WSJT-X/portaudio-v19/docs/pa_tut_open.html
Diane Bruce 8d353a5b3b - Import of portaudio v19
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/trunk@189 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2006-07-06 03:57:24 +00:00

53 lines
2.8 KiB
HTML

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="GENERATOR" content="Mozilla/4.73 [en]C-gatewaynet (Win98; U) [Netscape]">
<meta name="Author" content="Phil Burk">
<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.">
<meta name="KeyWords" content="audio, tutorial, library, portable, open-source, DirectSound,sound, music, JSyn, synthesis,">
<title>PortAudio Tutorial</title>
</head>
<body>
&nbsp;
<center><table COLS=1 WIDTH="100%" BGCOLOR="#FADA7A" >
<tr>
<td>
<center>
<h1>
PortAudio Tutorial</h1></center>
</td>
</tr>
</table></center>
<h2>
Opening a Stream using Defaults</h2>
<blockquote>The next step is to open a stream which is similar to opening
a file. You can specify whether you want audio input and/or output, how
many channels, the data format, sample rate, etc. There are two calls for
opening streams, <tt>Pa_OpenStream</tt>() and <tt>Pa_OpenDefaultStream</tt>().
<p><tt>Pa_OpenStream()</tt> takes extra&nbsp; parameters which give you
more control. You can normally just use <tt>Pa_OpenDefaultStream</tt>()
which just calls <tt>Pa_OpenStream()</tt> <tt>with</tt> some reasonable
default values.&nbsp; Let's open a stream for stereo output, using floating
point data, at 44100 Hz.
<blockquote>
<pre>err = Pa_OpenDefaultStream(
&nbsp;&nbsp;&nbsp; &amp;stream,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* passes back stream pointer */
&nbsp;&nbsp;&nbsp; 0,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* no input channels */
&nbsp;&nbsp;&nbsp; 2,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* stereo output */
&nbsp;&nbsp;&nbsp; paFloat32,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* 32 bit floating point output */
&nbsp;&nbsp;&nbsp; 44100,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* sample rate */
&nbsp;&nbsp;&nbsp; 256,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* frames per buffer */
&nbsp;&nbsp;&nbsp; 0,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* number of buffers, if zero then use default minimum */
&nbsp;&nbsp;&nbsp; patestCallback, /* specify our custom callback */
&nbsp;&nbsp;&nbsp; &amp;data );&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /* pass our data through to callback */</pre>
</blockquote>
If you want to use 16 bit integer data, pass <tt>paInt16</tt> instead of
<tt>paFloat32</tt>.</blockquote>
<font size=+2><a href="http://www.portaudio.com/">home</a> | <a href="pa_tutorial.html">contents</a>
| <a href="pa_tut_init.html">previous</a> |&nbsp; <a href="pa_tut_run.html">next</a></font>
</body>
</html>