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+<h1><a class="anchor" name="probe">Probing Device Capabilities</a></h1>A programmer may wish to query the available audio device capabilities before deciding which to use. The following example outlines how this can be done.<p>
+<div class="fragment"><pre class="fragment"><span class="comment">// probe.cpp</span>
+
+<span class="preprocessor">#include <iostream></span>
+<span class="preprocessor">#include "<a class="code" href="RtAudio_8h.html">RtAudio.h</a>"</span>
+
+<span class="keywordtype">int</span> main()
+{
+ <a class="code" href="classRtAudio.html">RtAudio</a> audio;
+
+ <span class="comment">// Determine the number of devices available</span>
+ <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> devices = audio.<a class="code" href="classRtAudio.html#a3">getDeviceCount</a>();
+
+ <span class="comment">// Scan through devices for various capabilities</span>
+ <a class="code" href="structRtAudio_1_1DeviceInfo.html">RtAudio::DeviceInfo</a> info;
+ <span class="keywordflow">for</span> ( <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=1; i<=devices; i++ ) {
+
+ info = audio.<a class="code" href="classRtAudio.html#a4">getDeviceInfo</a>( i );
+
+ <span class="keywordflow">if</span> ( info.<a class="code" href="structRtAudio_1_1DeviceInfo.html#o0">probed</a> == <span class="keyword">true</span> ) {
+ <span class="comment">// Print, for example, the maximum number of output channels for each device</span>
+ std::cout << <span class="stringliteral">"device = "</span> << i;
+ std::cout << <span class="stringliteral">": maximum output channels = "</span> << info.<a class="code" href="structRtAudio_1_1DeviceInfo.html#o2">outputChannels</a> << <span class="stringliteral">"\n"</span>;
+ }
+ }
+
+ <span class="keywordflow">return</span> 0;
+}
+</pre></div><p>
+The <a class="el" href="structRtAudio_1_1DeviceInfo.html">RtAudio::DeviceInfo</a> structure is defined in <a class="el" href="RtAudio_8h.html">RtAudio.h</a> and provides a variety of information useful in assessing the capabilities of a device:<p>
+<div class="fragment"><pre class="fragment"> <span class="keyword">typedef</span> <span class="keyword">struct </span><a class="code" href="structRtAudio_1_1DeviceInfo.html">RtAudio::DeviceInfo</a> {
+ <span class="keywordtype">bool</span> probed; <span class="comment">// true if the device capabilities were successfully probed.</span>
+ std::string name; <span class="comment">// Character string device identifier.</span>
+ <span class="keywordtype">int</span> outputChannels; <span class="comment">// Maximum output channels supported by device.</span>
+ <span class="keywordtype">int</span> inputChannels; <span class="comment">// Maximum input channels supported by device.</span>
+ <span class="keywordtype">int</span> duplexChannels; <span class="comment">// Maximum simultaneous input/output channels supported by device.</span>
+ <span class="keywordtype">bool</span> isDefaultOutput; <span class="comment">// true if this is the default output device.</span>
+ <span class="keywordtype">bool</span> isDefaultInput; <span class="comment">// true if this is the default input device.</span>
+ std::vector<int> sampleRates; <span class="comment">// Supported sample rates.</span>
+ <a class="code" href="RtAudio_8h.html#a1">RtAudioFormat</a> nativeFormats; <span class="comment">// Bit mask of supported data formats.</span>
+ };
+</pre></div><p>
+The following data formats are defined and fully supported by <a class="el" href="classRtAudio.html">RtAudio</a>:<p>
+<div class="fragment"><pre class="fragment"> <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> <a class="code" href="RtAudio_8h.html#a1">RtAudioFormat</a>;
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_SINT8; <span class="comment">// Signed 8-bit integer</span>
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_SINT16; <span class="comment">// Signed 16-bit integer</span>
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_SINT24; <span class="comment">// Signed 24-bit integer (lower 3 bytes of 32-bit signed integer.)</span>
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_SINT32; <span class="comment">// Signed 32-bit integer</span>
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_FLOAT32; <span class="comment">// 32-bit float normalized between +/- 1.0</span>
+ <span class="keyword">static</span> <span class="keyword">const</span> RtAudioFormat RTAUDIO_FLOAT64; <span class="comment">// 64-bit double normalized between +/- 1.0</span>
+</pre></div><p>
+The <code>nativeFormats</code> member of the <a class="el" href="structRtAudio_1_1DeviceInfo.html">RtAudio::DeviceInfo</a> structure is a bit mask of the above formats which are natively supported by the device. However, <a class="el" href="classRtAudio.html">RtAudio</a> will automatically provide format conversion if a particular format is not natively supported. When the <code>probed</code> member of the <a class="el" href="structRtAudio_1_1DeviceInfo.html">RtAudio::DeviceInfo</a> structure is false, the remaining structure members are undefined and the device is probably unusable.<p>
+Some audio devices may require a minimum channel value greater than one. <a class="el" href="classRtAudio.html">RtAudio</a> will provide automatic channel number compensation when the number of channels set by the user is less than that required by the device. Channel compensation is <em>NOT</em> possible when the number of channels set by the user is greater than that supported by the device.<p>
+It should be noted that the capabilities reported by a device driver or underlying audio API are not always accurate and/or may be dependent on a combination of device settings. For this reason, <a class="el" href="classRtAudio.html">RtAudio</a> does not rely on the queried values when attempting to open a stream. <HR>
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