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authorChris Robinson <[email protected]>2013-05-23 21:33:16 -0700
committerChris Robinson <[email protected]>2013-05-23 21:33:16 -0700
commit357cf72ab33ef1807da8ea6ce4633fd8e2a89553 (patch)
treee8fc4fb0183ae56bf15c31f9bf28890201ee143c /Alc/effects/distortion.c
parent23766831282507bc09b223b4ecb645490b5fab0b (diff)
Move remaining effects to the effects subdir
Diffstat (limited to 'Alc/effects/distortion.c')
-rw-r--r--Alc/effects/distortion.c402
1 files changed, 402 insertions, 0 deletions
diff --git a/Alc/effects/distortion.c b/Alc/effects/distortion.c
new file mode 100644
index 00000000..7828377c
--- /dev/null
+++ b/Alc/effects/distortion.c
@@ -0,0 +1,402 @@
+/**
+ * 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 ALdistortionStateFactory {
+ DERIVE_FROM_TYPE(ALeffectStateFactory);
+} ALdistortionStateFactory;
+
+static ALdistortionStateFactory DistortionFactory;
+
+
+/* Filters implementation is based on the "Cookbook formulae for audio *
+ * EQ biquad filter coefficients" by Robert Bristow-Johnson *
+ * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt */
+
+typedef enum ALEQFilterType {
+ LOWPASS,
+ BANDPASS,
+} ALEQFilterType;
+
+typedef struct ALEQFilter {
+ ALEQFilterType type;
+ ALfloat x[2]; /* History of two last input samples */
+ ALfloat y[2]; /* History of two last output samples */
+ ALfloat a[3]; /* Transfer function coefficients "a" */
+ ALfloat b[3]; /* Transfer function coefficients "b" */
+} ALEQFilter;
+
+typedef struct ALdistortionState {
+ DERIVE_FROM_TYPE(ALeffectState);
+
+ /* Effect gains for each channel */
+ ALfloat Gain[MaxChannels];
+
+ /* Effect parameters */
+ ALEQFilter bandpass;
+ ALEQFilter lowpass;
+ ALfloat attenuation;
+ ALfloat edge_coeff;
+} ALdistortionState;
+
+static ALvoid ALdistortionState_Destruct(ALdistortionState *state)
+{
+ (void)state;
+}
+
+static ALboolean ALdistortionState_DeviceUpdate(ALdistortionState *state, ALCdevice *device)
+{
+ return AL_TRUE;
+ (void)state;
+ (void)device;
+}
+
+static ALvoid ALdistortionState_Update(ALdistortionState *state, ALCdevice *Device, const ALeffectslot *Slot)
+{
+ ALfloat gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
+ ALfloat frequency = (ALfloat)Device->Frequency;
+ ALuint it;
+ ALfloat w0;
+ ALfloat alpha;
+ ALfloat bandwidth;
+ ALfloat cutoff;
+ ALfloat edge;
+
+ for(it = 0;it < MaxChannels;it++)
+ state->Gain[it] = 0.0f;
+ for(it = 0;it < Device->NumChan;it++)
+ {
+ enum Channel chan = Device->Speaker2Chan[it];
+ state->Gain[chan] = gain;
+ }
+
+ /* Store distorted signal attenuation settings */
+ state->attenuation = Slot->effect.Distortion.Gain;
+
+ /* Store waveshaper edge settings */
+ edge = sinf(Slot->effect.Distortion.Edge * (F_PI/2.0f));
+ state->edge_coeff = 2.0f * edge / (1.0f-edge);
+
+ /* Lowpass filter */
+ cutoff = Slot->effect.Distortion.LowpassCutoff;
+ /* Bandwidth value is constant in octaves */
+ bandwidth = (cutoff / 2.0f) / (cutoff * 0.67f);
+ w0 = 2.0f*F_PI * cutoff / (frequency*4.0f);
+ alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
+ state->lowpass.b[0] = (1.0f - cosf(w0)) / 2.0f;
+ state->lowpass.b[1] = 1.0f - cosf(w0);
+ state->lowpass.b[2] = (1.0f - cosf(w0)) / 2.0f;
