Interpolated Audio Subband Windows 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 audio quality while maintaining computational efficiency and memory savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement 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 segments the audio signal into overlapping frames and processes each frame independently with a smaller window function. This allows parallel processing of multiple frames, reducing overall delay while maintaining quality through the overlap-add reconstruction method.
Solution Approach 2:
The patent uses a smaller window function (partial action) that provides sufficient audio quality for most applications, avoiding the need for the full larger window function. This partial approach reduces delay and computational complexity while meeting quality requirements in the majority of cases.
2Measurement precision
If a larger window function with more coefficients is used, then audio quality is improved, but computational complexity increases
Solution Approach 1:
By segmenting the processing into multiple smaller frames with smaller window functions, the patent reduces the computational burden on each processing unit. The total computational complexity is distributed across multiple simpler operations rather than one complex operation.
Solution Approach 2:
The patent applies partial action by using smaller window functions that require fewer computational resources while providing adequate quality. This avoids the excessive computational requirements of larger window functions.
3Measurement 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 segments the audio processing into smaller frames, each requiring only a portion of the memory that would be needed for a single large window function. This segmentation reduces peak memory requirements while maintaining overall audio quality through proper overlap-add reconstruction.
4Loss of time
If a smaller window function with fewer coefficients is used, then delay is reduced and computational efficiency is improved, but audio quality deteriorates
Solution Approach 1:
The patent merges multiple processed frames using the overlap-add method, combining the results of several smaller window function applications. This merging process reconstructs the audio signal with quality comparable to or better than a single larger window function, while maintaining the delay and computational advantages of smaller windows.
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.