Alc/effects/distortion.c

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2013 by Mike Gorchak
   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 "config.h"
  22
  23 #include <math.h>
  24 #include <stdlib.h>
  25
  26 #include "alMain.h"
  27 #include "alAuxEffectSlot.h"
  28 #include "alError.h"
  29 #include "alu.h"
  30 #include "filters/defs.h"
  31
  32
  33 typedef struct ALdistortionState {
  34     DERIVE_FROM_TYPE(ALeffectState);
  35
  36     /* Effect gains for each channel */
  37     ALfloat Gain[MAX_OUTPUT_CHANNELS];
  38
  39     /* Effect parameters */
  40     BiquadState lowpass;
  41     BiquadState bandpass;
  42     ALfloat attenuation;
  43     ALfloat edge_coeff;
  44
  45     ALfloat Buffer[2][BUFFERSIZE];
  46 } ALdistortionState;
  47
  48 static ALvoid ALdistortionState_Destruct(ALdistortionState *state);
  49 static ALboolean ALdistortionState_deviceUpdate(ALdistortionState *state, ALCdevice *device);
  50 static ALvoid ALdistortionState_update(ALdistortionState *state, const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props);
  51 static ALvoid ALdistortionState_process(ALdistortionState *state, ALsizei SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALsizei NumChannels);
  52 DECLARE_DEFAULT_ALLOCATORS(ALdistortionState)
  53
  54 DEFINE_ALEFFECTSTATE_VTABLE(ALdistortionState);
  55
  56
  57 static void ALdistortionState_Construct(ALdistortionState *state)
  58 {
  59     ALeffectState_Construct(STATIC_CAST(ALeffectState, state));
  60     SET_VTABLE2(ALdistortionState, ALeffectState, state);
  61
  62     BiquadState_clear(&state->lowpass);
  63     BiquadState_clear(&state->bandpass);
  64 }
  65
  66 static ALvoid ALdistortionState_Destruct(ALdistortionState *state)
  67 {
  68     ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
  69 }
  70
  71 static ALboolean ALdistortionState_deviceUpdate(ALdistortionState *UNUSED(state), ALCdevice *UNUSED(device))
  72 {
  73     return AL_TRUE;
  74 }
  75
  76 static ALvoid ALdistortionState_update(ALdistortionState *state, const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props)
  77 {
  78     const ALCdevice *device = context->Device;
  79     ALfloat frequency = (ALfloat)device->Frequency;
  80     ALfloat coeffs[MAX_AMBI_COEFFS];
  81     ALfloat bandwidth;
  82     ALfloat cutoff;
  83     ALfloat edge;
  84
  85     /* Store waveshaper edge settings. */
  86     edge = sinf(props->Distortion.Edge * (F_PI_2));
  87     edge = minf(edge, 0.99f);
  88     state->edge_coeff = 2.0f * edge / (1.0f-edge);
  89
  90     cutoff = props->Distortion.LowpassCutoff;
  91     /* Bandwidth value is constant in octaves. */
  92     bandwidth = (cutoff / 2.0f) / (cutoff * 0.67f);
  93     /* Multiply sampling frequency by the amount of oversampling done during
  94      * processing.
  95      */
  96     BiquadState_setParams(&state->lowpass, BiquadType_LowPass, 1.0f,
  97         cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
  98     );
  99
 100     cutoff = props->Distortion.EQCenter;
 101     /* Convert bandwidth in Hz to octaves. */
 102     bandwidth = props->Distortion.EQBandwidth / (cutoff * 0.67f);
 103     BiquadState_setParams(&state->bandpass, BiquadType_BandPass, 1.0f,
 104         cutoff / (frequency*4.0f), calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
 105     );
 106
 107     CalcAngleCoeffs(0.0f, 0.0f, 0.0f, coeffs);
 108     ComputeDryPanGains(&device->Dry, coeffs, slot->Params.Gain * props->Distortion.Gain,
 109                        state->Gain);
 110 }
 111
 112 static ALvoid ALdistortionState_process(ALdistortionState *state, ALsizei SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALsizei NumChannels)
 113 {
 114     ALfloat (*restrict buffer)[BUFFERSIZE] = state->Buffer;
 115     const ALfloat fc = state->edge_coeff;
 116     ALsizei base;
 117     ALsizei i, k;
 118
 119     for(base = 0;base < SamplesToDo;)
 120     {
 121         /* Perform 4x oversampling to avoid aliasing. Oversampling greatly
 122          * improves distortion quality and allows to implement lowpass and
 123          * bandpass filters using high frequencies, at which classic IIR
 124          * filters became unstable.
 125          */
 126         ALsizei todo = mini(BUFFERSIZE, (SamplesToDo-base) * 4);
 127
 128         /* Fill oversample buffer using zero stuffing. Multiply the sample by
 129          * the amount of oversampling to maintain the signal's power.
 130          */
 131         for(i = 0;i < todo;i++)
 132             buffer[0][i] = !(i&3) ? SamplesIn[0][(i>>2)+base] * 4.0f : 0.0f;
 133
 134         /* First step, do lowpass filtering of original signal. Additionally
 135          * perform buffer interpolation and lowpass cutoff for oversampling
 136          * (which is fortunately first step of distortion). So combine three
 137          * operations into the one.
