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Add DiodeLadderFilter.swift (#30)
* Add `DiodeLadderFilter.swift` Based on the Will Pirkle and CCRMA Chugins emulation already present in Soundpipe -- `diode.c` * Add tests for `DiodeLadderFilter` * Add wait and fix sample rate Needed to change the sample rate back to normal for the other tests to work and also added a `wait()` for the parameter ramping test to record the correct values * Use MD5's from Rosetta I forgot that I'm using an M1 Mac and the workrunners use Intel Macs
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‎Sources/CSoundpipeAudioKit/Effects/DiodeLadderFilterDSP.mm‎

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// Copyright AudioKit. All Rights Reserved.
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#include "SoundpipeDSPBase.h"
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#include "ParameterRamper.h"
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#include "Soundpipe.h"
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enum DiodeLadderFilterParameter : AUParameterAddress {
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DiodeLadderFilterParameterCutoffFrequency,
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DiodeLadderFilterParameterResonance,
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};
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class DiodeLadderFilterDSP : public SoundpipeDSPBase {
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private:
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sp_diode *diode0;
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sp_diode *diode1;
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ParameterRamper cutoffFrequencyRamp;
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ParameterRamper resonanceRamp;
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public:
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DiodeLadderFilterDSP() {
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parameters[DiodeLadderFilterParameterCutoffFrequency] = &cutoffFrequencyRamp;
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parameters[DiodeLadderFilterParameterResonance] = &resonanceRamp;
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}
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void init(int channelCount, double sampleRate) override {
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SoundpipeDSPBase::init(channelCount, sampleRate);
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sp_diode_create(&diode0);
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sp_diode_init(sp, diode0);
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sp_diode_create(&diode1);
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sp_diode_init(sp, diode1);
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}
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void deinit() override {
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SoundpipeDSPBase::deinit();
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sp_diode_destroy(&diode0);
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sp_diode_destroy(&diode1);
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}
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void reset() override {
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SoundpipeDSPBase::reset();
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if (!isInitialized) return;
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sp_diode_init(sp, diode0);
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sp_diode_init(sp, diode1);
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}
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void process(FrameRange range) override {
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for (int i : range) {
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diode0->freq = diode1->freq = cutoffFrequencyRamp.getAndStep();
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diode0->res = diode1->res = resonanceRamp.getAndStep();
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float leftIn = inputSample(0, i);
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float rightIn = inputSample(1, i);
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float &leftOut = outputSample(0, i);
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float &rightOut = outputSample(1, i);
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sp_diode_compute(sp, diode0, &leftIn, &leftOut);
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sp_diode_compute(sp, diode1, &rightIn, &rightOut);
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}
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}
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};
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AK_REGISTER_DSP(DiodeLadderFilterDSP, "diod")
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AK_REGISTER_PARAMETER(DiodeLadderFilterParameterCutoffFrequency)
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AK_REGISTER_PARAMETER(DiodeLadderFilterParameterResonance)

‎Sources/SoundpipeAudioKit/Effects/DiodeLadderFilter.swift‎

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// Copyright AudioKit. All Rights Reserved. Revision History at http://github.com/AudioKit/SoundpipeAudioKit/
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import AudioKit
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import AudioKitEX
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import AVFoundation
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import CAudioKitEX
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/// Diode Ladder Filter is an new digital implementation of the VCS3 ladder filter
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/// based on the work of Will Pirkle
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/// "Virtual Analog (VA) Diode Ladder Filter"
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///
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public class DiodeLadderFilter: Node {
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let input: Node
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/// Connected nodes
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public var connections: [Node] { [input] }
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/// Underlying AVAudioNode
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public var avAudioNode = instantiate(effect: "diod")
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// MARK: - Parameters
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/// Specification for cutoffFrequency (still determining best ranges)
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public static let cutoffFrequencyDef = NodeParameterDef(
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identifier: "cutoffFrequency",
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name: "Cutoff Frequency",
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address: akGetParameterAddress("DiodeLadderFilterParameterCutoffFrequency"),
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defaultValue: 1000.0,
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range: 12.0 ... 20000.0,
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unit: .hertz
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)
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/// Filter cutoff frequency
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@Parameter(cutoffFrequencyDef) public var cutoffFrequency: AUValue
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/// Specification for resonance (still determining best ranges)
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public static let resonanceDef = NodeParameterDef(
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identifier: "resonance",
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name: "Resonance",
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address: akGetParameterAddress("DiodeLadderFilterParameterResonance"),
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defaultValue: 0.5,
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range: 0.0 ... 1.0,
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unit: .generic
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)
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/// Resonance
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@Parameter(resonanceDef) public var resonance: AUValue
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// MARK: - Initialization
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/// Initialize this filter node
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///
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/// - Parameters:
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/// - input: Input node to process
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/// - cutoffFrequency: Filter cutoff frequency
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/// - resonance: Resonance
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///
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public init(
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_ input: Node,
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cutoffFrequency: AUValue = cutoffFrequencyDef.defaultValue,
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resonance: AUValue = resonanceDef.defaultValue
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) {
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self.input = input
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setupParameters()
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self.cutoffFrequency = cutoffFrequency
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self.resonance = resonance
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}
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}

