Exploiting MPEG-7 texture descriptors for fast H.264 mode decision

A novel technique for exploring the use of indexing metadata in improving coding efficiency is proposed in this paper. The technique uses an MPEG-7 descriptor as the basis for a fast mode decision algorithm for H.264/AVC encoders. The descriptor is used to form homogenous clusters for each frame, within which limited available coding modes for each macroblock are defined. The coding mode of an already coded macroblock that belongs to the same cluster in the same frame as well as the statistics of the coding modes of similar clusters in previous frames, are used for limiting the range of available coding modes within each cluster. The results show that the proposed algorithm is able to achieve an average of 47% time-saving when compared to the full search method and 21% when compared to the fast mode decision algorithm employed in the JM12.2 reference H.264 software encoder. In both cases, results yield only a small degradation in rate-distortion performance and a negligible loss in subjective quality.