Audio Transform Windows Resized by Irregular Sampling
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Solution Overview
Problem
Existing audio signal processing technologies require significant memory space to store multiple analysis and synthesis windows for different transform sizes, which is inefficient and requires preliminary computations, compromising perfect reconstruction conditions.
Innovation Solution
The method involves irregular sampling of an initial window to apply a secondary transform of a different size without preliminary computations, using decimation or interpolation to adapt the window size while maintaining perfect or quasi-perfect reconstruction conditions, allowing a single window to be used for various transform sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple analysis and synthesis windows for different transform sizes are stored in memory, then adaptability to various transform sizes is improved, but memory space requirement increases
Solution Approach 1:
A single analysis window of size 2N is designed to serve multiple transform sizes (N, 2N, and other sizes) through irregular sampling. The window is constructed with specific symmetry properties and sampling patterns that allow extraction of appropriate-sized windows for different transform operations, making one window perform multiple functions that previously required separate windows for each size.
Solution Approach 2:
The invention changes the sampling pattern parameter from regular uniform sampling to irregular sampling with specific mathematical properties. By using sampling indices based on modular arithmetic and symmetry relationships, the same window can be adaptively downsampled to different sizes while maintaining the required reconstruction properties for each transform size.
2Adaptability or versatility
If multiple windows for different transform sizes are stored, then versatility is improved, but device complexity increases
Solution Approach 1:
The analysis window is designed as a universal structure that can be adaptively sampled to produce windows of different sizes. Instead of storing multiple separate windows, the system uses one window with built-in mathematical properties that enable it to serve multiple transform size requirements, thereby reducing device complexity.
Solution Approach 2:
The single analysis window is segmented through irregular sampling to produce different-sized windows as needed. The sampling process selectively extracts portions of the original window according to mathematical rules, creating smaller windows from the larger parent window without requiring separate storage for each size.
3Productivity
If window size is adapted to transform size, then coding efficiency is improved, but preliminary computations are required
Solution Approach 1:
The analysis window is pre-computed with specific mathematical properties and symmetry characteristics that enable direct irregular sampling. By preparing the window in advance with the correct structural properties, the system eliminates the need for preliminary computations during actual transform operations, as the window can be directly sampled to any required size using simple index calculations.
Data Source
AI summary
A method and device are provided for coding or decoding a digital audio signal by transform using analysis or synthesis weighting windows applied to sample frames. The method includes an irregular sampling of an initial window provided for a transform of given initial size N, to apply a secondary transform of size M different from N.