Intra prediction modes signalling in HEVC The High Efficiency Video Coding (HEVC) standard defines 35 Intra Prediction Modes (IPM) to provide an efficient compression of intra coded blocks. To signal these IPMs to the decoder a list of 3 Most Probable Modes (MPM) is created based on the IPMs of the neighbour Intra coded blocks. These MPMs will be transmitted in the bit stream with a reduced number of bits. However, the signalling scheme used in HEVC is not optimal and can be further improved. In this paper a method is proposed to enhance the Intra mode signalling in HEVC. The IPM signaling is first modelled as a tree with forks and leaves representing tests and labels, respectively. The proposed solution introduces new decision tree process by adding new tests and new labels not considered in HEVC. This solution provides a systematic way to find the best signalling scheme for a given set of data. Experimental results show that the proposed solution enables to reduce the BDRate by 0.38% in all Intra coding configuration.

Enhancement on the Entropy Coding of Intra Mode in VVC The emerging Versatile Video Coding (VVC) standard introduces several intra prediction modes and intra mode coding techniques. Most Probable Mode (MPM) is derived to enable efficient signaling for the selected intra mode. We propose the modification of intra mode coding for the MPM index. The first bin of mpm_idx is adaptively coded by regular coding engine or bypass engine according to neighboring intra modes. Two versions of the VVC Test Model (VTM) 2.0 and VTM4.0 were used to verify the proposed method with different numbers of MPM. Experimental results in 3MPMs show 0.10%, 0.11%, 0.12% BDrate savings for Y, U, and V components, respectively, for All Intra (AI) configuration. And the other results in 6MPM show 0.05%, 0.08%, 0.07% BDrate gains. No noticeable changes in runtimes of both encoder and decoder are observed.