ρ-domain source modeling and rate control for video coding and transmission

The coding bit rate, R, is considered as a function of ρ which is the percentage of zeros among the quantized DCT (discrete cosine transform) coefficients. We discover that the rate function, R(ρ), has some very interesting properties in the ρ-domain. By introducing the new concepts of characteristic rate curves and rate curve decomposition, a novel framework for source modeling is proposed. Using the proposed source model, we can estimate the rate-quantization (R-Q) curve before quantization and coding with relative error less than 5%. Based on the estimated R-Q curve, the output bit rate of the video encoder can be accurately controlled. Our extensive simulation results show that the proposed algorithm outperforms TMN8 (see Ribas-Corbera, J. and Lei, S., IEEE Trans. on Circuits and Systems for Video Technology, vol.9, p.172-85, 1999) and VM7 (see Chiang, T. and Zhang, Y.-Q., IEEE Trans. on Circuits and Systems for Video Technology, vol.7, p.246-50, 1997) rate control algorithms by providing more accurate and robust rate control