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66 lines
2.6 KiB
HTML
66 lines
2.6 KiB
HTML
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.75 [en]C-gatewaynet (Win98; U) [Netscape]">
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<meta name="Author" content="Phil Burk">
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<meta name="Description" content="Tutorial for PortAudio, a cross platform, open-source, audio I/O library.It provides a very simple API for recording and/or playing sound using a simple callback function.">
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<meta name="KeyWords" content="audio, tutorial, library, portable, open-source, DirectSound,sound, music, JSyn, synthesis,">
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<title>PortAudio Tutorial</title>
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</head>
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<body>
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<center><table COLS=1 WIDTH="100%" BGCOLOR="#FADA7A" >
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<tr>
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<td>
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<center>
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<h1>
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PortAudio Tutorial</h1></center>
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</td>
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</tr>
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</table></center>
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<h2>
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Querying for Available Devices</h2>
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<blockquote>There are often several different audio devices available in
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a computer with different capabilities. They can differ in the sample rates
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supported, bit widths, etc. PortAudio provides a simple way to query for
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the available devices, and then pass the selected device to Pa_OpenStream().
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For an example, see the file "pa_tests/pa_devs.c".
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<p>To determine the number of devices:
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<blockquote>
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<pre>numDevices = Pa_CountDevices();</pre>
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</blockquote>
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You can then query each device in turn by calling Pa_GetDeviceInfo() with
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an index.
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<blockquote>
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<pre>for( i=0; i<numDevices; i++ ) {
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pdi = Pa_GetDeviceInfo( i );</pre>
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</blockquote>
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It will return a pointer to a <tt>PaDeviceInfo</tt> structure which is
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defined as:
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<blockquote>
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<pre>typedef struct{
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int structVersion;
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const char *name;
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int maxInputChannels;
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int maxOutputChannels;
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/* Number of discrete rates, or -1 if range supported. */
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int numSampleRates;
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/* Array of supported sample rates, or {min,max} if range supported. */
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const double *sampleRates;
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PaSampleFormat nativeSampleFormat;
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}PaDeviceInfo;</pre>
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</blockquote>
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If the device supports a continuous range of sample rates, then numSampleRates
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will equal -1, and the sampleRates array will have two values, the minimum
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and maximum rate.
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<p>The device information is allocated by Pa_Initialize() and freed by
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Pa_Terminate() so you do not have to free() the structure returned by Pa_GetDeviceInfo().</blockquote>
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<font size=+2><a href="http://www.portaudio.com/">home</a> |
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<a href="pa_tutorial.html">contents</a>
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| <a href="pa_tut_util.html">previous</a> | <a href="pa_tut_rw.html">next</a></font>
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</body>
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</html>
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