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-rw-r--r--Alc/effects/distortion.c300
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diff --git a/Alc/effects/distortion.c b/Alc/effects/distortion.c
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+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 2013 by Mike Gorchak
+ * 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 "config.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+#include "alMain.h"
+#include "alFilter.h"
+#include "alAuxEffectSlot.h"
+#include "alError.h"
+#include "alu.h"
+
+
+typedef struct ALdistortionState {
+ DERIVE_FROM_TYPE(ALeffectState);
+
+ /* Effect gains for each channel */
+ ALfloat Gain[MaxChannels];
+
+ /* Effect parameters */
+ ALfilterState lowpass;
+ ALfilterState bandpass;
+ ALfloat attenuation;
+ ALfloat edge_coeff;
+} ALdistortionState;
+
+static ALvoid ALdistortionState_Destruct(ALdistortionState *UNUSED(state))
+{
+}
+
+static ALboolean ALdistortionState_deviceUpdate(ALdistortionState *UNUSED(state), ALCdevice *UNUSED(device))
+{
+ return AL_TRUE;
+}
+
+static ALvoid ALdistortionState_update(ALdistortionState *state, ALCdevice *Device, const ALeffectslot *Slot)
+{
+ ALfloat frequency = (ALfloat)Device->Frequency;
+ ALfloat bandwidth;
+ ALfloat cutoff;
+ ALfloat edge;
+ ALfloat gain;
+
+ /* Store distorted signal attenuation settings */
+ state->attenuation = Slot->EffectProps.Distortion.Gain;
+
+ /* Store waveshaper edge settings */
+ edge = sinf(Slot->EffectProps.Distortion.Edge * (F_PI_2));
+ edge = minf(edge, 0.99f);
+ state->edge_coeff = 2.0f * edge / (1.0f-edge);
+
+ /* Lowpass filter */
+ cutoff = Slot->EffectProps.Distortion.LowpassCutoff;
+ /* 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);
+
+ /* 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);
+
+ gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
+ SetGains(Device, gain, state->Gain);
+}
+
+static ALvoid ALdistortionState_process(ALdistortionState *state, ALuint SamplesToDo, const ALfloat *restrict SamplesIn, ALfloat (*restrict SamplesOut)[BUFFERSIZE])
+{
+ const ALfloat fc = state->edge_coeff;
+ float oversample_buffer[64][4];
+ ALuint base;
+ ALuint it;
+ ALuint ot;
+ ALuint kt;
+
+ for(base = 0;base < SamplesToDo;)
+ {
+ ALfloat temps[64];
+ ALuint td = minu(SamplesToDo-base, 64);
+
+ /* Perform 4x oversampling to avoid aliasing. */
+ /* Oversampling greatly improves distortion */
+ /* quality and allows to implement lowpass and */
+ /* bandpass filters using high frequencies, at */
+ /* which classic IIR filters became unstable. */
+
+ /* Fill oversample buffer using zero stuffing */
+ for(it = 0;it < td;it++)
+ {
+ oversample_buffer[it][0] = SamplesIn[it+base];
+ oversample_buffer[it][1] = 0.0f;
+ oversample_buffer[it][2] = 0.0f;
+ oversample_buffer[it][3] = 0.0f;
+ }
+
+ /* First step, do lowpass filtering of original signal, */
+ /* additionally perform buffer interpolation and lowpass */
+ /* cutoff for oversampling (which is fortunately first */
+ /* step of distortion). So combine three operations into */
+ /* the one. */
+ for(it = 0;it < td;it++)
+ {
+ for(ot = 0;ot < 4;ot++)
+ {
+ ALfloat smp;
+ smp = ALfilterState_processSingle(&state->lowpass, oversample_buffer[it][ot]);
+
+ /* Restore signal power by multiplying sample by amount of oversampling */
+ oversample_buffer[it][ot] = smp * 4.0f;
+ }
+ }
+
+ for(it = 0;it < td;it++)
+ {
+ /* Second step, do distortion using waveshaper function */
+ /* to emulate signal processing during tube overdriving. */
+ /* Three steps of waveshaping are intended to modify */
+ /* waveform without boost/clipping/attenuation process. */
+ for(ot = 0;ot < 4;ot++)
+ {
+ ALfloat smp = oversample_buffer[it][ot];
+
+ smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
+ smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp)) * -1.0f;
+ smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
+
+ /* Third step, do bandpass filtering of distorted signal */
+ smp = ALfilterState_processSingle(&state->bandpass, smp);
+ oversample_buffer[it][ot] = smp;
+ }
+
+ /* Fourth step, final, do attenuation and perform decimation, */
