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<li class="navelem"><a class="el" href="dir_a8a4892678035c62db3a4af7d9811050.html">IPlug</a></li><li class="navelem"><a class="el" href="dir_91051055e54918154e7732bfb3d5e02e.html">Extras</a></li>  </ul>
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  <div class="headertitle"><div class="title">NoiseGate.h</div></div>
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<div class="contents">
<a href="_noise_gate_8h.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/*</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> ==============================================================================</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> </span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> This file is part of the iPlug 2 library. Copyright (C) the iPlug 2 developers. </span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> </span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> See LICENSE.txt for  more info.</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> </span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> The class in this file is derived from the FAUST ef.gate_mono code</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> </span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> https://faustlibraries.grame.fr/libs/misceffects/#efgate_mono</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"></span> </div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> analyzers.lib/amp_follower_ar:author Jonatan Liljedahl, revised by Romain Michon</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> signals.lib/onePoleSwitching:author Jonatan Liljedahl, revised by Dario Sanfilippo</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> licence STK-4.3</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> </span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> https://github.com/grame-cncm/faustlibraries/blob/master/licenses/stk-4.3.0.md</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"> </span></div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment"> ==============================================================================</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment">*/</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span> </div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span> </div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="preprocessor">#include &quot;<a class="code" href="_i_plug_utilities_8h.html">IPlugUtilities.h</a>&quot;</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span> </div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span>BEGIN_IPLUG_NAMESPACE</div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span> </div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> T, <span class="keywordtype">int</span> NC = 1&gt;</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno"><a class="line" href="class_noise_gate.html">   35</a></span><span class="keyword">class </span><a class="code hl_class" href="class_noise_gate.html">NoiseGate</a></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span>{</div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span>  <span class="keywordtype">void</span> SetThreshold(<span class="keywordtype">double</span> thresholdDB)</div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span>  {</div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span>    mThreshold = <a class="code hl_function" href="group___i_plug_utilities.html#gac880d08b2331fd32d3ad76f979c489e5">DBToAmp</a>(thresholdDB);</div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span>  }</div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span>  </div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span>  <span class="keywordtype">void</span> SetSampleRate(<span class="keywordtype">double</span> sampleRate)</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span>  {</div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span>    mSampleRate = sampleRate;</div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span>  }</div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span>  </div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span>  <span class="keywordtype">void</span> SetAttackTime(<span class="keywordtype">double</span> attackTime)</div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span>  {</div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span>    mAttackTime = std::max(attackTime, (1.0 / mSampleRate));</div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>    mMinRate = std::min(mAttackTime, mReleaseTime);</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span>  }</div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span>  </div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span>  <span class="keywordtype">void</span> SetHoldTime(<span class="keywordtype">double</span> holdTime)</div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span>  {</div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span>    mHoldTime = std::max(holdTime, (1.0 / mSampleRate));</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span>  }</div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>  </div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span>  <span class="keywordtype">void</span> SetReleaseTime(<span class="keywordtype">double</span> releaseTime)</div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span>  {</div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span>    mReleaseTime = std::max(releaseTime, (1.0 / mSampleRate));</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span>    mMinRate = std::min(mAttackTime, mReleaseTime);</div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span>  }</div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span> </div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span>  <span class="keywordtype">void</span> ProcessBlock(T** inputs, T** outputs, T* sidechain, <span class="keywordtype">int</span> nChans, <span class="keywordtype">int</span> nFrames)</div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span>  {</div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span>    assert(nChans &lt;= NC);</div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span> </div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span>    <span class="keywordflow">for</span> (<span class="keyword">auto</span> s=0; s &lt;nFrames; s++)</div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span>    {</div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span>      <span class="keyword">auto</span> trigger = sidechain[s];</div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span>      <span class="keyword">auto</span> gain = processSample(trigger);</div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span>      <span class="keywordflow">for</span> (<span class="keyword">auto</span> c=0; c&lt;nChans; c++)</div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span>      {</div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>        outputs[c][s] = inputs[c][s] * gain;</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span>      }</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>    }</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>  }</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span> </div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span>  <span class="keyword">inline</span> T processSample(T sample) </div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span>  {</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span>    <span class="keyword">auto</span> ampFollower = [](T x, T&amp; y, <span class="keywordtype">double</span> att, <span class="keywordtype">double</span> rel, <span class="keywordtype">double</span> sr) {</div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>      <span class="keyword">auto</span> tau2pole = [](<span class="keywordtype">double</span> tau, <span class="keywordtype">double</span> sr) {</div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span>        <span class="keywordflow">return</span> std::exp(-1.0 / (tau * sr));</div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span>      };</div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span>      <span class="keyword">const</span> <span class="keyword">auto</span> absX = std::abs(x);</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span>      <span class="keyword">const</span> <span class="keyword">auto</span> coeff = (absX &gt; y) ? T(tau2pole(att, sr)) : T(tau2pole(rel, sr));</div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span>      y = (T(1) - coeff) * absX + coeff * y;</div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span>      <span class="keywordflow">return</span> y;</div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span>    };</div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span>    </div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span>    <span class="keyword">auto</span> rawGate = ampFollower(sample, mHistory2, mMinRate, mMinRate, mSampleRate) &gt; mThreshold;</div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span>    </div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span>    <span class="keywordflow">if</span> (rawGate &lt; mPrevGate)</div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span>    {</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span>      mHoldCounter = int(mHoldTime * mSampleRate);</div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span>    }</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span>    <span class="keywordflow">else</span> </div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span>    {</div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span>      <span class="keywordflow">if</span> (mHoldCounter &gt; 0)</div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span>      {</div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span>        mHoldCounter--;</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span>      }</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span>    }</div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span>    </div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span>    <span class="keyword">const</span> <span class="keyword">auto</span> heldGate = std::max(rawGate, mHoldCounter &gt; 0);</div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span>    <span class="keyword">const</span> <span class="keyword">auto</span> smoothed = ampFollower(T(heldGate), mHistory1, mAttackTime, mReleaseTime, mSampleRate);</div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span> </div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span>    mPrevGate = rawGate;</div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span>    </div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span>    <span class="keywordflow">return</span> smoothed;</div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span>  }</div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span> </div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span>  <span class="keywordtype">double</span> mThreshold = 0.5;</div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span>  <span class="keywordtype">double</span> mSampleRate = 48000.0;</div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>  <span class="keywordtype">double</span> mAttackTime = 0.01f;</div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span>  <span class="keywordtype">double</span> mHoldTime = 0.01f;</div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span>  <span class="keywordtype">double</span> mReleaseTime = 0.01f;</div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span>  <span class="keywordtype">double</span> mMinRate = mAttackTime;</div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span>  T mHistory1, mHistory2 = 0.0f;</div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span>  <span class="keywordtype">bool</span> mPrevGate = <span class="keyword">false</span>;</div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span>  <span class="keywordtype">int</span> mHoldCounter = 0;</div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span>};</div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span> </div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span>END_IPLUG_NAMESPACE</div>
<div class="ttc" id="a_i_plug_utilities_8h_html"><div class="ttname"><a href="_i_plug_utilities_8h.html">IPlugUtilities.h</a></div><div class="ttdoc">Utility functions and macros.</div></div>
<div class="ttc" id="aclass_noise_gate_html"><div class="ttname"><a href="class_noise_gate.html">NoiseGate</a></div><div class="ttdef"><b>Definition:</b> <a href="_noise_gate_8h_source.html#l00035">NoiseGate.h:36</a></div></div>
<div class="ttc" id="agroup___i_plug_utilities_html_gac880d08b2331fd32d3ad76f979c489e5"><div class="ttname"><a href="group___i_plug_utilities.html#gac880d08b2331fd32d3ad76f979c489e5">DBToAmp</a></div><div class="ttdeci">static double DBToAmp(double dB)</div><div class="ttdoc">Calculates gain from a given dB value.</div><div class="ttdef"><b>Definition:</b> <a href="_i_plug_utilities_8h_source.html#l00097">IPlugUtilities.h:97</a></div></div>
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