Fast Inter Mode Decision Algorithm Based on the MB Activity for MPEG-2 to H.264/AVC Transcoding

Recently H.264/AVC is widely used for the mobile and low bitrate video codec in the various multimedia terminals. On the other hand, the MPEG-2 MP@HL codec is becoming a center of digital video contents since it is the standard codec for the digital TV (DTV).To provide the bridge between the contents in MPEG-2 and mobile terminals, the transcoding of MPEG-2 contents into H.264/AVC format is inevitable technology in the digital video market. The main bottleneck in the process lies in the computational complexity. In H.264/AVC, the variable block size (VBS) mode decision (MD) is employed for the improved performance in the motion compensated prediction. In this paper, the residual DCT-domain macroblock (MB) energy obtained from MPEG-2 decoding process is used for the decision of the predicted block sizes in H.264/AVC encoder. By this early decision of block sizes, the original candidate modes can be reduced effectively, resulting in the reduction of the computational complexity. The simulation results show that the proposed algorithm can reduces 50% computational complexity, compared with the well-known cascaded transcoder while maintaining the video quality.