SpectrumAnalyzer.h File Reference

Real-time FFT-based spectrum analyser for audio visualisation. More...

#include "../Core/DspMath.h"
#include "../Core/FFT.h"
#include "../Core/WindowFunctions.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cassert>
#include <cmath>
#include <cstddef>
#include <memory>
#include <vector>

Include dependency graph for SpectrumAnalyzer.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Classes
class	dspark::SpectrumAnalyzer< T >
	Real-time FFT spectrum analyser with per-bin smoothing and peak hold. More...

Namespaces
namespace	dspark
	Main namespace for the DSPark framework.

Detailed Description

Real-time FFT-based spectrum analyser for audio visualisation.

Handles the complete pipeline: windowing -> FFT -> single-sided magnitude (amplitude-calibrated: a full-scale sine reads 0 dB) -> per-bin exponential smoothing -> dB conversion -> optional peak hold with dB/s decay.

Note

Performance: the FFT and transcendental math run synchronously inside pushSamples() whenever a hop completes. For large FFT sizes (>2048) on tight audio callbacks, consider a lock-free queue architecture where the GUI thread pulls samples and computes the FFT independently.

Threading:

• prepare() / reset(): setup thread (not concurrent with the audio or reader threads; reset() rewrites the reader-visible slots).
• pushSamples(): audio thread (stream owner). No-op before prepare().
• getMagnitudesDb() / getPeakHoldDb() / isNewDataReady(): ONE reader thread (GUI). Wait-free triple-buffer hand-off; never blocks the writer. The two arrays are acquired independently, so a pair of consecutive calls may straddle a frame boundary (benign for metering).
• setSmoothing() / setPeakDecay() / setPeakHoldEnabled() / setFloorDb(): any thread (relaxed atomics, picked up once per analysis frame). Non-finite values are ignored.

Dependencies: DspMath.h, FFT.h, WindowFunctions.h.

dspark::SpectrumAnalyzer<float> analyzer;
analyzer.prepare(48000.0, 2048);  // 48 kHz, 2048-point FFT
 
// In audio callback:
analyzer.pushSamples(buffer.getChannel(0), numSamples);
 
// In GUI paint (Timer at 60Hz):
if (analyzer.isNewDataReady()) {
    const float* spectrum = analyzer.getMagnitudesDb();
    // Draw spectrum...
}

Definition in file SpectrumAnalyzer.h.