Video Coding Intra Block Copy Reference Area Exclusion
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra picture block compensation due to constraints in search range during intra block copy mode, leading to delays and increased processing time when reconstructing samples from adjacent CTUs.
Innovation Solution
The proposed solution involves excluding the reconstructed samples of adjacent CTUs from the reference area for intra block copy mode, using padding samples to replace them, and accessing faster on-chip memory for reconstructed samples from neighboring CTUs to expedite the reconstruction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reconstructed samples of adjacent CTUs are used as reference samples for intra block copy mode, then prediction accuracy is improved, but processing time increases due to delays in accessing and reconstructing these samples
Solution Approach 1:
The patent extracts and excludes the problematic adjacent CTU from the reference area, separating it from the normal reference sample usage. By taking out the adjacent CTU that causes processing delays, the system can still perform intra block copy using other valid reference samples without the time penalty of waiting for those specific samples to be reconstructed.
Solution Approach 2:
The patent introduces padding samples as an intermediary element to fill the reference area where adjacent CTU samples would normally be used. These padding samples act as placeholders that allow the reference area to be fully populated without actually accessing the delayed reconstructed samples from adjacent CTUs, thus mediating between the need for complete reference data and the reality of processing delays.
2Quantity of substance
If the reference area includes adjacent CTUs, then more reference samples are available for intra block copy, but device complexity increases due to additional constraints and memory access requirements
Solution Approach 1:
The patent removes the adjacent CTU from the reference area definition, simplifying the system architecture by eliminating the need for complex constraints and additional memory access mechanisms that would be required to properly handle and coordinate the reconstruction of adjacent CTU samples.
Solution Approach 2:
The patent uses padding samples as temporary, disposable placeholders that fill the reference area without requiring permanent or complex storage mechanisms. These padding samples are simple values that can be easily generated and used, avoiding the need for complex memory management and sample coordination systems.
3Speed
If faster on-chip memory is used to access reconstructed samples, then processing speed improves, but device complexity and cost increase
Solution Approach 1:
The patent introduces padding samples as an intermediary that eliminates the need for fast memory access to adjacent CTU reconstructed samples. By using these placeholder samples, the system can operate with simpler, slower memory architectures without sacrificing the ability to perform intra block copy prediction.
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 receiving circuitry and processing circuitry. According to an aspect of the disclosure, the processing circuitry decodes prediction information of a current block in a first coding tree unit (CTU) in a picture from a coded video bitstream. The prediction information is indicative of an intra block copy mode. The processing circuitry excludes reconstructed samples of a second CTU that is adjacent to a left side of the first CTU in the picture from being reference samples for a reconstruction of the current block. Then, the processing circuitry reconstructs samples of the current block based on reference samples that are in the picture and constrained with the exclusion of the reconstructed samples of the second CTU.