Study Of Rate Control In H.264 Encoder

H.264 standard is the advanced video standard at present. It has low bit rate, high compression ratio, suitable net transport features. The rate control scheme of H.264 encoder is very important, as it can seriously affects the quality of encoder video sequence. The rate control scheme is varied in the different application. The classification and method of rate control scheme is introduced at first in the thesis. Two conventional rate control schemes are studied in the following. These schemes have been used in video encoder of H.263+ and MPEG-2.H.264 standard is more complicated than previous standard (such as H.263+), so the conventional rate control schemes can't be used in H.264 encoder process. Based on studying the two conventional rate control schemes of video standard and the rate control scheme of H.264 reference code, an approved rate control scheme of H.264 encoder is designed in the thesis. The scheme calculate rate control in two layers (macroblock layer and frame layer), the performance is approved than H.264 reference code.The approved rate control scheme is completed in two difference layers, the low layer is macroblock-layer, the high layer is frame-layer. The QP (Quantization Parameter) of each macroblock is calculated in macroblock-layer, the target bits of each frame is allocated in frame-layer. The coefficients of MAD are calculated using the method of least squares. The RTL code of the scheme is designed. The simulation and synthesis of the RTL code are completed.