New H.264 Intra-Rate Estimation And Inter-Rate Control Driven By improved MAD-Based Contrast Sensitivity
Résumé
This paper aims to improve H.264 bit-rate control. The proposed algorithm is based on a new and efficient Rate- Quantization (R-Q) model for the intra frame. For the inter frame, we propose to replace the current use of MAD by a new MAD-based human Contrast Sensitivity (MAD-CS) which is a more accurate complexity measure. R-Q model for the intra frame results from extensive experiments. The optimal initial quantization parameter QP is based on both target bit-rate and complexity of I-frame. The I-frame target bit-rate is derived from the global target bit-rate by using a new non linear model. MAD-CS includes the contrast sensitivity of the human visual system and weights the absolute differences by the probability of their occurrence. Extensive simulation results show that the use of MAD-CS and the proposed R-Q model achieves better rate control for intra frames, reduces the bit-rates when compared to the H.264 rate control adopted in JM reference software, minimizes the peak to signal ratio variations among encoded pictures and increases significantly as well subjective visual quality (measured by psycho visual experiments) as objective one.