US 9,866,829 B2 · Coding of syntax elements that correspond to coefficients of a coefficient block in video coding

Abstract

A video encoder performs multiple coding passes on coefficients in a coefficient block. During each coding pass, the video encoder encodes a different set of syntax elements for coefficients in the coefficient block. A video decoder uses the syntax elements for a coefficient to determine the value of the coefficient. When the video encoder performs a coding pass, the video encoder selects a coding context for a syntax element based at least in part on a syntax element generated in an earlier coding pass for a non-causal coefficient and based at least in part on a value of a syntax element generated during the current coding pass for a causal coefficient. The video encoder entropy encodes the syntax element based on the selected coding context. A video decoder performs a similar series of coding passes in which the video decoder selects coding contexts and entropy decodes the syntax elements.

Claims48

Dependent claims

A method for encoding video data, the method comprising:

generating, based on one or more predictive blocks and a block of the video data, a residual sample block;
generating, based on the residual sample block, a coefficient block;
encoding, during a first coding pass of coefficients of the coefficient block, a first set of syntax elements that correspond to coefficients of the coefficient block;
and
encoding, during a second coding pass of the coefficients of the coefficient block, a second set of syntax elements that correspond to at least some of the coefficients of the coefficient block, wherein encoding the second set of syntax elements comprises:
generating a first syntax element, the first syntax element being in the second set of syntax elements and corresponding to a current coefficient of the coefficient block;
selecting, based at least in part on a second syntax element and a third syntax element, a coding context for the first syntax element, wherein the second syntax element is in the first set of syntax elements and corresponds to a non-causal coefficient, wherein the third syntax element is in the second set of syntax elements and corresponds to a causal coefficient, the non-causal coefficient occurring after the current coefficient in a coding order of the second coding pass, the causal coefficient occurring before the current coefficient in the coding order of the second coding pass;
and
entropy encoding, based at least in part on the coding context selected for the first syntax element, the first syntax element.

6 more elements

A video encoding device that comprises:

a memory configured to store video data;
and
one or more processors configured to:
generate, based on one or more predictive blocks and a block of the video data, a residual sample block;
generate, based on the residual sample block, a coefficient block;
encode, during a first coding pass of coefficients of the coefficient block, a first set of syntax elements that correspond to coefficients of the coefficient block;
and
encode, during a second coding pass of the coefficients of the coefficient block, a second set of syntax elements that correspond to at least some of the coefficients of the coefficient block, wherein the one or more processors are configured such that during the second coding pass the one or more processors:
generate a first syntax element, the first syntax element being in the second set of syntax elements and corresponding to a current coefficient of the coefficient block;
select, based at least in part on a second syntax element and a third syntax element, a coding context for the first syntax element, wherein the second syntax element is in the first set of syntax elements and corresponds to a non-causal coefficient, wherein the third syntax element is in the second set of syntax elements and corresponds to a causal coefficient, the non-causal coefficient occurring after the current coefficient in a coding order of the second coding pass, the causal coefficient occurring before the current coefficient in the coding order of the second coding pass;
and
entropy encode, based at least in part on the coding context selected for the first syntax element, the first syntax element.

9 more elements

A method for decoding video data, the method comprising:

decoding, during a first coding pass of coefficients of a coefficient block, a first set of syntax elements that correspond to coefficients of the coefficient block;
decoding, during a second coding pass of the coefficients of the coefficient block, a second set of syntax elements that correspond to at least some of the coefficients of the coefficient block, wherein decoding the second set of syntax elements comprises:
selecting, based at least in part on a second syntax element and a third syntax element, a coding context for a first syntax element, the first syntax element being in the second set of syntax elements and corresponding to a current coefficient of the coefficient block, wherein the second syntax element is in the first set of syntax elements and corresponds to a non-causal coefficient, wherein the third syntax element is in the second set of syntax elements and corresponds to a causal coefficient, the non-causal coefficient occurring after the current coefficient in a coding order of the second coding pass, the causal coefficient occurring before the current coefficient in the coding order of the second coding pass;
and
entropy decoding, based at least in part on the coding context selected for the first syntax element, the first syntax element;
generating, based on the coefficients of the coefficient block, a residual sample block;
and
reconstructing, based on one or more predictive blocks and the residual sample block, a block of the video data.

5 more elements

A video decoding device that comprises:

a memory configured to store video data;
and
one or more processors configured to:
decode, during a first coding pass of coefficients of a coefficient block, a first set of syntax elements that correspond to coefficients of the coefficient block;
decode, during a second coding pass of the coefficients of the coefficient block, a second set of syntax elements that correspond to at least some of the coefficients of the coefficient block, wherein the one or more processors are configured such that during the second coding pass, the one or more processors:
select, based at least in part on a second syntax element and a third syntax element, a coding context for a first syntax element, the first syntax element being in the second set of syntax elements and corresponding to a current coefficient of the coefficient block, wherein the second syntax element is in the first set of syntax elements and corresponds to a non-causal coefficient, wherein the third syntax element is in the second set of syntax elements and corresponds to a causal coefficient, the non-causal coefficient occurring after the current coefficient in a coding order of the second coding pass, the causal coefficient occurring before the current coefficient in the coding order of the second coding pass;
and
entropy decode, based at least in part on the coding context selected for the first syntax element, the first syntax element;
generate, based on the coefficients of the coefficient block, a residual sample block;
and
reconstruct, based on one or more predictive blocks and the residual sample block, a block of the video data.

8 more elements

Dependencies are inferred from the claim text.

Coding of syntax elements that correspond to coefficients of a coefficient block in video coding

Life of this patent

Coding of syntax elements that correspond to coefficients of a coefficient block in video coding

Life of this patent

Abstract

Claims48