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<?xml version="1.0" encoding="UTF-8"?>
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  <title>QAudioSystemPlugin Class | Qt Multimedia 5.9</title>
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<td >Qt 5.9</td><td ><a href="qtmultimedia-index.html">Qt Multimedia</a></td><td ><a href="qtmultimedia-modules.html">C++ Classes</a></td><td >QAudioSystemPlugin</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.9.5 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#reimplemented-public-functions">Reimplemented Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QAudioSystemPlugin Class</h1>
<!-- $$$QAudioSystemPlugin-brief -->
<p>The <a href="qaudiosystemplugin.html">QAudioSystemPlugin</a> class provides an abstract base for audio plugins. <a href="#details">More...</a></p>
<!-- @@@QAudioSystemPlugin -->
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign">   <span class="preprocessor">#include &lt;QAudioSystemPlugin&gt;</span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += multimedia</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Inherits:</td><td class="memItemRight bottomAlign"> <a href="../qtcore/qobject.html">QObject</a> and QAudioSystemFactoryInterface</td></tr></table></div><ul>
<li><a href="qaudiosystemplugin-members.html">List of all members, including inherited members</a></li>
</ul>
<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#QAudioSystemPlugin">QAudioSystemPlugin</a></b>(QObject *<i>parent</i> = Q_NULLPTR)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#dtor.QAudioSystemPlugin">~QAudioSystemPlugin</a></b>()</td></tr>
</table></div>
<a name="reimplemented-public-functions"></a>
<h2 id="reimplemented-public-functions">Reimplemented Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> virtual QList&lt;QByteArray&gt; </td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#availableDevices">availableDevices</a></b>(QAudio::Mode <i>mode</i>) const override = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QAbstractAudioDeviceInfo *</td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#createDeviceInfo">createDeviceInfo</a></b>(const QByteArray &amp;<i>device</i>, QAudio::Mode <i>mode</i>) override = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QAbstractAudioInput *</td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#createInput">createInput</a></b>(const QByteArray &amp;<i>device</i>) override = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QAbstractAudioOutput *</td><td class="memItemRight bottomAlign"><b><a href="qaudiosystemplugin.html#createOutput">createOutput</a></b>(const QByteArray &amp;<i>device</i>) override = 0</td></tr>
</table></div>
<ul>
<li class="fn">32 public functions inherited from <a href="../qtcore/qobject.html#public-functions">QObject</a></li>
<li class="fn">4 public functions inherited from <a href="qaudiosystemfactoryinterface.html#public-functions">QAudioSystemFactoryInterface</a></li>
</ul>
<h3>Additional Inherited Members</h3>
<ul>
<li class="fn">1 property inherited from <a href="../qtcore/qobject.html#properties">QObject</a></li>
<li class="fn">1 public slot inherited from <a href="../qtcore/qobject.html#public-slots">QObject</a></li>
<li class="fn">2 signals inherited from <a href="../qtcore/qobject.html#signals">QObject</a></li>
<li class="fn">1 public variable inherited from <a href="../qtcore/qobject.html#public-variables">QObject</a></li>
<li class="fn">10 static public members inherited from <a href="../qtcore/qobject.html#static-public-members">QObject</a></li>
<li class="fn">9 protected functions inherited from <a href="../qtcore/qobject.html#protected-functions">QObject</a></li>
<li class="fn">2 protected variables inherited from <a href="../qtcore/qobject.html#protected-variables">QObject</a></li>
</ul>
<a name="details"></a>
<!-- $$$QAudioSystemPlugin-description -->
<div class="descr">
<h2 id="details">Detailed Description</h2>
<p>The <a href="qaudiosystemplugin.html">QAudioSystemPlugin</a> class provides an abstract base for audio plugins.</p>
<p>Writing a audio plugin is achieved by subclassing this base class, reimplementing the pure virtual functions <a href="qaudiosystemplugin.html#availableDevices">availableDevices</a>(), <a href="qaudiosystemplugin.html#createInput">createInput</a>(), <a href="qaudiosystemplugin.html#createOutput">createOutput</a>() and <a href="qaudiosystemplugin.html#createDeviceInfo">createDeviceInfo</a>() then exporting the class with the <a href="../qtcore/qtplugin.html#Q_PLUGIN_METADATA">Q_PLUGIN_METADATA</a>() macro.</p>
<p>The json file containing the meta data should contain a list of keys matching the plugin. Add &quot;default&quot; to your list of keys available to override the default audio device to be provided by your plugin.</p>
