source/modules/juce_dsp/widgets/juce_Limiter.h

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library.
   5    Copyright (c) 2022 - Raw Material Software Limited
   6
   7    JUCE is an open source library subject to commercial or open-source
   8    licensing.
   9
  10    By using JUCE, you agree to the terms of both the JUCE 7 End-User License
  11    Agreement and JUCE Privacy Policy.
  12
  13    End User License Agreement: www.juce.com/juce-7-licence
  14    Privacy Policy: www.juce.com/juce-privacy-policy
  15
  16    Or: You may also use this code under the terms of the GPL v3 (see
  17    www.gnu.org/licenses).
  18
  19    JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
  20    EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
  21    DISCLAIMED.
  22
  23   ==============================================================================
  24 */
  25
  26 namespace juce
  27 {
  28 namespace dsp
  29 {
  30
  31 /**
  32     A simple limiter with standard threshold and release time controls, featuring
  33     two compressors and a hard clipper at 0 dB.
  34
  35     @tags{DSP}
  36 */
  37 template <typename SampleType>
  38 class Limiter
  39 {
  40 public:
  41     //==============================================================================
  42     /** Constructor. */
  43     Limiter() = default;
  44
  45     //==============================================================================
  46     /** Sets the threshold in dB of the limiter.*/
  47     void setThreshold (SampleType newThreshold);
  48
  49     /** Sets the release time in milliseconds of the limiter.*/
  50     void setRelease (SampleType newRelease);
  51
  52     //==============================================================================
  53     /** Initialises the processor. */
  54     void prepare (const ProcessSpec& spec);
  55
  56     /** Resets the internal state variables of the processor. */
  57     void reset();
  58
  59     //==============================================================================
  60     /** Processes the input and output samples supplied in the processing context. */
  61     template <typename ProcessContext>
  62     void process (const ProcessContext& context) noexcept
  63     {
  64         const auto& inputBlock = context.getInputBlock();
  65         auto& outputBlock      = context.getOutputBlock();
  66         const auto numChannels = outputBlock.getNumChannels();
  67         const auto numSamples  = outputBlock.getNumSamples();
  68
  69         jassert (inputBlock.getNumChannels() == numChannels);
  70         jassert (inputBlock.getNumSamples()  == numSamples);
  71
  72         if (context.isBypassed)
  73         {
  74             outputBlock.copyFrom (inputBlock);
  75             return;
  76         }
  77
  78         firstStageCompressor.process (context);
  79
  80         auto secondContext = ProcessContextReplacing<SampleType> (outputBlock);
  81         secondStageCompressor.process (secondContext);
  82
  83         outputBlock.multiplyBy (outputVolume);
  84
  85         for (size_t channel = 0; channel < numChannels; ++channel)
  86         {
  87             FloatVectorOperations::clip (outputBlock.getChannelPointer (channel), outputBlock.getChannelPointer (channel),
  88                                          (SampleType) -1.0, (SampleType) 1.0, (int) numSamples);
  89         }
  90     }
  91
  92 private:
  93     //==============================================================================
  94     void update();
  95
  96     //==============================================================================
  97     Compressor<SampleType> firstStageCompressor, secondStageCompressor;
  98     SmoothedValue<SampleType, ValueSmoothingTypes::Linear> outputVolume;
  99
 100     double sampleRate = 44100.0;
 101     SampleType thresholddB = -10.0, releaseTime = 100.0;
 102 };
 103
 104 } // namespace dsp
 105 } // namespace juce