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Document the new features of this module

This commit is contained in:
Barry Warsaw 1998-10-31 23:19:00 +00:00
parent b0d1b068d9
commit 4a1cdd7f22
1 changed files with 26 additions and 5 deletions
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31
Doc/lib/libsunaudio.tex
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@ -18,13 +18,18 @@ describing what went wrong.
\end{excdesc}
\begin{funcdesc}{open}{mode}
This function opens the audio device and returns a sun audio device
This function opens the audio device and returns a Sun audio device
object. This object can then be used to do I/O on. The \var{mode} parameter
is one of \code{'r'} for record-only access, \code{'w'} for play-only
access, \code{'rw'} for both and \code{'control'} for access to the
control device. Since only one process is allowed to have the recorder
or player open at the same time it is a good idea to open the device
only for the activity needed. See \manpage{audio}{7I} for details.
As per the manpage, this module first looks in the environment
variable \code{AUDIODEV} for the base audio device filename. If not
found, it falls back to \file{/dev/audio}. The control device is
calculated by appending ``ctl'' to the base audio device.
\end{funcdesc}
@ -33,7 +38,8 @@ only for the activity needed. See \manpage{audio}{7I} for details.
The audio device objects are returned by \function{open()} define the
following methods (except \code{control} objects which only provide
\method{getinfo()}, \method{setinfo()} and \method{drain()}):
\method{getinfo()}, \method{setinfo()}, \method{fileno()}, and
\method{drain()}):
\begin{methoddesc}[audio device]{close}{}
This method explicitly closes the device. It is useful in situations
@ -41,6 +47,11 @@ where deleting the object does not immediately close it since there
are other references to it. A closed device should not be used again.
\end{methoddesc}
\begin{methoddesc}[audio device]{fileno}{}
Returns the file descriptor associated with the device. This can be
used to set up \code{SIGPOLL} notification, as described below.
\end{methoddocs}
\begin{methoddesc}[audio device]{drain}{}
This method waits until all pending output is processed and then returns.
Calling this method is often not necessary: destroying the object will
@ -106,6 +117,16 @@ symbolic constants like \constant{MIN_GAIN}, \constant{MAX_GAIN},
as used in the \C{} include file \code{<sun/audioio.h>}, with the
leading string \samp{AUDIO_} stripped.
Useability of the control device is limited at the moment, since there
is no way to use the ``wait for something to happen'' feature the
device provides.
The audio device supports asynchronous notification of various events,
through the SIGPOLL signal. Here's an example of how you might enable
this in Python:
\begin{verbatim}
def handle_sigpoll(signum, frame):
print 'I got a SIGPOLL update'
pp
import fcntl, signal, STROPTS
signal.signal(signal.SIGPOLL, handle_sigpoll)
fcntl.ioctl(audio_obj.fileno(), STROPTS.I_SETSIG, STROPTS.S_MSG)
\end{verbatim}