Pass in the Q parameter for setting the filter parameters

Also better handle the peaking filter gain.

4 files changed, 36 insertions, 21 deletions

diff --git a/Alc/effects/distortion.c b/Alc/effects/distortion.c
index 22e05c70..221cec39 100644
--- a/Alc/effects/distortion.c
+++ b/Alc/effects/distortion.c
@@ -72,14 +72,16 @@ static ALvoid ALdistortionState_update(ALdistortionState *state, ALCdevice *Devi
     /* Bandwidth value is constant in octaves */
     bandwidth = (cutoff / 2.0f) / (cutoff * 0.67f);
     ALfilterState_setParams(&state->lowpass, ALfilterType_LowPass, 1.0f,
-                            cutoff / (frequency*4.0f), bandwidth);
+        cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
+    );
 
     /* Bandpass filter */
     cutoff = Slot->EffectProps.Distortion.EQCenter;
     /* Convert bandwidth in Hz to octaves */
     bandwidth = Slot->EffectProps.Distortion.EQBandwidth / (cutoff * 0.67f);
     ALfilterState_setParams(&state->bandpass, ALfilterType_BandPass, 1.0f,
-                            cutoff / (frequency*4.0f), bandwidth);
+        cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
+    );
 
     ComputeAmbientGains(Device, Slot->Gain, state->Gain);
 }
diff --git a/Alc/effects/echo.c b/Alc/effects/echo.c
index b852a096..f5a53c36 100644
--- a/Alc/effects/echo.c
+++ b/Alc/effects/echo.c
@@ -85,8 +85,7 @@ static ALvoid ALechoState_update(ALechoState *state, ALCdevice *Device, const AL
 {
     ALfloat pandir[3] = { 0.0f, 0.0f, 0.0f };
     ALuint frequency = Device->Frequency;
-    ALfloat gain = Slot->Gain;
-    ALfloat lrpan;
+    ALfloat gain, lrpan;
 
     state->Tap[0].delay = fastf2u(Slot->EffectProps.Echo.Delay * frequency) + 1;
     state->Tap[1].delay = fastf2u(Slot->EffectProps.Echo.LRDelay * frequency);
@@ -96,9 +95,12 @@ static ALvoid ALechoState_update(ALechoState *state, ALCdevice *Device, const AL
 
     state->FeedGain = Slot->EffectProps.Echo.Feedback;
 
+    gain = minf(1.0f - Slot->EffectProps.Echo.Damping, 0.01f);
     ALfilterState_setParams(&state->Filter, ALfilterType_HighShelf,
-                            1.0f - Slot->EffectProps.Echo.Damping,
-                            LOWPASSFREQREF/frequency, 0.0f);
+                            gain, LOWPASSFREQREF/frequency,
+                            calc_rcpQ_from_slope(gain, 0.75f));
+
+    gain = Slot->Gain;
 
     /* First tap panning */
     pandir[0] = -lrpan;
diff --git a/Alc/effects/equalizer.c b/Alc/effects/equalizer.c
index 6a5ed549..244667ab 100644
--- a/Alc/effects/equalizer.c
+++ b/Alc/effects/equalizer.c
@@ -93,29 +93,37 @@ static ALboolean ALequalizerState_deviceUpdate(ALequalizerState *UNUSED(state),
 static ALvoid ALequalizerState_update(ALequalizerState *state, ALCdevice *device, const ALeffectslot *slot)
 {
     ALfloat frequency = (ALfloat)device->Frequency;
+    ALfloat gain, freq_mult;
 
     ComputeAmbientGains(device, slot->Gain, state->Gain);
 
-    /* Calculate coefficients for the each type of filter */
+    /* Calculate coefficients for the each type of filter. Note that the shelf
+     * filters' gain is for the reference frequency, which is the centerpoint
+     * of the transition band.
+     */
+    gain = sqrtf(slot->EffectProps.Equalizer.LowGain);
+    freq_mult = slot->EffectProps.Equalizer.LowCutoff/frequency;
     ALfilterState_setParams(&state->filter[0], ALfilterType_LowShelf,
-                            sqrtf(slot->EffectProps.Equalizer.LowGain),
-                            slot->EffectProps.Equalizer.LowCutoff/frequency,
-                            0.0f);
+        gain, freq_mult, calc_rcpQ_from_slope(gain, 0.75f)
+    );
 
