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<h3 class="section" id="Audio-File-Utilities-1"><span>33.1 Audio File Utilities<a class="copiable-link" href="#Audio-File-Utilities-1"> ¶</a></span></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>
<a class="anchor" id="XREFaudioinfo"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-audioinfo"><span><code class="def-type"><var class="var">info</var> =</code> <strong class="def-name">audioinfo</strong> <code class="def-code-arguments">(<var class="var">filename</var>)</code><a class="copiable-link" href="#index-audioinfo"> ¶</a></span></dt>
<dd><p>Return information about an audio file specified by <var class="var">filename</var>.
</p>
<p>The output <var class="var">info</var> is a structure containing the following fields:
</p>
<dl class="table">
<dt>‘<samp class="samp">Filename</samp>’</dt>
<dd><p>Name of the audio file.
</p>
</dd>
<dt>‘<samp class="samp">CompressionMethod</samp>’</dt>
<dd><p>Audio compression method. Unused, only present for compatibility with
<small class="sc">MATLAB</small>.
</p>
</dd>
<dt>‘<samp class="samp">NumChannels</samp>’</dt>
<dd><p>Number of audio channels.
</p>
</dd>
<dt>‘<samp class="samp">SampleRate</samp>’</dt>
<dd><p>Sample rate of the audio, in Hertz.
</p>
</dd>
<dt>‘<samp class="samp">TotalSamples</samp>’</dt>
<dd><p>Number of samples in the file.
</p>
</dd>
<dt>‘<samp class="samp">Duration</samp>’</dt>
<dd><p>Duration of the audio, in seconds.
</p>
</dd>
<dt>‘<samp class="samp">BitsPerSample</samp>’</dt>
<dd><p>Number of bits per sample.
</p>
</dd>
<dt>‘<samp class="samp">BitRate</samp>’</dt>
<dd><p>Audio bit rate. Unused, only present for compatibility with <small class="sc">MATLAB</small>.
</p>
</dd>
<dt>‘<samp class="samp">Title</samp>’</dt>
<dd><p><code class="code">"Title"</code> audio metadata value as a string, or empty if not present.
</p>
</dd>
<dt>‘<samp class="samp">Artist</samp>’</dt>
<dd><p><code class="code">"Artist"</code> audio metadata value as a string, or empty if not present.
</p>
</dd>
<dt>‘<samp class="samp">Comment</samp>’</dt>
<dd><p><code class="code">"Comment"</code> audio metadata value as a string, or empty if not present.
</p></dd>
</dl>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFaudioread">audioread</a>, <a class="ref" href="#XREFaudiowrite">audiowrite</a>.
</p></dd></dl>
<a class="anchor" id="XREFaudioread"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-audioread"><span><code class="def-type">[<var class="var">y</var>, <var class="var">fs</var>] =</code> <strong class="def-name">audioread</strong> <code class="def-code-arguments">(<var class="var">filename</var>)</code><a class="copiable-link" href="#index-audioread"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-audioread-1"><span><code class="def-type">[<var class="var">y</var>, <var class="var">fs</var>] =</code> <strong class="def-name">audioread</strong> <code class="def-code-arguments">(<var class="var">filename</var>, <var class="var">samples</var>)</code><a class="copiable-link" href="#index-audioread-1"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-audioread-2"><span><code class="def-type">[<var class="var">y</var>, <var class="var">fs</var>] =</code> <strong class="def-name">audioread</strong> <code class="def-code-arguments">(<var class="var">filename</var>, <var class="var">datatype</var>)</code><a class="copiable-link" href="#index-audioread-2"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-audioread-3"><span><code class="def-type">[<var class="var">y</var>, <var class="var">fs</var>] =</code> <strong class="def-name">audioread</strong> <code class="def-code-arguments">(<var class="var">filename</var>, <var class="var">samples</var>, <var class="var">datatype</var>)</code><a class="copiable-link" href="#index-audioread-3"> ¶</a></span></dt>
<dd><p>Read the audio file <var class="var">filename</var> and return the audio data <var class="var">y</var> and
sampling rate <var class="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 class="var">samples</var> specifies starting
and ending frames.
</p>
<p>The optional argument <var class="var">datatype</var> specifies the datatype to return.
If it is <code class="code">"native"</code>, then the type of data depends on how the data
is stored in the audio file.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFaudiowrite">audiowrite</a>, <a class="ref" href="#XREFaudioformats">audioformats</a>, <a class="ref" href="#XREFaudioinfo">audioinfo</a>.
</p></dd></dl>
<a class="anchor" id="XREFaudiowrite"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-audiowrite"><span><strong class="def-name">audiowrite</strong> <code class="def-code-arguments">(<var class="var">filename</var>, <var class="var">y</var>, <var class="var">fs</var>)</code><a class="copiable-link" href="#index-audiowrite"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-audiowrite-1"><span><strong class="def-name">audiowrite</strong> <code class="def-code-arguments">(<var class="var">filename</var>, <var class="var">y</var>, <var class="var">fs</var>, <var class="var">name</var>, <var class="var">value</var>, …)</code><a class="copiable-link" href="#index-audiowrite-1"> ¶</a></span></dt>
<dd>
<p>Write audio data from the matrix <var class="var">y</var> to <var class="var">filename</var> at sampling rate
<var class="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 class="table">
<dt>‘<samp class="samp">BitsPerSample</samp>’</dt>
<dd><p>Number of bits per sample. Valid values are 8, 16, 24, and 32. Default is
16.
</p>
</dd>
<dt>‘<samp class="samp">BitRate</samp>’</dt>
<dd><p>Valid argument name, but ignored. Left for compatibility with <small class="sc">MATLAB</small>.
</p>
</dd>
<dt>‘<samp class="samp">Quality</samp>’</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>‘<samp class="samp">Title</samp>’</dt>
<dd><p>Title for the audio file.
</p>
</dd>
<dt>‘<samp class="samp">Artist</samp>’</dt>
<dd><p>Artist name.
</p>
</dd>
<dt>‘<samp class="samp">Comment</samp>’</dt>
<dd><p>Comment.
</p></dd>
</dl>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFaudioread">audioread</a>, <a class="ref" href="#XREFaudioformats">audioformats</a>, <a class="ref" href="#XREFaudioinfo">audioinfo</a>.
</p></dd></dl>
<a class="anchor" id="XREFaudioformats"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-audioformats"><span><strong class="def-name">audioformats</strong> <code class="def-code-arguments">()</code><a class="copiable-link" href="#index-audioformats"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-audioformats-1"><span><strong class="def-name">audioformats</strong> <code class="def-code-arguments">(<var class="var">format</var>)</code><a class="copiable-link" href="#index-audioformats-1"> ¶</a></span></dt>
<dd><p>Display information about all supported audio formats.
</p>
<p>If the optional argument <var class="var">format</var> is given, then display only formats
with names that start with <var class="var">format</var>.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFaudioread">audioread</a>, <a class="ref" href="#XREFaudiowrite">audiowrite</a>.
</p></dd></dl>
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