Coded block pattern encoding with spatial prediction
AssigneeMicrosoft Corporation
InventorsChih-Lung Lin, Ming-Chieh Lee
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Abstract
The coded block parameters used to code blocks of image samples into structures called macroblocks are compressed more efficiently by exploiting the correlation between chrominance and luminance blocks in each macroblock. In particular, the coded block pattern for chrominance and luminance are combined into a single parameter for the macroblock and jointly coded with a single variable length code. To further enhance coding efficiency, the spatial coherence of coded block patterns can be exploited by using spatial prediction to compute predicted values for coded block pattern parameters.
Claims20
In a video encoder, a method of encoding one or more video images in a video sequence, the method comprising:
- for each macroblock of plural macroblocks in a video image, encoding a coded block pattern, wherein the macroblock comprises plural blocks, wherein the coded block pattern indicates which of the plural blocks of the macroblock have corresponding transform coefficient data in a bitstream, and wherein the encoding comprises for each macroblock of the plural macroblocks:
- for at least some blocks of the plural blocks of the macroblock, computing a predictor by spatial prediction on a block-by-block basis;
- and
- determining change information for at least part of the coded block pattern based at least in part on the coded block pattern and the predictor;
- encoding the change information as an entropy code, wherein the entropy code represents the change information;
- and
- outputting the entropy code in the bitstream.
In a video encoder, a method of encoding one or more video images in a video sequence, the method comprising:
- for each macroblock of plural macroblocks, encoding a coded block pattern, wherein the coded block pattern indicates which of plural blocks of the macroblock have corresponding transform coefficient data in a bitstream, and wherein the encoding comprises for each macroblock of the plural macroblocks:
- computing a predictor by spatial prediction, wherein the predictor includes plural predictor bits;
- determining information for the coded block pattern based at least in part on the coded block pattern and the plural predictor bits, wherein the information includes plural predictor adjustment bits;
- encoding the information as a variable length code, wherein the variable length code represents the information;
- and
- outputting the variable length code.
In a video encoder, a method of encoding one or more video images in a video sequence, the method comprising:
- for each intra-type macroblock of plural intra-type macroblocks, encoding a coded block pattern, wherein the coded block pattern indicates which of plural blocks of the intra-type macroblock have corresponding transform coefficient data in a bitstream, and wherein the encoding comprises for each intra-type macroblock of the plural intra-type macroblocks:
- computing a predictor by spatial prediction;
- determining information for the coded block pattern based at least in part on the coded block pattern and the predictor;
- and
- encoding the information as an entropy code, wherein the entropy code represents the information;
- and
- outputting an entropy code.
Dependencies are inferred from the claim text.