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<div class="section" id="Audio-File-Utilities">
<div class="header">
<p>
Next: <a href="Audio-Device-Information.html" accesskey="n" rel="next">Audio Device Information</a>, Up: <a href="Audio-Processing.html" accesskey="u" rel="up">Audio Processing</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Audio-File-Utilities-1"></span><h3 class="section">33.1 Audio File Utilities</h3>
<p>The following functions allow you to read, write and retrieve
information about audio files. Various formats are supported including
wav, flac and ogg vorbis.
</p>
<span id="XREFaudioinfo"></span><dl class="def">
<dt id="index-audioinfo"><span class="category">: </span><span><em><var>info</var> =</em> <strong>audioinfo</strong> <em>(<var>filename</var>)</em><a href='#index-audioinfo' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Return information about an audio file specified by <var>filename</var>.
</p>
<p>The output <var>info</var> is a structure containing the following fields:
</p>
<dl compact="compact">
<dt><span>‘<samp>Filename</samp>’</span></dt>
<dd><p>Name of the audio file.
</p>
</dd>
<dt><span>‘<samp>CompressionMethod</samp>’</span></dt>
<dd><p>Audio compression method. Unused, only present for compatibility with
<small>MATLAB</small>.
</p>
</dd>
<dt><span>‘<samp>NumChannels</samp>’</span></dt>
<dd><p>Number of audio channels.
</p>
</dd>
<dt><span>‘<samp>SampleRate</samp>’</span></dt>
<dd><p>Sample rate of the audio, in Hertz.
</p>
</dd>
<dt><span>‘<samp>TotalSamples</samp>’</span></dt>
<dd><p>Number of samples in the file.
</p>
</dd>
<dt><span>‘<samp>Duration</samp>’</span></dt>
<dd><p>Duration of the audio, in seconds.
</p>
</dd>
<dt><span>‘<samp>BitsPerSample</samp>’</span></dt>
<dd><p>Number of bits per sample.
</p>
</dd>
<dt><span>‘<samp>BitRate</samp>’</span></dt>
<dd><p>Audio bit rate. Unused, only present for compatibility with <small>MATLAB</small>.
</p>
</dd>
<dt><span>‘<samp>Title</samp>’</span></dt>
<dd><p><code>"Title"</code> audio metadata value as a string, or empty if not present.
</p>
</dd>
<dt><span>‘<samp>Artist</samp>’</span></dt>
<dd><p><code>"Artist"</code> audio metadata value as a string, or empty if not present.
</p>
</dd>
<dt><span>‘<samp>Comment</samp>’</span></dt>
<dd><p><code>"Comment"</code> audio metadata value as a string, or empty if not present.
</p></dd>
</dl>
<p><strong>See also:</strong> <a href="#XREFaudioread">audioread</a>, <a href="#XREFaudiowrite">audiowrite</a>.
</p></dd></dl>
<span id="XREFaudioread"></span><dl class="def">
<dt id="index-audioread"><span class="category">: </span><span><em>[<var>y</var>, <var>fs</var>] =</em> <strong>audioread</strong> <em>(<var>filename</var>)</em><a href='#index-audioread' class='copiable-anchor'> ¶</a></span></dt>
<dt id="index-audioread-1"><span class="category">: </span><span><em>[<var>y</var>, <var>fs</var>] =</em> <strong>audioread</strong> <em>(<var>filename</var>, <var>samples</var>)</em><a href='#index-audioread-1' class='copiable-anchor'> ¶</a></span></dt>
<dt id="index-audioread-2"><span class="category">: </span><span><em>[<var>y</var>, <var>fs</var>] =</em> <strong>audioread</strong> <em>(<var>filename</var>, <var>datatype</var>)</em><a href='#index-audioread-2' class='copiable-anchor'> ¶</a></span></dt>
<dt id="index-audioread-3"><span class="category">: </span><span><em>[<var>y</var>, <var>fs</var>] =</em> <strong>audioread</strong> <em>(<var>filename</var>, <var>samples</var>, <var>datatype</var>)</em><a href='#index-audioread-3' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Read the audio file <var>filename</var> and return the audio data <var>y</var> and
sampling rate <var>fs</var>.
