Research On Transform Technology And Rate Distortion Optimization Technology Of Video Coding

Video coding technology has been developed for decades and has brought a lot of convenience to human's daily life.However,there are still two problems need to be solved,low real-time and the lack of coding performance.New technologies was adopted by HEVC and VVC,which results in high complexity and insufficient speed of encoding and decoding.And high video resolution makes the coding performance of the existing video coding technology inadequate.Starting from the coding standards of H.265/HEVC and H.266/VVC,this paper will deeply explore the techniques of video coding transformation and rate-distortion optimization,so as to achieve the goal of reducing the complexity of video coding and better compression of video.The main research work and innovation points are as follows:1.A fast calculation method based on matrix decomposition is proposed for DCT-4/DST-4 matrix in transformation technology.The characteristics of DCT-4/DST-4 matrix are analyzed in detail,the shortcomings compared with DCT-2 matrix and the reason why DCT-4/DST-4 matrix can still be calculated rapidly are analyzed,because it has the origin symmetry without considering the sign.On this basis,a fast calculation method based on 4×4 matrix is proposed,which can reduce the multiplication times by 43.75%.Further more,the fast calculation of all 4×4 matrices is taken into account as a whole,and the intermediate variables of repeated calculation are found,which can reduces the required addition times.On the basis of the previous method,a fast calculation method based on 2×2matrix is proposed,and The Times of multiplication can be reduced to?3/4?of the original method.The fast calculation method based on 4×4 matrix is applied to VTM3.0.1,a testing platform of H.266/VVC,which uses the general video sequence of video coding standard to test.The experimental results show that the coding time is reduced by 3.7%and the decoding time is reduced by 9.4%,without any performance loss.2.For the time-domain rate distortion optimization technology under random access hierarchy,the shortcomings of the independent rate distortion optimization technology used in existing encoding standards and the time-domain dependency under random access hierarchy are analyzed,and a time-domain propagation chain is constructed based on it.Then,the rate-distortion optimization problem is decomposed into a time-domain-based form,and the propagation factor is introduced to estimate the degree of distortion propagation,and the calculated propagation factor is used to correct the rate-distortion optimization process.This method takes into account the correlation between frames,making up for the previous lack of independent rate distortion optimization.Experiments show that in VTM3.0,a test platform for H.266/VVC,this method achieves an average of 0.76%BD-Rate savings for encoding under RA conditions,and 1.5%BD-Rate savings on E sequences with a clear correlation between frames for video sequences with a fixed background.