发明名称 Methods and devices for context set selection
摘要 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.
申请公布号 US9584812(B2) 申请公布日期 2017.02.28
申请号 US201213354485 申请日期 2012.01.20
申请人 BlackBerry Limited 发明人 Ji Tianying;Nguyen Nguyen;He Dake
分类号 H04N7/30;H04N19/129;H04N19/176;H04N19/51;H04N19/593 主分类号 H04N7/30
代理机构 Rowand LLP 代理人 Rowand LLP
主权项 1. A method of decoding a bitstream of encoded video by reconstructing significant-coefficient flags for a transform unit, the transform unit comprising a sequence of blocks in a scan order, the bitstream encoding sets of significant-coefficient flags, each set corresponding to a respective block, each block having an associated significant-coefficient-group flag that indicates whether the significant-coefficient flags corresponding to that block are to be decoded from the bitstream or may be inferred to be zero, the method comprising: (i) for a set of significant-coefficient flags corresponding to a first block with an associated non-zero significant-coefficient-group flag, selecting a context set from a plurality of context sets for use in decoding significant-coefficient flags of that set based on a significant-coefficient-group flag associated with a block to the right of the first block and a significant-coefficient-group flag associated with a block below the first block, wherein the context sets identify the contexts to be used in context-adaptively decoding the significant-coefficient flags of that set of significant-coefficient flags, and wherein selecting includes selecting a first context set if both of the significant-coefficient-group flags are non-zero, and, otherwise, selecting a different, mutually exclusive context set; (ii) entropy decoding the significant-coefficient flags of that set using the selected context set by, for each significant-coefficient flag, selecting a context from within the selected context set for context-adaptively decoding that significant-coefficient flag; and (iii) moving to the next block in the scan order and returning to operation (i), wherein each significant-coefficient-group flag indicates whether its associated block is presumed to contain at least one non-zero significant-coefficient flag, wherein for each block in the sequence of blocks that has an associated significant coefficient-group flag that is decoded to be zero, there are no non-zero significant-coefficient flags in that block, and for each block in the sequence of blocks that has an associated significant-coefficient-group flag that is decoded to be non-zero, there is at least one non-zero significant-coefficient flag in that block, and wherein for each block in the sequence of blocks that has an associated significant-coefficient-group flag that is zero, all of the significant-coefficient flags in that block are set to zero instead of performing the selecting operation and the entropy decoding operation.
地址 Waterloo CA