一种HEVC码率控制改进算法

AN IMPROVED ALGORITHM FOR HEVC RATE CONTROL

HEVC(High Efficiency Video Coding)采用的基于R-λ模型的码率控制算法在控制输出码率的精确和提高编码效率上都取得了良好的效果。然而该算法没有考虑到实际视频编码中场景切换的影响。提出一种新的针对场景切换的码率控制算法。首先结合帧间的亮度差及其变换趋势判断是否发生场景切换,在场景切换发生时对码率控制的参数以及编码结构都做出及时调整。最后实验表明,与HEVC自带的码率控制相比,所提出的码率控制算法能够有效应对视频序列中的场景切换,提高了编码质量,降低了编码复杂度,并且保持精确的输出码率。

The rate control algorithm based on R-X model adopted by HEVC (High Efficiency Video Coding) has achieved greatperformance in both controlling the accuracy of output bitrate and improving coding efficiency. But it does not consider the influence broughtforward by scene changes in practical video coding. This paper proposes a new rate control algorithm for scene changes. We first detectwhether there are the scene changes by the difference of luma between frames and the variation tendency of the difference. When the scenechange occurs, the parameters in rate control and coding structure will be all adjusted instantly and adaptively. Experiment shows thatcomparing with the rate control in HEVC itself, ours can handle with scene changes in video sequences effectively. The quality is raised andthe coding complexity is decreased, while the accuracy of output bitrate is still maintained.