Filters.h File Reference

Multi-mode cascaded biquad filter engine with real-time parameter smoothing. More...

#include "../Core/AudioBuffer.h"
#include "../Core/AudioSpec.h"
#include "../Core/Biquad.h"
#include "../Core/DspMath.h"
#include "../Core/Smoothers.h"
#include "../Core/AnalogRandom.h"
#include "../Core/DenormalGuard.h"
#include "../Core/StateBlob.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cmath>
#include <cstdint>
#include <vector>

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Classes
class	dspark::FilterEngine< T, MaxChannels >
	Professional multi-mode filter with cascaded biquad stages. More...
struct	dspark::FilterEngine< T, MaxChannels >::CascadeInfo
	Per-stage Butterworth cascade layout for an LP/HP slope (for analysis). More...
struct	dspark::FilterEngine< T, MaxChannels >::ButterworthCascade

Namespaces
namespace	dspark
	Main namespace for the DSPark framework.

Detailed Description

Multi-mode cascaded biquad filter engine with real-time parameter smoothing.

Supports all standard filter shapes (LP, HP, BP, Peak, Shelves, Notch, Tilt, AllPass) with configurable slopes from 6 to 48 dB/oct via cascaded biquad stages. Parameters are smoothed per-sample to prevent zipper noise.

Warning

Biquad filters are not suited for audio-rate cutoff modulation. Nonlinearity and analog drift update the coefficients at chunk rate (every 16 samples) to maintain CPU stability and prevent severe phase distortion.

Dependencies: Core/AudioBuffer.h, Core/AudioSpec.h, Core/Biquad.h, Core/DspMath.h, Core/Smoothers.h, Core/AnalogRandom.h, Core/DenormalGuard.h, Core/StateBlob.h.

Threading: prepare(), enableAnalogDrift() and setState() belong to the setup thread; processBlock()/processSample()/reset() to the audio thread. The remaining parameter setters are safe from any thread (relaxed atomics read once per block); non-finite setter values are ignored. The shape helpers (setLowPass()/setShape()/...) write several atomics non-atomically as a group: the audio thread may see the new topology with the previous targets for one block (smoothed, click-free).

dspark::FilterEngine<float> filter;
filter.prepare(spec);
filter.setLowPass(2000.0f, 0.707f, 24);  // 2kHz, Butterworth Q, 24dB/oct
filter.processBlock(buffer);
 
// Real-time parameter changes from UI thread (thread-safe):
filter.setFrequency(4000.0f);

Definition in file Filters.h.