Cluster Adapted Signalling for Intra Prediction in HEVC

Abstract

International audienceThe High Efficiency Video Coding (HEVC) standard defines 35 Intra Prediction Modes (IPM) to provide an efficient compression of intra coded blocks. Those IPMs are signalled to the decoder through the use of three compression tools: prediction, clustering and coding. In this paper we provide improvements to these three tools through: new labels for the prediction, new tests for the clustering and new coding schemes for the coding. The most significant improvement consists in the provision of a cluster-dependent code: adapting the coding scheme to the available information enables the average symbol cost to get within close margin of the entropy of the data. The system providing the best compression efficiency based on these improvements is then computed, enabling significant reduction in the average cost required to code the IPMs. The proposed method builds a new coding system with the same complexity as HEVC with 0.41% bit-rates savings in All Intra coding configuration

Dynamic Lists for Efficient Coding of Intra Prediction Modes in the Future Video Coding Standard

“…The encoding and decoding run times are presented in Table VII. The results published in [34] and [35] emphasis better BD-BR results (−0.4%) with similar systems, it has to be noted that their implementations do not consider the complexity introduced by the increased number of MPM for the RD search in HEVC. The implementation for the system proposed in this work asserts that the number of modes tested in RD remains exactly the same as for the anchor.…”

“…In the case of Intra prediction, the PUs are square of sizes N × N and 2N × 2N with the associated CU of size 2N × 2N , N ∈ {4, 8, 16}. HEVC defines 35 IPMs including 1 planar mode, 1 DC mode and 33 directional modes to predict the PU pixels from the neighbour decoded pixels [20]. The IPMs are signalled in the bitstream to the decoder at the CU level and then all PUs associated to this CU share the same IPM [21].…”

“…both Intra and Inter coded slices. The number of IPMs has increased from 14 modes in AVC [11] to 35 and 67 in HEVC and JEM, respectively. These modes cover a wider range of directions towards the reference pixels to enhance the accuracy and efficiency of Intra prediction (See Fig.…”