Alc/effects/autowah.c

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2013 by Anis A. Hireche, Nasca Octavian Paul
   4  * This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  *  License along with this library; if not, write to the
  16  *  Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  * Or go to http://www.gnu.org/copyleft/lgpl.html
  19  */
  20
  21 #include <stdlib.h>
  22
  23 #include "config.h"
  24 #include "alu.h"
  25 #include "alFilter.h"
  26 #include "alError.h"
  27 #include "alMain.h"
  28 #include "alAuxEffectSlot.h"
  29
  30
  31 /* Auto-wah is simply a low-pass filter with a cutoff frequency that shifts up
  32  * or down depending on the input signal, and a resonant peak at the cutoff.
  33  *
  34  * Currently, we assume a cutoff frequency range of 20hz (no amplitude) to
  35  * 20khz (peak gain). Peak gain is assumed to be in normalized scale.
  36  */
  37
  38 typedef struct ALautowahState {
  39     DERIVE_FROM_TYPE(ALeffectState);
  40
  41     /* Effect gains for each channel */
  42     ALfloat Gain[MAX_OUTPUT_CHANNELS];
  43
  44     /* Effect parameters */
  45     ALfloat AttackRate;
  46     ALfloat ReleaseRate;
  47     ALfloat Resonance;
  48     ALfloat PeakGain;
  49     ALfloat GainCtrl;
  50     ALfloat Frequency;
  51
  52     /* Samples processing */
  53     ALfilterState LowPass;
  54 } ALautowahState;
  55
  56 static ALvoid ALautowahState_Destruct(ALautowahState *state)
  57 {
  58     ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
  59 }
  60
  61 static ALboolean ALautowahState_deviceUpdate(ALautowahState *state, ALCdevice *device)
  62 {
  63     state->Frequency = (ALfloat)device->Frequency;
  64     return AL_TRUE;
  65 }
  66
  67 static ALvoid ALautowahState_update(ALautowahState *state, const ALCdevice *device, const ALeffectslot *slot, const ALeffectProps *props)
  68 {
  69     ALfloat attackTime, releaseTime;
  70
  71     attackTime = props->Autowah.AttackTime * state->Frequency;
  72     releaseTime = props->Autowah.ReleaseTime * state->Frequency;
  73
  74     state->AttackRate = powf(1.0f/GAIN_SILENCE_THRESHOLD, 1.0f/attackTime);
  75     state->ReleaseRate = powf(GAIN_SILENCE_THRESHOLD/1.0f, 1.0f/releaseTime);
  76     state->PeakGain = props->Autowah.PeakGain;
  77     state->Resonance = props->Autowah.Resonance;
  78
  79     ComputeAmbientGains(device->Dry, slot->Params.Gain, state->Gain);
  80 }
  81
  82 static ALvoid ALautowahState_process(ALautowahState *state, ALuint SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALuint NumChannels)
  83 {
  84     ALuint it, kt;
  85     ALuint base;
  86
  87     for(base = 0;base < SamplesToDo;)
  88     {
  89         ALfloat temps[256];
  90         ALuint td = minu(256, SamplesToDo-base);
  91         ALfloat gain = state->GainCtrl;
  92
  93         for(it = 0;it < td;it++)
  94         {
  95             ALfloat smp = SamplesIn[0][it+base];
  96             ALfloat a[3], b[3];
  97             ALfloat alpha, w0;
  98             ALfloat amplitude;
  99             ALfloat cutoff;
 100
 101             /* Similar to compressor, we get the current amplitude of the
 102              * incoming signal, and attack or release to reach it. */
 103             amplitude = fabsf(smp);
 104             if(amplitude > gain)
 105                 gain = minf(gain*state->AttackRate, amplitude);
 106             else if(amplitude < gain)
 107                 gain = maxf(gain*state->ReleaseRate, amplitude);
 108             gain = maxf(gain, GAIN_SILENCE_THRESHOLD);
 109
 110             /* FIXME: What range does the filter cover? */
 111             cutoff = lerp(20.0f, 20000.0f, minf(gain/state->PeakGain, 1.0f));
 112
 113             /* The code below is like calling ALfilterState_setParams with
 114              * ALfilterType_LowPass. However, instead of passing a bandwidth,
 115              * we use the resonance property for Q. This also inlines the call.
