Audio Subband Filterbank Windows for Delay-Memory Trade-Offs
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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 among 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 memory usage, while maintaining 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 frequency response quality is improved, but memory requirements and computational complexity increase
Solution Approach 1:
The patent creates a smaller window function as a simplified copy or representation of the larger window function by downsampling its coefficients. This copied version retains the essential frequency response characteristics while requiring less memory storage and computational resources for processing.
2Measurement precision
If a larger window function with more coefficients is used, then frequency response quality is improved, but computational complexity increases
Solution Approach 1:
The patent creates a smaller window function as a simplified copy or representation of the larger window function by downsampling its coefficients. This copied version retains the essential frequency response characteristics while requiring less memory storage and computational resources for processing.
3Quantity of substance
If a smaller window function with fewer coefficients is used, then memory usage is reduced, but frequency response quality deteriorates
Solution Approach 1:
The patent extracts only the essential characteristics of the larger window function by downsampling its coefficients to create a smaller version. This extraction process removes redundant information while preserving the core frequency response properties needed for audio processing.
4Measurement precision
If traditional window functions are used, then quality is maintained, but delay increases
Solution Approach 1:
The patent changes the parameter of window function length by using a smaller window function with fewer coefficients. This parameter change reduces the processing delay while the downsampling technique ensures that the essential quality characteristics are preserved through efficient representation of the original larger window function.
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.