Image Complexity Adaptive Intra-Frame Rate control Algorithm for H.264/AVC

Aiming at the bad effect of intra-frame rate control (RC) of H.264, this paper proposed an image complexity adaptive intra-frame RC algorithm. First, in order to acquire intra-frame coding complexity more accurately, our algorithm analyzes intra-frame by Sobel operator and establishes edge direction histogram for each 4x4 block, then gets the most probable intra prediction mode and corresponding reconstructed blocks, finally obtains the residual picture which is close to the actual coding residual. The mean absolute value of residual picture was used to represent the intra-frame coding complexity, combined with our empirical rate-quantization (R-Q) model and target bits allocation method from exhaustive experiments, and the intra QP was determined accurately. Extensive experimental results show that our algorithm not only obtains more accurate intra-frame output bit-rate, more consistent subjective quality and more steady PSNR fluctuation compared with existing algorithm, but also prevents buffer overflow and frame skip effectively.