DC coefficient signaling at small quantization step sizes
First Claim
1. A computing device comprising a processor and memory, wherein the computing device implements a video decoder configured to perform operations comprising:
- receiving, in a bitstream, encoded data for a video picture; and
decoding the encoded data to reconstruct the video picture, including;
selecting a variable length code (VLC) table from among multiple sets of VLC tables, wherein a first set of the multiple sets of VLC tables is adapted for low motion video, and wherein a second set of the multiple sets of VLC tables is adapted for high motion video;
using the selected VLC table to decode a VLC from the encoded data in the bitstream, wherein the VLC, at least in part, indicates a value of a DC differential for a DC coefficient of a current block of the video picture, the DC differential representing a difference between the DC coefficient and a DC predictor; and
reconstructing the DC coefficient based at least in part on the value of the DC differential.
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Accused Products
Abstract
Described tools and techniques relate to signaling for DC coefficients at small quantization step sizes. The techniques and tools can be used in combination or independently. For example, a tool such as a video encoder or decoder processes a VLC that indicates a DC differential for a DC coefficient, a FLC that indicates a value refinement for the DC differential, and a third code that indicates the sign for the DC differential. Even with the small quantization step sizes, the tool uses a VLC table with DC differentials for DC coefficients above the small quantization step sizes. The FLCs for DC differentials have lengths that vary depending on quantization step size.
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Citations
20 Claims
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1. A computing device comprising a processor and memory, wherein the computing device implements a video decoder configured to perform operations comprising:
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receiving, in a bitstream, encoded data for a video picture; and decoding the encoded data to reconstruct the video picture, including; selecting a variable length code (VLC) table from among multiple sets of VLC tables, wherein a first set of the multiple sets of VLC tables is adapted for low motion video, and wherein a second set of the multiple sets of VLC tables is adapted for high motion video; using the selected VLC table to decode a VLC from the encoded data in the bitstream, wherein the VLC, at least in part, indicates a value of a DC differential for a DC coefficient of a current block of the video picture, the DC differential representing a difference between the DC coefficient and a DC predictor; and reconstructing the DC coefficient based at least in part on the value of the DC differential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A computer-implemented method of decoding video using a computing device that implements a video decoder, the method comprising, with the computing device that implements the video decoder:
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receiving, in a bitstream, encoded data for a video picture; and decoding the encoded data to reconstruct the video picture, including; selecting a variable length code (VLC) table from among multiple sets of VLC tables, wherein a first set of the multiple sets of VLC tables is adapted for low motion video, and wherein a second set of the multiple sets of VLC tables is adapted for high motion video; using the selected VLC table to decode a VLC from the encoded data in the bitstream, wherein the VLC, at least in part, indicates a value of a DC differential for a DC coefficient of a current block of the video picture, the DC differential representing a difference between the DC coefficient and a DC predictor; and reconstructing the DC coefficient based at least in part on the value of the DC differential. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. One or more computer-readable memory devices storing computer-executable instructions for causing a computer system programmed thereby to perform decoding operations comprising:
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receiving, in a bitstream, encoded data for a video picture; and decoding the encoded data to reconstruct the video picture, including; selecting a variable length code (VLC) table from among multiple sets of VLC tables, wherein a first set of the multiple sets of VLC tables is adapted for low motion video, and wherein a second set of the multiple sets of VLC tables is adapted for high motion video; using the selected VLC table to decode a VLC from the encoded data in the bitstream, wherein the VLC, at least in part, indicates a value of a DC differential for a DC coefficient of a current block of the video picture, the DC differential representing a difference between the DC coefficient and a DC predictor; and reconstructing the DC coefficient based at least in part on the value of the DC differential. - View Dependent Claims (20)
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Specification