US 2016/0080742 A1 · CODING OF SIGNIFICANCE MAPS AND TRANSFORM COEFFICIENT BLOCKS

Abstract

A higher coding efficiency for coding a significance map indicating positions of significant transform coefficients within a transform coefficient block is achieved by the scan order by which the sequentially extracted syntax elements indicating, for associated positions within the transform coefficient block, as to whether at the respective position a significant or insignificant transform coefficient is situated, are sequentially associated to the positions of the transform coefficient block, among the positions of the transform coefficient block depends on the positions of the significant transform coefficients indicated by previously associated syntax elements. Alternatively, the first-type elements may be context-adaptively entropy decoded using contexts which are individually selected for each of the syntax elements dependent on a number of significant transform coefficients in a neighborhood of the respective syntax element, indicated as being significant by any of the preceding syntax elements.

Claims21

Dependent claims

An apparatus for decoding a transform coefficient block, the apparatus comprising:

a decoder configured to extract, from a data stream, a significance map indicating positions of significant transform coefficients within the transform coefficient block, and the significant transform coefficients within the transform coefficient block;
and
an associator configured to associate the extracted significant transform coefficients with their respective positions in the transform coefficient block in a coefficient scan order, wherein according to the coefficient scan order, sub-blocks of the transform coefficient block are scanned in a sub-block scan order, and the transform coefficients within each sub-block are scanned in a position sub-scan order,
wherein the decoder is configured to use, in extracting the significant transform coefficients, context-adaptive entropy decoding, a selected set of contexts from a plurality sets of contexts, wherein, for each sub-block, the selected set of contexts is determined based on a statistic of the transform coefficients within a previously traversed sub-block of the transform coefficient block, or a statistic of the transform coefficients of a co-located sub-block in a previously decoded transform coefficient block.

1 more element

An apparatus for encoding a transform coefficient block, wherein the apparatus is configured to code, using context-adaptive entropy encoding, significant transform coefficients within the transform coefficient block into a data stream, wherein the apparatus is configured to code the significant transform coefficients in a coefficient scan order, wherein, according to the coefficient scan order, the transform coefficient block is scanned in sub-blocks of the transform coefficient block in a sub-block scan order, and the transform coefficients within each sub-block are scanned in a position sub-scan order,

wherein the apparatus is further configured to use, in context-adaptive entropy encoding, a selected set of contexts from a plurality sets of contexts, wherein, for each sub-block, the selected set is based on a statistic of the transform coefficients within a previously traversed sub-block of the transform coefficient block, or a statistic of the transform coefficients of a co-located sub-block in a previously encoded transform coefficient block.

A data stream stored in a non-transitory storage medium, the data stream comprising an encoded significance map indicating positions of significant transform coefficients within a transform coefficient block, and the significant transform coefficients within the transform coefficient block, wherein the significant transform coefficients are coded into the data stream by context-adaptive entropy encoding in a coefficient scan order, wherein, according to the coefficient scan order, sub-blocks of the transform coefficient block are scanned in a sub-block scan order, and the transform coefficients within each sub-block are scanned in a position sub-scan order,

wherein the significant transform coefficients are context-adapted entropy encoded using a selected set of contexts from a plurality sets of contexts, wherein, for each sub-block, the selected set is determined based on a statistic of the transform coefficients within a previously traversed sub-block of the transform coefficient block, or a statistic of the transform coefficients of a co-located sub-block in a previously encoded transform coefficient block.

A non-transitory computer readable digital storage medium comprising stored thereon a computer program comprising a program code for performing, when running on a computer, a method for decoding a transform coefficient block, the method comprising:

extracting, from a data stream, a significance map indicating positions of significant transform coefficients within the transform coefficient block, and the significant transform coefficients;
and
associating the extracted significant transform coefficients with their respective positions in the transform coefficient block in a coefficient scan order, wherein, according to the coefficient scan order, sub-blocks of the transform coefficient block are scanned in a sub-block scan order, and the transform coefficients within each sub-block are scanned in a position sub-scan order,
wherein, in extracting the significant transform coefficients based on context-adaptive entropy decoding, a selected set of contexts from a plurality sets of contexts is used, wherein, for each sub-block, the selected set is determined based on a statistic of the transform coefficients within a previously traversed sub-block of the transform coefficient block, or a statistic of the transform coefficients of a co-located sub-block in a previously decoded transform coefficient block.

1 more element

Dependencies are inferred from the claim text.

Coding of significance maps and transform coefficient blocks

Life of this patent

Coding of significance maps and transform coefficient blocks

Life of this patent

Abstract

Claims21