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Rewrite intro paragraphs and add a "See also" box for the link to the

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official OSS docs.

Markup fixes: change \code{} variously to \function{}, \method{}, or
\constant{} as appropriate.
This commit is contained in:
Greg Ward 2003-03-10 02:09:51 +00:00
parent 074472ba98
commit 3e34f59ce2
1 changed files with 57 additions and 54 deletions
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109
Doc/lib/libossaudiodev.tex
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@ -1,26 +1,27 @@
\section{\module{ossaudiodev} --- \section{\module{ossaudiodev} ---
Access to Open Sound System-compatible audio hardware} Access to OSS-compatible audio devices}
\declaremodule{builtin}{ossaudiodev} \declaremodule{builtin}{ossaudiodev}
\platform{OSS} \platform{Linux, FreeBSD}
\modulesynopsis{Access to OSS-compatible audio hardware.} \modulesynopsis{Access to OSS-compatible audio devices.}
% I know FreeBSD uses OSS -- what about Net- and Open-? % XXX OSS is standard for Linux and FreeBSD -- what about NetBSD?
This module allows you to access the Open Sound System audio interface. % OpenBSD? others?
The Open Sound System interface is present on Linux and FreeBSD. This module allows you to access the OSS (Open Sound System) audio
interface. OSS is available for a wide range of open-source and
commercial Unices, and is the standard audio interface for Linux (up to
kernel 2.4) and FreeBSD.
This module provides a very "bare bones" wrapper over the IOCTLs used to \begin{seealso}
access the audio hardware. The best---albeit rather daunting---way to \seetitle[http://www.opensound.com/pguide/oss.pdf]
get a feel for the interface is from the Open Sound System official {Open Sound System Programmer's Guide}
documentation: {the official documentation for the OSS C API}
\seetext{The module defines a large number of constants supplied by
the OSS device driver; see \file{<sys/soundcard.h>} on either
Linux or FreeBSD for a listing .}
\end{seealso}
\url{http://www.opensound.com/pguide/oss.pdf} \module{ossaudiodev} defines the following variables and functions:
The module defines a number of constants which may be used to program
the device. These constants are the same as those defined in the C
include file \code{<sys/soundcard.h>}.
\code{ossaudiodev} defines the following variables and functions:
\begin{excdesc}{error} \begin{excdesc}{error}
This exception is raised on errors. The argument is a string describing This exception is raised on errors. The argument is a string describing
@ -31,7 +32,7 @@ what went wrong.
This function opens the audio device and returns an OSS audio device This function opens the audio device and returns an OSS audio device
object. This object can then be used to do I/O on. The \var{device} object. This object can then be used to do I/O on. The \var{device}
parameter is the audio device filename to use. If it is not specified, parameter is the audio device filename to use. If it is not specified,
this module first looks in the environment variable \code{AUDIODEV} for this module first looks in the environment variable \envvar{AUDIODEV} for
a device to use. If not found, it falls back to \file{/dev/dsp}. a device to use. If not found, it falls back to \file{/dev/dsp}.
The \var{mode} parameter is one of \code{'r'} for record-only access, The \var{mode} parameter is one of \code{'r'} for record-only access,
@ -46,7 +47,7 @@ for reading or writing, but not both at once.
opens the mixer device and returns an OSS mixer device object. The opens the mixer device and returns an OSS mixer device object. The
\var{device} parameter is the mixer device filename to use. If it is \var{device} parameter is the mixer device filename to use. If it is
not specified, this module first looks in the environment variable not specified, this module first looks in the environment variable
\code{MIXERDEV} for a device to use. If not found, it falls back to \envvar{MIXERDEV} for a device to use. If not found, it falls back to
\file{/dev/mixer}. You may specify \code{'r'}, \code{'rw'} or \file{/dev/mixer}. You may specify \code{'r'}, \code{'rw'} or
\code{'w'} for \var{mode}; the default is \code{'r'}. \code{'w'} for \var{mode}; the default is \code{'r'}.
@ -59,9 +60,9 @@ Setting up the device
To set up the device, three functions must be called in the correct To set up the device, three functions must be called in the correct
sequence: sequence:
\begin{enumerate} \begin{enumerate}
\item \code{setfmt()} to set the output format, \item \method{setfmt()} to set the output format,
\item \code{channels()} to set the number of channels, and \item \method{channels()} to set the number of channels, and
\item \code{speed()} to set the sample rate. \item \method{speed()} to set the sample rate.
