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