Modified contexts for level coding of video data
AssigneeResearch In Motion Limited
InventorsXiang YU, Jing WANG, Dake HE
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Abstract
Methods and devices for reconstructing coefficient levels from a bitstream of encoded video data for a coefficient group in a transform unit, and corresponding methods and devices for encoding are provided. The method of reconstructing includes, for each of the non-zero coefficients in the coefficient group, in scan order, decoding a greater-than-one flag for that non-zero coefficient if fewer than two previously-decoded greater-than-one flags for that coefficient group are equal to one. The coefficient levels for the non-zero coefficients are reconstructed based, at least in part, upon the decoded greater-than-one flags.
Claims20
A method of reconstructing, from a bitstream of encoded video data, coefficient levels for a coefficient group in a transform unit, wherein the bitstream includes encoded significant-coefficient flags indicating non-zero coefficients in the coefficient group, the method comprising:
- for each of the non-zero coefficients in the coefficient group, in a scan order, decoding a greater-than-one flag for that non-zero coefficient if fewer than two previously-decoded greater-than-one flags for that coefficient group are equal to one;
- and
- reconstructing the coefficient levels for the non-zero coefficients based, at least in part, upon the decoded greater-than-one flags.
A decoder for reconstructing, from a bitstream of encoded video data, coefficient levels for a coefficient group in a transform unit, wherein the bitstream includes encoded significant-coefficient flags indicating non-zero coefficients in the coefficient group, the decoder comprising:
- a processor;
- a memory;
- and
- a decoding application stored in memory and containing instructions for configuring the processor to:
- for each of the non-zero coefficients in the coefficient group, in a scan order, decode a greater-than-one flag for that non-zero coefficient if fewer than two previously-decoded greater-than-one flags for that coefficient group are equal to one;
- and
- reconstruct the coefficient levels for the non-zero coefficients based, at least in part, upon the decoded greater-than-one flags.
A method of encoding coefficient levels for a coefficient group in a transform unit to generate a bitstream of encoded video data, the method comprising:
- encoding significant-coefficient flags for the coefficient group in a scan order, wherein the significant coefficient flags indicate non-zero coefficients;
- and
- for each of the non-zero coefficients in the coefficient group, in the scan order, encoding a greater-than-one flag for that non-zero coefficient if fewer than two previously-encoded greater-than-one flags for that coefficient group are equal to one.
Dependencies are inferred from the claim text.