Add the Auto Filter rack effect

- LPF, HPF, BPF and Notch at 12 or 24 dB/oct

- Two LFOs with Synth's waveform and sync options, one on the cutoff and
  one on the resonance

- Envelope follower on the cutoff, with attack and release

- Bipolar non-linear intensities, stereo phase offset, gain and mix

- Normalize the band-pass peak to unity, so resonance narrows the band
  instead of setting its level

Author: juzzlin

CHANGELOG

@@ -9,6 +9,13 @@ New features:
   - Pulse Width, Vocal Formant, Resonant Sweep and Organ Drawbar
   - Wavetables are now built on first use instead of at startup
 
+* Add the Auto Filter rack effect
+  - LPF, HPF, BPF and Notch at 12 or 24 dB/oct
+  - Two LFOs with Synth's waveform and sync options: one on the cutoff, one
+    on the resonance
+  - Envelope follower on the cutoff, with attack and release
+  - Bipolar intensities, stereo phase offset, output gain and mix
+
 * Add the Multiband Compressor rack effect
   - Three bands split by Linkwitz-Riley crossovers that sum back flat
   - Per-band threshold, ratio, knee, attack, release, makeup, bypass and solo

src/CMakeLists.txt

@@ -50,6 +50,7 @@ set(QML_SOURCE_FILES
     ${QML_BASE_DIR}/Dialogs/LoudnessReportDialog.qml
     ${QML_BASE_DIR}/Dialogs/AudioRenderDialog.qml
     ${QML_BASE_DIR}/Dialogs/AutoDuckerDialog.qml
+    ${QML_BASE_DIR}/Dialogs/AutoFilterDialog.qml
     ${QML_BASE_DIR}/Dialogs/AutoPannerDialog.qml
     ${QML_BASE_DIR}/Dialogs/BassGrinderDialog.qml
     ${QML_BASE_DIR}/Dialogs/BassSynthDialog.qml

src/common/constants.cpp

@@ -261,6 +261,11 @@ QString autoDucker()
     return "autoducker";
 }
 
+QString autoFilter()
+{
+    return "autofilter";
+}
+
 QString eq8BandParametric()
 {
     return "eq8bandparametric";
@@ -1262,6 +1267,11 @@ QString xmlKeyStereoMode()
     return "stereoMode";
 }
 
+QString xmlKeyStereoPhase()
+{
+    return "stereoPhase";
+}
+
 QString xmlKeyRate()
 {
     return "rate";
@@ -1387,6 +1397,16 @@ QString xmlKeyResonance()
     return "resonance";
 }
 
+QString xmlKeyFilterType()
+{
+    return "filterType";
+}
+
+QString xmlKeyFilterSlope()
+{
+    return "filterSlope";
+}
+
 QString xmlKeyKeyTrack()
 {
     return "keyTrack";

src/common/constants.hpp

@@ -170,6 +170,7 @@ QString endless();
 QString panner();
 QString autoPanner();
 QString autoDucker();
+QString autoFilter();
 QString eq8BandParametric();
 QString eq8BandParametricLegacy();
 QString vintagePassiveEq();
@@ -416,6 +417,7 @@ QString xmlKeyMultiKeyTrack();
 QString xmlKeyVoiceMode();
 QString xmlKeyMode();
 QString xmlKeyStereoMode();
+QString xmlKeyStereoPhase();
 QString xmlKeyBaseRate();
 QString xmlKeyRate();
 QString xmlKeyDepth();
@@ -445,6 +447,8 @@ QString xmlKeyVoiceBalance();
 QString xmlKeyVoiceUpperMale8();
 QString xmlKeyPitchBendRange();
 QString xmlKeyResonance();
+QString xmlKeyFilterType();
+QString xmlKeyFilterSlope();
 QString xmlKeyKeyTrack();
 QString xmlKeyAttack();
 QString xmlKeyDecay();

src/domain/CMakeLists.txt

@@ -52,6 +52,7 @@ set(HEADER_FILES
     effects/air_band_eq.hpp
     effects/all_pass_filter.hpp
     effects/auto_ducker.hpp
+    effects/auto_filter.hpp
     effects/auto_panner.hpp
     effects/bass_grinder.hpp
     effects/clipper.hpp
@@ -176,6 +177,7 @@ set(SOURCE_FILES
     effects/air_band_eq.cpp
     effects/all_pass_filter.cpp
     effects/auto_ducker.cpp
+    effects/auto_filter.cpp
     effects/auto_panner.cpp
     effects/bass_grinder.cpp
     effects/chorus.cpp

src/domain/dsp/lfo.cpp

@@ -66,6 +66,11 @@ void Lfo::setPhase(double phase)
     }
 }
 
+double Lfo::phase() const
+{
+    return m_phase;
+}
+
 void Lfo::reset()
 {
     m_phase = 0.0;

src/domain/dsp/lfo.hpp

@@ -51,6 +51,7 @@ class Lfo : public DspComponent
     void setWaveform(Waveform waveform);
     void setMode(Mode mode);
     void setPhase(double phase);
+    double phase() const;
     void trigger();
     double nextSample();
     void reset();