Alc/effects/equalizer.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 "alFilter.h"
  28 #include "alAuxEffectSlot.h"
  29 #include "alError.h"
  30 #include "alu.h"
  31
  32
  33 /*  The document  "Effects Extension Guide.pdf"  says that low and high  *
  34  *  frequencies are cutoff frequencies. This is not fully correct, they  *
  35  *  are corner frequencies for low and high shelf filters. If they were  *
  36  *  just cutoff frequencies, there would be no need in cutoff frequency  *
  37  *  gains, which are present.  Documentation for  "Creative Proteus X2"  *
  38  *  software describes  4-band equalizer functionality in a much better  *
  39  *  way.  This equalizer seems  to be a predecessor  of  OpenAL  4-band  *
  40  *  equalizer.  With low and high  shelf filters  we are able to cutoff  *
  41  *  frequencies below and/or above corner frequencies using attenuation  *
  42  *  gains (below 1.0) and amplify all low and/or high frequencies using  *
  43  *  gains above 1.0.                                                     *
  44  *                                                                       *
  45  *     Low-shelf       Low Mid Band      High Mid Band     High-shelf    *
  46  *      corner            center             center          corner      *
  47  *     frequency        frequency          frequency       frequency     *
  48  *    50Hz..800Hz     200Hz..3000Hz      1000Hz..8000Hz  4000Hz..16000Hz *
  49  *                                                                       *
  50  *          |               |                  |               |         *
  51  *          |               |                  |               |         *
  52  *   B -----+            /--+--\            /--+--\            +-----    *
  53  *   O      |\          |   |   |          |   |   |          /|         *
  54  *   O      | \        -    |    -        -    |    -        / |         *
  55  *   S +    |  \      |     |     |      |     |     |      /  |         *
  56  *   T      |   |    |      |      |    |      |      |    |   |         *
  57  * ---------+---------------+------------------+---------------+-------- *
  58  *   C      |   |    |      |      |    |      |      |    |   |         *
  59  *   U -    |  /      |     |     |      |     |     |      \  |         *
  60  *   T      | /        -    |    -        -    |    -        \ |         *
  61  *   O      |/          |   |   |          |   |   |          \|         *
  62  *   F -----+            \--+--/            \--+--/            +-----    *
  63  *   F      |               |                  |               |         *
  64  *          |               |                  |               |         *
  65  *                                                                       *
  66  * Gains vary from 0.126 up to 7.943, which means from -18dB attenuation *
  67  * up to +18dB amplification. Band width varies from 0.01 up to 1.0 in   *
  68  * octaves for two mid bands.                                            *
  69  *                                                                       *
  70  * Implementation is based on the "Cookbook formulae for audio EQ biquad *
  71  * filter coefficients" by Robert Bristow-Johnson                        *
  72  * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt                   */
  73
  74
  75 /* The maximum number of sample frames per update. */
  76 #define MAX_UPDATE_SAMPLES 256
  77
  78 typedef struct ALequalizerState {
  79     DERIVE_FROM_TYPE(ALeffectState);
  80
  81     /* Effect gains for each channel */
  82     ALfloat Gain[MAX_EFFECT_CHANNELS][MAX_OUTPUT_CHANNELS];
  83
  84     /* Effect parameters */
  85     ALfilterState filter[4][MAX_EFFECT_CHANNELS];
  86
  87     ALfloat SampleBuffer[4][MAX_EFFECT_CHANNELS][MAX_UPDATE_SAMPLES];
  88 } ALequalizerState;
  89
  90 static ALvoid ALequalizerState_Destruct(ALequalizerState *state)
  91 {
  92     ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
  93 }
  94
  95 static ALboolean ALequalizerState_deviceUpdate(ALequalizerState *UNUSED(state), ALCdevice *UNUSED(device))
  96 {
  97     return AL_TRUE;
  98 }
  99
 100 static ALvoid ALequalizerState_update(ALequalizerState *state, const ALCdevice *device, const ALeffectslot *slot, const ALeffectProps *props)
 101 {
 102     ALfloat frequency = (ALfloat)device->Frequency;
 103     ALfloat gain, freq_mult;
 104     aluMatrixf matrix;
 105     ALuint i;
 106
 107     aluMatrixfSet(&matrix,
 108         1.0f, 0.0f, 0.0f, 0.0f,
 109         0.0f, 1.0f, 0.0f, 0.0f,
 110         0.0f, 0.0f, 1.0f, 0.0f,
 111         0.0f, 0.0f, 0.0f, 1.0f
 112     );
 113
 114     STATIC_CAST(ALeffectState,state)->OutBuffer = device->FOAOut.Buffer;
 115     STATIC_CAST(ALeffectState,state)->OutChannels = device->FOAOut.NumChannels;
 116     for(i = 0;i < MAX_EFFECT_CHANNELS;i++)
 117         ComputeFirstOrderGains(device->FOAOut, matrix.m[i], slot->Params.Gain,
 118                                state->Gain[i]);
 119
 120     /* Calculate coefficients for the each type of filter. Note that the shelf
 121      * filters' gain is for the reference frequency, which is the centerpoint
 122      * of the transition band.
