Interdigital Madison Patent Holdings, Sas

Interdigital Vc Holdings, Inc.

Gagan Rath

Fabrice Urban

Fabien Racape

Edouard Francois

A method and apparatus for performing intra prediction for encoding or decoding adds multiple prediction modes to those of prior intra prediction schemes. A horizontal mode, a vertical mode, and a diagonal mode are added. Reference pixels for each of the added modes can come from multiple pixel positions away from a block to be encoded or decoded. Reference pixels to the left and above a block are reconstructed from those already coded. Reference pixels from right of, and below, a block are estimated or extrapolated and can be based on other pixels around the block. An index can be sent in a bitstream indicating which prediction was used.

Intra prediction mode extension

Methods and apparatus for using wide-angle intra prediction for rectangular blocks enable greater prediction angles. Wide-angle intra prediction enables intra prediction direction angles beyond the conventional 45 and −135 degrees. In one embodiment, when a video block to be coded or decoded is non-square, additional intra prediction directions are enabled in the direction of the longer block edge and more reference samples are available along that edge. An index is used to indicate the prediction direction and can be adapted according to the additional intra predictions in the longer direction, with correspondingly fewer prediction directions along the shorter block edge. This preserves the number of prediction modes that need to be indexed but allows their angles to correspond to the shape of the block.

Directions for wide angle intra prediction

A method and apparatus for performing intra prediction mode partitioning predicts pixels of a video coding block using a plurality of intra prediction modes over a plurality of regions of the video coding block. Predictions can be based on reference arrays using at least one reference line above the block to be coded and/or using at least one reference column to the left of the block to be coded. Different prediction modes are used in different regions of the coding block. In at least one embodiment, the video coding block is split into a plurality of partitions in addition to having a plurality of intra prediction modes over different regions of the block. Signaling enables a decoder to determine the number of regions within a coding block. In at least another embodiment, prediction modes allowable within regions of a video coding block differ by one angular position.

Intra prediction mode partitioning

A method and apparatus for performing prediction for encoding or decoding uses intra prediction with sub-partitions. The sub-partitions are oriented either horizontally or vertically and can use wide-angle modes different than that of the video block they originate from. Reference samples for a sub-partition are those of the video block when reference samples for the sub-partition are not available, such as due to direction. In an embodiment, when a sub-partition is square, conventional intra prediction directions are used. Reference samples can be used from a block above and right of the video block or left and below the video block using a mapping along a prediction direction, vertically, or horizontally.

Wide angle intra prediction with sub-partitions

Methods and apparatus for performing intra prediction in an encoder or a decoder for non-square blocks enable a combination of reference samples from a row above the non-square block and a row to the left of the non-square block to be used for the prediction. In one embodiment, a weighted combination of reference samples are used. In another embodiment, the angles of prediction are extended in the longer direction of the non-square block, such that less angles of prediction are used in the shorter direction.

Wide angle intra prediction and position dependent intra prediction combination

A method of performing intra prediction for encoding or decoding uses multiple layers of reference samples. The layers are formed into reference arrays that are used by a function, such as a weighted combination, to form a final prediction. The weights can be variable, chosen from among a number of number of sets of weights. The prediction is used in encoding or decoding a block of video data. The weights can be determined in a number of ways, and for a given prediction mode, the same weights, or different weights can be used for all pixels in a target block. If the weights are varied, they can depend on the distance of the target pixel from reference arrays. An index can be sent indicating which set of weights is to be used.

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Bhubaneswar, India

Gagan Rath