Multiple Sign Bit Hiding Within a Transform Unit
AssigneeVelos Media, LLC
InventorsJing Wang, Xiang Yu, Dake He
Life of this patent
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Abstract
Methods of encoding and decoding for video data are described for encoding or decoding coefficients for a transform unit. In particular, the sign bits for the non-zero coefficients are encoded using sign bit hiding. Two or more sets of coefficients are defined for the transform unit and a sign bit may be hidden for each set, subject to satisfaction of a threshold test. The sets may correspond to coefficient groups that are otherwise used in multi-level significance map encoding and decoding.
Claims9
A method of decoding a bitstream of encoded video, by reconstructing coefficients for a transform unit, comprising:
- for each coefficient group, in a transform unit, that includes a first non-zero coefficient and a last non-zero coefficient:
- determining that a number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds a threshold;
- and
- based on the determination that the number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds the threshold, apply sign bit hiding by:
- summing, to produce a summing result, absolute values of the non-zero coefficients in the coefficient group, and
- based on the summing result, assigning a sign to a coefficient in the coefficient group.
A decoder for decoding a bitstream of encoded video, by reconstructing coefficients for a transform unit, the decoder comprising:
- a processor;
- a memory;
- and
- a decoding application stored in memory and containing instructions that, when executed, cause the decoder to:
- for each coefficient group, in a transform unit, that includes a first non-zero coefficient and a last non-zero coefficient:
- determine that a number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds a threshold;
- and
- based on the determination that the number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds the threshold, apply sign bit hiding, whereby the instructions, when executed by the processor, cause the decoder to:
- sum, to produce a summing result, an absolute value of the coefficients in the coefficient group, and
- based on the summing result, assign a sign to the coefficient in the coefficient group.
A non-transitory processor-readable medium storing processor-executable instructions, which, when executed by a processor, causes the processor to decode a bitstream of encoded video, by reconstructing coefficients for a transform unit, and wherein the instructions, when executed, further cause the processor to:
- for each coefficient group, in a transform unit, that includes a first non-zero coefficient and a last non-zero coefficient:
- determine that a number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds a threshold;
- and
- based on the determination that the number of coefficients between the first non-zero coefficient in the coefficient group and the last non-zero coefficient in the coefficient group exceeds the threshold, apply sign bit hiding, whereby the instructions, when executed, cause the processor to:
- sum, to produce a summing result, an absolute value of the coefficients in the coefficient group, and
- based on the summing result, assign a sign to the coefficient in the coefficient group.
Dependencies are inferred from the claim text.