Abstract:

A rate control algorithm for adaptive prediction error and quantization matrix is proposed in order to improve the performance of rate control in H.264 further. Firstly, the new algorithm determines whether discrete cosine transform (DCT) is applied to the macroblock according to the gradient directional weight of macroblock and to the simplified rate distortion model. Secondly, the quantization parameter (QP) is calculated through a new dual target bits allocation model, and then the slope coefficient is calculated by the weighted average of slope in the macroblock. Finally, the macroblock is quantized by the quantization matrix determined according to QP and slope coefficient. Simulation shows that, compared with rate control algorithm of basicunit in H.264, the proposed algorithm restricts coding time dramatically and controls bitrate precisely. Moreover, the peak signal noise ratio (PSNR) is increased with 021dB in the proposed algorithm.

Key words: rate control, prediction error, quantization matrix, quantization parameter