A bit-rate control method for low bit-rate video coding based on high bit-rate period emphasis

A bit-rate control method for high-quality video distribution at low bit rates is proposed. That method involves first encoding the video signal with predetermined coding parameters and then dividing it into three periods of high, medium, and low coding rates. The periods of high coding rate are allocated bit rates equal to or greater than the transmission bit rate to improve image quality. Moreover, the bit rate for periods of low coding rate is lowered so that the bit rate allocated to periods of high coding rate can be made greater. Preliminary experiments show that this high coding rate period emphasis method is consistent with the characteristics of human vision. The results of subjective tests on image quality that were conducted on a video distribution system using the proposed method show that for a transmission bit rate of 128 kbps with the proposed bit rate control method, the image quality is equivalent to a fixed bit rate that is approximately 1.9 times higher.