alc/effects/autowah.cpp

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2018 by Raul Herraiz.
   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 <cmath>
  24 #include <cstdlib>
  25
  26 #include <algorithm>
  27
  28 #include "al/auxeffectslot.h"
  29 #include "alcmain.h"
  30 #include "alcontext.h"
  31 #include "alu.h"
  32 #include "filters/biquad.h"
  33 #include "vecmat.h"
  34
  35 namespace {
  36
  37 #define MIN_FREQ 20.0f
  38 #define MAX_FREQ 2500.0f
  39 #define Q_FACTOR 5.0f
  40
  41 struct AutowahState final : public EffectState {
  42     /* Effect parameters */
  43     float mAttackRate;
  44     float mReleaseRate;
  45     float mResonanceGain;
  46     float mPeakGain;
  47     float mFreqMinNorm;
  48     float mBandwidthNorm;
  49     float mEnvDelay;
  50
  51     /* Filter components derived from the envelope. */
  52     struct {
  53         float cos_w0;
  54         float alpha;
  55     } mEnv[BUFFERSIZE];
  56
  57     struct {
  58         /* Effect filters' history. */
  59         struct {
  60             float z1, z2;
  61         } Filter;
  62
  63         /* Effect gains for each output channel */
  64         float CurrentGains[MAX_OUTPUT_CHANNELS];
  65         float TargetGains[MAX_OUTPUT_CHANNELS];
  66     } mChans[MAX_AMBI_CHANNELS];
  67
  68     /* Effects buffers */
  69     alignas(16) float mBufferOut[BUFFERSIZE];
  70
  71
  72     void deviceUpdate(const ALCdevice *device) override;
  73     void update(const ALCcontext *context, const ALeffectslot *slot, const EffectProps *props, const EffectTarget target) override;
  74     void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut) override;
  75
  76     DEF_NEWDEL(AutowahState)
  77 };
  78
  79 void AutowahState::deviceUpdate(const ALCdevice*)
  80 {
  81     /* (Re-)initializing parameters and clear the buffers. */
  82
  83     mAttackRate    = 1.0f;
  84     mReleaseRate   = 1.0f;
  85     mResonanceGain = 10.0f;
  86     mPeakGain      = 4.5f;
  87     mFreqMinNorm   = 4.5e-4f;
  88     mBandwidthNorm = 0.05f;
  89     mEnvDelay      = 0.0f;
  90
  91     for(auto &e : mEnv)
  92     {
  93         e.cos_w0 = 0.0f;
  94         e.alpha = 0.0f;
  95     }
  96
  97     for(auto &chan : mChans)
  98     {
  99         std::fill(std::begin(chan.CurrentGains), std::end(chan.CurrentGains), 0.0f);
 100         chan.Filter.z1 = 0.0f;
 101         chan.Filter.z2 = 0.0f;
 102     }
 103 }
 104
 105 void AutowahState::update(const ALCcontext *context, const ALeffectslot *slot, const EffectProps *props, const EffectTarget target)
 106 {
 107     const ALCdevice *device{context->mDevice.get()};
 108     const auto frequency = static_cast<float>(device->Frequency);
 109
 110     const float ReleaseTime{clampf(props->Autowah.ReleaseTime, 0.001f, 1.0f)};
 111
 112     mAttackRate    = std::exp(-1.0f / (props->Autowah.AttackTime*frequency));
 113     mReleaseRate   = std::exp(-1.0f / (ReleaseTime*frequency));
 114     /* 0-20dB Resonance Peak gain */
 115     mResonanceGain = std::sqrt(std::log10(props->Autowah.Resonance)*10.0f / 3.0f);
 116     mPeakGain      = 1.0f - std::log10(props->Autowah.PeakGain/AL_AUTOWAH_MAX_PEAK_GAIN);
 117     mFreqMinNorm   = MIN_FREQ / frequency;
 118     mBandwidthNorm = (MAX_FREQ-MIN_FREQ) / frequency;
 119
 120     mOutTarget = target.Main->Buffer;
 121     auto set_gains = [slot,target](auto &chan, al::span<const float,MAX_AMBI_CHANNELS> coeffs)
 122     { ComputePanGains(target.Main, coeffs.data(), slot->Params.Gain, chan.TargetGains); };
 123     SetAmbiPanIdentity(std::begin(mChans), slot->Wet.Buffer.size(), set_gains);
 124 }
 125
 126 void AutowahState::process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
 127 {
 128     const float attack_rate{mAttackRate};
 129     const float release_rate{mReleaseRate};
 130     const float res_gain{mResonanceGain};
 131     const float peak_gain{mPeakGain};
 132     const float freq_min{mFreqMinNorm};
 133     const float bandwidth{mBandwidthNorm};
 134
 135     float env_delay{mEnvDelay};
 136     for(size_t i{0u};i < samplesToDo;i++)
 137     {
 138         float w0, sample, a;
 139
 140         /* Envelope follower described on the book: Audio Effects, Theory,
 141          * Implementation and Application.
