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diff --git a/pd/portaudio/docs/pa_impl_startstop.html b/pd/portaudio/docs/pa_impl_startstop.html new file mode 100644 index 00000000..0f2d0ce5 --- /dev/null +++ b/pd/portaudio/docs/pa_impl_startstop.html @@ -0,0 +1,190 @@ +<!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/4.75 [en]C-gatewaynet (Win98; U) [Netscape]"> + <meta name="Author" content="Phil Burk"> + <meta name="Description" content="Internal docs. How a stream is started or stopped."> + <meta name="KeyWords" content="audio, tutorial, library, portable, open-source, DirectSound,sound, music, JSyn, synthesis,"> + <title>PortAudio Implementation - Start/Stop</title> +</head> +<body> + +<center><table COLS=1 WIDTH="100%" BGCOLOR="#FADA7A" > +<tr> +<td> +<center> +<h1> +PortAudio Implementation</h1></center> +</td> +</tr> +</table></center> + +<h2> +Starting and Stopping Streams</h2> +PortAudio is generally executed in two "threads". The foreground thread +is the application thread. The background "thread" may be implemented as +an actual thread, an interrupt handler, or a callback from a timer thread. +<p>There are three ways that PortAudio can stop a stream. In each case +we look at the sequence of events and the messages sent between the two +threads. The following variables are contained in the internalPortAudioStream. +<blockquote><tt>int past_IsActive; +/* Background is still playing. */</tt> +<br><tt>int past_StopSoon; /* Stop +when last buffer done. */</tt> +<br><tt>int past_StopNow; /* +Stop IMMEDIATELY. */</tt></blockquote> + +<h3> +Pa_AbortStream()</h3> +This function causes the background thread to terminate as soon as possible +and audio I/O to stop abruptly. +<br> +<table BORDER COLS=2 WIDTH="60%" > +<tr> +<td><b>Foreground Thread</b></td> + +<td><b>Background Thread</b></td> +</tr> + +<tr> +<td>sets <tt>StopNow</tt></td> + +<td></td> +</tr> + +<tr> +<td></td> + +<td>sees <tt>StopNow</tt>, </td> +</tr> + +<tr> +<td></td> + +<td>clears IsActive, stops thread</td> +</tr> + +<tr> +<td>waits for thread to exit</td> + +<td></td> +</tr> + +<tr> +<td>turns off audio I/O</td> + +<td></td> +</tr> +</table> + +<h3> +Pa_StopStream()</h3> +This function stops the user callback function from being called and then +waits for all audio data written to the output buffer to be played. In +a system with very low latency, you may not hear any difference between +<br> +<table BORDER COLS=2 WIDTH="60%" > +<tr> +<td><b>Foreground Thread</b></td> + +<td><b>Background Thread</b></td> +</tr> + +<tr> +<td>sets StopSoon</td> + +<td></td> +</tr> + +<tr> +<td></td> + +<td>stops calling user callback</td> +</tr> + +<tr> +<td></td> + +<td>continues until output buffer empty</td> +</tr> + +<tr> +<td></td> + +<td>clears IsActive, stops thread</td> +</tr> + +<tr> +<td>waits for thread to exit</td> + +<td></td> +</tr> + +<tr> +<td>turns off audio I/O</td> + +<td></td> +</tr> +</table> + +<h3> +User callback returns one.</h3> +If the user callback returns one then the user callback function will no +longer be called. Audio output will continue until all audio data written +to the output buffer has been played. Then the audio I/O is stopped, the +background thread terminates, and the stream becomes inactive. +<br> +<table BORDER COLS=2 WIDTH="60%" > +<tr> +<td><b>Foreground Thread</b></td> + +<td><b>Background Thread</b></td> +</tr> + +<tr> +<td></td> + +<td>callback returns 1</td> +</tr> + +<tr> +<td></td> + +<td>sets StopSoon</td> +</tr> + +<tr> +<td></td> + +<td>stops calling user callback</td> +</tr> + +<tr> +<td></td> + +<td>continues until output buffer empty</td> +</tr> + +<tr> +<td></td> + +<td>clears IsActive, stops thread</td> +</tr> + +<tr> +<td>waits for thread to exit</td> + +<td></td> +</tr> + +<tr> +<td>turns off audio I/O</td> + +<td></td> +</tr> +</table> + +<br> +</body> +</html> |