mirror of
https://github.com/python/cpython.git
synced 2025-11-03 19:34:08 +00:00
112 lines
4.5 KiB
TeX
112 lines
4.5 KiB
TeX
\chapter{SunOS Specific Services}
|
|
|
|
The modules described in this chapter provide interfaces to features
|
|
that are unique to the SunOS operating system (versions 4 and 5; the
|
|
latter is also known as Solaris version 2).
|
|
|
|
\section{Built-in Module \sectcode{sunaudiodev}}
|
|
\bimodindex{sunaudiodev}
|
|
|
|
This module allows you to access the sun audio interface. The sun
|
|
audio hardware is capable of recording and playing back audio data
|
|
in U-LAW format with a sample rate of 8K per second. A full
|
|
description can be gotten with \samp{man audio}.
|
|
|
|
The module defines the following variables and functions:
|
|
|
|
\renewcommand{\indexsubitem}{(in module sunaudiodev)}
|
|
\begin{excdesc}{error}
|
|
This exception is raised on all errors. The argument is a string
|
|
describing what went wrong.
|
|
\end{excdesc}
|
|
|
|
\begin{funcdesc}{open}{mode}
|
|
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 the audio manpage for details.
|
|
\end{funcdesc}
|
|
|
|
\subsection{Audio Device Objects}
|
|
|
|
The audio device objects are returned by \code{open} define the
|
|
following methods (except \code{control} objects which only provide
|
|
getinfo, setinfo and drain):
|
|
|
|
\renewcommand{\indexsubitem}{(audio device method)}
|
|
|
|
\begin{funcdesc}{close}{}
|
|
This method explicitly closes the device. It is useful in situations
|
|
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{funcdesc}
|
|
|
|
\begin{funcdesc}{drain}{}
|
|
This method waits until all pending output is processed and then returns.
|
|
Calling this method is often not necessary: destroying the object will
|
|
automatically close the audio device and this will do an implicit drain.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{flush}{}
|
|
This method discards all pending output. It can be used avoid the
|
|
slow response to a user's stop request (due to buffering of up to one
|
|
second of sound).
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getinfo}{}
|
|
This method retrieves status information like input and output volume,
|
|
etc. and returns it in the form of
|
|
an audio status object. This object has no methods but it contains a
|
|
number of attributes describing the current device status. The names
|
|
and meanings of the attributes are described in
|
|
\file{/usr/include/sun/audioio.h} and in the audio man page. Member names
|
|
are slightly different from their C counterparts: a status object is
|
|
only a single structure. Members of the \code{play} substructure have
|
|
\samp{o_} prepended to their name and members of the \code{record}
|
|
structure have \samp{i_}. So, the C member \code{play.sample_rate} is
|
|
accessed as \code{o_sample_rate}, \code{record.gain} as \code{i_gain}
|
|
and \code{monitor_gain} plainly as \code{monitor_gain}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{ibufcount}{}
|
|
This method returns the number of samples that are buffered on the
|
|
recording side, i.e.
|
|
the program will not block on a \code{read} call of so many samples.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{obufcount}{}
|
|
This method returns the number of samples buffered on the playback
|
|
side. Unfortunately, this number cannot be used to determine a number
|
|
of samples that can be written without blocking since the kernel
|
|
output queue length seems to be variable.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{read}{size}
|
|
This method reads \var{size} samples from the audio input and returns
|
|
them as a python string. The function blocks until enough data is available.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{setinfo}{status}
|
|
This method sets the audio device status parameters. The \var{status}
|
|
parameter is an device status object as returned by \code{getinfo} and
|
|
possibly modified by the program.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{write}{samples}
|
|
Write is passed a python string containing audio samples to be played.
|
|
If there is enough buffer space free it will immediately return,
|
|
otherwise it will block.
|
|
\end{funcdesc}
|
|
|
|
There is a companion module, \code{SUNAUDIODEV}, which defines useful
|
|
symbolic constants like \code{MIN_GAIN}, \code{MAX_GAIN},
|
|
\code{SPEAKER}, etc. The names of
|
|
the constants are the same names as used in the C include file
|
|
\file{<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.
|