HEVC (High Efficiency Video Coding) CTU (Coding Tree Unit) grade code rate control method based on optimal bit allocation

Abstract

The invention discloses an HEVC (High Efficiency Video Coding) CTU (Coding Tree Unit) grade code rate control method based on optimal bit allocation, and belongs to the field of video coding. In particular, a new R-D estimation is provided to replace an existing R-lambda estimation, and an optimal bit allocation equation is deduced through the new R-D estimation, thereby realizing optimal bit allocation for an R-lambda code rate control model on a CTU. Furthermore, a recursive Taylor expansion algorithm is provided to solve the originally-unsolvable equation at a very high convergence speed, thereby obtaining an approximate closed-form solution, and realizing optimal bit allocation. Meanwhile, a method for performing optimal bit reallocation on remaining bits is provided through the recursive Taylor expansion algorithm. The code rate control method is a first algorithm for realizing HEVC optimal bit allocation at very low coding complexity. The code rate control method has the advantages of higher rate distortion, higher RC accuracy and higher robustness in dynamic picture change compared with other existing R-lambda code rate control models.

Description

technical field [0001] The invention relates to an HEVCCTU-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 distorti...

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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