Intra Block Copy Reference Memory Segmentation for Video Decoding
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Solution Overview
Problem
Current video coding techniques face limitations in efficiently utilizing the reference sample memory for intra block copy (IBC) due to constrained memory sizes, which restricts the search range and efficiency of IBC, particularly in video compression standards like VVC where CTUs are divided into smaller blocks, limiting the availability of reference samples for IBC.
Innovation Solution
The proposed solution involves optimizing the reference sample memory by limiting its size to one, two, or three sets of 64×64 luma samples, allowing for more efficient utilization by storing reference samples across CTUs, enabling IBC to reference samples within specific memory constraints, and optimizing the search range for IBC by determining the availability of reference blocks based on their location within the CTU structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reference sample memory size is limited to reduce complexity and cost, then device complexity and memory cost are reduced, but the search range for intra block copy is restricted, reducing coding efficiency
Solution Approach 1:
The reference sample memory is segmented into multiple storage units, each capable of storing a portion of reference samples. This segmentation allows the system to manage limited memory resources efficiently while still providing access to sufficient reference samples for IBC operations across multiple CTUs.
Solution Approach 2:
The patent extends the reference sample storage beyond a single CTU by utilizing multiple storage units that can collectively hold reference samples from multiple CTUs. This dimensional expansion in memory organization allows the system to overcome the limitation of small memory size while maintaining efficient access patterns.
2Quantity of substance
If the reference sample memory stores only one set of 64x64 luma samples to minimize memory usage, then memory cost is reduced, but the availability of reference samples for IBC is limited, reducing compression efficiency
Solution Approach 1:
Each storage unit in the reference sample memory is designed to be multi-functional, capable of storing reference samples for different CTUs at different times. This universality allows the limited memory capacity to serve multiple purposes and support IBC operations across the entire picture, not just within a single CTU.
Solution Approach 2:
The system implements a dynamic memory management strategy where reference samples are discarded from storage units after being used for IBC operations, and new reference samples are recovered and stored in their place. This continuous discarding and recovering process allows the limited memory to effectively handle reference samples for multiple CTUs over time.
Data Source
AI summary
A method for video decoding at a decoder is provided. In the method, reconstructed samples of a reconstructed block of a picture are stored in a first reference sample memory. The first reference sample memory is configured to store at least one set of a number of luma samples and corresponding chroma samples of the reconstructed block. Further, reconstructed samples of a current block of the picture are stored in a second reference sample memory. The second reference sample memory is configured to store only one set of the number of luma samples and corresponding chroma samples of the current block. A current sub-block in the current block is reconstructed using an intra block copy (IBC) mode based on the stored reconstructed samples of a reference sub-block of the reconstructed block or the stored reconstructed samples of a reference sub-block of the current block.