\end{enumerate} \end{enumerate}
The audio device objects are returned by \function{open()} define the The audio device objects are returned by \function{open()} define the
@ -86,15 +87,16 @@ Python string. The function blocks until enough data is available.
Writes Python string \var{data} to the audio device and returns the Writes Python string \var{data} to the audio device and returns the
number of bytes written. If the audio device is opened in blocking number of bytes written. If the audio device is opened in blocking
mode, the entire string is always written. If the device is opened in mode, the entire string is always written. If the device is opened in
nonblocking mode, some data may not be written---see \code{writeall}. nonblocking mode, some data may not be written---see
\method{writeall()}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{writeall}{data} \begin{methoddesc}[audio device]{writeall}{data}
Writes the entire Python string \var{data} to the audio device. If the Writes the entire Python string \var{data} to the audio device. If the
device is opened in blocking mode, behaves identially to \code{write}; device is opened in blocking mode, behaves identially to
in nonblocking mode, waits until the device becomes available before \method{write()}; in nonblocking mode, waits until the device becomes
feeding it more data. Returns None, since the amount of data written is available before feeding it more data. Returns \code{None}, since the
always equal to the amount of data supplied. amount of data written is always equal to the amount of data supplied.
\end{methoddesc} \end{methoddesc}
Simple IOCTLs: Simple IOCTLs:
@ -113,7 +115,7 @@ soundcard. On a typical Linux system, these formats are:
\begin{tableii}{l|l}{constant}{Format}{Description} \begin{tableii}{l|l}{constant}{Format}{Description}
\lineii{AFMT_MU_LAW} \lineii{AFMT_MU_LAW}
{a logarithmic encoding. This is the default format on {a logarithmic encoding. This is the default format on
/dev/audio and is the format used by Sun .au files.} \file{/dev/audio} and is the format used by Sun .au files.}
\lineii{AFMT_A_LAW} \lineii{AFMT_A_LAW}
{a logarithmic encoding} {a logarithmic encoding}
\lineii{AFMT_IMA_ADPCM} \lineii{AFMT_IMA_ADPCM}
@ -135,16 +137,16 @@ soundcard. On a typical Linux system, these formats are:
{Signed, 16-bit big-endian audio} {Signed, 16-bit big-endian audio}
\end{tableii} \end{tableii}
Most systems support only a subset of these formats. Many devices only Most systems support only a subset of these formats. Many devices only
support \code{AFMT_U8}; the most common format used today is support \constant{AFMT_U8}; the most common format used today is
\code{AFMT_S16_LE}. \constant{AFMT_S16_LE}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{setfmt}{format} \begin{methoddesc}[audio device]{setfmt}{format}
Used to set the current audio format to \var{format}---see Used to set the current audio format to \var{format}---see
\code{getfmts} for a list. May also be used to return the current audio \method{getfmts()} for a list. May also be used to return the current
format---do this by passing an ``audio format'' of \code{AFMT_QUERY}. audio format---do this by passing an ``audio format'' of
Returns the audio format that the device was set to, which may not be \constant{AFMT_QUERY}. Returns the audio format that the device was set
the requested format. to, which may not be the requested format.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{channels}{num_channels} \begin{methoddesc}[audio device]{channels}{num_channels}
@ -170,20 +172,20 @@ sample rates. Common rates are:
Waits until the sound device has played every byte in its buffer and Waits until the sound device has played every byte in its buffer and
returns. This also occurs when the sound device is closed. The OSS returns. This also occurs when the sound device is closed. The OSS
documentation recommends simply closing and re-opening the device rather documentation recommends simply closing and re-opening the device rather
than using \code{sync}. than using \method{sync()}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{reset} \begin{methoddesc}[audio device]{reset}
Immediately stops and playing or recording and returns the device to a Immediately stops and playing or recording and returns the device to a
state where it can accept commands. The OSS documentation recommends state where it can accept commands. The OSS documentation recommends
closing and re-opening the device after calling \code{reset}. closing and re-opening the device after calling \method{reset()}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{post} \begin{methoddesc}[audio device]{post}
To be used like a lightweight \code{sync}, the \code{post} IOCTL informs To be used like a lightweight \method{sync()}, the \method{post()}
the audio device that there is a likely to be a pause in the audio IOCTL informs the audio device that there is a likely to be a pause in
output---i.e., after playing a spot sound effect, before waiting for the audio output---i.e., after playing a spot sound effect, before
user input, or before doing disk IO. waiting for user input, or before doing disk I/O.
