Pivotta

One turn, the whole horizon.

One-knob performance filter: turn left and a low-pass sweeps down from the top to the deep bass, turn right and a high-pass sweeps up to thin the sound out; the centre is a clean bypass. Resonance adds a peak at the cutoff; Steep switches 12 to 24 dB/oct.

● Freeorg.sournd.filter.pivotta

Hear it

Hear its studio demo. The live engine, with every parameter, is in your download.

Details

Engine id: org.sournd.filter.pivotta
Category: Filter
Type: Dj filter, low pass
Licence: Free, closed library (use it in any plugin)
Version: 1.0.0
Parameters: 4
Latency: none
Tail: 0.05 s
Sidechain input: no
Channels: mono or stereo

Parameters

The id is the C ABI parameter id and the JUCE parameter id (as a decimal string).

Id	Key	Name	Min	Max	Default	Unit	Taper
0	`filter`	Filter	-100	100	0	%	linear
1	`resonance`	Resonance	0	100	20	%	linear
2	`steep`	Steep	0	1	1	-	linear
3	`mix`	Mix	0	100	100	%	linear

How it is made

Original sOURnd design: two cascaded zero-delay-feedback state-variable filters whose mode follows the knob's side, a logarithmic cutoff map per side, a dead zone and a smooth blend around the centre for an exact bypass, and resonance split between the stages.

CMake

cmake

juce_add_module(path/to/sournd_engine)
target_include_directories(MyPlugin PRIVATE path/to/include)
target_link_libraries(MyPlugin PRIVATE sournd_engine path/to/libsournd_cabi.a)

Three lines. Full steps: JUCE quick start.

C++ (JUCE)

cpp

#include <sournd_engine/sournd_engine.h>

sournd::SourndEngine engine { "org.sournd.filter.pivotta" };
juce::AudioProcessorValueTreeState parameters { *this, nullptr, "Parameters",
    sournd::SourndEngineParameters::createLayout (engine) };
sournd::SourndEngineParameters bridge { engine, parameters };

// prepareToPlay
engine.prepare ({ sampleRate, (juce::uint32) maximumBlock, 2 });
bridge.prepare (sampleRate);
setLatencySamples ((int) engine.latency());

// processBlock
bridge.apply ((uint32_t) buffer.getNumSamples());
juce::dsp::AudioBlock<float> block { buffer };
engine.process (juce::dsp::ProcessContextReplacing<float> { block });

// get/setStateInformation: hold getCallbackLock() around saveState / loadState,
// so state work never overlaps processBlock (full example: /docs/juce/)

Plain C

sournd_engine *e = NULL;
if (sournd_engine_create("org.sournd.filter.pivotta", &e) == SOURND_OK) {
    sournd_engine_prepare(e, 48000.0, 512);
    sournd_engine_set_param(e, 0, 0); /* Filter */
    sournd_engine_process(e, in, out, 2, frames);
    sournd_engine_destroy(e);
}

Ask your AI

Paste this into your coding assistant:

Prompt

Add the sournd engine org.sournd.filter.pivotta to my JUCE plugin. Follow https://sournd.com/docs/juce/index.md
and the engine reference at https://sournd.com/engines/pivotta/index.md. Expose every parameter through APVTS.