Multi-level representation of reordered transform coefficients
First Claim
1. A computing device comprising a processing unit, memory and storage media storing computer-executable instructions which, when executed, cause the computing device to perform a method of encoding video, the method comprising:
- selecting one of a plurality of scan orders;
outputting information indicating the selected scan order in a bit stream;
applying the selected scan order to reorder plural frequency coefficients of a block;
entropy coding the reordered plural frequency coefficients using a multi-level nested-set representation of the reordered plural frequency coefficients, including;
representing a first set of one or more of the reordered plural frequency coefficients as a summary representation with a first symbol at a first level of the multi-level nested-set representation;
entropy coding the first symbol and a second symbol at the first level of the multi-level nested-set representation; and
at a given level of the multi-level nested set representation that is lower than the first level;
encoding plural symbols at the given level, each of the plural symbols at the given level representing a set of one or more of the reordered plural frequency coefficients; and
for each of the plural symbols at the given level, determining whether to split the set for the symbol into plural subsets and, if so, encoding plural sub-symbols at a lower level of the multi-level nested-set representation, each of the plural sub-symbols at the lower level representing one of the plural subsets; and
outputting the entropy coded frequency coefficients in the bit stream.
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Abstract
Techniques and tools for encoding and decoding a block of frequency coefficients are presented. An encoder selects a scan order from multiple available scan orders and then applies the selected scan order to a two-dimensional matrix of transform coefficients, grouping non-zero values of the frequency coefficients together in a one-dimensional string. The encoder entropy encodes the one-dimensional string of coefficient values according to a multi-level nested set representation. In decoding, a decoder entropy decodes the one-dimensional string of coefficient values from the multi-level nested set representation. The decoder selects the scan order from among multiple available scan orders and then reorders the coefficients back into a two-dimensional matrix using the selected scan order.
212 Citations
29 Claims
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1. A computing device comprising a processing unit, memory and storage media storing computer-executable instructions which, when executed, cause the computing device to perform a method of encoding video, the method comprising:
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selecting one of a plurality of scan orders; outputting information indicating the selected scan order in a bit stream; applying the selected scan order to reorder plural frequency coefficients of a block; entropy coding the reordered plural frequency coefficients using a multi-level nested-set representation of the reordered plural frequency coefficients, including; representing a first set of one or more of the reordered plural frequency coefficients as a summary representation with a first symbol at a first level of the multi-level nested-set representation; entropy coding the first symbol and a second symbol at the first level of the multi-level nested-set representation; and at a given level of the multi-level nested set representation that is lower than the first level; encoding plural symbols at the given level, each of the plural symbols at the given level representing a set of one or more of the reordered plural frequency coefficients; and for each of the plural symbols at the given level, determining whether to split the set for the symbol into plural subsets and, if so, encoding plural sub-symbols at a lower level of the multi-level nested-set representation, each of the plural sub-symbols at the lower level representing one of the plural subsets; and outputting the entropy coded frequency coefficients in the bit stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a computing device that implements a video encoder, a method of encoding video, the method comprising:
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selecting one of a plurality of scan orders; outputting information indicating the selected scan order in a bit stream; applying the selected scan order to reorder plural frequency coefficients of a block; with the computing device that implements the video encoder, entropy coding the reordered plural frequency coefficients using a multi-level nested-set representation of the reordered plural frequency coefficients, including; representing a first set of one or more of the reordered plural frequency coefficients as a summary representation with a first symbol at a first level of the multi-level nested-set representation; entropy coding the first symbol and a second symbol at the first level of the multi-level nested-set representation; and at a given level of the multi-level nested set representation that is lower than the first level; encoding plural symbols at the given level, each of the plural symbols at the given level representing a set of one or more of the reordered plural frequency coefficients; and for each of the plural symbols at the given level, determining whether to split the set for the symbol into plural subsets and, if so, encoding plural sub-symbols at a lower level of the multi-level nested-set representation, each of the plural sub-symbols at the lower level representing one of the plural subsets; and outputting the entropy coded frequency coefficients in the bit stream. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification