H.263 coding optimization: temporal subsampling driven by motion analysis

The paper describes a coding optimization strategy in conformity with the recent ITU-T H.263 Recommendation for videophone sequences at bitrates less than 64 Kbit/s. The optimization algorithm jointly selects the temporal position of the frames to be coded and the coding mode (l, P or PB) of the selected frames. The decision is based on the observation, on a group of frames, of an 'activity' parameter, representing the variation of each frame with respect to the last coded one. The proposed strategy produces coded sequences with average frame rates lower than those produced by a non optimized coder, and a better visual quality of the single frame. However, the activity parameters evaluation, and the observation of several candidates, requires a greater delay, buffer size and complexity of the coding algorithm.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.