Very Low Bit-Rate Video Coder with Object-Oriented Bandwidth Allocation Technology
面向对象分配带宽的极低比特率视频编码器

How to improve the subjective visual quality of the video coded at low bit rate is an interested subject of many people. This paper proposes a video coding system based on object oriented bandwidth allocation(OOBA) technology to improve the subject quality of coded images. Exploiting human subjective visual characteristic sufficiently, this coder divides video sequence into multi video objects(VO) and allocates more bandwidth for the VO with more subjective significance to improve subjective quality of images coded at low bit rate. Each object is composed of macroblocks and coded separately. In bit stream context, the OOBA coder is compatible with H 263. For reasonable bandwidth allocation, present three schemes to allocate bandwidth for multi objects: rate distortion(R D) model based scheme ,sequence analysis based scheme and ratio weighting scheme. The result of experiments shows that the PSNR of OOBA coder is a little lower than that of frame based coder, but the subjective quality is much better. So, it proves the OOBA coder effective and indicates it is not enough to evaluate a video coder only with objective criterion such as PSNR .