A Universal Rate Control Scheme for Video Transcoding

Video transcoding is proposed for the bitrate adaption, spatial and/or temporal resolutions adaption, and video format conversion. In video streaming application, it converts videos at server to the compatible versions demanded by networks or clients´ devices, so that the videos can be delivered over networks and displayed in the clients´ devices successfully. This paper provides a universal rate control scheme for various video transcoding purposes. First, a new rate-distortion (R-D) model is established theoretically for better representing the real R-D feature of transcoding. Second, a window-level rate control algorithm is proposed for providing smooth visual quality with compliant buffer constraint by utilizing the two-pass R-D model and a new proposed sliding window buffer control strategy. Finally, a universal rate control scheme for transcoding is developed based on the established R-D model and the proposed window-level rate control algorithm. The extensive experimental results demonstrate that as compared to other state-of-the-art rate control algorithms for transcoding, the proposed scheme can achieve more bit control accuracy with the average mismatch below 0.2%, and much more consistent visual quality with 0.1 dB-0.3 dB peak-to-signal noise ratio improvement in average, while with low computational complexity.