Systems and methods for template matching for adaptive MVD resolution
The various implementations described herein include methods and systems for coding video. The methods include receiving a motion vector difference (MVD) of a video block from the video stream; in response to a determination that an adaptive MVD resolution mode of an inter prediction mode is signaled, searching for a first template of a prediction video block for the video block, and the first/second template is the neighboring reconstructed/predicted samples of the prediction video block/current block, and the prediction video block is a reconstructed/predicted forward or backward video block of the video block; locating the first template of the prediction video block that is a best match for a second template of the video block; refining a motion vector (MV) of the video block based on at least the second template, the located first template, and the MVD; and reconstructing/processing the video block based on at least the refined MV.
1. A method of decoding a video stream performed at a computing system having memory and control circuitry, the method comprising:
determining, based on a value of an inter-prediction syntax element from the video stream, whether an adaptive motion vector difference (MVD) resolution mode is signaled, the adaptive MVD resolution mode being an inter-prediction mode with adaptive motion vector difference (MVD) pixel resolution;
receiving a motion vector difference (MVD) of a video block from the video stream;
in response to a determination that the adaptive MVD resolution mode is signaled, searching for a first template of a prediction video block for the video block, wherein the first template is neighboring reconstructed samples of the prediction video block, and the prediction video block is a reconstructed forward or backward video block of the video block;
locating the first template of the prediction video block that is a best match for a second template of the video block, the second template being neighboring reconstructed samples of the video block corresponding to a temporally collocated template of the first template;
refining a motion vector (MV) of the video block based on at least the second template, the located first template, and the MVD; and
reconstructing the video block based on at least the refined MV.
2. The method of claim 1 , wherein searching for the first template of the prediction video block for the video block comprises determining a search area size based on a magnitude of the MVD and searching based on the search area size.
3. The method of claim 2 , wherein determining the search area size based on the magnitude of the MVD comprises increasing the search area as the magnitude of the MVD increases or keeping the search area unchanged as the magnitude of the MVD increases.
4. The method of claim 2 , wherein determining the search area size based on the magnitude of the MVD comprises determining a same search area when the MVD is in the same MV class.
5. The method of claim 2 , wherein determining the search area size based on the magnitude of the MVD comprises determining a same search area when the magnitude of the MVD is equal to or greater than a threshold.
6. The method of claim 1 , wherein refining the MV of the video block comprises determining a refining granularity of the MV based on the magnitude of the MVD.
7. The method of claim 6 , wherein determining the refining granularity of the MV based on the magnitude of the MVD comprises implementing a fractional precision MV refinement only when the magnitude of the MVD is equal to or less than a threshold.
8. The method of claim 1 , wherein refining the MV of the video block comprises restricting the MV to one or more pre-determined directions during refining.
9. The method of claim 1 , wherein searching for the first template of the prediction video block for the video block comprises determining a search direction based on a direction of the MVD and searching based on the search direction.
10. The method of claim 1 , wherein before searching, determining, based on a second syntax element from the video stream, whether a template matching mode is signaled for the one or more video blocks, and conducting searching in response to a determination that the template matching mode is signaled.
11. The method of claim 10 , wherein the second syntax element is signaled in one or more of sequence level, frame level, and/or slice level.
12. The method of claim 10 , wherein when the adaptive MVD resolution mode is signaled, a finest allowed MVD resolution depends on whether the template matching mode is signaled.
13. A computing system comprising a memory for storing computer instructions and control circuitry in communication with the memory, wherein the control circuitry, when executing the computer instructions, is configured to cause the computing system to perform a method of decoding a video stream, the method including:
determining, based on a value of an inter-prediction syntax element from the video stream, whether an adaptive motion vector difference (MVD) resolution mode is signaled, the adaptive MVD resolution mode being an inter-prediction mode with adaptive motion vector difference (MVD) pixel resolution;
receiving a motion vector difference (MVD) of a video block from the video stream;
in response to a determination that the adaptive MVD resolution mode is signaled, searching for a first template of a prediction video block for the video block, wherein the first template is neighboring reconstructed samples of the prediction video block, and the prediction video block is a reconstructed forward or backward video block of the video block;
locating the first template of the prediction video block that is a best match for a second template of the video block, the second template being neighboring reconstructed samples of the video block corresponding to a temporally collocated template of the first template;
refining a motion vector (MV) of the video block based on at least the second template, the located first template, and the MVD; and
reconstructing the video block based on at least the refined MV.
14. The computing system of claim 13 , wherein searching for the first template of the prediction video block for the video block comprises determining a search area size based on a magnitude of the MVD and searching based on the search area size.
15. The computing system of claim 14 , wherein determining the search area size based on the magnitude of the MVD comprises increasing the search area as the magnitude of the MVD increases or keeping the search area unchanged as the magnitude of the MVD increases.
16. The computing system of claim 14 , wherein determining the search area size based on the magnitude of the MVD comprises determining a same search area when the MVD is in the same MV class.
17. The computing system of claim 14 , wherein determining the search area size based on the magnitude of the MVD comprises determining a same search area when the magnitude of the MVD is equal to or greater than a threshold.
18. The computing system of claim 13 , wherein refining the MV of the video block comprises determining a refining granularity of the MV based on the magnitude of the MVD.
19. The computing system of claim 13 , wherein searching for the first template of the prediction video block for the video block comprises determining a search direction based on a direction of the MVD and searching based on the search direction.
20. A non-transitory computer readable medium for storing computer instructions, the computer instructions, when executed by control circuitry of a computing system, cause the computing system to perform a method of decoding a video stream including:
determining, based on a value of an inter-prediction syntax element from the video stream, whether an adaptive motion vector difference (MVD) resolution mode is signaled, the adaptive MVD resolution mode being an inter-prediction mode with adaptive motion vector difference (MVD) pixel resolution;
receiving a motion vector difference (MVD) of a video block from the video stream;
in response to a determination that the adaptive MVD resolution mode is signaled, searching for a first template of a prediction video block for the video block, wherein the first template is neighboring reconstructed samples of the prediction video block, and the prediction video block is a reconstructed forward or backward video block of the video block;
locating the first template of the prediction video block that is a best match for a second template of the video block, the second template being neighboring reconstructed samples of the video block corresponding to a temporally collocated template of the first template;
refining a motion vector (MV) of the video block based on at least the second template, the located first template, and the MVD; and
reconstructing the video block based on at least the refined MV.