Two-source decomposition and discrete-cosine-transform - Hadamard-transform coding of low-correlation interframe differences

International standards such as ITU-T H.263 (H.261) and ISO MPEG use a hybr id coding scheme based on the discrete cosine transform (DCT). Although the DCT is an established technique for encoding interframe differences, it is not an optimal transform for low-correlation interframe differences, since its energy compaction performance largely depends on the correlation of th e data. In this paper an effective technique for encoding interframe differ ence is proposed and verified on an MPEG2 software encoder. The technique d ecomposes the interframe difference into two sources in order to exploit th eir improved statistical properties. The two-source interframe difference i s encoded with a combined transform, which consists of the DCT and the Hada mard transform (HT). Two-source decomposition increases the correlation of the decomposed prediction error, and the DCT-HT scheme is shown to efficien tly encode the decomposed interframe difference with increased performance. Analytic and experimental comparison shows that the proposed DCT-HT scheme gives significant objective and subjective gains over the conventional DCT -based video encoding method. (C) 2001 Society of Photo-Optical Instrumenta tion Engineers.