From ae6b5d89ea93b95c2990895077cf5e8f0bba9ad9 Mon Sep 17 00:00:00 2001 From: Guenter Geiger Date: Mon, 2 Feb 2004 11:28:02 +0000 Subject: This commit was generated by cvs2svn to compensate for changes in r1301, which included commits to RCS files with non-trunk default branches. svn path=/trunk/; revision=1302 --- pd/portaudio_v18/docs/pa_impl_startstop.html | 190 +++++++++++++++++++++++++++ 1 file changed, 190 insertions(+) create mode 100644 pd/portaudio_v18/docs/pa_impl_startstop.html (limited to 'pd/portaudio_v18/docs/pa_impl_startstop.html') diff --git a/pd/portaudio_v18/docs/pa_impl_startstop.html b/pd/portaudio_v18/docs/pa_impl_startstop.html new file mode 100644 index 00000000..0f2d0ce5 --- /dev/null +++ b/pd/portaudio_v18/docs/pa_impl_startstop.html @@ -0,0 +1,190 @@ + + + + + + + + + PortAudio Implementation - Start/Stop + + +  +
+ + + +
+
+

+PortAudio Implementation

+
+ +

+Starting and Stopping Streams

+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. +

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. +

int   past_IsActive;     +/* Background is still playing. */ +
int   past_StopSoon;     /* Stop +when last buffer done. */ +
int   past_StopNow;      /* +Stop IMMEDIATELY. */
+ +

+Pa_AbortStream()

+This function causes the background thread to terminate as soon as possible +and audio I/O to stop abruptly. +
  + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Foreground ThreadBackground Thread
sets StopNow
sees StopNow, 
clears IsActive, stops thread
waits for thread to exit
turns off audio I/O
+ +

+Pa_StopStream()

+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 +
  + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Foreground ThreadBackground Thread
sets StopSoon
stops calling user callback
continues until output buffer empty
clears IsActive, stops thread
waits for thread to exit
turns off audio I/O
+ +

+User callback returns one.

+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. +
  + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Foreground ThreadBackground Thread
callback returns 1
sets StopSoon
stops calling user callback
continues until output buffer empty
clears IsActive, stops thread
waits for thread to exit
turns off audio I/O
+ +
  + + -- cgit v1.2.1