Blackberry Corporation

Xiaofeng Wang

Dake He

Jing Wang

Tianying Ji

David Flynn

Methods and devices for encoding and decoding video are described that partition transform blocks into coefficient groups. The coefficients within non-zero coefficients are run-length coded in a reverse scan order within the group. Prior to coefficient coding, data is encoded indicating which coefficient group in group scan order is the last to contain a non-zero coefficient. Then data is encoded indicating the position within that last non-zero coefficient group of the last non-zero coefficient in scan order inside the coefficient group. Thus the decoder is able to decode run-length data knowing the positions of the coefficients and eliminating the need for end-of-block flags.

Transform coefficient coding for context-adaptive binary entropy coding of video

Methods and devices for encoding and decoding video using mode-dependent context determination in the case of level-run pair coding of transform coefficients are described. Intra-coding modes may be grouped into classes and each class may be associated with a partitioning of a coefficient group into regions. The region in which a coefficient falls determines, in part, the context selected for encoding bins associated with that coefficient, including a level, if the coefficient is non-zero, and a run if the coefficient correspond to the bin of a binarized run value.

Context determination for entropy coding of run-length encoded transform coefficients

Methods and devices for video coding are described. If an intra-prediction mode to be used in encoding a block of residual data is in a specific predetermined class, e.g., the horizontal class, then at least a portion of a quantized transformed block of residual data is transposed during encoding. Likewise, if an intra-prediction mode that was used to generate an encoded block of residual data is in such a class, then at least a portion of an entropy-decoded block of residual data is transposed during decoding.

Transposing a block of transform coefficients, based upon an intra-prediction mode

Methods and devices for video coding are described. When encoding a non-zero coefficient group (CG) prior to the last such group in a group scan ordering within a transform block, data representative of the true (x,y)-position of the last non-zero transform coefficient in a scan ordering within that CG is modified, to improve coding efficiency, based upon at least one of (a) an intra-prediction mode used to encode the block and (b) at least one coefficient group neighboring that CG. Upon decoding a CG thus encoded, the modification is un-done to retrieve the true (x,y)-position.

Growing community of inventors

Markham, Canada

Xiaofeng Wang