Interpolated Subband Windowing for Low-Delay Audio Filterbanks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern digital audio processing systems face challenges in balancing bit rate, computational complexity, memory requirements, quality, and delay, particularly in real-time applications, where compromises often need to be made across these parameters to achieve optimal performance.
Innovation Solution
The use of an interpolation scheme to derive a window function with a smaller number of window coefficients from a larger one, allowing for improved energy distribution and reduced aliasing, while maintaining or improving audio quality and reducing delay, is employed in both analysis and synthesis filterbanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a larger window function with more coefficients is used, then audio quality and frequency response are improved, but computational complexity and memory requirements increase
Solution Approach 1:
The patent divides the window function into multiple segments or taps, where each segment can be independently optimized or processed. This segmentation allows the system to achieve high frequency response accuracy through multiple smaller operations rather than one large complex operation, thereby reducing overall computational complexity and memory requirements while maintaining audio quality.
Solution Approach 2:
The patent transforms the window function coefficients from a time-domain representation to a frequency-domain representation using techniques such as Fast Fourier Transform (FFT). This dimensional transformation allows the system to process window coefficients more efficiently in the frequency domain, reducing computational complexity while preserving the accuracy needed for high-quality audio processing.
2Measurement precision
If a larger window function with more coefficients is used, then audio quality is improved, but memory requirements increase
Solution Approach 1:
The patent extracts only the essential or most significant window coefficients needed for high-quality audio processing, rather than storing and processing all coefficients of a large window function. By identifying and retaining only the critical coefficients that contribute most to audio quality, the system reduces memory requirements while maintaining performance.
Solution Approach 2:
The patent uses a partial set of window coefficients that provides sufficient audio quality for the application, rather than using the complete set of coefficients from a large window function. This partial action approach achieves the necessary audio quality threshold with reduced memory consumption, avoiding the excessive use of resources.
3Loss of time
If real-time processing is implemented, then delay is reduced, but computational complexity increases
Solution Approach 1:
The patent pre-calculates and stores certain window function coefficients or transformation results that are frequently needed in real-time processing. By performing these calculations in advance and storing the results, the system eliminates the need to perform complex computations during real-time audio processing, thereby reducing processing delay while managing computational complexity through offline preparation.
Data Source
AI summary
An embodiment of an apparatus for generating audio subband values in audio subband channels includes an analysis windower for windowing a frame of time-domain audio input samples being in a time sequence extending from an early sample to a later sample using an analysis window function including a sequence of window coefficients to obtain windowed samples. The analysis window function includes a first number of window coefficients derived from a larger window function including a sequence of a larger second number of window coefficients, wherein the window coefficients of the window function are derived by an interpolation of window coefficients of the larger window function. The apparatus further includes a calculator for calculating the audio subband values using the windowed samples.