‎Tests/SoundpipeAudioKitTests/Effects Tests/DiodeLadderFilterTests.swift‎

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// Copyright AudioKit. All Rights Reserved. Revision History at http://github.com/AudioKit/SoundpipeAudioKit/
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import AudioKit
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import SoundpipeAudioKit
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import XCTest
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class DiodeLadderFilterTests: XCTestCase {
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func testBypass() {
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let engine = AudioEngine()
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let input = Oscillator(waveform: Table(.sine),
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frequency: 440,
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amplitude: 1.0,
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detuningOffset: 0.0,
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detuningMultiplier: 1.0)
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let filter = DiodeLadderFilter(input)
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engine.output = filter
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input.start()
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let audio = engine.startTest(totalDuration: 2.0)
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let originalAudio = engine.render(duration: 1.0)
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audio.append(originalAudio)
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filter.bypass()
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let bypassedAudio = engine.render(duration: 1.0)
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audio.append(bypassedAudio)
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guard let originalAudioPeak = originalAudio.peak()?.amplitude else {
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XCTFail("The audio data appears to have no peak")
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return
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}
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guard let bypassedAudioPeak = bypassedAudio.peak()?.amplitude else {
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XCTFail("The audio data appears to have no peak")
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return
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}
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XCTAssertNotEqual(originalAudioPeak, bypassedAudioPeak, accuracy: 0.01)
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testMD5(audio)
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}
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func testInitialParameterValues() {
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let input = Oscillator(waveform: Table(.sine),
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frequency: 440,
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amplitude: 1.0,
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detuningOffset: 0.0,
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detuningMultiplier: 1.0)
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let filter = DiodeLadderFilter(input)
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guard let filterParamTree = filter.au.parameterTree else {
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XCTFail("No parameter tree found")
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return
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}
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let cutoffFrequencyAddress = DiodeLadderFilter.cutoffFrequencyDef.address
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let resonanceAddress = DiodeLadderFilter.resonanceDef.address
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guard let cutoffFrequencyParam = filterParamTree.parameter(withAddress: cutoffFrequencyAddress) else {
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XCTFail("Parameter address not found for: \(DiodeLadderFilter.cutoffFrequencyDef.name)")
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return
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}
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guard let resonanceParam = filterParamTree.parameter(withAddress: resonanceAddress) else {
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XCTFail("Parameter address not found for: \(DiodeLadderFilter.resonanceDef.name)")
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return
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}
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XCTAssertEqual(cutoffFrequencyParam.value, DiodeLadderFilter.cutoffFrequencyDef.defaultValue)
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XCTAssertEqual(filter.cutoffFrequency, DiodeLadderFilter.cutoffFrequencyDef.defaultValue)
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XCTAssertEqual(resonanceParam.value, DiodeLadderFilter.resonanceDef.defaultValue)
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XCTAssertEqual(filter.resonance, DiodeLadderFilter.resonanceDef.defaultValue)
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}
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func testParameterRamping() {
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let engine = AudioEngine()
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let input = Oscillator(waveform: Table(.sine),
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frequency: 440,
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amplitude: 1.0,
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detuningOffset: 0.0,
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detuningMultiplier: 1.0)
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let filter = DiodeLadderFilter(input)
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guard let filterParamTree = filter.au.parameterTree else {
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XCTFail("No parameter tree found")
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return
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}
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let cutoffFrequencyAddress = DiodeLadderFilter.cutoffFrequencyDef.address
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let resonanceAddress = DiodeLadderFilter.resonanceDef.address
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guard let cutoffFrequencyParam = filterParamTree.parameter(withAddress: cutoffFrequencyAddress) else {
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XCTFail("Parameter address not found for: \(DiodeLadderFilter.cutoffFrequencyDef.name)")
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return
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}
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guard let resonanceParam = filterParamTree.parameter(withAddress: resonanceAddress) else {
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XCTFail("Parameter address not found for: \(DiodeLadderFilter.resonanceDef.name)")
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return
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}
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engine.output = filter
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input.start()
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let audio = engine.startTest(totalDuration: 1.0)
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let initialFreq: AUValue = 12.0
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let finalFreq: AUValue = 500.0
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let initialRes: AUValue = 0.2
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let finalRes: AUValue = 1.0
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let duration: Float = 1.0
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filter.$cutoffFrequency.ramp(from: initialFreq, to: finalFreq, duration: duration)
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filter.$resonance.ramp(from: initialRes, to: finalRes, duration: duration)
