Local Illumination Compensation Buffer for Video Decoding Latency
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Solution Overview
Problem
Existing video compression techniques face inefficiencies due to the need for access to reconstructed pixels of neighboring blocks for Local Illumination Compensation (LIC), which introduces latency and disrupts conventional decoder pipeline architectures.
Innovation Solution
A Local Illumination Compensation (LIC) system that stores LIC parameters in a dedicated buffer, allowing for LIC application without requiring access to reconstructed pixels of neighboring blocks, by computing and storing LIC parameters based on specific sub-portions of decoded CUs and using them for subsequent CUs, thereby reducing memory load and improving coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LIC method is used requiring access to reconstructed pixels of neighboring blocks, then LIC can be applied for compensation, but latency increases and conventional decoder pipeline architecture is disrupted
Solution Approach 1:
The patent pre-computes and stores LIC parameters in a dedicated buffer during the encoding process, so that when decoding occurs, the parameters are already available without requiring access to neighboring reconstructed pixels. This preliminary computation eliminates the latency issue while maintaining LIC compensation accuracy.
Solution Approach 2:
The patent introduces a dedicated buffer as an intermediary storage mechanism that holds LIC parameters independently from the neighboring block pixel data. This intermediary allows the decoder to access LIC parameters without needing to access reconstructed pixels of neighboring blocks, thus resolving the contradiction between compensation accuracy and decoding latency.
2Reliability
If access to reconstructed pixels of neighboring blocks is required for LIC, then illumination compensation can be performed, but decoder pipeline architecture becomes more complex
Solution Approach 1:
The patent extracts the LIC parameter computation and storage from the conventional decoder pipeline that requires access to neighboring reconstructed pixels. By taking out this functionality and implementing it separately through pre-computed stored parameters, the patent simplifies the decoder pipeline architecture while maintaining illumination compensation capability.
Solution Approach 2:
The dedicated buffer acts as an intermediary that decouples the LIC parameter storage from the neighboring block pixel access requirement. This intermediary simplifies the decoder pipeline by providing a direct access path to LIC parameters without requiring complex coordination with neighboring block reconstruction processes.
3Productivity
If LIC parameters are stored in dedicated buffer for subsequent CUs, then memory load is reduced and coding efficiency improves, but memory usage increases
Solution Approach 1:
The patent changes the representation of LIC data from raw pixel-based parameters to compressed parameter indices stored in a dedicated buffer. This parameter transformation reduces the amount of data that needs to be stored and processed, improving coding efficiency while controlling memory usage through efficient parameter encoding.
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).