Local bandwidth constrained fast inverse motion compensation for DCT-domain video transcoding

DCT-based digital video coding standards such as MPEG and H.26x are becoming more widely adopted for multimedia applications. Since the standards differ in their format and syntax, video transcoding, where a pre-coded video bit-stream is converted from one format to another format, is of interest for purposes such as channel bandwidth adaptation and video composition. DCT-domain video transcoding is generally more efficient than spatial domain transcoding. However, since the data is organized block by block in the DCT-domain, inverse motion compensation becomes the bottleneck for DCT-domain methods. We propose a novel local bandwidth constrained fast inverse motion compensation algorithm operating in the DCT-domain. Relative to Chang´s (1995)algorithm, the proposed algorithm achieves computational improvement of 25% to 55% without visual degradation. A by-product of the proposed algorithm is a reduction of blocking artifacts in very low bit-rate compressed video sequences