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为解决H.264/AVC视频编码标准中码率预测不准确的问题,基于JM80提出了一种改进的BU层码率控制算法。该算法假设编码复杂度均匀分布在图像宏块的每个点上,根据宏块运动矢量预测出下一帧的编码复杂度,进而预测出宏块的量化步长和输出比特数的关系,因而比JM80采用的模型更直接和准确。该算法同时采用基于Lagrange乘子法的率失真最优准则的比特分配策略。仿真结果显示出经该算法控制后的输出码率非常接近目标码率,且和JM80中方法相比,对所有测试序列都有明显的峰值信噪比(PSNR)增益。
In order to solve the problem of inaccurate rate prediction in H.264 / AVC video coding standard, an improved control method of BU layer rate control based on JM80 is proposed. The algorithm assumes that the coding complexity is uniformly distributed at each point of the image macroblock. The coding complexity of the next frame is predicted according to the motion vector of the macroblock, and then the relationship between the quantization step of the macroblock and the number of output bits is predicted. More than JM80 models used more direct and accurate. The algorithm also adopts the bit allocation strategy of the optimal rate-distortion criterion based on Lagrange multiplier method. The simulation results show that the output code rate controlled by the algorithm is very close to the target code rate, and has obvious peak PSNR gain for all test sequences compared with the JM80 method.