Incremental rate control for H.264 AVC scalable extension

Abstract

The emerging H.264 Scalable Video Coding (H.264/SVC) requires the rate control algorithm to regulate the output bit rate of all the coarse-grain-scalability, temporal, spatial and combined enhancement layers. In order to address this topic, in this research, we propose an incremental rate control algorithm for H.264/SVC to control each layer's encoding rate close to the target bit rate. The proposed algorithm introduces a number of efficient methods. First, based on our previous work on H.264/AVC rate control, a Rate-Complexity-Quantization (R-C-Q) model is extended in scalable video coding. Second, a complexity measure for Intra-frames based on their gradient and histogram information is used to precisely determine Quantization Parameters (QPs) for Intra-frames using the R-C-Q model. Third, we adopt an incremental approach to compute QPs of inter-frames. Fourth, a Proportional + Integral + Derivative (PID) buffer controller is presented to provide robust buffer control for each layer of H.264/SVC bitstream. Finally the QPs for hierarchical B-frames are adaptively decided by their neighbor inter-frames. Our extensive simulation results demonstrate that, our algorithm outperforms JVT-W043 rate control algorithm, adopted in the H.264/SVC reference software, by providing more accurate output bit rate for each layer, maintaining stable buffer fullness, reducing frame skipping finally, improving the overall coding quality.