可伸缩性视频编码的码率分配算法

本文研究了渐进的精细的可伸缩性(Progressive Fine Granular Scalable,PFGS)视频编码的增强层码流的码率分配问题,它是由PFGS各帧的增强层码流长度不同引起的.我们首先建立了PFGS增强层的多帧联合的率失真(rate-distortion,R-D)函数,并通过MPEG-4标准测试序列检验了它的正确性.然后利用联合率失真函数给出了局部最优的码率分配算法,并进行了简化使得它的复杂性极低,非常适合流化视频(streaming video)服务器使用.实验结果显示本文提出的算法不仅使得各帧图像的解码质量比较平衡,而且将PFGS的编码效率提高了将近0.5dB.

A Rate Allocation Scheme for Progressive Fine Granular Scalable Video Coding

The enhancement layer rate allocation problem is examined in progressive fine granular scalable (PFGS) video coding.The problem arises from the fact that different frames in the enhancement layer have different rates in PFGS coding.A rate-distortion (R-D) function for a multi-frame group is first established for enhancement layer PFGS coding,followed by experiments to verify its validity using real test sequences.Optimal rate allocation among frames in the group is then given based on the R-D function,together with a simple implementation that is suitable for applications like streaming video.Experiments show that,compared with uniform bit allocation,optimal bit allocation not only makes the quality variation in decoded video much smoother,but also improves the average PSNR of PFGS coding by 0.3~0.5dB.