Layer-Aware Motion Vector Refinement for Multilayer Video Coding
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Solution Overview
Problem
Existing video coding technologies face challenges in handling motion vector refinement when reference pictures are from a different layer than the current picture, leading to errors such as division by zero, which degrade the user experience.
Innovation Solution
The method allows for selective disabling of motion vector refinement when reference pictures are from a different layer than the current picture, using a motion vector refinement flag to manage this process, and enables reference picture resampling for the entire coded video sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If motion vector refinement is applied when reference pictures are from a different layer, then coding precision may be improved, but errors such as division by zero occur degrading reliability
Solution Approach 1:
The patent applies preliminary anti-action by checking the layer relationship between current picture and reference pictures before performing motion vector refinement. The condition `if (refPicLayer != currentLayer) { dmvrFlag = 0; }` prevents the refinement process from executing when layer mismatch is detected, thereby avoiding division by zero errors and ensuring coding reliability while preserving precision when conditions are appropriate
2Manufacturing precision
If motion vector refinement is always enabled, then coding precision is maintained, but computational complexity and processing time increase
Solution Approach 1:
The patent implements dynamics by making the motion vector refinement process conditional rather than static. The `dmvrFlag` variable dynamically controls whether refinement is performed based on real-time assessment of layer compatibility and picture type conditions. This adaptive approach maintains precision when beneficial while reducing unnecessary computational complexity in inappropriate scenarios
3Reliability
If motion vector refinement is selectively disabled based on layer differences, then coding errors are prevented, but additional conditional checks increase processing overhead
Solution Approach 1:
The patent applies preliminary action by performing the layer comparison check `refPicLayer != currentLayer` before initiating the motion vector refinement process. This early detection mechanism prevents unnecessary processing and potential errors, ensuring reliability while minimizing time loss by avoiding both erroneous refinement operations and extensive error handling procedures
Data Source
AI summary
A method of decoding includes receiving the coded video bitstream, the coded video bitstream containing reference picture lists; obtaining reference pictures for a current picture from the reference picture lists; setting a motion vector refinement flag to a first value to enable motion vector refinement for a current block of the current picture when the reference pictures are in a same layer as the current picture; setting the motion vector refinement flag to a second value to disable the motion vector refinement for the current block of the current picture when the reference pictures are in a different layer than the current picture; and refining a motion vector corresponding to the current block when the motion vector refinement flag is set to the first value.