Moving picture coding system for digital storage media using hybrid coding

摘要

A coding system using a hybrid coding method with motion compensated interframe DPCM, Discrete Cosine Transform and frame interpolation methods was examined as a moving picture coding system for digital storage media such as CD-ROM. The encoder, reducing the frame frequency of an input picture by half, performs hybrid coding, and the decoder performs frame interpolation to give a playback picture. It was verified that by using this technique before coding, S/N about 1.5 dB better than by direct coding could be obtained in some frames. In frame interpolation, overwriting by changing motion compensated block size has solved the problem of unoverwritten area. Local distortion which is a problem in frame interpolation is reduced by detecting distortion and coding with an encoder. Information quantity necessary for this is about 10% of overall quantity. In intraframe coding, control of quantization step size by activity has improved the picture quality in parts with small amplitude of luminance.