Interpolated Audio Window Coefficients for Low-Delay Subband Processing
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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 in 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 minimizing delay, is employed in both analysis and synthesis filterbanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a larger window function with more window coefficients is used, then audio quality and frequency response are improved, but memory requirements and computational complexity increase
Solution Approach 1:
The patent creates a simplified copy of the window function by deriving a smaller set of window coefficients from a larger window function through interpolation. This copied version maintains the essential characteristics and audio quality of the original while requiring significantly less memory storage, directly resolving the contradiction between audio quality and memory requirements
Solution Approach 2:
The patent changes the parameter of window function size by deriving a smaller window function from a larger one through interpolation. This parameter transformation allows the system to use fewer coefficients (reducing memory and computation) while maintaining audio quality through the mathematical interpolation process that preserves spectral characteristics
2Manufacturing precision
If a larger window function with more window coefficients is used, then audio quality and frequency response are improved, but computational complexity increases
Solution Approach 1:
The patent creates a computationally efficient copy of the window function by deriving a smaller set of coefficients from the original larger window function. This copied version reduces the number of multiplication operations required in the audio processing pipeline while maintaining audio quality, directly addressing the contradiction between audio quality and computational complexity
Solution Approach 2:
The patent transforms the computational parameter by reducing the window function size through interpolation. This parameter change decreases the computational load (fewer coefficients to process) while preserving audio quality through the mathematical relationships maintained during the derivation process
3Productivity
If real-time processing is implemented with standard window functions, then processing speed is improved, but delay is increased due to the need to process complete frames
Solution Approach 1:
The patent segments the window function into a smaller derived version that can be applied to shorter processing intervals. This segmentation enables the system to process audio data in smaller chunks rather than waiting for complete large frames, thereby reducing delay while maintaining processing efficiency and real-time capability
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.