Function-Based Scan Order for Video Transform Coefficients
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Solution Overview
Problem
Current video coding techniques face inefficiencies in scanning residual transform coefficients, particularly in grouping non-zero coefficients for entropy coding, as existing scan orders may not adapt effectively to varying block sizes and content, leading to suboptimal compression performance.
Innovation Solution
A function-based definition of scan order is introduced, where parameter values such as transform unit size, scan orientation, and scan orientation strength are used to dynamically define and adjust the scan order for transform coefficients, allowing for flexible and efficient grouping of non-zero coefficients during entropy coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed scan order is used for transform coefficients, then the coding process is simple and fast, but the compression performance is suboptimal because non-zero coefficients are not effectively grouped
Solution Approach 1:
The scan order is made dynamic by selecting from multiple predefined scan orders based on transform unit size and coefficient characteristics. Instead of using a single fixed scan order, the system adapts the scan order to match the specific characteristics of each transform block, improving the grouping of non-zero coefficients while maintaining implementation simplicity through a有限的 set of predefined options.
Solution Approach 2:
The invention changes the parameters that define scan order (such as scan direction and pattern) based on transform unit size and coefficient distribution characteristics. By varying these parameters according to the specific coding context, the system optimizes the grouping of non-zero coefficients without requiring complex adaptive algorithms.
2Productivity
If extensive scan order data is stored to achieve optimal coefficient grouping, then compression performance improves, but memory requirements and processing overhead increase
Solution Approach 1:
A small set of predefined scan orders serves multiple functions and contexts. Instead of storing separate scan order data for each possible transform unit size and content type, the invention uses a universal set of scan orders that can be applied across different scenarios by selecting the appropriate one based on simple criteria such as transform unit size and coefficient characteristics.
Solution Approach 2:
Instead of storing detailed scan order information and searching for the best match, the invention inverts the approach by deriving the scan order selection from compact parameters (transform unit size and coefficient characteristics). This reduces the storage requirement from extensive scan order data to minimal parameter information.
3Productivity
If adaptive scan orders are used to group non-zero coefficients, then entropy coding performance improves, but the complexity of determining scan order increases
Solution Approach 1:
Multiple scan orders are predefined and prepared in advance. During encoding, the system only needs to select from these pre-prepared options based on simple criteria such as transform unit size and coefficient characteristics, rather than generating adaptive scan orders on-the-fly. This preliminary preparation significantly reduces the computational complexity during the actual coding process.
Solution Approach 2:
The invention uses simple parameter changes (transform unit size and coefficient characteristics) to select from predefined scan orders. This approach achieves adaptivity without complex algorithms, as the scan order selection is determined by straightforward parameter comparison rather than sophisticated optimization processes.
Data Source
AI summary
Video coding devices and methods use a function-based definition of scan order to scan transform coefficients associated with a block of residual video data. A video coder may define a scan order for coefficients based on a predefined function and one or more parameter values. A video encoder may use a function-based scan order to scan a two-dimensional array of coefficients to produce a one-dimensional array of coefficients for use in producing encoded video data. The video encoder may signal the parameters to a video decoder, or the video decoder may infer one or more of the parameters. The video decoder may use the function-based scan order to scan a one-dimensional array of coefficients to reproduce the two-dimensional array of coefficients for use in producing decoded video data. In each case, the scan order may vary according to the parameter values, which may include block size, orientation, and/or orientation strength.