+    gain = slot->EffectProps.Equalizer.Mid1Gain;
+    freq_mult = slot->EffectProps.Equalizer.Mid1Center/frequency;
     ALfilterState_setParams(&state->filter[1], ALfilterType_Peaking,
-                            sqrtf(slot->EffectProps.Equalizer.Mid1Gain),
-                            slot->EffectProps.Equalizer.Mid1Center/frequency,
-                            slot->EffectProps.Equalizer.Mid1Width);
+        gain, freq_mult, calc_rcpQ_from_bandwidth(freq_mult, slot->EffectProps.Equalizer.Mid1Width)
+    );
 
+    gain = slot->EffectProps.Equalizer.Mid2Gain;
+    freq_mult = slot->EffectProps.Equalizer.Mid2Center/frequency;
     ALfilterState_setParams(&state->filter[2], ALfilterType_Peaking,
-                            sqrtf(slot->EffectProps.Equalizer.Mid2Gain),
-                            slot->EffectProps.Equalizer.Mid2Center/frequency,
-                            slot->EffectProps.Equalizer.Mid2Width);
+        gain, freq_mult, calc_rcpQ_from_bandwidth(freq_mult, slot->EffectProps.Equalizer.Mid2Width)
+    );
 
+    gain = sqrtf(slot->EffectProps.Equalizer.HighGain);
+    freq_mult = slot->EffectProps.Equalizer.HighCutoff/frequency;
     ALfilterState_setParams(&state->filter[3], ALfilterType_HighShelf,
-                            sqrtf(slot->EffectProps.Equalizer.HighGain),
-                            slot->EffectProps.Equalizer.HighCutoff/frequency,
-                            0.0f);
+        gain, freq_mult, calc_rcpQ_from_slope(gain, 0.75f)
+    );
 }
 
 static ALvoid ALequalizerState_process(ALequalizerState *state, ALuint SamplesToDo, const ALfloat *restrict SamplesIn, ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALuint NumChannels)
diff --git a/Alc/effects/reverb.c b/Alc/effects/reverb.c
index 6c3f2691..71e12b33 100644
--- a/Alc/effects/reverb.c
+++ b/Alc/effects/reverb.c
@@ -1112,6 +1112,7 @@ static ALvoid ALreverbState_update(ALreverbState *State, ALCdevice *Device, cons
     const ALeffectProps *props = &Slot->EffectProps;
     ALuint frequency = Device->Frequency;
     ALfloat lfscale, hfscale, hfRatio;
+    ALfloat gainlf, gainhf;
     ALfloat cw, x, y;
 
     if(Slot->EffectType == AL_EFFECT_EAXREVERB && !EmulateEAXReverb)
@@ -1121,11 +1122,13 @@ static ALvoid ALreverbState_update(ALreverbState *State, ALCdevice *Device, cons
 
     // Calculate the master filters
     hfscale = props->Reverb.HFReference / frequency;
+    gainhf = maxf(props->Reverb.GainHF, 0.0001f);
     ALfilterState_setParams(&State->LpFilter, ALfilterType_HighShelf,
-                            props->Reverb.GainHF, hfscale, 0.0f);
+                            gainhf, hfscale, calc_rcpQ_from_slope(gainhf, 0.75f));
     lfscale = props->Reverb.LFReference / frequency;
+    gainlf = maxf(props->Reverb.GainLF, 0.0001f);
     ALfilterState_setParams(&State->HpFilter, ALfilterType_LowShelf,
-                            props->Reverb.GainLF, lfscale, 0.0f);
+                            gainlf, lfscale, calc_rcpQ_from_slope(gainlf, 0.75f));
 
     // Update the modulator line.
     UpdateModulator(props->Reverb.ModulationTime, props->Reverb.ModulationDepth,