+ /* store only one sample out of 4. */
+ temps[it] = oversample_buffer[it][0] * state->attenuation;
+ }
+
+ for(kt = 0;kt < MaxChannels;kt++)
+ {
+ ALfloat gain = state->Gain[kt];
+ if(!(gain > GAIN_SILENCE_THRESHOLD))
+ continue;
+
+ for(it = 0;it < td;it++)
+ SamplesOut[kt][base+it] += gain * temps[it];
+ }
+
+ base += td;
+ }
+}
+
+static void ALdistortionState_Delete(ALdistortionState *state)
+{
+ free(state);
+}
+
+DEFINE_ALEFFECTSTATE_VTABLE(ALdistortionState);
+
+
+typedef struct ALdistortionStateFactory {
+ DERIVE_FROM_TYPE(ALeffectStateFactory);
+} ALdistortionStateFactory;
+
+static ALeffectState *ALdistortionStateFactory_create(ALdistortionStateFactory *UNUSED(factory))
+{
+ ALdistortionState *state;
+
+ state = malloc(sizeof(*state));
+ if(!state) return NULL;
+ SET_VTABLE2(ALdistortionState, ALeffectState, state);
+
+ ALfilterState_clear(&state->lowpass);
+ ALfilterState_clear(&state->bandpass);
+
+ return STATIC_CAST(ALeffectState, state);
+}
+
+DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALdistortionStateFactory);
+
+
+ALeffectStateFactory *ALdistortionStateFactory_getFactory(void)
+{
+ static ALdistortionStateFactory DistortionFactory = { { GET_VTABLE2(ALdistortionStateFactory, ALeffectStateFactory) } };
+
+ return STATIC_CAST(ALeffectStateFactory, &DistortionFactory);
+}
+
+
+void ALdistortion_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint UNUSED(val))
+{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
+void ALdistortion_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
+{
+ ALdistortion_setParami(effect, context, param, vals[0]);
+}
+void ALdistortion_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
+{
+ ALeffectProps *props = &effect->Props;
+ switch(param)
+ {
+ case AL_DISTORTION_EDGE:
+ if(!(val >= AL_DISTORTION_MIN_EDGE && val <= AL_DISTORTION_MAX_EDGE))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Distortion.Edge = val;
+ break;
+
+ case AL_DISTORTION_GAIN:
+ if(!(val >= AL_DISTORTION_MIN_GAIN && val <= AL_DISTORTION_MAX_GAIN))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Distortion.Gain = val;
+ break;
+
+ case AL_DISTORTION_LOWPASS_CUTOFF:
+ if(!(val >= AL_DISTORTION_MIN_LOWPASS_CUTOFF && val <= AL_DISTORTION_MAX_LOWPASS_CUTOFF))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Distortion.LowpassCutoff = val;
+ break;
+
+ case AL_DISTORTION_EQCENTER:
+ if(!(val >= AL_DISTORTION_MIN_EQCENTER && val <= AL_DISTORTION_MAX_EQCENTER))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Distortion.EQCenter = val;
+ break;
+
+ case AL_DISTORTION_EQBANDWIDTH:
+ if(!(val >= AL_DISTORTION_MIN_EQBANDWIDTH && val <= AL_DISTORTION_MAX_EQBANDWIDTH))
+ SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
+ props->Distortion.EQBandwidth = val;
+ break;
+
+ default:
+ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
+ }
+}
+void ALdistortion_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
+{
+ ALdistortion_setParamf(effect, context, param, vals[0]);
+}
+
+void ALdistortion_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint *UNUSED(val))
+{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
+void ALdistortion_getParamiv(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
+{
+ ALdistortion_getParami(effect, context, param, vals);
+}
+void ALdistortion_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
+{
+ const ALeffectProps *props = &effect->Props;
+ switch(param)
+ {
+ case AL_DISTORTION_EDGE:
+ *val = props->Distortion.Edge;
+ break;
+
+ case AL_DISTORTION_GAIN:
+ *val = props->Distortion.Gain;
+ break;
+
+ case AL_DISTORTION_LOWPASS_CUTOFF:
+ *val = props->Distortion.LowpassCutoff;
+ break;
+
+ case AL_DISTORTION_EQCENTER:
+ *val = props->Distortion.EQCenter;
+ break;
+
+ case AL_DISTORTION_EQBANDWIDTH:
+ *val = props->Distortion.EQBandwidth;
+ break;
+
+ default:
+ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
+ }
+}
+void ALdistortion_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
+{
+ ALdistortion_getParamf(effect, context, param, vals);
+}
+
+DEFINE_ALEFFECT_VTABLE(ALdistortion);
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