transcoding between TS and PS has an important application, which can be applied to convert the digital television (DTV) broadcasting bitstreams to the bitstreams for digital video disc (DVD) application. An important technical issue for transcoding between PS and TS is the rate control algorithm. Usually, for DVD application, the video is encoded by variable bit rate (VBR) in order to provide constant quality over whole sequence, while for DTV application due to buffer requirement the video should be encoded by constant bit rate (CBR). hi this paper, a novel VBR rate control algorithm is proposed for the on-line video transcoding process. In this algorithm, the bit allocation strategy at picture level, which is based on a bit producing model and hyperbolic R-D function, is first discussed. Then, the rate control algorithm at macroblock level with R-D optimization is proposed. Experiment results show that the proposed VBR transcoding algorithm achieved the better image quality compared with CBR transcoding at the same bit rate.