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diff --git a/Doc/lib/libsun.tex b/Doc/lib/libsun.tex new file mode 100644 index 0000000..9624b9c --- /dev/null +++ b/Doc/lib/libsun.tex @@ -0,0 +1,113 @@ +\chapter{SUNOS ONLY} + +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 object methods} + +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 immedeately 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. This is because that feature makes heavy use of signals, and +these do not map too well onto Python. |