Research On Technology Of Inter-prediction And Rate-distortion Optimization In Video Coding

In the era of rapid development of science and technology,technological innovation in the field of images have brought convenience and high-quality experience to people 's daily lives,which are irreplaceable.Therefore,the further development of this field is given high expectation.With the improvement of video resolution,the amount of data information carried by videos has also increased dramatically.It takes up a lot of bandwidth occupation during video transmission.At the same time,it is urgent to solve the shortage of storage space caused by video data.Video coding has attracted widespread attention as a key to solving these problems.Two major international organizations——the ITU_T and ISO have collaborated on several video coding standards.In this thesis,we will thoroughly explore the technology of inter prediction and rate-distortion optimization.All researches are based on H.265/HEVC or H.266/VVC.In order to improve the efficiency and quality of video coding,the main efforts and innovations are as follows:1.Aiming at a kind of technique in inter prediction which is called HMVP,we optimize it according to its shortcomings.The process of adding HMVP candidates to the Merge candidate list,which needs multiple redundancy checks.It seriously affects the complexity of video coding.Therefore,an optimization method is researched.In this method,the nearest motion candidate in HMVP list is not used,and the number of candidates in the process of redundancy check is restricted.In this way,the maximum number of redundancy checks will be reduced.At last,the method is applied to the H.266/VVC reference software VTM3.0,universal video sequence of the video coding standard is adopted to test.In LD configuration,both of encoding time and decoding time are reduced.2.Aiming at the motion compensation for 360-degree video mapping to cube.The process of mapping and the shortcoming of videos with more irregular motion under translational motion compensation model are specifically analyzed.A linear projection is introduced to represent the warped motion model.Finally,the warped motion model is introduced into coding process with locally adaptive.This method is applied to the H.265 / HEVC reference software HM16.6.In LD and RA configuration,the method can bring some BD-rate savings.3.Aiming at rate-distortion optimization in low delay configuration,we analyze the temporal relationship under the low delay condition and deficiencies of independent rate-distortion optimization which is used in current coding standards.A propagation factor is introduced into rate-distortion optimization.Moreover,the method of calculating distortion is revised.This method is applied to the H.266/VVC reference software VTM3.0,which uses the universal video sequence of the video coding standard for testing.In LD configuration,the BD-rate achieves certain savings.