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