Alc/effects/distortion.cpp

   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 "alcontext.h"
  28 #include "alAuxEffectSlot.h"
  29 #include "alError.h"
  30 #include "alu.h"
  31 #include "filters/defs.h"
  32
  33
  34 struct ALdistortionState final : public ALeffectState {
  35     /* Effect gains for each channel */
  36     ALfloat Gain[MAX_OUTPUT_CHANNELS];
  37
  38     /* Effect parameters */
  39     BiquadFilter lowpass;
  40     BiquadFilter bandpass;
  41     ALfloat attenuation;
  42     ALfloat edge_coeff;
  43
  44     ALfloat Buffer[2][BUFFERSIZE];
  45 };
  46
  47 static ALvoid ALdistortionState_Destruct(ALdistortionState *state);
  48 static ALboolean ALdistortionState_deviceUpdate(ALdistortionState *state, ALCdevice *device);
  49 static ALvoid ALdistortionState_update(ALdistortionState *state, const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props);
  50 static ALvoid ALdistortionState_process(ALdistortionState *state, ALsizei SamplesToDo, const ALfloat (*RESTRICT SamplesIn)[BUFFERSIZE], ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE], ALsizei NumChannels);
  51 DECLARE_DEFAULT_ALLOCATORS(ALdistortionState)
  52
  53 DEFINE_ALEFFECTSTATE_VTABLE(ALdistortionState);
  54
  55
  56 static void ALdistortionState_Construct(ALdistortionState *state)
  57 {
  58     new (state) ALdistortionState{};
  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     state->~ALdistortionState();
  67 }
  68
  69 static ALboolean ALdistortionState_deviceUpdate(ALdistortionState *state, ALCdevice *UNUSED(device))
  70 {
  71     BiquadFilter_clear(&state->lowpass);
  72     BiquadFilter_clear(&state->bandpass);
  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     BiquadFilter_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     BiquadFilter_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     ComputePanGains(&device->Dry, coeffs, slot->Params.Gain*props->Distortion.Gain, 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 struct DistortionStateFactory final : public EffectStateFactory {
 179     ALeffectState *create() override;
 180 };
 181
 182 ALeffectState *DistortionStateFactory::create()
 183 {
 184     ALdistortionState *state;
 185     NEW_OBJ0(state, ALdistortionState)();
 186     return state;
 187 }
 188
 189 EffectStateFactory *DistortionStateFactory_getFactory(void)
 190 {
 191     static DistortionStateFactory DistortionFactory{};
 192     return &DistortionFactory;
 193 }
 194
 195
 196 void ALdistortion_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint UNUSED(val))
 197 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
 198 void ALdistortion_setParamiv(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
 199 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
 200 void ALdistortion_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
 201 {
 202     ALeffectProps *props = &effect->Props;
 203     switch(param)
 204     {
 205         case AL_DISTORTION_EDGE:
 206             if(!(val >= AL_DISTORTION_MIN_EDGE && val <= AL_DISTORTION_MAX_EDGE))
 207                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion edge out of range");
 208             props->Distortion.Edge = val;
 209             break;
 210
 211         case AL_DISTORTION_GAIN:
 212             if(!(val >= AL_DISTORTION_MIN_GAIN && val <= AL_DISTORTION_MAX_GAIN))
 213                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion gain out of range");
 214             props->Distortion.Gain = val;
 215             break;
 216
 217         case AL_DISTORTION_LOWPASS_CUTOFF:
 218             if(!(val >= AL_DISTORTION_MIN_LOWPASS_CUTOFF && val <= AL_DISTORTION_MAX_LOWPASS_CUTOFF))
 219                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion low-pass cutoff out of range");
 220             props->Distortion.LowpassCutoff = val;
 221             break;
 222
 223         case AL_DISTORTION_EQCENTER:
 224             if(!(val >= AL_DISTORTION_MIN_EQCENTER && val <= AL_DISTORTION_MAX_EQCENTER))
 225                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ center out of range");
 226             props->Distortion.EQCenter = val;
 227             break;
 228
 229         case AL_DISTORTION_EQBANDWIDTH:
 230             if(!(val >= AL_DISTORTION_MIN_EQBANDWIDTH && val <= AL_DISTORTION_MAX_EQBANDWIDTH))
 231                 SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ bandwidth out of range");
 232             props->Distortion.EQBandwidth = val;
 233             break;
 234
 235         default:
 236             alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
 237                        param);
 238     }
 239 }
 240 void ALdistortion_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
 241 { ALdistortion_setParamf(effect, context, param, vals[0]); }
 242
 243 void ALdistortion_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(val))
 244 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
 245 void ALdistortion_getParamiv(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
 246 { alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
 247 void ALdistortion_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
 248 {
 249     const ALeffectProps *props = &effect->Props;
 250     switch(param)
 251     {
 252         case AL_DISTORTION_EDGE:
 253             *val = props->Distortion.Edge;
 254             break;
 255
 256         case AL_DISTORTION_GAIN:
 257             *val = props->Distortion.Gain;
 258             break;
 259
 260         case AL_DISTORTION_LOWPASS_CUTOFF:
 261             *val = props->Distortion.LowpassCutoff;
 262             break;
 263
 264         case AL_DISTORTION_EQCENTER:
 265             *val = props->Distortion.EQCenter;
 266             break;
 267
 268         case AL_DISTORTION_EQBANDWIDTH:
 269             *val = props->Distortion.EQBandwidth;
 270             break;
 271
 272         default:
 273             alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
 274                        param);
 275     }
 276 }
 277 void ALdistortion_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
 278 { ALdistortion_getParamf(effect, context, param, vals); }
 279
 280 DEFINE_ALEFFECT_VTABLE(ALdistortion);