Video encoding mode decisions according to content categories
View Patent ↗In some embodiments, encoding modes for a video image block are enabled according to similarity measures of the block with respect to multiple content categories. Content categories may identify potentially overlapping content types such as sky, water, grass, skin, and red content. In a priority mode, the encoding modes specified by a priority content category (e.g. a red category) are selectively enabled for the block, regardless of the block's similarity to other (non-priority) content categories, provided the block is sufficiently similar to the priority category. In a dominant mode, the encoding modes enabled by a maximum-similarity content category are enabled for the block. In an all-inclusive mode, any mode enabled by any sufficiently-similar content category is enabled for the block. Enabled encoding modes may be further evaluated for selection for the block. Encoding modes may include inter/intra modes, macroblock partition sizes, and intra-prediction directions.
1. A video-encoder-implemented video encoding method comprising:
determining a plurality of similarity measures for a video image block, each similarity measure being an indicator of a similarity of the video image block to a content category selected from a plurality of content categories, the plurality of content categories including a subset of priority content categories and a subset of non-priority content categories, the plurality of content categories including the subsets of priority and non-priority of content categories being defined according to at least two subsets selected from a group consisting of texture, motion, edge and color content;
determining whether the similarity measure of the video image block with respect to a priority content category selected from the subset of the priority content categories exceeds a predetermined threshold
if the similarity measure of the video image block with respect to the priority content category exceeds the predetermined threshold, selecting an encoding mode for the video image block according to the priority content category and substantially independently of the non-priority content categories; and
if the similarity measure of the video image block with respect to at least one priority content category does not exceed the predetermined threshold, selecting an encoding mode for the video image block according to at least one of the non-priority content categories.
2. The method of claim 1 , wherein the plurality of content categories includes a red content category characterized by a minimum red content.
3. The method of claim 1 , wherein said each similarity measure characterizes a similarity of a set of neighbors of the video image block to the content category selected from the plurality of content categories.
4. The method of claim 1 , wherein said each similarity measure is proportional to a number of neighbors of the video image block that meet a similarity condition with respect to the content category selected from the plurality of content categories.
5. The method of claim 1 , wherein the subset of priority content categories includes at least two priority content categories having different priorities, and wherein selecting the encoding mode for the video image block is performed according to a maximum-priority content category selected from the subset of priority content categories.
6. The method of claim 1 , wherein selecting the encoding mode comprises selecting between an intra encoding mode and an inter encoding mode.
7. The method of claim 1 , wherein selecting the encoding mode comprises selecting a set of enabled intra-prediction directions for the video image block.
8. The method of claim 1 , wherein selecting the encoding mode comprises selecting an enabled block partition size for the video image block.
9. A video-encoder-implemented video encoding method comprising:
determining a plurality of similarity measures of a video image block with respect to a corresponding plurality of content categories, each content category in the plurality of content categories having at least one subset selected from a group consisting of texture, motion and color;
selecting a maximum-similarity content category from the plurality of content categories according to the plurality of similarity measures;
selecting an encoding mode for the video image block according to a set of encoding modes enabled by the maximum-similarity content category; and
wherein said each similarity measure is proportional to a number of neighbors of the video image block that meet a similarity condition with respect to a corresponding content category.
10. The method of claim 9 , wherein each similarity measure characterizes a similarity of a set of neighbors of the video image block to a corresponding content category.
11. The method of claim 9 , wherein selecting the encoding mode comprises selecting between an intra encoding mode and an inter encoding mode.
12. The method of claim 9 , wherein selecting the encoding mode comprises selecting a set of enabled intra-prediction directions for the video image block.
13. The method of claim 9 , wherein selecting the encoding mode comprises selecting an enabled block partition size for the video image block.
14. A video-encoder-implemented video encoding method comprising:
determining a plurality of similarity measures of a video image block with respect to a corresponding plurality of content categories that are defined according to at least two subsets selected from a group consisting of texture, motion, edge and color content; and
enabling a set of encoding modes for the video image block according to the plurality of similarity measures and according to a set of enabled encoding modes defined for the plurality of content categories, wherein an encoding mode in the set of encoding modes for the video image block is enabled, only if the encoding mode is enabled by a content category in the plurality of content categories and if a corresponding similarity measure of the video image block with respect to the content category indicates that the video image block is sufficiently similar to the content category.
15. The method of claim 14 , wherein the similarity measure of the video image block with respect to the content category characterizes a similarity of a set of neighbors of the video image block to the content category.
16. The method of claim 14 , wherein the similarity measure of the video image block with respect to the content category is proportional to a number of neighbors of the video image block that meet a similarity condition with respect to the content category.
17. The method of claim 14 , wherein enabling the set of encoding modes comprises enabling at least one encoding mode selected from an intra encoding mode and an inter encoding mode.
18. The method of claim 14 , wherein enabling the set of encoding modes comprises enabling an intra-prediction direction for the video image block.
19. The method of claim 14 , wherein enabling the set of encoding modes comprises enabling a block partition size for the video image block.
20. A video-encoder-implemented video encoding method comprising:
(1) setting a value of an encoding-mode parameter for a block in a video frame to a combination of a plurality of content-category-level parameters defined for a corresponding plurality of content categories, the combination being based on a plurality of weights that are associated with the plurality of content categories;
(2) determining each weight in the plurality of weights by;
(a) determining whether a content of the block meets a qualification condition with respect to the content category in the plurality of content categories, wherein the qualification condition depends on a content of the block;
(b) when the qualification condition is met, setting said each weight to be proportional to a number of neighbors of the block meeting a similarity condition with respect to the content category; and
(3) selecting an encoding mode for the block according to the value of the encoding mode parameter for the block.
21. The method of claim 20 , wherein the combination is a weighted linear combination, wherein each weight in the weighted linear combination characterizes a similarity of the block to a content category.
22. A video encoder comprising: a content category processing unit enabling an encoding mode and setting at least one quantization precision indicator for a block in a video frame, (1) according to a set of similarity measures of the block with respect to a plurality of content categories and (2) according to a set of encoding modes enabled by the plurality of content-categories,
encoding logic connected to the content category processing unit, the encoding logic encoding the block according to the encoding mode and the at least one quantization precision indicator;
wherein the plurality of content categories being defined according to at least two subsets selected from a group consisting of texture, motion, edge and color content; and
wherein the set of encoding mode comprises an intra encoding mode, an inter encoding mode, a mode for selecting a set of enabled intra-prediction direction for the video image block, and a mode for selecting an enabled block partition size for the video image block.