 116              */
 117             w0 = F_TAU * cutoff / state->Frequency;
 118
 119             /* FIXME: Resonance controls the resonant peak, or Q. How? Not sure
 120              * that Q = resonance*0.1. */
 121             alpha = sinf(w0) / (2.0f * state->Resonance*0.1f);
 122             b[0] = (1.0f - cosf(w0)) / 2.0f;
 123             b[1] =  1.0f - cosf(w0);
 124             b[2] = (1.0f - cosf(w0)) / 2.0f;
 125             a[0] =  1.0f + alpha;
 126             a[1] = -2.0f * cosf(w0);
 127             a[2] =  1.0f - alpha;
 128
 129             state->LowPass.a1 = a[1] / a[0];
 130             state->LowPass.a2 = a[2] / a[0];
 131             state->LowPass.b1 = b[1] / a[0];
 132             state->LowPass.b2 = b[2] / a[0];
 133             state->LowPass.input_gain = b[0] / a[0];
 134
 135             temps[it] = ALfilterState_processSingle(&state->LowPass, smp);
 136         }
 137         state->GainCtrl = gain;
 138
 139         for(kt = 0;kt < NumChannels;kt++)
 140         {
 141             ALfloat gain = state->Gain[kt];
 142             if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
 143                 continue;
 144
 145             for(it = 0;it < td;it++)
 146                 SamplesOut[kt][base+it] += gain * temps[it];
 147         }
 148
 149         base += td;
 150     }
 151 }
 152
 153 DECLARE_DEFAULT_ALLOCATORS(ALautowahState)
 154
 155 DEFINE_ALEFFECTSTATE_VTABLE(ALautowahState);
 156
 157
 158 typedef struct ALautowahStateFactory {
 159     DERIVE_FROM_TYPE(ALeffectStateFactory);
 160 } ALautowahStateFactory;
 161
 162 static ALeffectState *ALautowahStateFactory_create(ALautowahStateFactory *UNUSED(factory))
 163 {
 164     ALautowahState *state;
 165
 166     state = ALautowahState_New(sizeof(*state));
 167     if(!state) return NULL;
 168     SET_VTABLE2(ALautowahState, ALeffectState, state);
 169
 170     state->AttackRate = 1.0f;
 171     state->ReleaseRate = 1.0f;
 172     state->Resonance = 2.0f;
 173     state->PeakGain = 1.0f;
 174     state->GainCtrl = 1.0f;
 175
 176     ALfilterState_clear(&state->LowPass);
 177
 178     return STATIC_CAST(ALeffectState, state);
 179 }
 180
 181 DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALautowahStateFactory);
 182
 183 ALeffectStateFactory *ALautowahStateFactory_getFactory(void)
 184 {
 185     static ALautowahStateFactory AutowahFactory = { { GET_VTABLE2(ALautowahStateFactory, ALeffectStateFactory) } };
 186
 187     return STATIC_CAST(ALeffectStateFactory, &AutowahFactory);
 188 }
 189
 190
 191 void ALautowah_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint UNUSED(val))
 192 { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
 193 void ALautowah_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
 194 {
 195     ALautowah_setParami(effect, context, param, vals[0]);
 196 }
 197 void ALautowah_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
 198 {
 199     ALeffectProps *props = &effect->Props;
 200     switch(param)
 201     {
 202         case AL_AUTOWAH_ATTACK_TIME:
 203             if(!(val >= AL_AUTOWAH_MIN_ATTACK_TIME && val <= AL_AUTOWAH_MAX_ATTACK_TIME))
 204                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 205             props->Autowah.AttackTime = val;
 206             break;
 207
 208         case AL_AUTOWAH_RELEASE_TIME:
 209             if(!(val >= AL_AUTOWAH_MIN_RELEASE_TIME && val <= AL_AUTOWAH_MAX_RELEASE_TIME))
 210                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 211             props->Autowah.ReleaseTime = val;
 212             break;
 213
 214         case AL_AUTOWAH_RESONANCE:
 215             if(!(val >= AL_AUTOWAH_MIN_RESONANCE && val <= AL_AUTOWAH_MAX_RESONANCE))
 216                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 217             props->Autowah.Resonance = val;
 218             break;
 219
 220         case AL_AUTOWAH_PEAK_GAIN:
 221             if(!(val >= AL_AUTOWAH_MIN_PEAK_GAIN && val <= AL_AUTOWAH_MAX_PEAK_GAIN))
 222                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 223             props->Autowah.PeakGain = val;
 224             break;
 225
 226         default:
 227             SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
 228     }
 229 }
 230 void ALautowah_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
 231 {
 232     ALautowah_setParamf(effect, context, param, vals[0]);
 233 }
 234
 235 void ALautowah_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint *UNUSED(val))
 236 { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
 237 void ALautowah_getParamiv(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
 238 {
 239     ALautowah_getParami(effect, context, param, vals);
 240 }
 241 void ALautowah_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
 242 {
 243     const ALeffectProps *props = &effect->Props;
 244     switch(param)
 245     {
 246         case AL_AUTOWAH_ATTACK_TIME:
 247             *val = props->Autowah.AttackTime;
 248             break;
 249
 250         case AL_AUTOWAH_RELEASE_TIME:
 251             *val = props->Autowah.ReleaseTime;
 252             break;
 253
 254         case AL_AUTOWAH_RESONANCE:
 255             *val = props->Autowah.Resonance;
 256             break;
 257
 258         case AL_AUTOWAH_PEAK_GAIN:
 259             *val = props->Autowah.PeakGain;
 260             break;
 261
 262         default:
 263             SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
 264     }
 265 }
 266 void ALautowah_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
 267 {
 268     ALautowah_getParamf(effect, context, param, vals);
 269 }
 270
 271 DEFINE_ALEFFECT_VTABLE(ALautowah);