math-dsp

DSP utilities for audio signal generation and FFT-based analysis.

Library name: math_audio_dsp Version: 0.3.1

Overview

This crate provides two core modules:

• signals -- Test signal generation (tones, sweeps, noise) with utility functions for fade, padding, and channel manipulation
• analysis -- FFT-based frequency analysis including spectrum computation (Welch's method and single-FFT), acoustic metrics (RT60, clarity C50/C80, THD), microphone compensation, and CSV I/O

Signal Generation

Generate common test signals as Vec<f32>:

Signal Utilities

Example

use math_audio_dsp::signals;

// Generate a 1 kHz tone at 0.5 amplitude, 48 kHz, 2 seconds
let tone = signals::gen_tone(1000.0, 0.5, 48000, 2.0);

// Generate a 20-20k Hz log sweep
let sweep = signals::gen_log_sweep(20.0, 20000.0, 0.8, 48000, 5.0);

// Prepare for playback with 20ms fade and 250ms silence padding
let ready = signals::prepare_signal_for_playback(tone, 48000, 20.0, 250.0);

Analysis

Standalone WAV Analysis

Analyze a WAV file or sample buffer and get frequency response (magnitude + phase) on a log-spaced frequency grid:

use math_audio_dsp::analysis::{WavAnalysisConfig, analyze_wav_buffer, analyze_wav_file};

// Analyze a buffer
let config = WavAnalysisConfig::default(); // Welch's method, 2000 points, 20-20kHz
let result = analyze_wav_buffer(&samples, 48000, &config)?;
// result.frequencies, result.magnitude_db, result.phase_deg

// Analyze a WAV file directly
let result = analyze_wav_file(Path::new("recording.wav"), &config)?;

Pre-built configs for common use cases:

Configuration fields: num_points, min_freq, max_freq, fft_size, overlap, single_fft, pink_compensation, no_window.

Recording Analysis (Reference vs Recorded)

Compare a recorded WAV against a known reference signal to extract the system's transfer function:

use math_audio_dsp::analysis::analyze_recording;

let result = analyze_recording(
    Path::new("recorded.wav"),
    &reference_signal,
    48000,
    Some((20.0, 20000.0)), // sweep range for THD computation
)?;

The AnalysisResult includes:

Acoustic Metrics

Available as standalone functions for custom impulse responses:

use math_audio_dsp::analysis::*;

// Broadband RT60 (T20 extrapolation from Schroeder decay)
let rt60 = compute_rt60_broadband(&impulse, 48000.0);

// Broadband clarity
let (c50, c80) = compute_clarity_broadband(&impulse, 48000.0);

// Frequency-dependent RT60 and clarity (octave-band filtered, interpolated)
let rt60_spectrum = compute_rt60_spectrum(&impulse, 48000.0, &frequencies);
let (c50_spectrum, c80_spectrum) = compute_clarity_spectrum(&impulse, 48000.0, &frequencies);

// Spectrogram
let (matrix_db, freq_bins, time_bins) = compute_spectrogram(&impulse, 48000.0, 512, 128);

// Group delay from phase data
let group_delay = compute_group_delay(&frequencies, &phase_deg);

Microphone Compensation

Load calibration data and apply inverse compensation to measurements:

use math_audio_dsp::analysis::MicrophoneCompensation;

// Load from CSV (freq_hz,spl_db) or TXT (space/tab-separated)
let mic = MicrophoneCompensation::from_file(Path::new("mic_cal.csv"))?;

// Interpolate at a specific frequency
let deviation_db = mic.interpolate_at(1000.0);

// Pre-compensate a sweep signal
let compensated = mic.apply_to_sweep(&sweep, 20.0, 20000.0, 48000, true);

Smoothing and CSV I/O

use math_audio_dsp::analysis::*;

// Octave smoothing (f32 and f64 variants)
let smoothed = smooth_response_f32(&frequencies, &magnitudes, 1.0 / 24.0);

// Write/read analysis CSV
write_wav_analysis_csv(&wav_result, Path::new("output.csv"))?;
write_analysis_csv(&recording_result, Path::new("output.csv"), Some(&mic_compensation))?;
let loaded = read_analysis_csv(Path::new("output.csv"))?;

Binary: wav2csv

CLI tool to analyze a WAV file and output frequency/SPL/phase as CSV.

# Default (Welch's method)
wav2csv recording.wav

# Log sweep analysis
wav2csv sweep.wav --single-fft --pink-compensation --no-window

# Custom parameters
wav2csv recording.wav -o output.csv -n 4000 --min-freq 10 --max-freq 24000 --fft-size 32768

Options: --num-points, --min-freq, --max-freq, --fft-size, --overlap, --single-fft, --pink-compensation, --no-window, -o/--output.

Dependencies

Testing

cargo test -p math-dsp --lib
cargo check -p math-dsp && cargo clippy -p math-dsp