+ state->lowpass.a[0] = 1.0f + alpha;
+ state->lowpass.a[1] = -2.0f * cosf(w0);
+ state->lowpass.a[2] = 1.0f - alpha;
+
+ /* Bandpass filter */
+ cutoff = Slot->effect.Distortion.EQCenter;
+ /* Convert bandwidth in Hz to octaves */
+ bandwidth = Slot->effect.Distortion.EQBandwidth / (cutoff * 0.67f);
+ w0 = 2.0f*F_PI * cutoff / (frequency*4.0f);
+ alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
+ state->bandpass.b[0] = alpha;
+ state->bandpass.b[1] = 0;
+ state->bandpass.b[2] = -alpha;
+ state->bandpass.a[0] = 1.0f + alpha;
+ state->bandpass.a[1] = -2.0f * cosf(w0);
+ state->bandpass.a[2] = 1.0f - alpha;
+}
+
+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];
+ ALfloat tempsmp;
+ 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++)
+ {
+ tempsmp = state->lowpass.b[0] / state->lowpass.a[0] * oversample_buffer[it][ot] +
+ state->lowpass.b[1] / state->lowpass.a[0] * state->lowpass.x[0] +
+ state->lowpass.b[2] / state->lowpass.a[0] * state->lowpass.x[1] -
+ state->lowpass.a[1] / state->lowpass.a[0] * state->lowpass.y[0] -
+ state->lowpass.a[2] / state->lowpass.a[0] * state->lowpass.y[1];
+
+ state->lowpass.x[1] = state->lowpass.x[0];
+ state->lowpass.x[0] = oversample_buffer[it][ot];
+ state->lowpass.y[1] = state->lowpass.y[0];
+ state->lowpass.y[0] = tempsmp;
+ /* Restore signal power by multiplying sample by amount of oversampling */
+ oversample_buffer[it][ot] = tempsmp * 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 */
+ tempsmp = state->bandpass.b[0] / state->bandpass.a[0] * smp +
+ state->bandpass.b[1] / state->bandpass.a[0] * state->bandpass.x[0] +
+ state->bandpass.b[2] / state->bandpass.a[0] * state->bandpass.x[1] -
+ state->bandpass.a[1] / state->bandpass.a[0] * state->bandpass.y[0] -
+ state->bandpass.a[2] / state->bandpass.a[0] * state->bandpass.y[1];
+
+ state->bandpass.x[1] = state->bandpass.x[0];
+ state->bandpass.x[0] = smp;
+ state->bandpass.y[1] = state->bandpass.y[0];
+ state->bandpass.y[0] = tempsmp;
+
+ oversample_buffer[it][ot] = tempsmp;
+ }
+
+ /* 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 > 0.00001f))
+ continue;
+
+ for(it = 0;it < td;it++)
+ SamplesOut[kt][base+it] += gain * temps[it];
+ }
+
+ base += td;
+ }
+}
+
+static ALeffectStateFactory *ALdistortionState_getCreator(void)
+{
+ return STATIC_CAST(ALeffectStateFactory, &DistortionFactory);
+}
+
+DEFINE_ALEFFECTSTATE_VTABLE(ALdistortionState);
+
+
+static ALeffectState *ALdistortionStateFactory_create(void)
+{
+ ALdistortionState *state;
+
+ state = malloc(sizeof(*state));
+ if(!state) return NULL;
+ SET_VTABLE2(ALdistortionState, ALeffectState, state);
+
+ state->bandpass.type = BANDPASS;
+ state->lowpass.type = LOWPASS;
+
+ /* Initialize sample history only on filter creation to avoid */
+ /* sound clicks if filter settings were changed in runtime. */
+ state->bandpass.x[0] = 0.0f;
+ state->bandpass.x[1] = 0.0f;
+ state->lowpass.y[0] = 0.0f;
+ state->lowpass.y[1] = 0.0f;
+
+ return STATIC_CAST(ALeffectState, state);
+}
+
+static ALvoid ALdistortionStateFactory_destroy(ALeffectState *effect)
+{
+ ALdistortionState *state = STATIC_UPCAST(ALdistortionState, ALeffectState, effect);
+ ALdistortionState_Destruct(state);
