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