 123      */
 124     gain = sqrtf(props->Equalizer.LowGain);
 125     freq_mult = props->Equalizer.LowCutoff/frequency;
 126     ALfilterState_setParams(&state->filter[0][0], ALfilterType_LowShelf,
 127         gain, freq_mult, calc_rcpQ_from_slope(gain, 0.75f)
 128     );
 129     /* Copy the filter coefficients for the other input channels. */
 130     for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
 131     {
 132         state->filter[0][i].a1 = state->filter[0][0].a1;
 133         state->filter[0][i].a2 = state->filter[0][0].a2;
 134         state->filter[0][i].b0 = state->filter[0][0].b0;
 135         state->filter[0][i].b1 = state->filter[0][0].b1;
 136         state->filter[0][i].b2 = state->filter[0][0].b2;
 137         state->filter[0][i].process = state->filter[0][0].process;
 138     }
 139
 140     gain = props->Equalizer.Mid1Gain;
 141     freq_mult = props->Equalizer.Mid1Center/frequency;
 142     ALfilterState_setParams(&state->filter[1][0], ALfilterType_Peaking,
 143         gain, freq_mult, calc_rcpQ_from_bandwidth(
 144             freq_mult, props->Equalizer.Mid1Width
 145         )
 146     );
 147     for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
 148     {
 149         state->filter[1][i].a1 = state->filter[1][0].a1;
 150         state->filter[1][i].a2 = state->filter[1][0].a2;
 151         state->filter[1][i].b0 = state->filter[1][0].b0;
 152         state->filter[1][i].b1 = state->filter[1][0].b1;
 153         state->filter[1][i].b2 = state->filter[1][0].b2;
 154         state->filter[1][i].process = state->filter[1][0].process;
 155     }
 156
 157     gain = props->Equalizer.Mid2Gain;
 158     freq_mult = props->Equalizer.Mid2Center/frequency;
 159     ALfilterState_setParams(&state->filter[2][0], ALfilterType_Peaking,
 160         gain, freq_mult, calc_rcpQ_from_bandwidth(
 161             freq_mult, props->Equalizer.Mid2Width
 162         )
 163     );
 164     for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
 165     {
 166         state->filter[2][i].a1 = state->filter[2][0].a1;
 167         state->filter[2][i].a2 = state->filter[2][0].a2;
 168         state->filter[2][i].b0 = state->filter[2][0].b0;
 169         state->filter[2][i].b1 = state->filter[2][0].b1;
 170         state->filter[2][i].b2 = state->filter[2][0].b2;
 171         state->filter[2][i].process = state->filter[2][0].process;
 172     }
 173
 174     gain = sqrtf(props->Equalizer.HighGain);
 175     freq_mult = props->Equalizer.HighCutoff/frequency;
 176     ALfilterState_setParams(&state->filter[3][0], ALfilterType_HighShelf,
 177         gain, freq_mult, calc_rcpQ_from_slope(gain, 0.75f)
 178     );
 179     for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
 180     {
 181         state->filter[3][i].a1 = state->filter[3][0].a1;
 182         state->filter[3][i].a2 = state->filter[3][0].a2;
 183         state->filter[3][i].b0 = state->filter[3][0].b0;
 184         state->filter[3][i].b1 = state->filter[3][0].b1;
 185         state->filter[3][i].b2 = state->filter[3][0].b2;
 186         state->filter[3][i].process = state->filter[3][0].process;
 187     }
 188 }
 189
 190 static ALvoid ALequalizerState_process(ALequalizerState *state, ALuint SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALuint NumChannels)
 191 {
 192     ALfloat (*Samples)[MAX_EFFECT_CHANNELS][MAX_UPDATE_SAMPLES] = state->SampleBuffer;
 193     ALuint it, kt, ft;
 194     ALuint base;
 195
 196     for(base = 0;base < SamplesToDo;)
 197     {
 198         ALuint td = minu(MAX_UPDATE_SAMPLES, SamplesToDo-base);
 199
 200         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 201             ALfilterState_process(&state->filter[0][ft], Samples[0][ft], &SamplesIn[ft][base], td);
 202         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 203             ALfilterState_process(&state->filter[1][ft], Samples[1][ft], Samples[0][ft], td);