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audio.append(engine.render(duration: 0.02))
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wait(for: 0.02)
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XCTAssertEqual(filter.cutoffFrequency, initialFreq)
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XCTAssertEqual(cutoffFrequencyParam.value, initialFreq)
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XCTAssertEqual(filter.resonance, initialRes)
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XCTAssertEqual(resonanceParam.value, initialRes)
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audio.append(engine.render(duration: 0.98))
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XCTAssertEqual(filter.cutoffFrequency, finalFreq)
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XCTAssertEqual(cutoffFrequencyParam.value, finalFreq)
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XCTAssertEqual(filter.resonance, finalRes)
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XCTAssertEqual(resonanceParam.value, finalRes)
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testMD5(audio)
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}
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func testReset() {
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let engine = AudioEngine()
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let input = Oscillator(waveform: Table(.sine),
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frequency: 440,
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amplitude: 1.0,
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detuningOffset: 0.0,
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detuningMultiplier: 1.0)
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let filter = DiodeLadderFilter(input)
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engine.output = filter
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input.start()
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let audio = engine.startTest(totalDuration: 2.0)
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guard let sampleRate = engine.mainMixerNode?.outputFormat.sampleRate else {
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XCTFail("No sample rate to render audio")
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return
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}
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if sampleRate == 0 {
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XCTFail("Can't render audio with 0 Hz sample rate")
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}
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audio.append(engine.render(duration: 1.0))
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XCTAssertEqual(audio.toFloatChannelData()?[0].count, Int(sampleRate))
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filter.reset()
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audio.append(engine.render(duration: 1.0))
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XCTAssertEqual(audio.toFloatChannelData()?[0].count, Int(sampleRate) * 2)
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testMD5(audio)
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}
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func testSampleRateChange() {
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let engine = AudioEngine()
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let input = Oscillator(waveform: Table(.sine),
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frequency: 440,
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amplitude: 1.0,
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detuningOffset: 0.0,
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detuningMultiplier: 1.0)
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let filter = DiodeLadderFilter(input)
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engine.output = filter
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input.start()
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let audio = engine.startTest(totalDuration: 2.090909090909091)
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guard let sampleRate = engine.mainMixerNode?.outputFormat.sampleRate else {
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XCTFail("No sample rate to render audio")
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return
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}
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if sampleRate == 0 {
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XCTFail("Can't render audio with 0 Hz sample rate")
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}
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XCTAssertEqual(sampleRate, Settings.sampleRate)
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audio.append(engine.render(duration: 1.0))
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XCTAssertEqual(audio.toFloatChannelData()?[0].count, Int(sampleRate))
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Settings.sampleRate = 48000
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guard let newSampleRate = engine.mainMixerNode?.outputFormat.sampleRate else {
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XCTFail("No sample rate to render audio")
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return
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}
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XCTAssertEqual(Settings.sampleRate, newSampleRate)
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audio.append(engine.render(duration: 1.0))
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XCTAssertEqual(audio.toFloatChannelData()?[0].count, Int(sampleRate) + Int(newSampleRate))
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testMD5(audio)
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Settings.sampleRate = 44100 // Put this back to default for other tests
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}
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// for waiting in the background for realtime testing
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func wait(for interval: TimeInterval) {
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let delayExpectation = XCTestExpectation(description: "delayExpectation")
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DispatchQueue.main.asyncAfter(deadline: .now() + interval) {
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delayExpectation.fulfill()
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}
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wait(for: [delayExpectation], timeout: interval + 1)
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}
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}

‎Tests/SoundpipeAudioKitTests/ValidatedMD5s.swift‎

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"-[BalancerTests testDefault]": "26e2c62078ee266c120677b7386ab292",
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"-[ConvolutionTests testConvolution]": "d585f94eba7aedafd7987c68af78ff75",
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"-[ConvolutionTests testStereoConvolution]": "4b7904aebc448fc6d5fbcdefba320b2a",
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"-[DiodeLadderFilterTests testBypass]": "2aeb94f662f38dde83d9bb70c5ceeac0",
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"-[DiodeLadderFilterTests testParameterRamping]": "b82608eee1e82b421d0ecc3425764c1e",
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"-[DiodeLadderFilterTests testReset]": "72e56cdab82e8f23ea0473bf261861ec",
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"-[DiodeLadderFilterTests testSampleRateChange]": "bf552ba8542b20f9c229c0d510cd443c",
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"-[DrumSynthTests testSynthKick]": "bc0323f2529a42eb1c30245cae4662cf",
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"-[DrumSynthTests testSynthSnare]": "8642993a77e40ce3d3d505b8e0782205",
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"-[DryWetMixerTests testBalance0]": "54fb40c15242198d45b31b6a79187d07",

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