Bit allocation and rate control based on human visual sensitivity for interframe coders

Video coding standards such as the CCITT H.261 and the ISO 11172 allow substantial freedom in the exact methodology used to allocate bits to different parameters and control the output bit rate. Thus, different standard conforming coders can give different picture quality depending on the bit allocation and rate control strategy used at the encoder. The authors propose a new bit allocation and rate control strategy that is based on some assumptions about the sensitivity of the human visual system to distortion. They use the ISO 11172 standard in their examples, although the strategy is equally applicable to other DCT based interframe coding schemes. The new scheme shows considerable quality improvement over conventional schemes in the informal subjective tests