<pre class="cpp">

  { <span class="string">&quot;Keys&quot;</span>: <span class="operator">[</span> <span class="string">&quot;default&quot;</span> <span class="operator">]</span> }

</pre>
<p>Unit tests are available to help in debugging new plugins.</p>
<p>Qt comes with plugins for Windows (WinMM and WASAPI), Linux (ALSA and PulseAudio), macOS / iOS (CoreAudio), Android (OpenSL ES) and QNX.</p>
<p>If no audio plugins are available, a fallback dummy backend will be used. This should print out warnings if this is the case when you try and use <a href="qaudioinput.html">QAudioInput</a> or <a href="qaudiooutput.html">QAudioOutput</a>. To fix this problem, make sure the dependencies for the Qt plugins are installed on the system and reconfigure Qt (e.g&#x2e; alsa-devel package on Linux), or create your own plugin with a default key to always override the dummy fallback. The easiest way to determine if you have only a dummy backend is to get a list of available audio devices.</p>
<p><a href="qaudiodeviceinfo.html#availableDevices">QAudioDeviceInfo::availableDevices</a>(<a href="qaudio.html#Mode-enum">QAudio::AudioOutput</a>).size() = 0 (dummy backend)</p>
</div>
<p><b>See also </b><a href="qabstractaudiodeviceinfo.html">QAbstractAudioDeviceInfo</a>, <a href="qabstractaudiooutput.html">QAbstractAudioOutput</a>, and <a href="qabstractaudioinput.html">QAbstractAudioInput</a>.</p>
<!-- @@@QAudioSystemPlugin -->
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$QAudioSystemPlugin[overload1]$$$QAudioSystemPluginQObject* -->
<h3 class="fn" id="QAudioSystemPlugin"><a name="QAudioSystemPlugin"></a>QAudioSystemPlugin::<span class="name">QAudioSystemPlugin</span>(<span class="type"><a href="../qtcore/qobject.html#QObject">QObject</a></span> *<i>parent</i> = Q_NULLPTR)</h3>
<p>Construct a new audio plugin with <i>parent</i>. This is invoked automatically by the <a href="../qtcore/qtplugin.html#Q_PLUGIN_METADATA">Q_PLUGIN_METADATA</a>() macro.</p>
<!-- @@@QAudioSystemPlugin -->
<!-- $$$~QAudioSystemPlugin[overload1]$$$~QAudioSystemPlugin -->
<h3 class="fn" id="dtor.QAudioSystemPlugin"><a name="dtor.QAudioSystemPlugin"></a>QAudioSystemPlugin::<span class="name">~QAudioSystemPlugin</span>()</h3>
<p>Destroy the audio plugin</p>
<p>You never have to call this explicitly. Qt destroys a plugin automatically when it is no longer used.</p>
<!-- @@@~QAudioSystemPlugin -->
<!-- $$$availableDevices[overload1]$$$availableDevicesQAudio::Mode -->
<h3 class="fn" id="availableDevices"><a name="availableDevices"></a><code>[override pure virtual] </code><span class="type"><a href="../qtcore/qlist.html">QList</a></span>&lt;<span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span>&gt; QAudioSystemPlugin::<span class="name">availableDevices</span>(<span class="type"><a href="qaudio.html#Mode-enum">QAudio::Mode</a></span> <i>mode</i>) const</h3>
<p>Returns a list of available audio devices for <i>mode</i></p>
<!-- @@@availableDevices -->
<!-- $$$createDeviceInfo[overload1]$$$createDeviceInfoconstQByteArray&QAudio::Mode -->
<h3 class="fn" id="createDeviceInfo"><a name="createDeviceInfo"></a><code>[override pure virtual] </code><span class="type"><a href="qabstractaudiodeviceinfo.html">QAbstractAudioDeviceInfo</a></span> *QAudioSystemPlugin::<span class="name">createDeviceInfo</span>(const <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> &amp;<i>device</i>, <span class="type"><a href="qaudio.html#Mode-enum">QAudio::Mode</a></span> <i>mode</i>)</h3>
<p>Returns a pointer to a <a href="qabstractaudiodeviceinfo.html">QAbstractAudioDeviceInfo</a> created using <i>device</i> and <i>mode</i></p>
<!-- @@@createDeviceInfo -->
<!-- $$$createInput[overload1]$$$createInputconstQByteArray& -->
<h3 class="fn" id="createInput"><a name="createInput"></a><code>[override pure virtual] </code><span class="type"><a href="qabstractaudioinput.html">QAbstractAudioInput</a></span> *QAudioSystemPlugin::<span class="name">createInput</span>(const <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> &amp;<i>device</i>)</h3>
<p>Returns a pointer to a <a href="qabstractaudioinput.html">QAbstractAudioInput</a> created using <i>device</i> identifier</p>
<!-- @@@createInput -->
<!-- $$$createOutput[overload1]$$$createOutputconstQByteArray& -->
<h3 class="fn" id="createOutput"><a name="createOutput"></a><code>[override pure virtual] </code><span class="type"><a href="qabstractaudiooutput.html">QAbstractAudioOutput</a></span> *QAudioSystemPlugin::<span class="name">createOutput</span>(const <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> &amp;<i>device</i>)</h3>
<p>Returns a pointer to a <a href="qabstractaudiooutput.html">QAbstractAudioOutput</a> created using <i>device</i> identifier</p>
<!-- @@@createOutput -->
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