A Fast Video Transcoding Algorithm Based on Hybrid Characteristic of Multi-Scale Videos

As a key technique in network multimedia signal processing, video transcoding becomes a hot topic in recent years. This paper presents a fast intra mode decision scheme for down-sizing video transcoding in H.264 based on hybrid characteristic of multi-scale videos. In order to reduce the high computational complexity of using conventional intra prediction in the H.264 re-encoder, the proposed scheme firstly utilizes 2D-histogram to extract the spatial characteristic of macro-blocks in the downsized video to choose from intra 16×16 and intra 4×4. Then Support Vector Machine (SVM) is used to exploit the correlation between coding information extracted from the input highresolution bit-stream and the coding modes of macro-blocks in down-sized video frames. After the SVM classifier, improbable modes in the nine intra 4×4 modes are eliminated and only a small number of candidate modes are carried out using the RDO operations. Hence, remarkable computing time can be saved, up to 74%, while maintaining nearly the same quality of the transcoded pictures.