Non-Square Block Intra Prediction With Fewer Direction Bits
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction, particularly for non-square blocks, as they often require a large number of bits to represent less likely prediction directions, leading to suboptimal compression ratios.
Innovation Solution
The proposed solution involves decoding syntax elements for non-square blocks with a unique set of intra prediction directions that exclude or reassign modes from the standard square block set, optimizing the angular range and aspect ratio to minimize direction usage and improve compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional intra prediction with standard direction sets is used for non-square blocks, then all possible prediction directions are available, but the number of bits required to represent less likely directions increases
Solution Approach 1:
The patent segments the prediction direction set into two parts: a first set of intra prediction directions specific to non-square blocks, and a second set for square blocks. This segmentation allows the non-square block prediction to use only the most relevant directions, reducing the bit cost while maintaining necessary adaptability.
Solution Approach 2:
The patent applies local quality by providing different prediction direction sets tailored to specific block shapes. Non-square blocks receive a customized first set of directions optimized for their geometry, while square blocks use the second set, ensuring each block type gets the most appropriate prediction options without unnecessary overhead.
2Reliability
If a comprehensive set of intra prediction directions is used for all blocks, then all prediction scenarios are covered, but the bitrate increases due to encoding more direction information
Solution Approach 1:
The patent extracts and removes the least likely prediction directions from the standard set when coding non-square blocks. By taking out only the necessary first set of directions for non-square blocks, the patent maintains prediction accuracy for relevant scenarios while reducing the bitrate required to encode direction information.
Solution Approach 2:
The patent implements dynamic adaptation by selecting different prediction direction sets based on block shape characteristics. The system dynamically chooses between the first set (for non-square blocks) and second set (for square blocks), optimizing the balance between prediction accuracy and bitrate for each specific block type.
Data Source
AI summary
In a method for video encoding in an encoder, a sample of a block that is a non-square block having a rectangular shape is received. The sample of the non-square block is predicted based on a first set of intra prediction directions for the non-square block, the first set of intra prediction directions including a first subset of intra prediction directions in a second set of intra prediction directions for a square block and not including a second subset of intra prediction directions in the second set of intra prediction directions. At least one syntax element that is indicative of the block being the non-square block that has the rectangular shape is determined. A video bitstream of the sample of the non-square block is encoded based on the at least one syntax element.