pd/portaudio_v18/docs/pa_tut_open.html


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<h1>
PortAudio Tutorial</h1></center>
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<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.
<p>First declare a variable to receive the stream pointer:
<blockquote>
<pre>PortAudioStream&nbsp;&nbsp; *stream;</pre>
</blockquote>
There are two calls for opening streams, <tt>Pa_OpenStream</tt>() and <tt>Pa_OpenDefaultStream</tt>().
P<tt>a_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>
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