Low-delay rate control for DCT video coding via rho-domain source modeling

By introducing the new concepts of characteristic rate curves and rate-curv e decomposition, a generic source-modeling framework is developed for trans form coding of videos. Based on this framework, the rate-quantization (R-Q) and distortion-quantization (D-Q) functions (collectively called R-D funct ions in this work) of the video encoder can be accurately estimated with ve ry low computational complexity before quantization and coding. With the ac curate estimation of the R-Q function, a frame-level rate control algorithm is proposed for DCT video coding. The proposed algorithm outperforms the T MN8 rate control algorithm by providing more accurate and robust rate regul ation and better picture quality. Based on the estimated R-D functions, an encoder-based rate-shape-smoothing algorithm is proposed. With this smoothi ng algorithm, the output bit stream of the encoder has both a smoothed rate shape and a consistent picture quality, which are highly desirable in prac tical video coding and transmission.