Block-Level BDOF Control for Reference Picture Resampling
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Solution Overview
Problem
Existing video coding technologies face inefficiencies when dealing with bi-directional optical flow (BDOF) due to the need to disable it for an entire coded video sequence when reference picture resampling is enabled, leading to increased resource usage and reduced user experience.
Innovation Solution
The ability to selectively enable or disable BDOF for individual blocks based on the spatial resolution match between current and reference pictures, allowing for refined motion vector processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BDOF is enabled for the entire coded video sequence when reference picture resampling is enabled, then motion vector refinement is improved, but processor and memory resource usage increases
Solution Approach 1:
The patent applies local quality by enabling BDOF selectively at the block level rather than uniformly across the entire video sequence. Each block is evaluated independently based on whether its reference pictures have the same resolution, allowing the refinement process to be applied only where necessary (when resolutions match) and skipped where unnecessary (when resolutions differ), thus optimizing the balance between precision and resource consumption.
Solution Approach 2:
The patent segments the coded video sequence into individual blocks and evaluates each block independently for BDOF applicability. This segmentation allows the system to apply BDOF refinement only to specific blocks where reference pictures have matching resolutions, rather than processing the entire sequence uniformly, thereby reducing overall computational burden while maintaining precision where needed.
2Use of energy by moving object
If BDOF is disabled for the entire coded video sequence when reference picture resampling is enabled, then processor and memory resource usage is reduced, but coding efficiency deteriorates
Solution Approach 1:
The patent restores coding efficiency by applying BDOF locally to blocks where it is beneficial (those with matching reference picture resolutions) while avoiding it where it would be wasteful (blocks with mismatched resolutions). This selective application maintains the precision benefits of BDOF for relevant blocks without incurring the full resource cost of sequence-wide application.
Solution Approach 2:
The patent implements partial action by applying BDOF refinement only to the subset of blocks where reference pictures have the same resolution, rather than applying it to all blocks. This partial application is sufficient to maintain coding efficiency for the majority of blocks where resolution matching occurs, while avoiding excessive resource consumption on blocks where resolution mismatch makes BDOF inapplicable.
3Measurement precision
If BDOF is applied to blocks with different resolution reference pictures, then motion vector refinement is performed, but processing accuracy deteriorates
Solution Approach 1:
The patent ensures processing accuracy by applying BDOF refinement only to blocks where the reference pictures have the same resolution as the current block. This local quality control prevents the application of refinement algorithms to incompatible blocks, thereby maintaining the reliability and accuracy of the motion vector refinement process where it is actually beneficial.
Data Source
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AI summary
A method of decoding implemented by a video decoder including determining, by the video decoder, whether a resolution of a current picture being decoded is the same as the resolution of reference pictures identified by a reference picture list associated with the current picture; enabling, by the video decoder, bi-direction optical flow (BDOF) for a current block of the current picture when the resolution of the current picture is determined to be the same as the resolution of each of the reference pictures; disabling, by the video decoder, the BDOF for the current block of the current picture when the resolution of the current picture is determined to be different than the resolution of either of the reference pictures; and refining, by the video decoder, motion vectors corresponding to the current block using the BDOF when the BDOF is enabled for the current block.