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<div class="refentry" title="0dbfs">
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<h2>
<span class="refentrytitle">0dbfs</span>
</h2>
<p>0dbfs —
Sets the value of 0 decibels using full scale amplitude.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp12998928"></a>
<h2>Description</h2>
<p>
Sets the value of 0 decibels using full scale amplitude.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp12999680"></a>
<h2>Syntax</h2>
<pre class="synopsis"><span class="command"><strong>0dbfs</strong></span> = iarg</pre>
<pre class="synopsis"><span class="command"><strong>0dbfs</strong></span> </pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp13010688"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iarg</em></span> -- the value of 0 decibels using full scale amplitude.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp13011640"></a>
<h2>Performance</h2>
<p>
The default is 32767, so all existing orcs <span class="emphasis"><em>should</em></span> work.
</p>
<p>
Amplitude values in Csound are always relative to a "<a class="link" href="Zerodbfs.html" title="0dbfs"><em class="citetitle">0dbfs</em></a>" value representing the peak available amplitude before clipping. In the original Csound, this value was always 32767, corresponding to the bipolar range of a 16bit soundfile or 16bit AD/DA codec. This remains the <span class="emphasis"><em>default</em></span> peak amplitude for Csound, for backward compatibility. The <a class="link" href="Zerodbfs.html" title="0dbfs"><em class="citetitle">0dbfs</em></a> value enables Csound to produce appropriately scaled values to whatever output format is being used, whether 16bit integer, 24bit integer, 32bit floats, or even 32bit integers.
</p>
<p>
OdBFS can be defined in the header, to set the amplitude reference Csound will use, but it can also be used as a varible inside instruments like this:
</p>
<div class="informalexample">
<pre class="programlisting">ipeak <span class="op">=</span> <span class="ohdr">0dbfs</span></pre>
</div>
<p>
</p>
<div class="informalexample">
<pre class="programlisting">
asig <span class="opc">oscil</span> <span class="ohdr">0dbfs</span>, freq, 1
<span class="opc">out</span> asig * 0.3 * <span class="ohdr">0dbfs</span></pre>
</div>
<p>
</p>
<p>
The purpose of the <span class="emphasis"><em>0dbfs</em></span> opcode is for people to start to code 0dbfs-relatively (and use the <a class="link" href="ampdbfs.html" title="ampdbfs"><em class="citetitle">ampdbfs()</em></a> opcodes a lot more!), rather than use explicit sample values. Using 0dbfs=1 is in accordance to industry practice, as ranges from -1 to 1 are used in most commercial plugin formats and in most other synthesis systems like Pure Data.
</p>
<p>
Floats written to a file, when <span class="emphasis"><em>0dbfs = 1</em></span>, will in effect go through no range translation at all. So the numbers in the file are exactly what the orc says they are.
</p>
<p>For more details on amplitude values in Csound, see the section <a class="link" href="UsingDesign.html#AmplitudeCsound" title="Amplitude values in Csound"><em class="citetitle">Amplitude values in Csound</em></a></p>
</div>
<div class="refsect1" title="Example">
<a id="idp13059328"></a>
<h2>Example</h2>
<p>
Here is an example of the 0dbfs opcode. It uses the file <a class="ulink" href="examples/0dbfs.csd" target="_top"><em class="citetitle">0dbfs.csd</em></a>.
</p>
<div class="example">
<a id="idp13060848"></a>
<p class="title">
<strong>Example 31. Example of the 0dbfs 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>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
<span class="comment">; Audio out Audio in No messages</span>
-odac -iadc -d <span class="comment">;;;RT audio I/O</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o 0dbfs.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="comment">; Initialize the global variables.</span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 10
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="comment">; Set the 0dbfs to 1.</span>
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1
<span class="oblock">instr</span> 1 <span class="comment">; from linear amplitude (0-1 range)</span>
<span class="opc">print</span> p4
a1 <span class="opc">oscil</span> p4, 440, 1
<span class="opc">outs</span> a1, a1
<span class="oblock">endin</span>
<span class="oblock">instr</span> 2 <span class="comment">; from linear amplitude (0-32767 range)</span>
iamp <span class="op">=</span> p4 <span class="op">/</span> 32767
<span class="opc">print</span> iamp
a1 <span class="opc">oscil</span> iamp, 440, 1
<span class="opc">outs</span> a1, a1
<span class="oblock">endin</span>
<span class="oblock">instr</span> 3 <span class="comment">; from dB FS</span>
iamp <span class="op">=</span> <span class="opc">ampdbfs</span>(p4)
<span class="opc">print</span> iamp
a1 <span class="opc">oscil</span> iamp, 440, 1
<span class="opc">outs</span> a1, a1
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="comment">; Table #1, a sine wave.</span>
<span class="stamnt">f</span> 1 0 16384 10 1
<span class="stamnt">i</span> 1 0 1 1
<span class="stamnt">i</span> 1 + 1 0.5
<span class="stamnt">i</span> 1 + 1 0.1
<span class="stamnt">s</span>
<span class="stamnt">i</span> 2 0 1 32767
<span class="stamnt">i</span> 2 + 1 [32767/2]
<span class="stamnt">i</span> 2 + 1 [3276.7]
<span class="stamnt">s</span>
<span class="stamnt">i</span> 3 0 1 0
<span class="stamnt">i</span> 3 + 1 -6
<span class="stamnt">i</span> 3 + 1 -20
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
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<p><br class="example-break" />
</p>
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<div class="refsect1" title="See also">
<a id="idp13063136"></a>
<h2>See also</h2>
<p>
<a class="link" href="ampdbfs.html" title="ampdbfs">
<em class="citetitle">ampdbfs()</em>
</a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp13064040"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Richard Dobson</td>
</tr>
<tr>
<td>May 2002</td>
</tr>
</table>
<p>
</p>
<p>New in version 4.10</p>
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