Blackberry Corporation

Velos Media, LLC

Tianying Ji

Dake He

Nguyen Nguyen

Jing Wang

Xiaofeng Wang

Xiang Yu

Methods of encoding and decoding for video data are described for encoding or decoding multi-level significance maps. Distinct context sets may be used for encoding the significant-coefficient flags in different regions of the transform unit. In a fixed case, the regions are defined by coefficient group borders. In one example, the upper-left coefficient group is a first region and the other coefficient groups are a second region. In a dynamic case, the regions are defined by coefficient group borders, but the encoder and decoder dynamically determine in which region each coefficient group belongs. Coefficient groups may be assigned to one region or another based on, for example, whether their respective significant-coefficient-group flags were inferred or not.

Methods and devices for context set selection

Methods of encoding and decoding for video data are described in which multi-level significance maps are used in the encoding and decoding processes. The significant-coefficient flags that form the significance map are grouped into contiguous groups, and a significant-coefficient-group flag signifies for each group whether that group contains no non-zero significant-coefficient flags. If there are no non-zero significant-coefficient flags in the group, then the significant-coefficient-group flag is set to zero. The set of significant-coefficient-group flags is encoded in the bitstream. Any significant-coefficient flags that fall within a group that has a significant-coefficient-group flag that is non-zero are encoded in the bitstream, whereas significant-coefficient flags that fall within a group that has a significant-coefficient-group flag that is zero are not encoded in the bitstream.

Multi-level significance maps for encoding and decoding

Methods of encoding and decoding for video data are described in which multi-level significance maps are used in the encoding and decoding processes. The significant-coefficient flags that form the significance map are grouped into contiguous groups, and a significant-coefficient-group flag signifies for each group whether that group contains no non-zero significant-coefficient flags. A multi-level scan order may be used in which significant-coefficient flags are scanned group-by-group. The group scan order specifies the order in which the groups are processed, and the scan order specifies the order in which individual significant-coefficient flags within the group are processed. The bitstream may interleave the significant-coefficient-group flags and their corresponding significant-coefficient flags, if any.

Multi-level significance map scanning

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 decoding, in a video decoder, a block of enhancement-layer transform domain data for an enhancement-layer encoded video and corresponding to a reconstructed block of reference-layer transform domain data, are provided. The method includes determining a context for an enhancement-layer element based, at least in part, upon elements in the corresponding reconstructed block of reference-layer transform domain data, wherein the elements are identified by a template and wherein the position of the template in the reference-layer reconstructed block is based upon the position of that enhancement-layer element in the block of enhancement-layer transform domain data.

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Albany, CA, United States of America

Tianying Ji