Method based on Coding Tree Unit Level Rate-Distortion Optimization for Rate Control in Video Coding

An encoding method in an encoding device using coding tree unit (CTU) level rate-distortion (R-D) optimization for rate control (RC) in video coding, comprising:

• generating, in an encoding device, multiple frames of a received input video in a frame generating module;
• generating, in the coding device, one or more coding tree units from at least one frame of the received input video;
• dividing a frame of the input video into one or more CTUs in a CTU module;
• determining one or more CTU level coding bits through R-D performance optimization, comprising using a divisive normalization framework to characterize a CTU level perceptual distortion (D′(R)), in relation with a CTU level mean square error (MSE) distortion (D(R)), and a divisive normalized factor (f), by:
• D′(R)=D(R)/f2,
• where R is the CTU level coding bit rate;
• wherein the relationship between the perceptual distortion D′(R) and the bit rate R is depicted with a R-D logarithmic model:
• D′(R)=ln(c×R−k)
• where c and k are model parameters depending on the video content;
• estimating the model parameters k of the frame on basis of the coding statistics of a previous frame;
• wherein an optimal value of a parameter kj for a j-th CTU in the current frame is obtained by minimizing the difference between a true distortion Dreal of a co-located j-th CTU in the previous frame and an estimated distortion Dcomp for the j-th CTU of the current frame;
• and
• generating a video bitstream based on coded video.