Intra Block Copy Buffer Default Value Refreshing
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Solution Overview
Problem
Current video coding technologies face challenges in achieving improved compression ratios with minimal sacrifice in picture quality, especially when dealing with limited network resources and increasing demands for higher video quality, due to constraints in bitstream conformance and memory usage in intra block copy (IBC) referencing.
Innovation Solution
The implementation of a dedicated buffer for IBC referencing, initialized with default values, which removes block vector validation bitstream conformance constraints, allowing for robustness in coded bitstreams and avoiding undefined samples, thereby eliminating the need for additional memory and bitstream conformance checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated buffer for IBC referencing is implemented with default value initialization, then robustness of coded bitstream is improved and undefined samples are avoided, but device complexity increases due to additional buffer structure
Solution Approach 1:
The buffer is pre-initialized with default values (e.g., -1) before use, ensuring that any undefined or uninitialized samples are immediately identifiable and can be handled appropriately. This preliminary action prevents undefined behavior in IBC prediction while maintaining a relatively simple buffer structure without requiring complex validation logic during decoding.
2Ease of operation
If block vector validation bitstream conformance constraints are removed, then ease of operation is improved and robustness increases, but measurement precision worsens due to lack of validation checks
Solution Approach 1:
The patent extracts and removes the complex block vector validation bitstream conformance constraints from the decoding process. By taking out these restrictive validation checks, the system achieves easier operation and improved robustness, allowing more flexible IBC prediction while relying on the pre-initialized buffer to prevent undefined sample access rather than complex runtime validation.
3Manufacturing precision
If additional line memory is allocated for IBC prediction, then manufacturing precision is improved and undefined samples are avoided, but loss of substance increases due to additional memory resources
Solution Approach 1:
Instead of allocating additional line memory throughout the system, the patent applies a localized solution by initializing specific buffer regions with default values where IBC reference samples are stored. This local quality approach ensures precision in IBC prediction by marking undefined areas with default values (-1) without requiring extensive additional memory resources across the entire decoding system.
Data Source
AI summary
A method of coding implemented by a decoding device, comprising initializing a dedicated buffer for intra block copy (IBC) referencing, when a current coding tree unit (CTU) to be decoded is a first CTU of a CTU row, determining whether a current block in the current CTU is predicted using IBC mode, obtaining an IBC block vector for the current block when the current block is predicted using IBC mode, and obtaining predicted sample values for the current block, based on reference samples from the dedicated buffer and the IBC block vector for the current block.