Adaptive Scan Order for Video Coding
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Solution Overview
Problem
Existing video compression schemes face challenges in efficiently encoding and decoding digital video streams due to high data volume and computational requirements, particularly in managing large scan distances between coefficients, which increases hardware costs and complexity.
Innovation Solution
A method is introduced to generate a new scan order for transform blocks of coefficients, limiting the maximum scan distance to a predetermined value, thereby optimizing hardware implementations by reducing the size of the line buffer and improving coding efficiency through context-adaptive scan orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional scan order is used for coding transform coefficients, then coding flexibility is maintained, but the scan distance becomes large which increases line buffer size and hardware complexity
Solution Approach 1:
The patent applies dynamics by making the scan order adaptive rather than fixed. The scan order is dynamically adjusted based on the position of non-zero coefficients in the transform block, allowing the coding scheme to adapt to different coefficient distributions while maintaining limited scan distance, thus reducing line buffer size without sacrificing coding flexibility
Solution Approach 2:
The patent changes the parameter of scan order by introducing a modified scan pattern that limits the maximum distance between consecutive non-zero coefficients. This parameter change transforms the conventional unlimited scan distance into a bounded scan distance, directly reducing the required line buffer size and hardware complexity
2Device complexity
If the scan distance is limited to reduce hardware complexity, then line buffer size is reduced, but coding efficiency may be compromised
Solution Approach 1:
The patent applies local quality by tailoring the scan order to the local characteristics of the transform block. Instead of using a uniform scan pattern, the scan order is locally optimized based on the actual positions of non-zero coefficients, ensuring coding efficiency is maintained while adhering to the limited scan distance constraint for reduced hardware complexity
3Ease of manufacture
If a fixed scan order is used, then hardware implementation is simpler, but adaptation to different coefficient patterns is lost
Solution Approach 1:
The patent resolves this contradiction by implementing a dynamic scan order that is generated through a systematic process based on coefficient positions. This dynamic approach maintains adaptability to different coefficient patterns while following a deterministic generation method that keeps hardware implementation manageable, avoiding the need for complex adaptive algorithms
Data Source
AI summary
Generating a new scan order includes incrementing a next index value after assigning the next index value to a coefficient in the new scan order; assigning, to a first coefficient at a first scan index m in the original scan order, a first scan index in the new scan order, the first coefficient is a context coefficient for entropy coding a parent coefficient that is at a parent scan index n in the original scan order; adding, to a list, a first item indicative of the parent coefficient and parent scan index n; before assigning a second scan index to a second coefficient that is at a second index m+j in the original scan order, wherein j>1, assigning the next index value to the parent coefficient, and removing the first item from the list; and assigning the next index value to the second coefficient in the new scan order.