Intra Block Copy Coding with Derived Block Vectors for Screen Content
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Solution Overview
Problem
Existing video compression methods fail to effectively encode screen content, leading to low compression performance and quality issues such as blurred curves and texts due to their inability to accommodate the unique characteristics of screen content.
Innovation Solution
A method for video coding that involves deriving a block vector for intra block copy coding by adding a first block vector and a second block vector, used to predict and encode current video blocks, improving compression efficiency for screen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional video compression methods are used to encode screen content, then the general video compression function is achieved, but the reconstruction quality of screen content deteriorates with blurred curves and texts
Solution Approach 1:
The patent segments the video content processing into different modes: intra block copy mode for screen content with sharp edges and text, and conventional inter/intra prediction modes for natural video. This segmentation allows each mode to be optimized for its specific content type, improving screen content reconstruction quality without completely replacing conventional methods.
Solution Approach 2:
The patent dynamically selects between different coding modes (intra block copy, inter prediction, intra prediction) based on the characteristics of the current video block. By adapting the coding approach to the local content characteristics, the system achieves high reconstruction quality for screen content while maintaining compatibility with conventional video coding for other content types.
2Productivity
If intra block copy coding with block vector derivation is implemented, then compression performance for screen content is improved, but the device complexity increases
Solution Approach 1:
The patent performs preliminary classification to determine whether a video block is suitable for intra block copy mode before applying the complex block vector derivation process. This preliminary action filters out blocks that would benefit more from conventional methods, reducing the overall computational complexity while maintaining high compression performance for suitable blocks.
Solution Approach 2:
The block vector derivation process utilizes already-coded neighboring blocks and their block vectors as reference information, allowing the current block to derive its own prediction parameters from available data without requiring extensive external computation. This self-service approach reduces device complexity by leveraging local redundancy.
3Productivity
If conventional video coding technologies are used, then the coding process is simple, but the compression efficiency for screen content deteriorates
Solution Approach 1:
The patent applies different coding strategies to different regions of the video content based on local characteristics. Screen content regions with sharp edges and text are encoded using intra block copy mode with block vector derivation, while natural video regions use conventional prediction modes. This local quality approach optimizes compression efficiency for screen content without unnecessarily complicating the coding process for all blocks.
Data Source
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AI summary
Systems and methods are described for encoding and decoding video using derived block vectors as predictors in intra block copy mode. In an exemplary encoding method, an encoder identifies at least a first candidate block vector for the prediction of an input video block, where the first candidate block vector points to a first candidate block. The encoder then identifies a first predictive vector (e.g. a block vector or a motion vector) that was used to encode the first candidate block. From the first candidate block vector and the first predictive vector, the encoder generates a derived predictive vector from the first candidate block vector and the first predictive vector. The encoder then encodes the video block in the bit stream using the derived predictive vector for the prediction of the input video block.