Method and apparatus for omnidirectional video coding with adaptive intra most probable modes

Abstract

In omnidirectional videos, only some intra prediction directions may be relevant for intra prediction. For example, for a video generated from an equi-rectangular mapping, only the horizontal directions may be relevant for intra prediction around the poles. To improve compression efficiency, we propose to reduce the number of possible directions, based on the location of the block to be encoded or decoded in the frame. In various embodiments, we may adapt the derivation of the MPM in order to take into account the reduction of intra directions depending on geometric distortions. The encoding method can also be adapted to reduce the number of modes to estimate for a block in omnidirectional videos. The coding of the syntax elements representing the intra direction can also be improved.

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