 204         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 205             ALfilterState_process(&state->filter[2][ft], Samples[2][ft], Samples[1][ft], td);
 206         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 207             ALfilterState_process(&state->filter[3][ft], Samples[3][ft], Samples[2][ft], td);
 208
 209         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 210         {
 211             for(kt = 0;kt < NumChannels;kt++)
 212             {
 213                 ALfloat gain = state->Gain[ft][kt];
 214                 if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
 215                     continue;
 216
 217                 for(it = 0;it < td;it++)
 218                     SamplesOut[kt][base+it] += gain * Samples[3][ft][it];
 219             }
 220         }
 221
 222         base += td;
 223     }
 224 }
 225
 226 DECLARE_DEFAULT_ALLOCATORS(ALequalizerState)
 227
 228 DEFINE_ALEFFECTSTATE_VTABLE(ALequalizerState);
 229
 230
 231 typedef struct ALequalizerStateFactory {
 232     DERIVE_FROM_TYPE(ALeffectStateFactory);
 233 } ALequalizerStateFactory;
 234
 235 ALeffectState *ALequalizerStateFactory_create(ALequalizerStateFactory *UNUSED(factory))
 236 {
 237     ALequalizerState *state;
 238     int it, ft;
 239
 240     state = ALequalizerState_New(sizeof(*state));
 241     if(!state) return NULL;
 242     SET_VTABLE2(ALequalizerState, ALeffectState, state);
 243
 244     /* Initialize sample history only on filter creation to avoid */
 245     /* sound clicks if filter settings were changed in runtime.   */
 246     for(it = 0; it < 4; it++)
 247     {
 248         for(ft = 0;ft < MAX_EFFECT_CHANNELS;ft++)
 249             ALfilterState_clear(&state->filter[it][ft]);
 250     }
 251
 252     return STATIC_CAST(ALeffectState, state);
 253 }
 254
 255 DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALequalizerStateFactory);
 256
 257 ALeffectStateFactory *ALequalizerStateFactory_getFactory(void)
 258 {
 259     static ALequalizerStateFactory EqualizerFactory = { { GET_VTABLE2(ALequalizerStateFactory, ALeffectStateFactory) } };
 260
 261     return STATIC_CAST(ALeffectStateFactory, &EqualizerFactory);
 262 }
 263
 264
 265 void ALequalizer_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint UNUSED(val))
 266 { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
 267 void ALequalizer_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
 268 {
 269     ALequalizer_setParami(effect, context, param, vals[0]);
 270 }
 271 void ALequalizer_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
 272 {
 273     ALeffectProps *props = &effect->Props;
 274     switch(param)
 275     {
 276         case AL_EQUALIZER_LOW_GAIN:
 277             if(!(val >= AL_EQUALIZER_MIN_LOW_GAIN && val <= AL_EQUALIZER_MAX_LOW_GAIN))
 278                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 279             props->Equalizer.LowGain = val;
 280             break;
 281
 282         case AL_EQUALIZER_LOW_CUTOFF:
 283             if(!(val >= AL_EQUALIZER_MIN_LOW_CUTOFF && val <= AL_EQUALIZER_MAX_LOW_CUTOFF))
 284                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 285             props->Equalizer.LowCutoff = val;
 286             break;
 287
 288         case AL_EQUALIZER_MID1_GAIN:
 289             if(!(val >= AL_EQUALIZER_MIN_MID1_GAIN && val <= AL_EQUALIZER_MAX_MID1_GAIN))
 290                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 291             props->Equalizer.Mid1Gain = val;
 292             break;
 293
 294         case AL_EQUALIZER_MID1_CENTER:
 295             if(!(val >= AL_EQUALIZER_MIN_MID1_CENTER && val <= AL_EQUALIZER_MAX_MID1_CENTER))
 296                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 297             props->Equalizer.Mid1Center = val;
 298             break;
 299
 300         case AL_EQUALIZER_MID1_WIDTH:
 301             if(!(val >= AL_EQUALIZER_MIN_MID1_WIDTH && val <= AL_EQUALIZER_MAX_MID1_WIDTH))
