IBC Block Intra Prediction Mode Propagation
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently propagating intra prediction mode information for intra block copy (IBC) blocks, which affects coding efficiency and compression performance.
Innovation Solution
The method involves deriving and propagating intra prediction modes for IBC blocks using a block vector (BV) to reference a reconstructed intra copied block, and storing this information for intra mode propagation to neighboring blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intra prediction mode information is not propagated for IBC blocks, then device complexity is reduced, but coding efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by deriving and storing the intra prediction mode of the reference block before it is needed for propagating to the current IBC block. This allows the decoder to efficiently retrieve and use the pre-computed intra mode information without performing complex calculations during the main decoding process, thereby improving coding efficiency while managing device complexity.
Solution Approach 2:
The patent uses copying by replicating the intra prediction mode information from the reference block to the current IBC block. Instead of recalculating the intra mode for each IBC block, the decoder copies the mode information from the corresponding reference block, significantly reducing computational complexity while maintaining coding efficiency.
2Productivity
If intra prediction mode is propagated using reference blocks, then compression performance is improved, but loss of information increases due to additional bitstream data
Solution Approach 1:
The patent merges the propagation of block vector information and intra prediction mode information into a unified process. By combining these two types of information propagation, the patent reduces overall bitstream overhead while improving compression performance, as the same reference block structure serves dual purposes.
Solution Approach 2:
The reference block structure is designed to serve multiple functions: it provides both the block vector for IBC and the intra prediction mode information. This multi-functionality reduces the need for separate data structures and bitstream elements, thereby reducing information loss overhead while maintaining improved compression performance.
3Productivity
If intra prediction mode propagation is implemented for all blocks, then coding efficiency is improved, but ease of operation deteriorates due to increased processing requirements
Solution Approach 1:
The patent applies local quality by implementing intra prediction mode propagation selectively only for IBC blocks rather than all blocks. This localized approach improves coding efficiency where it is most needed (for IBC blocks) while avoiding unnecessary processing for other block types, thereby maintaining ease of operation.
Solution Approach 2:
The patent implements partial action by applying intra prediction mode propagation only to the extent necessary for IBC blocks. Rather than universally applying the technique to all block types, the patent applies it partially where beneficial, improving coding efficiency while keeping processing requirements manageable and ease of operation acceptable.
Data Source
AI summary
In a method of video decoding, coded information of a current block in a current picture of a video is received from a coded video bitstream. The coded information indicates that the current block is an intra block copy (IBC) block. The current block is divided into a plurality of partitions based on a geometric partition mode (GPM). An intra prediction mode for a subblock is derived from one of the plurality of partitions as an intra mode of a pixel positioned at a location of a reference subblock in a reference block referenced by a block vector of the IBC block. The intra prediction mode for the subblock is stored. A neighboring block of the current block is determined as an IBC block. A most probable mode (MPM) list for the neighboring block is constructed using the stored intra prediction mode for the subblock of the current block.