Adaptive rate control in frame-layer for real-time H.264/AVC

Rate control has been treated as a critical issue of H.264/AVC including previous video coding standards. The purpose of this paper is to improve allocation of the number of bits without skipping the frame by accurately estimating the target bits in H.264/AVC rate control. In our scheme, we propose an enhancement method of the target frame rate based H.264/AVC bit allocation. The enhancement uses a frame complexity estimation to improve the existing mean absolute difference (MAD) complexity measurement. Bit allocation to each frame is not just computed by target frame rate but also adjusted by a combined frame complexity measure. To prevent an undesirable buffer overflow or underflow in short of channel bandwidth, the computed quantization parameter (QP) for the current frame is adjusted based on actual encoding results at that point. The objective of QP and adjustment is to produce bits as close to the target frame as possible, which is especially important for low bandwidth based real-time applications. Simulation results show that the proposed rate control scheme achieves a similar or smaller PSNR deviation, and achieves time saving of more than 99% over JM 12.1 rate control algorithm.