</p>
<p>The audio data is stored as matrix with rows corresponding to audio frames
and columns corresponding to channels.
</p>
<p>The optional two-element vector argument <var>samples</var> specifies starting
and ending frames.
</p>
<p>The optional argument <var>datatype</var> specifies the datatype to return.
If it is <code>"native"</code>, then the type of data depends on how the data
is stored in the audio file.
</p>
<p><strong>See also:</strong> <a href="#XREFaudiowrite">audiowrite</a>, <a href="#XREFaudioformats">audioformats</a>, <a href="#XREFaudioinfo">audioinfo</a>.
</p></dd></dl>
<span id="XREFaudiowrite"></span><dl class="def">
<dt id="index-audiowrite"><span class="category">: </span><span><em></em> <strong>audiowrite</strong> <em>(<var>filename</var>, <var>y</var>, <var>fs</var>)</em><a href='#index-audiowrite' class='copiable-anchor'> ¶</a></span></dt>
<dt id="index-audiowrite-1"><span class="category">: </span><span><em></em> <strong>audiowrite</strong> <em>(<var>filename</var>, <var>y</var>, <var>fs</var>, <var>name</var>, <var>value</var>, …)</em><a href='#index-audiowrite-1' class='copiable-anchor'> ¶</a></span></dt>
<dd>
<p>Write audio data from the matrix <var>y</var> to <var>filename</var> at sampling rate
<var>fs</var> with the file format determined by the file extension.
</p>
<p>Additional name/value argument pairs may be used to specify the
following options:
</p>
<dl compact="compact">
<dt><span>‘<samp>BitsPerSample</samp>’</span></dt>
<dd><p>Number of bits per sample. Valid values are 8, 16, 24, and 32. Default is
16.
</p>
</dd>
<dt><span>‘<samp>BitRate</samp>’</span></dt>
<dd><p>Valid argument name, but ignored. Left for compatibility with <small>MATLAB</small>.
</p>
</dd>
<dt><span>‘<samp>Quality</samp>’</span></dt>
<dd><p>Quality setting for the Ogg Vorbis compressor. Values can range between 0
and 100 with 100 being the highest quality setting. Default is 75.
</p>
</dd>
<dt><span>‘<samp>Title</samp>’</span></dt>
<dd><p>Title for the audio file.
</p>
</dd>
<dt><span>‘<samp>Artist</samp>’</span></dt>
<dd><p>Artist name.
</p>
</dd>
<dt><span>‘<samp>Comment</samp>’</span></dt>
<dd><p>Comment.
</p></dd>
</dl>
<p><strong>See also:</strong> <a href="#XREFaudioread">audioread</a>, <a href="#XREFaudioformats">audioformats</a>, <a href="#XREFaudioinfo">audioinfo</a>.
</p></dd></dl>
<span id="XREFaudioformats"></span><dl class="def">
<dt id="index-audioformats"><span class="category">: </span><span><em></em> <strong>audioformats</strong> <em>()</em><a href='#index-audioformats' class='copiable-anchor'> ¶</a></span></dt>
<dt id="index-audioformats-1"><span class="category">: </span><span><em></em> <strong>audioformats</strong> <em>(<var>format</var>)</em><a href='#index-audioformats-1' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Display information about all supported audio formats.
</p>
<p>If the optional argument <var>format</var> is given, then display only formats
with names that start with <var>format</var>.
</p>
<p><strong>See also:</strong> <a href="#XREFaudioread">audioread</a>, <a href="#XREFaudiowrite">audiowrite</a>.
</p></dd></dl>
</div>
<hr>
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Next: <a href="Audio-Device-Information.html">Audio Device Information</a>, Up: <a href="Audio-Processing.html">Audio Processing</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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