A hevc CTU-level code rate control method based on optimal bit allocation

Abstract

The invention discloses a HEVC CTU-level code rate control method based on optimal bit allocation, belonging to the field of video coding, specifically, in order to realize optimal bit allocation for the R-λ code rate control model in a coding tree unit (CTU) , propose a new R‑D estimate to replace the existing R‑λ estimate, and use it to deduce the optimal bit allocation equation. Furthermore, a recursive Taylor expansion algorithm is proposed to solve the original unsolvable equation with a fast convergence speed, and then obtain an approximate closed solution, so as to realize the optimal bit allocation. At the same time, the recursive Taylor expansion algorithm is also used to propose an optimal bit redistribution method for the remaining bits. The advantages of the present invention are: it is the first algorithm that realizes HEVC optimal bit allocation with very low coding complexity, and is superior to other existing R-R in terms of rate distortion, RC accuracy and robustness to dynamic picture transformation, etc. Lambda rate control model.

Description

technical field [0001] The invention relates to an HEVC CTU-level code rate control method based on optimal bit allocation, and belongs to the technical field of video coding. Background technique [0002] In the field of video coding, rate control aims to minimize distortion for a given bit rate of the compressed video. If the bitrate of the compressed video is greater than the bandwidth provided, the excess bits will accumulate in the encoding buffer, causing the video to skip frames if the buffer overflows. On the contrary, if the provided bandwidth is too large, bandwidth resources will be wasted, because these abundant bandwidth resources can be used to improve the quality of compressed video. Generally, at a given bit rate, rate control is implemented by optimizing bit allocation and then mapping the allocated bits to quantization parameters. Therefore, video coding rate control has two goals, the first is to use the best bit allocation to achieve the minimum distort...

AI Technical Summary

Problems solved by technology

However, for the HEVC standard, most existing cutting-edge rate control models mainly focus on achieving the second goal of rate control, which is to estimate the quantization parameter using the allocated bits, while some cutting-edge work is devoted to the first Goals, such as research on bit allocation for the R-λ model, have yet to achieve optimal bit allocation for HEVC rate control

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