IIR Audio Filtering for Low-Latency Timbre Matching
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Solution Overview
Problem
Existing audio sample libraries face challenges in reducing storage footprint while maintaining realistic sound quality and processing efficiency, particularly during live performances, due to high computational demands and latency issues with compression algorithms.
Innovation Solution
The use of Infinite Impulse Response (IIR) filters to transform audio samples into timbral sonic characteristics of a target sound, allowing for a condensed sample library with minimal storage and processing requirements, utilizing short target samples and deriving IIR coefficients to replace multiple dynamic layers, enabling real-time processing without compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If audio data is compressed to reduce storage footprint, then storage space is conserved, but latency occurs during real-time playback and audio quality degrades
Solution Approach 1:
The patent extracts only the essential spectral characteristics (spectrogram data) from complete audio samples, storing merely the frequency-time representation rather than the full audio waveform. This extraction allows dramatic footprint reduction while enabling instant playback without compression latency, as the spectrogram data can be directly synthesized into audio without decompression overhead.
Solution Approach 2:
The patent transforms audio data from time-domain waveforms into frequency-domain spectrograms, changing the representation parameters from amplitude-time to frequency-time. This parameter transformation enables more efficient storage and faster access, as spectrograms capture the essential timbral information in a compact format that can be rapidly converted back to audio without compression artifacts or latency.
2Reliability
If multiple dynamic layers are sampled to maintain realistic timbre across volume levels, then audio quality is improved, but storage footprint increases
Solution Approach 1:
The patent creates spectral copies rather than audio waveform copies. Instead of storing multiple complete audio samples at different dynamic levels, it stores a single spectrogram that captures the essential timbral characteristics, which can then be used to generate or modify audio output across different volume levels without requiring separate sampled layers for each dynamic condition.
Solution Approach 2:
The patent makes the stored spectrogram data universally applicable across multiple dynamic levels and playing conditions. A single spectrogram representation serves multiple functions: it can be used for playback at various volumes, for generating timbral variations, and for adapting to different musical contexts, eliminating the need for separate dedicated samples for each scenario.
3Quantity of substance
If Impulse Response (IR) processing is used to reduce footprint, then storage space is reduced, but computational processing power requirements increase significantly
Solution Approach 1:
The patent applies partial processing by storing only the essential spectral envelope information in spectrogram form rather than complete impulse responses. This partial representation captures the critical timbral characteristics needed for realistic playback while requiring significantly less computational power to process than full IR convolution, achieving a balance between footprint reduction and processing efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces storage and processing needs, allowing for realistic sound recreation on portable devices with limited resources, while maintaining high audio quality and preventing latency, thus enabling efficient live performances.
Implementation Method 1
utilizing short target samples and deriving IIR coefficients to replace multiple dynamic layers, enabling real-time processing without compression
Data Source
AI summary
An audio sampler is provided, comprising a sample library having stored therein a plurality of main audio samples and a plurality of infinite impulse response (IIR) coefficients divided into subset, each subset corresponding to one of the main audio samples; a sample playback engine comprising an input receiving the main audio samples and outputting a playback signal; and, an IIR filter receiving the corresponding subset of IIR coefficients and applying the IIR filter to the main audio samples or to the playback signal.