 142          */
 143         sample = peak_gain * std::fabs(samplesIn[0][i]);
 144         a = (sample > env_delay) ? attack_rate : release_rate;
 145         env_delay = lerp(sample, env_delay, a);
 146
 147         /* Calculate the cos and alpha components for this sample's filter. */
 148         w0 = minf((bandwidth*env_delay + freq_min), 0.46f) * al::MathDefs<float>::Tau();
 149         mEnv[i].cos_w0 = std::cos(w0);
 150         mEnv[i].alpha = std::sin(w0)/(2.0f * Q_FACTOR);
 151     }
 152     mEnvDelay = env_delay;
 153
 154     auto chandata = std::addressof(mChans[0]);
 155     for(const auto &insamples : samplesIn)
 156     {
 157         /* This effectively inlines BiquadFilter_setParams for a peaking
 158          * filter and BiquadFilter_processC. The alpha and cosine components
 159          * for the filter coefficients were previously calculated with the
 160          * envelope. Because the filter changes for each sample, the
 161          * coefficients are transient and don't need to be held.
 162          */
 163         float z1{chandata->Filter.z1};
 164         float z2{chandata->Filter.z2};
 165
 166         for(size_t i{0u};i < samplesToDo;i++)
 167         {
 168             const float alpha{mEnv[i].alpha};
 169             const float cos_w0{mEnv[i].cos_w0};
 170             float input, output;
 171             float a[3], b[3];
 172
 173             b[0] =  1.0f + alpha*res_gain;
 174             b[1] = -2.0f * cos_w0;
 175             b[2] =  1.0f - alpha*res_gain;
 176             a[0] =  1.0f + alpha/res_gain;
 177             a[1] = -2.0f * cos_w0;
 178             a[2] =  1.0f - alpha/res_gain;
 179
 180             input = insamples[i];
 181             output = input*(b[0]/a[0]) + z1;
 182             z1 = input*(b[1]/a[0]) - output*(a[1]/a[0]) + z2;
 183             z2 = input*(b[2]/a[0]) - output*(a[2]/a[0]);
 184             mBufferOut[i] = output;
 185         }
 186         chandata->Filter.z1 = z1;
 187         chandata->Filter.z2 = z2;
 188
 189         /* Now, mix the processed sound data to the output. */
 190         MixSamples({mBufferOut, samplesToDo}, samplesOut, chandata->CurrentGains,
 191             chandata->TargetGains, samplesToDo, 0);
 192         ++chandata;
 193     }
 194 }
 195
 196
 197 void Autowah_setParamf(EffectProps *props, ALenum param, float val)
 198 {
 199     switch(param)
 200     {
 201     case AL_AUTOWAH_ATTACK_TIME:
 202         if(!(val >= AL_AUTOWAH_MIN_ATTACK_TIME && val <= AL_AUTOWAH_MAX_ATTACK_TIME))
 203             throw effect_exception{AL_INVALID_VALUE, "Autowah attack time out of range"};
 204         props->Autowah.AttackTime = val;
 205         break;
 206
 207     case AL_AUTOWAH_RELEASE_TIME:
 208         if(!(val >= AL_AUTOWAH_MIN_RELEASE_TIME && val <= AL_AUTOWAH_MAX_RELEASE_TIME))
 209             throw effect_exception{AL_INVALID_VALUE, "Autowah release time out of range"};
 210         props->Autowah.ReleaseTime = val;
 211         break;
 212
 213     case AL_AUTOWAH_RESONANCE:
 214         if(!(val >= AL_AUTOWAH_MIN_RESONANCE && val <= AL_AUTOWAH_MAX_RESONANCE))
 215             throw effect_exception{AL_INVALID_VALUE, "Autowah resonance out of range"};