\end{methoddesc} \end{methoddesc}
Convenience methods Convenience methods
@ -191,10 +193,11 @@ Convenience methods
\begin{methoddesc}[audio device]{setparameters}{samplerate,num_channels,format,emulate} \begin{methoddesc}[audio device]{setparameters}{samplerate,num_channels,format,emulate}
Initialise the sound device in one method. \var{samplerate}, Initialise the sound device in one method. \var{samplerate},
\var{channels} and \var{format} should be as specified in the \var{channels} and \var{format} should be as specified in the
\code{speed}, \code{channels} and \code{setfmt} methods. If \method{speed()}, \method{channels()} and \method{setfmt()}
\var{emulate} is true, attempt to find the closest matching format methods. If \var{emulate} is true, attempt to find the closest matching
instead, otherwise raise ValueError if the device does not support the format instead, otherwise raise ValueError if the device does not
format. The default is to raise ValueError on unsupported formats. support the format. The default is to raise ValueError on unsupported
formats.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[audio device]{bufsize}{} \begin{methoddesc}[audio device]{bufsize}{}
@ -229,9 +232,9 @@ Mixer interface
\begin{methoddesc}[mixer device]{controls}{} \begin{methoddesc}[mixer device]{controls}{}
This method returns a bitmask specifying the available mixer controls This method returns a bitmask specifying the available mixer controls
(``Control'' being a specific mixable ``channel'', such as (``Control'' being a specific mixable ``channel'', such as
\code{SOUND_MIXER_PCM} or \code{SOUND_MIXER_SYNTH}). This \constant{SOUND_MIXER_PCM} or \constant{SOUND_MIXER_SYNTH}). This
bitmask indicates a subset of all available mixer channels---the bitmask indicates a subset of all available mixer channels---the
\code{SOUND_MIXER_*} constants defined at module level. To determine if, \constant{SOUND_MIXER_*} constants defined at module level. To determine if,
for example, the current mixer object supports a PCM mixer, use the for example, the current mixer object supports a PCM mixer, use the
following Python code: following Python code:
@ -242,10 +245,10 @@ if mixer.channels() & (1 << ossaudiodev.SOUND_MIXER_PCM):
<code> <code>
\end{verbatim} \end{verbatim}
For most purposes, the \code{SOUND_MIXER_VOLUME} (Master volume) and For most purposes, the \constant{SOUND_MIXER_VOLUME} (Master volume) and
\code{SOUND_MIXER_PCM} channels should suffice---but code that uses the \constant{SOUND_MIXER_PCM} channels should suffice---but code that uses the
mixer should be flexible when it comes to choosing sound channels. On mixer should be flexible when it comes to choosing sound channels. On
the Gravis Ultrasound, for example, \code{SOUND_MIXER_VOLUME} does not the Gravis Ultrasound, for example, \constant{SOUND_MIXER_VOLUME} does not
exist. exist.
\end{methoddesc} \end{methoddesc}
@ -253,21 +256,21 @@ exist.
Returns a bitmask indicating stereo mixer channels. If a bit is set, Returns a bitmask indicating stereo mixer channels. If a bit is set,
the corresponding channel is stereo; if it is unset, the channel is the corresponding channel is stereo; if it is unset, the channel is
either monophonic or not supported by the mixer (use in combination with either monophonic or not supported by the mixer (use in combination with
\function{channels} to determine which). \method{channels()} to determine which).
See the code example for the \function{channels} function for an example See the code example for the \method{channels()} function for an example
of getting data from a bitmask. of getting data from a bitmask.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[mixer device]{reccontrols}{} \begin{methoddesc}[mixer device]{reccontrols}{}
Returns a bitmask specifying the mixer controls that may be used to Returns a bitmask specifying the mixer controls that may be used to
record. See the code example for \function{controls} for an example of record. See the code example for \method{controls()} for an example of
reading from a bitmask. reading from a bitmask.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}[mixer device]{get}{channel} \begin{methoddesc}[mixer device]{get}{channel}
Returns the volume of a given mixer channel. The returned volume is a Returns the volume of a given mixer channel. The returned volume is a
2-tuple of \code{left volume, right volume}. Volumes are specified as 2-tuple \code{(left_volume,right_volume)}. Volumes are specified as
numbers from 0 (silent) to 100 (full volume). If the channel is numbers from 0 (silent) to 100 (full volume). If the channel is
monophonic, a 2-tuple is still returned, but both channel volumes are monophonic, a 2-tuple is still returned, but both channel volumes are
the same. the same.