Optimal adaptive quantizing in low bit rate video coding

Most existing rate control techniques for low bit-rate video aim at finding optimal quantization values which effect the image quality for inter-coding frames. By analyzing the relationship between quantization distortion and the coding order and considering influences of intra-coding frames in video coding, we present a novel adaptive quantization scheme. First, quantization parameter's calculation order is dependent upon the macroblock activity, not the coding scan order. Second, quantization values of intra-coding frames can be modified according to their spatial activities. We implement our technique in H.263 and compare its performance to TMN8 rate control. The experimental results show that the suggested algorithm performs better than TMN8 in terms of PSNR and improves the image subjective quality.