 216         props->Autowah.Resonance = val;
 217         break;
 218
 219     case AL_AUTOWAH_PEAK_GAIN:
 220         if(!(val >= AL_AUTOWAH_MIN_PEAK_GAIN && val <= AL_AUTOWAH_MAX_PEAK_GAIN))
 221             throw effect_exception{AL_INVALID_VALUE, "Autowah peak gain out of range"};
 222         props->Autowah.PeakGain = val;
 223         break;
 224
 225     default:
 226         throw effect_exception{AL_INVALID_ENUM, "Invalid autowah float property 0x%04x", param};
 227     }
 228 }
 229 void Autowah_setParamfv(EffectProps *props,  ALenum param, const float *vals)
 230 { Autowah_setParamf(props, param, vals[0]); }
 231
 232 void Autowah_setParami(EffectProps*, ALenum param, int)
 233 { throw effect_exception{AL_INVALID_ENUM, "Invalid autowah integer property 0x%04x", param}; }
 234 void Autowah_setParamiv(EffectProps*, ALenum param, const int*)
 235 {
 236     throw effect_exception{AL_INVALID_ENUM, "Invalid autowah integer vector property 0x%04x",
 237         param};
 238 }
 239
 240 void Autowah_getParamf(const EffectProps *props, ALenum param, float *val)
 241 {
 242     switch(param)
 243     {
 244     case AL_AUTOWAH_ATTACK_TIME:
 245         *val = props->Autowah.AttackTime;
 246         break;
 247
 248     case AL_AUTOWAH_RELEASE_TIME:
 249         *val = props->Autowah.ReleaseTime;
 250         break;
 251
 252     case AL_AUTOWAH_RESONANCE:
 253         *val = props->Autowah.Resonance;
 254         break;
 255
 256     case AL_AUTOWAH_PEAK_GAIN:
 257         *val = props->Autowah.PeakGain;
 258         break;
 259
 260     default:
 261         throw effect_exception{AL_INVALID_ENUM, "Invalid autowah float property 0x%04x", param};
 262     }
 263
 264 }
 265 void Autowah_getParamfv(const EffectProps *props, ALenum param, float *vals)
 266 { Autowah_getParamf(props, param, vals); }
 267
 268 void Autowah_getParami(const EffectProps*, ALenum param, int*)
 269 { throw effect_exception{AL_INVALID_ENUM, "Invalid autowah integer property 0x%04x", param}; }
 270 void Autowah_getParamiv(const EffectProps*, ALenum param, int*)
 271 {
 272     throw effect_exception{AL_INVALID_ENUM, "Invalid autowah integer vector property 0x%04x",
 273         param};
 274 }
 275
 276 DEFINE_ALEFFECT_VTABLE(Autowah);
 277
 278
 279 struct AutowahStateFactory final : public EffectStateFactory {
 280     EffectState *create() override { return new AutowahState{}; }
 281     EffectProps getDefaultProps() const noexcept override;
 282     const EffectVtable *getEffectVtable() const noexcept override { return &Autowah_vtable; }
 283 };
 284
 285 EffectProps AutowahStateFactory::getDefaultProps() const noexcept
 286 {
 287     EffectProps props{};
 288     props.Autowah.AttackTime = AL_AUTOWAH_DEFAULT_ATTACK_TIME;
 289     props.Autowah.ReleaseTime = AL_AUTOWAH_DEFAULT_RELEASE_TIME;
 290     props.Autowah.Resonance = AL_AUTOWAH_DEFAULT_RESONANCE;
 291     props.Autowah.PeakGain = AL_AUTOWAH_DEFAULT_PEAK_GAIN;
 292     return props;
 293 }
 294
 295 } // namespace
 296
 297 EffectStateFactory *AutowahStateFactory_getFactory()
 298 {
 299     static AutowahStateFactory AutowahFactory{};
 300     return &AutowahFactory;
 301 }