 138          */
 139         BiquadState_process(&state->lowpass, buffer[1], buffer[0], todo);
 140
 141         /* Second step, do distortion using waveshaper function to emulate
 142          * signal processing during tube overdriving. Three steps of
 143          * waveshaping are intended to modify waveform without boost/clipping/
 144          * attenuation process.
 145          */
 146         for(i = 0;i < todo;i++)
 147         {
 148             ALfloat smp = buffer[1][i];
 149
 150             smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
 151             smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp)) * -1.0f;
 152             smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
 153
 154             buffer[0][i] = smp;
 155         }
 156
 157         /* Third step, do bandpass filtering of distorted signal. */
 158         BiquadState_process(&state->bandpass, buffer[1], buffer[0], todo);
 159
 160         todo >>= 2;
 161         for(k = 0;k < NumChannels;k++)
 162         {
 163             /* Fourth step, final, do attenuation and perform decimation,
 164              * storing only one sample out of four.
 165              */
 166             ALfloat gain = state->Gain[k];
 167             if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
 168                 continue;
 169
 170             for(i = 0;i < todo;i++)
 171                 SamplesOut[k][base+i] += gain * buffer[1][i*4];
 172         }
 173
 174         base += todo;
 175     }
 176 }
 177
 178
 179 typedef struct DistortionStateFactory {
 180     DERIVE_FROM_TYPE(EffectStateFactory);
 181 } DistortionStateFactory;
 182
 183 static ALeffectState *DistortionStateFactory_create(DistortionStateFactory *UNUSED(factory))
 184 {
 185     ALdistortionState *state;
 186
 187     NEW_OBJ0(state, ALdistortionState)();
 188     if(!state) return NULL;
 189
 190     return STATIC_CAST(ALeffectState, state);
 191 }
 192
 193 DEFINE_EFFECTSTATEFACTORY_VTABLE(DistortionStateFactory);
 194
 195
 196 EffectStateFactory *DistortionStateFactory_getFactory(void)
 197 {
 198     static DistortionStateFactory DistortionFactory = { { GET_VTABLE2(DistortionStateFactory, EffectStateFactory) } };
 199
 200     return STATIC_CAST(EffectStateFactory, &DistortionFactory);
 201 }
 202
 203
 204 void ALdistortion_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint UNUSED(val))
 205 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
 206 void ALdistortion_setParamiv(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
 207 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
 208 void ALdistortion_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
 209 {
 210     ALeffectProps *props = &effect->Props;
 211     switch(param)
 212     {
 213         case AL_DISTORTION_EDGE:
 214             if(!(val >= AL_DISTORTION_MIN_EDGE && val <= AL_DISTORTION_MAX_EDGE))
 215                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion edge out of range");
 216             props->Distortion.Edge = val;
 217             break;
 218
 219         case AL_DISTORTION_GAIN:
 220             if(!(val >= AL_DISTORTION_MIN_GAIN && val <= AL_DISTORTION_MAX_GAIN))
 221                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion gain out of range");
 222             props->Distortion.Gain = val;
 223             break;
 224
 225         case AL_DISTORTION_LOWPASS_CUTOFF:
 226             if(!(val >= AL_DISTORTION_MIN_LOWPASS_CUTOFF && val <= AL_DISTORTION_MAX_LOWPASS_CUTOFF))
 227                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion low-pass cutoff out of range");
 228             props->Distortion.LowpassCutoff = val;
 229             break;
 230
 231         case AL_DISTORTION_EQCENTER:
 232             if(!(val >= AL_DISTORTION_MIN_EQCENTER && val <= AL_DISTORTION_MAX_EQCENTER))
 233                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ center out of range");
 234             props->Distortion.EQCenter = val;
 235             break;
 236
 237         case AL_DISTORTION_EQBANDWIDTH:
 238             if(!(val >= AL_DISTORTION_MIN_EQBANDWIDTH && val <= AL_DISTORTION_MAX_EQBANDWIDTH))
 239                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ bandwidth out of range");
 240             props->Distortion.EQBandwidth = val;
 241             break;
 242
 243         default:
 244             alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
 245                        param);
 246     }
 247 }
 248 void ALdistortion_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
 249 { ALdistortion_setParamf(effect, context, param, vals[0]); }
 250
 251 void ALdistortion_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(val))
 252 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
 253 void ALdistortion_getParamiv(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
 254 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
 255 void ALdistortion_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
 256 {
 257     const ALeffectProps *props = &effect->Props;
 258     switch(param)
 259     {
 260         case AL_DISTORTION_EDGE:
 261             *val = props->Distortion.Edge;
 262             break;
 263
 264         case AL_DISTORTION_GAIN:
 265             *val = props->Distortion.Gain;
 266             break;
 267
 268         case AL_DISTORTION_LOWPASS_CUTOFF:
 269             *val = props->Distortion.LowpassCutoff;
 270             break;
 271
 272         case AL_DISTORTION_EQCENTER:
 273             *val = props->Distortion.EQCenter;
 274             break;
 275
 276         case AL_DISTORTION_EQBANDWIDTH:
 277             *val = props->Distortion.EQBandwidth;
 278             break;
 279
 280         default:
 281             alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
 282                        param);
 283     }
 284 }
 285 void ALdistortion_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
 286 { ALdistortion_getParamf(effect, context, param, vals); }
 287
 288 DEFINE_ALEFFECT_VTABLE(ALdistortion);