Video Coding Conformance Check for Inter Prediction Modes
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Solution Overview
Problem
Current video coding technologies face challenges in efficiently handling inter prediction modes when the current picture is used as a reference picture, leading to invalid coded video bitstreams due to compatibility issues with tools like affine merge mode, merge mode with motion vector difference, triangular prediction mode, and intra-inter mode.
Innovation Solution
The proposed solution involves processing circuitry that decodes prediction information from a coded video bitstream, performs conformance checks to determine the validity of the bitstream based on usage information, and reconstructs samples using default motion vectors or temporal reference pictures when the current picture is used as a reference, excluding it from merge lists and using sub-block based temporal motion vector prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inter prediction modes are used with the current picture as a reference picture, then video coding flexibility is improved, but bitstream validity deteriorates due to compatibility issues with tools like affine merge mode, merge mode with motion vector difference, triangular prediction mode, and intra-inter mode
Solution Approach 1:
The prediction process is segmented into multiple stages: conformance checking of usage information, determination of bitstream validity, and conditional reconstruction. This segmentation allows the system to identify and handle incompatible prediction modes separately, preventing bitstream invalidity while maintaining flexibility for compatible modes.
Solution Approach 2:
A conformance check mechanism acts as an intermediary between the prediction mode selection and the actual prediction process. This intermediary validates usage information against reference picture constraints before execution, preventing incompatible modes from causing bitstream invalidity while allowing compatible modes to proceed.
2Reliability
If the current picture is excluded from merge lists and default motion vectors are used, then bitstream conformance is improved, but prediction accuracy deteriorates
Solution Approach 1:
The system dynamically changes parameters based on conformance check results: when the current picture is used as a reference, usage information for incompatible modes is modified or restricted, and default motion vectors are applied. This parameter adaptation maintains bitstream conformance while preserving adequate prediction accuracy through alternative valid modes.
3Productivity
If sub-block based temporal motion vector prediction is implemented, then compression efficiency is improved, but computational complexity increases
Solution Approach 1:
The current picture is divided into sub-blocks for temporal motion vector prediction, where each sub-block can have its own motion vector derived from corresponding sub-blocks in reference pictures. This segmentation enables finer-grained motion compensation, improving compression efficiency while distributing computational load across multiple smaller units.
Solution Approach 2:
Motion vectors for sub-blocks are predicted in advance from temporal reference pictures before the actual reconstruction process. This preliminary action reduces the amount of data that needs to be encoded and transmitted, improving compression efficiency while the prediction calculations are performed during the decoding phase.
Data Source
AI summary
Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes receiving circuitry and processing circuitry. The processing circuitry decodes prediction information of a current block within a current picture from a coded video bitstream. The prediction information is indicative of usage information of an inter prediction mode that is not compatible with using the current picture as a reference picture for the current block. Then, the processing circuitry determines whether the coded video bitstream is valid based on a conformance check of the usage information to the reference picture for the current block.