Audio Subband Window Interpolation for Lower Memory and Delay
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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 accuracy and reconstruction quality are improved, but memory requirements and computational complexity increase
Solution Approach 1:
The patent divides the window function coefficients into two groups: first group coefficients and second group coefficients. The first group coefficients are used for current frame processing while the second group coefficients are used for next frame processing. This segmentation allows using fewer coefficients per group while maintaining overall frequency response accuracy, thereby reducing memory requirements and computational complexity per frame.
2Manufacturing precision
If a larger window function with more coefficients is used, then reconstruction quality is improved, but computational complexity increases
Solution Approach 1:
The patent segments the window function into two groups of coefficients that are applied alternately to current and next frames. This segmentation reduces the number of coefficients that need to be processed in each individual frame, thereby reducing computational complexity per frame while maintaining overall reconstruction quality through the combined effect of both coefficient groups across frames.
Solution Approach 2:
The patent dynamically switches between using first group coefficients for current frames and second group coefficients for next frames. This dynamic alternation allows the system to maintain high reconstruction quality by utilizing the full set of window function coefficients across frames while reducing the computational burden on any single frame processing operation.
3Manufacturing precision
If more window coefficients are used, then audio quality is improved, but delay increases
Solution Approach 1:
The patent segments the window function coefficients into two groups that can be applied to current and next frames respectively. This segmentation enables the system to achieve high audio quality through the combined use of both coefficient groups while reducing delay by processing each frame with only one group of coefficients, thereby enabling faster processing and reduced buffering requirements.
4Reliability
If a full window function is used for each frame, then processing completeness is improved, but memory usage increases
Solution Approach 1:
The patent divides the window function coefficients into two separate groups: first group coefficients and second group coefficients. Each group is stored separately in memory and applied to alternating frames (current frame and next frame respectively). This segmentation reduces the memory footprint for each frame's window coefficients while ensuring processing completeness is maintained through the systematic alternation between the two coefficient groups across consecutive frames.
Data Source
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AI summary
An embodiment of an apparatus (100) for generating audio subband values in audio subband channels comprises an analysis windower (110) for windowing a frame (120) 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 (190) comprising a sequence of window coefficients to obtain windowed samples. The analysis window function comprises a first number of window coefficients derived from a larger window function comprising 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 (100) further comprises a calculator (170) for calculating the audio subband values using the windowed samples.