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无线视频传输系统中,网络带宽往往是有限和动态变化的,这将导致视频信息在传输过程中的质量差以及不稳定,此时需要在视频编解码中采用码率控制进行调控。针对X264平均比特率(ABR)算法的不足,提出了两种改进措施:其一,根据实际输出比特和目标比特之差在帧层增加补偿算法来调整当前帧的量化参数(QP);其二,改善缓存区增长函数以限制缓存区的过快增长。改进算法通过对同一视频序列不同目标码率以及不同视频序列同一目标码率两种方式进行实验仿真验证。仿真结果表明,在峰值信噪比(PSNR)平均值基本不变的情况下,输出的实际码率更加接近于目标码率。
In the wireless video transmission system, the bandwidth of the network is often limited and dynamically changing, which leads to poor quality and unstable video information during transmission. In this case, bit rate control needs to be adopted in video coding and decoding. According to the shortage of X264 average bit rate (ABR) algorithm, two improvement measures are proposed: one is to adjust the quantization parameter (QP) of the current frame based on the difference between the actual output bit and the target bit; , Improve the buffer growth function to limit the buffer area growth too fast. The improved algorithm verifies the simulation by two different ways: different target rate of the same video sequence and same target rate of different video sequences. The simulation results show that the actual bit rate of the output is closer to the target bit rate under the condition that the average value of PSNR is almost the same.