 302                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 303             props->Equalizer.Mid1Width = val;
 304             break;
 305
 306         case AL_EQUALIZER_MID2_GAIN:
 307             if(!(val >= AL_EQUALIZER_MIN_MID2_GAIN && val <= AL_EQUALIZER_MAX_MID2_GAIN))
 308                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 309             props->Equalizer.Mid2Gain = val;
 310             break;
 311
 312         case AL_EQUALIZER_MID2_CENTER:
 313             if(!(val >= AL_EQUALIZER_MIN_MID2_CENTER && val <= AL_EQUALIZER_MAX_MID2_CENTER))
 314                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 315             props->Equalizer.Mid2Center = val;
 316             break;
 317
 318         case AL_EQUALIZER_MID2_WIDTH:
 319             if(!(val >= AL_EQUALIZER_MIN_MID2_WIDTH && val <= AL_EQUALIZER_MAX_MID2_WIDTH))
 320                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 321             props->Equalizer.Mid2Width = val;
 322             break;
 323
 324         case AL_EQUALIZER_HIGH_GAIN:
 325             if(!(val >= AL_EQUALIZER_MIN_HIGH_GAIN && val <= AL_EQUALIZER_MAX_HIGH_GAIN))
 326                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 327             props->Equalizer.HighGain = val;
 328             break;
 329
 330         case AL_EQUALIZER_HIGH_CUTOFF:
 331             if(!(val >= AL_EQUALIZER_MIN_HIGH_CUTOFF && val <= AL_EQUALIZER_MAX_HIGH_CUTOFF))
 332                 SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
 333             props->Equalizer.HighCutoff = val;
 334             break;
 335
 336         default:
 337             SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
 338     }
 339 }
 340 void ALequalizer_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
 341 {
 342     ALequalizer_setParamf(effect, context, param, vals[0]);
 343 }
 344
 345 void ALequalizer_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint *UNUSED(val))
 346 { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); }
 347 void ALequalizer_getParamiv(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
 348 {
 349     ALequalizer_getParami(effect, context, param, vals);
 350 }
 351 void ALequalizer_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
 352 {
 353     const ALeffectProps *props = &effect->Props;
 354     switch(param)
 355     {
 356         case AL_EQUALIZER_LOW_GAIN:
 357             *val = props->Equalizer.LowGain;
 358             break;
 359
 360         case AL_EQUALIZER_LOW_CUTOFF:
 361             *val = props->Equalizer.LowCutoff;
 362             break;
 363
 364         case AL_EQUALIZER_MID1_GAIN:
 365             *val = props->Equalizer.Mid1Gain;
 366             break;
 367
 368         case AL_EQUALIZER_MID1_CENTER:
 369             *val = props->Equalizer.Mid1Center;
 370             break;
 371
 372         case AL_EQUALIZER_MID1_WIDTH:
 373             *val = props->Equalizer.Mid1Width;
 374             break;
 375
 376         case AL_EQUALIZER_MID2_GAIN:
 377             *val = props->Equalizer.Mid2Gain;
 378             break;
 379
 380         case AL_EQUALIZER_MID2_CENTER:
 381             *val = props->Equalizer.Mid2Center;
 382             break;
 383
 384         case AL_EQUALIZER_MID2_WIDTH:
 385             *val = props->Equalizer.Mid2Width;
 386             break;
 387
 388         case AL_EQUALIZER_HIGH_GAIN:
 389             *val = props->Equalizer.HighGain;
 390             break;
 391
 392         case AL_EQUALIZER_HIGH_CUTOFF:
 393             *val = props->Equalizer.HighCutoff;
 394             break;
 395
 396         default:
 397             SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
 398     }
 399 }
 400 void ALequalizer_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
 401 {
 402     ALequalizer_getParamf(effect, context, param, vals);
 403 }
 404
 405 DEFINE_ALEFFECT_VTABLE(ALequalizer);