Reducing Spatial Resolution for MPEG-4 / H.264 Transcoding with Efficient Motion Reusing

Efficient downscaling in a transcoder is important when the output video should be converted to a lower resolution video. In this paper, we present a fast MPEG-4 simple profile (SP) to H.264 transcoder with reducing spatial resolution from CIF to QCIF video format. Based on frame image characteristics and motion information in MPEG-4 decoder, we limit motion modes, generate prediction motion vectors and build an adaptive search range for motion estimation in H.264 encoder. Simulation results show that our transcoder reduces transcoding time considerably while video quality is kept almost optimal.