Requantization techniques for H.264/AVC rate reduction transcoding

In order to cope with the increasing number of different display devices and the heterogeneity of transmission networks, fast and elegant adaptation of video content is required. Transcoding can be used for reduction of the bitrate, without fully decoding and recoding the bitstream. A significant reduction in computational complexity can be achieved by reusing information from the incoming bitstream, such as motion vectors, and by working as much as possible in the transform domain. We investigated architectures for bitrate reduction transcoding of intra-coded pictures, comparing the decoder-encoder cascade with different reduced complexity transcoders. Results show that the transform-domain architecture can achieve the quality of the pixel-domain transcoder, and approximates the quality of a decoder-encoder cascade. Keywords—H.264/AVC, transcoding, requantization, rate reduction