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|
.TH AUDIO 3
.SH NAME
audio \- digital audio input and output
.SH SYNOPSIS
.B bind -a '#A' /dev
.PP
.B /dev/audio
.br
.B /dev/audioctl
.SH DESCRIPTION
The
.I audio
device serves a one-level directory containing two files,
giving access to the host or native audio device in a platform-independent way.
.PP
.B Audio
is the data file, which can be read or written to exchange data with the device. Audio
data is a sequence of stereo samples, left sample first, each of which is a 16 bit little-endian
two's complement integer.
.PP
.B Audioctl
is the associated control file, which sets the characteristics of the device.
Reads return lines of the form
.TP
.B "\fIsource\fP [in out] \fIvalue\fP"
.TP
.B "\fIsource\fP in \fIvalue\fP out \fIvalue\fP"
.TP
.B "\fIsource\fP [in out] left \fIvalue\fP right \fIvalue\fP"
.TP
.B "\fIsource\fP in left \fIvalue\fP right \fIvalue\fP out left \fIvalue\fP right \fIvalue\fP"
The qualifiers
.BR in ,
.B out
and
.BR left ,
.B right
are omitted if they
are not applicable or if the input/output and/or left/right values are
the same.
The
.I source
is one of
.BR audio ,
.BR aux1 ,
.BR aux2 ,
.BR line ,
.BR mono ,
.BR mic ,
.BR rate ,
.B chans
or
.BR bits .
If
.I source
is one of the ports
.BR audio ,
.BR aux1 ,
.BR aux2 ,
.BR line ,
.B mono
or
.BR mic ,
.I value
represents
the volume
on a scale of 0 (quiet) to 100 (loud). The default volume is 50 for the
.B audio
port and 0 for the
remainder. If the
.I source
is
.BR rate ,
.I value
represents the
rate at which the data was recorded in Hz. The default is 22050.
If the
.I source
is
.BR chans ,
.I value
is the number of channels of audio data - 2 (the default) for stereo, otherwise mono. If the
.I source
is
.BR bits ,
.I value
is one of 4, 8 or 16, the sample size in bits.
.TP
.B [in out] enc \fIformat\fP
Outputs the recording format on the input and/or output channels.
.I Format
is one of
.BR ulaw ,
.BR alaw ,
.BR pcm ,
.B pcm16
or
.B adpcm
.TP
.B loop \fIvalue\fP
.I Value
is 0 or 1 to disable or enable loopback respectively.
.PP
Writes control the device with strings of a similar format as that for reads.
.TP
.B "\fIsource\fP [in out] \fIvalue\fP"
.TP
.B "\fIsource\fP in \fIvalue\fP out \fIvalue\fP"
.TP
.B "\fIsource\fP [in out] left \fIvalue\fP right \fIvalue\fP"
.TP
.B "\fIsource\fP in left \fIvalue\fP right \fIvalue\fP out left \fIvalue\fP right \fIvalue\fP"
Set the corresponding value/volume for the particular
.I source.
The same conventions apply
as in the read case above. The default value of
.I source
is
.BR audio .
.TP
.B reset
Set all attributes to their default value.
.TP
.B loop \fIvalue\fP
Enable (1) or disable (0) loopback mode.
.TP
.B [in out] enc \fIformat\fP
Set the recording format on the input and/or output channels to
.I format.
.I Format
is one of
.BR ulaw ,
.BR alaw ,
.BR pcm ,
.BR adpcm .
.TP
.B [left right] dev \fIinput\fP
Set the input source of the left and/or right ADCs.
.I Input
is one of
.BR mic ,
.BR line ,
.BR aux1 ,
.BR loop .
.SH SOURCE
.B /emu/port/devaudio*.c
.br
.B /emu/*/devaudio.c
.br
.B /os/*/devaudio.c
.br
.B /os/*/devcs4231.c
.SH SEE ALSO
.IR auplay (1)
.br
.IR audio (6)
.SH BUGS
The device has not been implemented on every platform that could provide it,
particularly hosted implementations.
.br
.B /os/port/devaudio.c
(a driver for the SB16) implements an older interface of broadly similar form,
but using
.B volume
not
.BR audioctl ,
and supports a subset of the commands described above.
.br
The device is exclusive-use and cannot mix streams from several clients.
|
