Stored Illumination Compensation for Low-Latency Video Decoding
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Solution Overview
Problem
Existing video encoding and decoding methods require access to reconstructed pixels of neighboring blocks for Local Illumination Compensation (LIC), which introduces latency and disrupts conventional decoder pipeline architectures.
Innovation Solution
A system that uses stored illumination compensation (IC) parameters, decoupled from coding unit level storage, and computes LIC parameters on-the-fly or beforehand, allowing for efficient LIC without requiring access to reconstructed neighboring pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LIC method is used requiring access to reconstructed neighboring pixels, then LIC can be applied to improve coding efficiency, but latency is introduced and decoder pipeline architecture is disrupted
Solution Approach 1:
The patent pre-computes LIC parameters for reference pictures before the actual decoding process. These pre-computed parameters are stored and then applied during decoding, eliminating the need to wait for reconstructed neighboring pixels and thus reducing latency while maintaining coding efficiency improvements
Solution Approach 2:
The patent introduces an intermediary mechanism where LIC parameters are computed and stored in a buffer before being applied to current blocks. This intermediary buffer decouples the LIC parameter computation from the actual decoding process, allowing conventional decoder pipeline architecture to be maintained while still benefiting from LIC
2Productivity
If LIC parameters are computed on-the-fly during decoding, then coding efficiency is improved, but computational complexity and processing time increase
Solution Approach 1:
The patent performs LIC parameter computation in advance during encoding or picture buffer preparation, rather than computing them on-the-fly during decoding. This preliminary computation shifts the computational burden to a more suitable timing when reference pictures are already available, reducing real-time computational complexity while maintaining coding efficiency
Solution Approach 2:
The system uses already-reconstructed reference pictures to compute LIC parameters self-service during the encoding process, making these parameters available for subsequent decoding operations without requiring complex real-time computations during decoding
3Loss of time
If stored LIC parameters are used instead of computing them during decoding, then latency is reduced and pipeline architecture is maintained, but memory storage requirements increase
Solution Approach 1:
The patent stores LIC parameters at the picture or slice level rather than at the block level, and only stores parameters when needed (e.g., when inter prediction is used). This localized storage approach reduces overall memory requirements while still providing the necessary parameters to reduce latency during decoding operations
Data Source
AI summary
A Local illumination compensation system for video encoding and decoding uses memory for storing illumination compensation parameters and does not require access to reconstructed pixels of neighboring blocks. A set of illumination compensation parameters is stored in a dedicated buffer, which is of limited size, and which is decoupled from the coding unit level storage of information. The buffer contains a set of illumination compensation parameters, which may be, for example, computed (or determined in some other manner) on the fly or determined beforehand (for example for example obtained from the video signal or from a device).