+ free(state);
+}
+
+DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALdistortionStateFactory);
+
+
+static void init_distortion_factory(void)
+{
+ SET_VTABLE2(ALdistortionStateFactory, ALeffectStateFactory, &DistortionFactory);
+}
+
+ALeffectStateFactory *ALdistortionStateFactory_getFactory(void)
+{
+ static pthread_once_t once = PTHREAD_ONCE_INIT;
+ pthread_once(&once, init_distortion_factory);
+ return STATIC_CAST(ALeffectStateFactory, &DistortionFactory);
+}
+
+
+void distortion_SetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
+{
+ effect=effect;
+ val=val;
+
+ switch(param)
+ {
+ default:
+ alSetError(context, AL_INVALID_ENUM);
+ break;
+ }
+}
+void distortion_SetParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
+{
+ distortion_SetParami(effect, context, param, vals[0]);
+}
+void distortion_SetParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
+{
+ switch(param)
+ {
+ case AL_DISTORTION_EDGE:
+ if(val >= AL_DISTORTION_MIN_EDGE && val <= AL_DISTORTION_MAX_EDGE)
+ effect->Distortion.Edge = val;
+ else
+ alSetError(context, AL_INVALID_VALUE);
+ break;
+
+ case AL_DISTORTION_GAIN:
+ if(val >= AL_DISTORTION_MIN_GAIN && val <= AL_DISTORTION_MAX_GAIN)
+ effect->Distortion.Gain = val;
+ else
+ alSetError(context, AL_INVALID_VALUE);
+ break;
+
+ case AL_DISTORTION_LOWPASS_CUTOFF:
+ if(val >= AL_DISTORTION_MIN_LOWPASS_CUTOFF && val <= AL_DISTORTION_MAX_LOWPASS_CUTOFF)
+ effect->Distortion.LowpassCutoff = val;
+ else
+ alSetError(context, AL_INVALID_VALUE);
+ break;
+
+ case AL_DISTORTION_EQCENTER:
+ if(val >= AL_DISTORTION_MIN_EQCENTER && val <= AL_DISTORTION_MAX_EQCENTER)
+ effect->Distortion.EQCenter = val;
+ else
+ alSetError(context, AL_INVALID_VALUE);
+ break;
+
+ case AL_DISTORTION_EQBANDWIDTH:
+ if(val >= AL_DISTORTION_MIN_EQBANDWIDTH && val <= AL_DISTORTION_MAX_EQBANDWIDTH)
+ effect->Distortion.EQBandwidth = val;
+ else
+ alSetError(context, AL_INVALID_VALUE);
+ break;
+
+ default:
+ alSetError(context, AL_INVALID_ENUM);
+ break;
+ }
+}
+void distortion_SetParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
+{
+ distortion_SetParamf(effect, context, param, vals[0]);
+}
+
+void distortion_GetParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint *val)
+{
+ effect=effect;
+ val=val;
+
+ switch(param)
+ {
+ default:
+ alSetError(context, AL_INVALID_ENUM);
+ break;
+ }
+}
+void distortion_GetParamiv(ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
+{
+ distortion_GetParami(effect, context, param, vals);
+}
+void distortion_GetParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
+{
+ switch(param)
+ {
+ case AL_DISTORTION_EDGE:
+ *val = effect->Distortion.Edge;
+ break;
+
+ case AL_DISTORTION_GAIN:
+ *val = effect->Distortion.Gain;
+ break;
+
+ case AL_DISTORTION_LOWPASS_CUTOFF:
+ *val = effect->Distortion.LowpassCutoff;
+ break;
+
+ case AL_DISTORTION_EQCENTER:
+ *val = effect->Distortion.EQCenter;
+ break;
+
+ case AL_DISTORTION_EQBANDWIDTH:
+ *val = effect->Distortion.EQBandwidth;
+ break;
+
+ default:
+ alSetError(context, AL_INVALID_ENUM);
+ break;
+ }
+}
+void distortion_GetParamfv(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
+{
+ distortion_GetParamf(effect, context, param, vals);
+}