alc/effects/compressor.cpp

   1 /**
   2  * This file is part of the OpenAL Soft cross platform audio library
   3  *
   4  * Copyright (C) 2013 by Anis A. Hireche
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are met:
   8  *
   9  * * Redistributions of source code must retain the above copyright notice,
  10  *   this list of conditions and the following disclaimer.
  11  *
  12  * * Redistributions in binary form must reproduce the above copyright notice,
  13  *   this list of conditions and the following disclaimer in the documentation
  14  *   and/or other materials provided with the distribution.
  15  *
  16  * * Neither the name of Spherical-Harmonic-Transform nor the names of its
  17  *   contributors may be used to endorse or promote products derived from
  18  *   this software without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  * POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include "config.h"
  34
  35 #include <array>
  36 #include <cstdlib>
  37 #include <iterator>
  38 #include <utility>
  39
  40 #include "alc/effects/base.h"
  41 #include "almalloc.h"
  42 #include "alnumeric.h"
  43 #include "alspan.h"
  44 #include "core/ambidefs.h"
  45 #include "core/bufferline.h"
  46 #include "core/devformat.h"
  47 #include "core/device.h"
  48 #include "core/effectslot.h"
  49 #include "core/mixer.h"
  50 #include "core/mixer/defs.h"
  51 #include "intrusive_ptr.h"
  52
  53 struct ContextBase;
  54
  55
  56 namespace {
  57
  58 #define AMP_ENVELOPE_MIN  0.5f
  59 #define AMP_ENVELOPE_MAX  2.0f
  60
  61 #define ATTACK_TIME  0.1f /* 100ms to rise from min to max */
  62 #define RELEASE_TIME 0.2f /* 200ms to drop from max to min */
  63
  64
  65 struct CompressorState final : public EffectState {
  66     /* Effect gains for each channel */
  67     struct {
  68         uint mTarget{InvalidChannelIndex};
  69         float mGain{1.0f};
  70     } mChans[MaxAmbiChannels];
  71
  72     /* Effect parameters */
  73     bool mEnabled{true};
  74     float mAttackMult{1.0f};
  75     float mReleaseMult{1.0f};
  76     float mEnvFollower{1.0f};
  77
  78
  79     void deviceUpdate(const DeviceBase *device, const Buffer &buffer) override;
  80     void update(const ContextBase *context, const EffectSlot *slot, const EffectProps *props,
  81         const EffectTarget target) override;
  82     void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn,
  83         const al::span<FloatBufferLine> samplesOut) override;
  84
  85     DEF_NEWDEL(CompressorState)
  86 };
  87
  88 void CompressorState::deviceUpdate(const DeviceBase *device, const Buffer&)
  89 {
  90     /* Number of samples to do a full attack and release (non-integer sample
  91      * counts are okay).
  92      */
  93     const float attackCount{static_cast<float>(device->Frequency) * ATTACK_TIME};
  94     const float releaseCount{static_cast<float>(device->Frequency) * RELEASE_TIME};
  95
  96     /* Calculate per-sample multipliers to attack and release at the desired
  97      * rates.
  98      */
  99     mAttackMult  = std::pow(AMP_ENVELOPE_MAX/AMP_ENVELOPE_MIN, 1.0f/attackCount);
 100     mReleaseMult = std::pow(AMP_ENVELOPE_MIN/AMP_ENVELOPE_MAX, 1.0f/releaseCount);
 101 }
 102
 103 void CompressorState::update(const ContextBase*, const EffectSlot *slot,
 104     const EffectProps *props, const EffectTarget target)
 105 {
 106     mEnabled = props->Compressor.OnOff;
 107
 108     mOutTarget = target.Main->Buffer;
 109     auto set_channel = [this](size_t idx, uint outchan, float outgain)
 110     {
 111         mChans[idx].mTarget = outchan;
 112         mChans[idx].mGain = outgain;
 113     };
 114     target.Main->setAmbiMixParams(slot->Wet, slot->Gain, set_channel);
 115 }
 116
 117 void CompressorState::process(const size_t samplesToDo,
 118     const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
 119 {
 120     for(size_t base{0u};base < samplesToDo;)
 121     {
 122         float gains[256];
 123         const size_t td{minz(256, samplesToDo-base)};
 124
 125         /* Generate the per-sample gains from the signal envelope. */
 126         float env{mEnvFollower};
 127         if(mEnabled)
 128         {
 129             for(size_t i{0u};i < td;++i)
 130             {
 131                 /* Clamp the absolute amplitude to the defined envelope limits,
 132                  * then attack or release the envelope to reach it.
 133                  */
 134                 const float amplitude{clampf(std::fabs(samplesIn[0][base+i]), AMP_ENVELOPE_MIN,
 135                     AMP_ENVELOPE_MAX)};
 136                 if(amplitude > env)
 137                     env = minf(env*mAttackMult, amplitude);
 138                 else if(amplitude < env)
 139                     env = maxf(env*mReleaseMult, amplitude);
 140
 141                 /* Apply the reciprocal of the envelope to normalize the volume
 142                  * (compress the dynamic range).
 143                  */
 144                 gains[i] = 1.0f / env;
 145             }
 146         }
 147         else
 148         {
 149             /* Same as above, except the amplitude is forced to 1. This helps
 150              * ensure smooth gain changes when the compressor is turned on and
 151              * off.
 152              */
 153             for(size_t i{0u};i < td;++i)
 154             {
 155                 const float amplitude{1.0f};
 156                 if(amplitude > env)
 157                     env = minf(env*mAttackMult, amplitude);
 158                 else if(amplitude < env)
 159                     env = maxf(env*mReleaseMult, amplitude);
 160
 161                 gains[i] = 1.0f / env;
 162             }
 163         }
 164         mEnvFollower = env;
 165
 166         /* Now compress the signal amplitude to output. */
 167         auto chan = std::cbegin(mChans);
 168         for(const auto &input : samplesIn)
 169         {
 170             const size_t outidx{chan->mTarget};
 171             if(outidx != InvalidChannelIndex)
 172             {
 173                 const float *RESTRICT src{input.data() + base};
 174                 float *RESTRICT dst{samplesOut[outidx].data() + base};
 175                 const float gain{chan->mGain};
 176                 if(!(std::fabs(gain) > GainSilenceThreshold))
 177                 {
 178                     for(size_t i{0u};i < td;i++)
 179                         dst[i] += src[i] * gains[i] * gain;
 180                 }
 181             }
 182             ++chan;
 183         }
 184
 185         base += td;
 186     }
 187 }
 188
 189
 190 struct CompressorStateFactory final : public EffectStateFactory {
 191     al::intrusive_ptr<EffectState> create() override
 192     { return al::intrusive_ptr<EffectState>{new CompressorState{}}; }
 193 };
 194
 195 } // namespace
 196
 197 EffectStateFactory *CompressorStateFactory_getFactory()
 198 {
 199     static CompressorStateFactory CompressorFactory{};
 200     return &CompressorFactory;
 201 }