H.264可伸缩视频编码层间码率控制算法

H.264 scalable video coding inter-layer rate control

为H.264/AVC标准的可伸缩编码(SVC)扩展提出了一种自适应的层间码率控制算法。该算法提出了一个选择模型,通过当前层的前一帧或者前一层的当前帧来预测Inter帧所需比特数。首先,将码率—复杂度—量化因子(R-C-Q)模型引入可伸缩的视频编码;接着,使用一个已有的比例—积分—微分(PID)缓冲区控制器来根据缓冲区状态提供当前Inter帧的比特数估计;然后,为了在视频画面发生急剧变化时获得更为精确的估计,利用前一层中的当前帧所用实际比特数来进一步进行当前Inter帧比特数估计;最后,使用选择模型决定最终的预测比特数,并通过R-C-Q模型计算出量化因子(QP)。实验结果表明,相对于推荐的JVT-043码率控制算法,所提出的算法可以在SVC的每层获得更加精确的实际输出比特率,保持缓冲区充盈度的稳定,同时减少跳帧和质量波动,提高整体编码质量。

An adaptive inter-layer rate control scheme was proposed for H. 264/AVC scalable extension. A switched model was put forward to predict the number of bits used for encoding inter frame either from the previous frame of the current layer or from the current frame of the previous layer. First, a Rate-Complexity-Quantization （R-C-Q） model was extended in scalable video coding. Second, the Proportional ＋ Integral ＋ Derivative （PID） buffer controller was adopted to provide the inter frame bit estimation according to the buffer state. Third, to achieve more accurate prediction when an abrupt change happens, the bit estimation was predicted from the actual bit of the current frame of the previous layer. Finally, a switched model was used to decide the bit estimation, and then the Quantization Parameter （QP） could be calculated according to the R-C-Q model. The simulation results demonstrate that the proposed algorithm outperforms JVT-W043 rate control algorithm by providing more accurate output bit rate for each layer, maintaining stable buffer fullness, reducing frame skipping and quality fluctuation, and improves the overall coding quality.