Adaptive multiple quantization
First Claim
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1. A method of coding/decoding video, comprising:
- signaling a quantizer specifier mode for the video sequence, the quantizer specifier mode indicating if a deadzone-to-step size ratio of a quantizer is implicitly signaled from a value of a syntax element representing a quantizer scale or explicitly signaled at a frame level;
adaptively selecting among multiple quantizers based at least in part on bit rate constraints for coding a picture in a video sequence, wherein said adaptively selecting comprises a selection from quantizers having at least two different deadzone-to-step size ratios; and
quantizing transform coefficients for blocks of the picture using the adaptively selected quantizer having the deadzone-to-step size ratio implicitly or explicitly signaled at frame level.
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Abstract
With adaptive multiple quantization, a video or other digital media codec can adaptively select among multiple quantizers to apply to transform coefficients based on content or bit rate constraints, so as to improve quality through rate-distortion optimization. The switch in quantizers can be signaled at the sequence level or frame level of the bitstream syntax, or can be implicitly specified in the syntax.
204 Citations
15 Claims
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1. A method of coding/decoding video, comprising:
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signaling a quantizer specifier mode for the video sequence, the quantizer specifier mode indicating if a deadzone-to-step size ratio of a quantizer is implicitly signaled from a value of a syntax element representing a quantizer scale or explicitly signaled at a frame level; adaptively selecting among multiple quantizers based at least in part on bit rate constraints for coding a picture in a video sequence, wherein said adaptively selecting comprises a selection from quantizers having at least two different deadzone-to-step size ratios; and quantizing transform coefficients for blocks of the picture using the adaptively selected quantizer having the deadzone-to-step size ratio implicitly or explicitly signaled at frame level. - View Dependent Claims (2, 3)
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4. The method of decoding a compressed video sequence using adaptive multiple quantization, the method comprising:
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decoding a quantizer specifier element signaled for the compressed video sequence; decoding syntax elements for individual pictures from the compressed video sequence indicating which of multiple quantizers to use on the respective individual pictures of the compressed video sequence based at least in part on the quantizer specifier element signaled for the compressed video sequence, wherein at least one choice of value of the quantizer specifier element indicates an adaptive choice of deadzone-to-step size ratio type of the quantizers to use on individual pictures is coded by the syntax elements for said individual pictures; and inverse quantizing quantized transform coefficients of the individual pictures using the respective quantizer indicated by the decoded syntax elements to use on the individual pictures. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform a method comprising:
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decoding a quantizer specifier element signaled for a compressed video sequence; decoding syntax elements for individual pictures from the compressed video sequence indicating which of multiple quantizers to use on the respective individual pictures of the compressed video sequence based at least in part on the quantizer specifier element signaled for compressed video sequence, wherein at least one choice of value of the quantizer specifier element indicates an adaptive choice of deadzone-to-step size ratio type of the quantizers to use on individual pictures is coded by the syntax elements for said individual pictures; and inverse quantizing quantized transform coefficients of the individual pictures using the respective quantizer indicated by the decoded syntax elements to use on the individual pictures. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification