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Diffstat (limited to 'Alc/effects/autowah.c')
| -rw-r--r-- | Alc/effects/autowah.c | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/Alc/effects/autowah.c b/Alc/effects/autowah.c new file mode 100644 index 00000000..cc207858 --- /dev/null +++ b/Alc/effects/autowah.c @@ -0,0 +1,293 @@ +/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 2013 by Anis A. Hireche, Nasca Octavian Paul
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ * Or go to http://www.gnu.org/copyleft/lgpl.html
+ */
+
+#include <stdlib.h>
+
+#include "config.h"
+#include "alu.h"
+#include "alFilter.h"
+#include "alError.h"
+#include "alMain.h"
+#include "alAuxEffectSlot.h"
+
+
+/* You can tweak the octave of this dynamic filter just changing next macro
+ * guitar - (default) 2.0f
+ * bass - 4.0f
+ */
+#define OCTAVE 2.0f
+
+
+typedef struct ALautowahStateFactory {
+ DERIVE_FROM_TYPE(ALeffectStateFactory);
+} ALautowahStateFactory;
+
+static ALautowahStateFactory AutowahFactory;
+
+
+/* We use a lfo with a custom low-pass filter to generate autowah
+ * effect and a high-pass filter to avoid distortion and aliasing.
+ * By adding the two filters up, we obtain a dynamic bandpass filter.
+ */
+
+typedef struct ALautowahState {
+ DERIVE_FROM_TYPE(ALeffectState);
+
+ /* Effect gains for each channel */
+ ALfloat Gain[MaxChannels];
+
+ /* Effect parameters */
+ ALfloat AttackTime;
+ ALfloat ReleaseTime;
+ ALfloat Resonance;
+ ALfloat PeakGain;
+ ALuint Frequency;
+
+ /* Samples processing */
+ ALuint lfo;
+ ALfilterState low_pass;
+ ALfilterState high_pass;
+} ALautowahState;
+
+static ALvoid ALautowahState_Destruct(ALautowahState *state)
+{
+ (void)state;
+}
+
+static ALboolean ALautowahState_deviceUpdate(ALautowahState *state, ALCdevice *device)
+{
+ return AL_TRUE;
+ (void)state;
+ (void)device;
+}
+
+static ALvoid ALautowahState_update(ALautowahState *state, ALCdevice *Device, const ALeffectslot *Slot)
+{
+ ALuint i;
+ ALfloat gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
+
+ /* computing high-pass cutoff and bandwidth */
+ const ALfloat cutoff = LOWPASSFREQREF / (Device->Frequency * 4.0f);
+ const ALfloat bandwidth = (cutoff / 2.0f) / (cutoff * 0.67f);
+
+ /* computing high-pass filter coefficients */
+ ALfilterState_setParams(&state->high_pass,
+ ALfilterType_HighPass, 1.0f,
+ cutoff, bandwidth);
+
+ state->AttackTime = Slot->EffectProps.Autowah.AttackTime;
+ state->ReleaseTime = Slot->EffectProps.Autowah.ReleaseTime;
+ state->Frequency = Device->Frequency;
+ state->PeakGain = Slot->EffectProps.Autowah.PeakGain;
+ state->Resonance = Slot->EffectProps.Autowah.Resonance;
+
+ state->lfo = 0;
+
+ ALfilterState_clear(&state->low_pass);
+
+ for(i = 0;i < MaxChannels;i++)
+ state->Gain[i] = 0.0f;
+ for(i = 0;i < Device->NumChan;i++)
+ {
+ enum Channel chan = Device->Speaker2Chan[i];
+ state->Gain[chan] = gain;
+ }
+}
+
+static ALvoid ALautowahState_process(ALautowahState *state, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[BUFFERSIZE])
+{
+ ALuint it, kt;
+ ALuint base;
+
+ for(base = 0;base < SamplesToDo;)
+ {
+ ALfloat temps[64];
+ ALuint td = minu(SamplesToDo-base, 64);
+
+ for(it = 0;it < td;it++)
+ {
+ ALfloat smp = SamplesIn[it+base];
+ ALfloat frequency, omega, alpha, peak;
+
+ /* lfo for low-pass shaking */
+ if((state->lfo++) % 30 == 0)
+ {
+ /* Using custom low-pass filter coefficients, to handle the resonance and peak-gain properties. */
+ frequency = (1.0f + cosf(state->lfo * (1.0f / lerp(1.0f, 4.0f, state->AttackTime * state->ReleaseTime)) * 2.0f * F_PI / state->Frequency)) / OCTAVE;
+ frequency = expf((frequency - 1.0f) * 6.0f);
+
+ /* computing cutoff frequency and peak gain */
+ omega = F_PI * frequency;
+ alpha = sinf(omega) / (16.0f * (state->Resonance / AL_AUTOWAH_MAX_RESONANCE));
+ peak = lerp(1.0f, 10.0f, state->PeakGain / AL_AUTOWAH_MAX_PEAK_GAIN);
+
+ /* computing low-pass filter coefficients */
+ state->low_pass.b[0] = (1.0f - cosf(omega)) / 2.0f;
+ state->low_pass.b[1] = 1.0f - cosf(omega);
+ state->low_pass.b[2] = (1.0f - cosf(omega)) / 2.0f;
+ state->low_pass.a[0] = 1.0f + alpha / peak;
