Audio Subband Window Interpolation for Delay-Quality Tradeoffs
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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 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 coefficients from a larger one, allowing for improved energy distribution of window coefficients, which reduces delay and increases quality while maintaining computational efficiency and memory savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a larger window function with more coefficients is used, then audio quality is improved, but delay increases and computational complexity increases
Solution Approach 1:
The patent divides the audio signal processing into subband channels, where each subband uses a smaller window function with fewer coefficients. This segmentation allows the system to achieve acceptable audio quality in each subband while using computationally efficient small window functions, avoiding the need for a single large window function that would increase delay and complexity.
Solution Approach 2:
The patent applies different window function sizes to different subband channels based on their specific requirements. Lower subbands that require higher precision use larger window functions, while higher subbands use smaller window functions. This local optimization maintains audio quality where needed while reducing overall delay and computational complexity.
2Manufacturing precision
If a larger window function with more coefficients is used, then audio quality is improved, but computational complexity increases
Solution Approach 1:
The patent divides the audio signal processing into subband channels, where each subband uses a smaller window function with fewer coefficients. This segmentation allows the system to achieve acceptable audio quality in each subband while using computationally efficient small window functions, avoiding the need for a single large window function that would increase delay and complexity.
Solution Approach 2:
The patent uses minimal window function sizes (e.g., 2-4 coefficients) for each subband channel, which is sufficient for the required audio quality in that specific band. This partial action approach avoids the excessive computational complexity that would result from using uniformly large window functions across all frequency bands.
3Manufacturing 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 divides the audio signal processing into subband channels, where each subband uses a smaller window function with fewer coefficients. This segmentation allows the system to achieve acceptable audio quality in each subband while using computationally efficient small window functions, avoiding the need for a single large window function that would increase delay and complexity.
4Manufacturing precision
If spectral band replication is used to improve quality, then audio quality is improved, but delay increases
Solution Approach 1:
The patent performs preliminary processing of the audio signal by dividing it into subbands and applying appropriate window functions and filtering to each subband before reconstruction. This preliminary action in the frequency domain allows for more efficient processing that reduces the overall delay compared to traditional spectral band replication methods that operate on the entire frequency spectrum.
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.