根据缓存器的状态和信道速率为待编码帧在图像层上预分配目的视频编码比特数 ,使用DCT系数分布特性来表征图像特性 ,继而为帧内每一具体宏块选定最佳量化因子 ,提出了基于DCT系数分布特性的码率控制策略 .并分析了算法的复杂度 ,提出了改进策略 .模拟实验表明 ,该码率控制策略能有效地减少、避免缓存器出现上、下溢的情况 ,而输出码率趋于稳定 .提高了重建图像的信噪比 ,并且在视频图像质量没有明显失真的前提下 ,改进了计算复杂度 .Rate control strategy based on the distributed character of DCT coefficients is proposed , we allocates the target number of bits firstly on picture layer based on the status of the buffer and the channel rate, and then denotes the characteristics of the picture by the distributed characteristics of the DCT coefficients and select a best quantized parameter for every macroblock in a frame. The complexity of the algorithm is analyzed and an improved method is proposed. The experiment shows that this rate control strategy can effectively reduce and avoid the overflow and underflow of the encoder buffer, and the output bit rates tend to stabilization. The PSNR of the reconstructed picture is raised, and the complexity of the algorithm is improved with no visible distortion in video image.安徽省教委自然科学基金资助项目 (99j10 0 18