+ state->low_pass.a[1] = -2.0f * cosf(omega);
+ state->low_pass.a[2] = 1.0f - alpha / peak;
+
+ state->low_pass.b[2] /= state->low_pass.a[0];
+ state->low_pass.b[1] /= state->low_pass.a[0];
+ state->low_pass.b[0] /= state->low_pass.a[0];
+ state->low_pass.a[2] /= state->low_pass.a[0];
+ state->low_pass.a[1] /= state->low_pass.a[0];
+ state->low_pass.a[0] /= state->low_pass.a[0];
+ }
+
+ /* do high-pass filter */
+ smp = ALfilterState_processSingle(&state->high_pass, smp);
+
+ /* do low-pass filter */
+ temps[it] = ALfilterState_processSingle(&state->low_pass, smp);
+ }
+
+ for(kt = 0;kt < MaxChannels;kt++)
+ {
+ ALfloat gain = state->Gain[kt];
+ if(!(gain > 0.00001f))
+ continue;
+
+ for(it = 0;it < td;it++)
+ SamplesOut[kt][base+it] += gain * temps[it];
+ }
+
+ base += td;
+ }
+}
+
+static void ALautowahState_Delete(ALautowahState *state)
+{
+ free(state);
+}
+
+DEFINE_ALEFFECTSTATE_VTABLE(ALautowahState);
+
+
+static ALeffectState *ALautowahStateFactory_create(ALautowahStateFactory *factory)
+{
+ ALautowahState *state;
+ (void)factory;
+
+ state = malloc(sizeof(*state));
+ if(!state) return NULL;
+ SET_VTABLE2(ALautowahState, ALeffectState, state);
+
+ ALfilterState_clear(&state->low_pass);
+ ALfilterState_clear(&state->high_pass);
+
+ return STATIC_CAST(ALeffectState, state);
+}
+
+DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALautowahStateFactory);
+
+ALeffectStateFactory *ALautowahStateFactory_getFactory(void)
+{
+ SET_VTABLE2(ALautowahStateFactory, ALeffectStateFactory, &AutowahFactory);
+ return STATIC_CAST(ALeffectStateFactory, &AutowahFactory);
+}
+
+
+void ALautowah_setParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
+{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)effect;(void)param;(void)val; }
+void ALautowah_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
+{
+ ALautowah_setParami(effect, context, param, vals[0]);
+}
+
+void ALautowah_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
+{
+ ALeffectProps *props = &effect->Props;
+ switch(param)
+ {
+ case AL_AUTOWAH_ATTACK_TIME:
+ if(!(val >= AL_AUTOWAH_MIN_ATTACK_TIME && val <= AL_AUTOWAH_MAX_ATTACK_TIME))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Autowah.AttackTime = val;
+ break;
+
+ case AL_AUTOWAH_RELEASE_TIME:
+ if(!(val >= AL_AUTOWAH_MIN_RELEASE_TIME && val <= AL_AUTOWAH_MAX_RELEASE_TIME))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Autowah.ReleaseTime = val;
+ break;
+
+ case AL_AUTOWAH_RESONANCE:
+ if(!(val >= AL_AUTOWAH_MIN_RESONANCE && val <= AL_AUTOWAH_MAX_RESONANCE))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Autowah.Resonance = val;
+ break;
+
+ case AL_AUTOWAH_PEAK_GAIN:
+ if(!(val >= AL_AUTOWAH_MIN_PEAK_GAIN && val <= AL_AUTOWAH_MAX_PEAK_GAIN))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Autowah.PeakGain = val;
+ break;
+
+ default:
+ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
+ }
+}
+
+void ALautowah_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
+{
+ ALautowah_setParamf(effect, context, param, vals[0]);
+}
+
+void ALautowah_getParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint *val)
+{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)effect;(void)param;(void)val; }
+void ALautowah_getParamiv(ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
+{
+ ALautowah_getParami(effect, context, param, vals);
+}
+void ALautowah_getParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
+{
+ const ALeffectProps *props = &effect->Props;
+ switch(param)
+ {
+ case AL_AUTOWAH_ATTACK_TIME:
+ *val = props->Autowah.AttackTime;
+ break;
+
+ case AL_AUTOWAH_RELEASE_TIME:
+ *val = props->Autowah.ReleaseTime;
+ break;
+
+ case AL_AUTOWAH_RESONANCE:
+ *val = props->Autowah.Resonance;
+ break;
+
+ case AL_AUTOWAH_PEAK_GAIN:
+ *val = props->Autowah.PeakGain;
+ break;
+
+ default:
+ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
+ }
+}
+
+void ALautowah_getParamfv(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
+{
+ ALautowah_getParamf(effect, context, param, vals);
+}
+
+DEFINE_ALEFFECT_VTABLE(ALautowah);
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