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<h2>
<span class="refentrytitle">rms</span>
</h2>
<p>rms —
Determines the root-mean-square amplitude of an audio signal.
</p>
</div>
<div class="refsect1">
<a id="idm281472894472184"></a>
<h2>Description</h2>
<p>
Determines the root-mean-square amplitude of an audio signal. It low-pass filters the actual value, to average in the manner of a VU meter.
</p>
</div>
<div class="refsect1">
<a id="idm281472894417832"></a>
<h2>Syntax</h2>
<pre class="synopsis">kres <span class="command"><strong>rms</strong></span> asig [, ihp] [, iskip]</pre>
</div>
<div class="refsect1">
<a id="idm281472894415688"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ihp</em></span> (optional, default=10) -- half-power point (in Hz) of a special internal low-pass filter. The default value is 10.
</p>
<p>
<span class="emphasis"><em>iskip</em></span> (optional, default=0) -- initial disposition of internal data space (see <a class="link" href="reson.html" title="reson"><em class="citetitle">reson</em></a>). The default value is 0.
</p>
</div>
<div class="refsect1">
<a id="idm281472894412104"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>asig</em></span> -- input audio signal
</p>
<p>
<span class="emphasis"><em>kres</em></span> -- low-pass filtered rms value of the input signal
</p>
<p>
<span class="emphasis"><em>rms</em></span> output values <span class="emphasis"><em>kres</em></span> will trace the root-mean-square value of the audio input <span class="emphasis"><em>asig</em></span>. This unit is not a signal modifier, but functions rather as a signal power-gauge. It uses an internal low-pass filter to make the response smoother. <span class="emphasis"><em>ihp</em></span> can be used to control this smoothing. The higher the value, the "snappier" the measurement.
</p>
<p>
This opcode can also be used as an evelope follower.
</p>
<p>
The <span class="emphasis"><em>kres</em></span> output from this opcode is given in amplitude and depends on <a class="link" href="Zerodbfs.html" title="0dbfs"><em class="citetitle">0dbfs</em></a>. If you want the output in decibels, you can use <a class="link" href="dbamp.html" title="dbamp"><em class="citetitle">dbamp</em></a>
</p>
</div>
<div class="refsect1">
<a id="idm281472894403992"></a>
<h2>Examples</h2>
<p>
</p>
<div class="informalexample">
<pre class="programlisting">
arms <span class="opc">rms</span> asig <span class="comment">; get rms value of signal asig</span>
</pre>
</div>
<p>
</p>
<p>
Here is an example of the rms opcode. It uses the file <a class="ulink" href="examples/rms.csd" target="_top"><em class="citetitle">rms.csd</em></a>.
</p>
<div class="example">
<a id="idm281472894399320"></a>
<p class="title">
<strong>Example 838. Example of the rms opcode.</strong>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<div class="refsect1">
<a id="idm281472714912008"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
<span class="c1">; Select audio/midi flags here according to platform</span>
<span class="c1">; Audio out Audio in No messages</span>
-odac -iadc -d -m0 <span class="c1">;;;RT audio I/O</span>
<span class="c1">; For Non-realtime ouput leave only the line below:</span>
<span class="c1">; -o rms.wav -W ;;; for file output any platform</span>
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="c1">; Initialize the global variables.</span>
<span class="vg">sr</span> <span class="o">=</span> <span class="mi">44100</span>
<span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">128</span>
<span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">1</span>
<span class="c1">;Example by Andres Cabrera 2007</span>
<span class="vg">0dbfs</span> <span class="o">=</span> <span class="mi">1</span>
<span class="nb">FLpanel</span> <span class="s">"rms"</span><span class="p">,</span> <span class="mi">400</span><span class="p">,</span> <span class="mi">100</span><span class="p">,</span> <span class="mi">50</span><span class="p">,</span> <span class="mi">50</span>
gk<span class="n">rmstext</span><span class="p">,</span> gi<span class="n">hrmstext</span> <span class="nb">FLtext</span> <span class="s">"Rms"</span><span class="p">,</span> <span class="o">-</span><span class="mi">100</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">110</span><span class="p">,</span> <span class="mi">30</span><span class="p">,</span> <span class="mi">60</span><span class="p">,</span> <span class="mi">50</span>
gk<span class="n">ihp</span><span class="p">,</span> gi<span class="n">handle</span> <span class="nb">FLtext</span> <span class="s">"ihp"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="mf">0.05</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">100</span><span class="p">,</span> <span class="mi">30</span><span class="p">,</span> <span class="mi">220</span><span class="p">,</span> <span class="mi">50</span>
gk<span class="n">rmsslider</span><span class="p">,</span> gi<span class="n">hrmsslider</span> <span class="nb">FLslider</span> <span class="s">""</span><span class="p">,</span> <span class="o">-</span><span class="mi">60</span><span class="p">,</span> <span class="o">-</span><span class="mf">0.5</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mi">380</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="mi">10</span>
<span class="nb">FLpanelEnd</span>
<span class="nb">FLrun</span>
<span class="nb">FLsetVal_i</span> <span class="mi">5</span><span class="p">,</span> gi<span class="n">handle</span>
<span class="c1">; Instrument #1.</span>
<span class="kd">instr</span> <span class="nf">1</span>
a<span class="n">1</span> <span class="nb">inch</span> <span class="mi">1</span>
<span class="nl">label</span><span class="p">:</span>
k<span class="n">val</span> <span class="nb">rms</span> a<span class="n">1</span><span class="p">,</span> <span class="nb">i</span><span class="p">(</span>gk<span class="n">ihp</span><span class="p">)</span> <span class="c1">;measures rms of input channel 1</span>
<span class="nb">rireturn</span>
k<span class="n">val</span> <span class="o">=</span> <span class="nb">dbamp</span><span class="p">(</span>k<span class="n">val</span><span class="p">)</span> <span class="c1">; convert to db full scale</span>
<span class="nb">printk</span> <span class="mf">0.5</span><span class="p">,</span> k<span class="n">val</span>
<span class="nb">FLsetVal</span> <span class="mi">1</span><span class="p">,</span> k<span class="n">val</span><span class="p">,</span> gi<span class="n">hrmsslider</span> <span class="c1">;update the slider and text values</span>
<span class="nb">FLsetVal</span> <span class="mi">1</span><span class="p">,</span> k<span class="n">val</span><span class="p">,</span> gi<span class="n">hrmstext</span>
k<span class="n">newihp</span> <span class="nb">changed</span> gk<span class="n">ihp</span> <span class="c1">; reinit when ihp text has changed</span>
<span class="k">if</span> <span class="p">(</span>k<span class="n">newihp</span> <span class="o">==</span> <span class="mi">1</span><span class="p">)</span> <span class="k">then</span>
<span class="nb">reinit</span> <span class="n">label</span> <span class="c1">;needed because ihp is an i-rate parameter</span>
<span class="k">endif</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="c1">; Play Instrument #1 for one minute</span>
<span class="nb">i</span> <span class="mi">1</span> <span class="mi">0</span> <span class="mi">60</span>
<span class="nb">e</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
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<p><br class="example-break" />
</p>
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<div class="refsect1">
<a id="idm281472894395032"></a>
<h2>See Also</h2>
<p>
<a class="link" href="balance.html" title="balance"><em class="citetitle">balance</em></a>,
<a class="link" href="gain.html" title="gain"><em class="citetitle">gain</em></a>
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