Local Illumination Compensation for Video Decoding Latency
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Solution Overview
Problem
Current video coding technologies face challenges in reducing redundancy and improving compression efficiency, particularly in handling illumination changes across pictures, which affects the accuracy of prediction and reconstruction in video decoding.
Innovation Solution
The implementation of Local Illumination Compensation (LIC) mode in video encoding and decoding, where LIC parameters are derived to adjust predictions based on neighboring regions, enabling more accurate reconstruction and reducing latency by parallelizing inter-coded blocks while minimizing memory access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional video coding without illumination compensation is used, then decoding complexity is low, but prediction accuracy deteriorates under illumination changes
Solution Approach 1:
The patent introduces illumination compensation parameters (a and b) that modify the prediction process by adjusting for illumination changes. These parameters are derived from neighboring blocks and applied to compensate for brightness and contrast variations, thereby improving prediction accuracy without fundamentally changing the decoding architecture
Solution Approach 2:
The illumination compensation parameters are derived in advance from neighboring blocks before the actual prediction is performed. This preliminary derivation allows the compensation to be applied during the prediction process without adding significant computational overhead during decoding
2Loss of time
If sequential decoding of blocks is performed, then memory access is simplified, but decoding latency increases
Solution Approach 1:
The patent divides the current picture into multiple blocks that can be decoded independently in parallel. By deriving illumination compensation parameters for each block separately and using only already-decoded neighboring blocks, the method enables parallel processing while maintaining correctness
Solution Approach 2:
The illumination compensation parameters act as intermediaries that are pre-computed from neighboring blocks and then used during parallel prediction. This allows parallel blocks to access compensation information without requiring complex synchronization or additional memory accesses
3Measurement precision
If illumination compensation is applied, then prediction accuracy improves, but computational load increases
Solution Approach 1:
The patent applies illumination compensation selectively based on whether neighboring blocks are available and whether illumination changes are detected. The compensation is applied partially only where needed, avoiding unnecessary computations in blocks where neighboring information is unavailable or where illumination changes are minimal
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 processing circuitry that decodes prediction information for a plurality of first blocks in a current coded picture that is a part of a coded video sequence. The prediction information indicates that the plurality of first blocks is coded in a local illumination compensation (LIC) mode. The processing circuitry selects a neighboring region for each of the plurality of first blocks. The selected neighboring region and the respective first block form a second block. The processing circuitry performs an inter prediction for the plurality of second blocks in parallel. The processing circuitry determines a set of LIC parameters for each of the plurality of first blocks based on the selected neighboring region of the respective first block and reconstructs the plurality of first blocks based on the sets of LIC parameters.