AUDIO(3) AUDIO(3)
NAME
audio - audio device
SYNOPSIS
bind -a #A /dev
9 /dev/audio
/dev/audioctl
/dev/audiostat
/dev/volume
DESCRIPTION
The audio device serves a one-level directory, giving access
to the stereo audio ports. Audio is the data file, which
can be written for audio playback. Audio data is a sequence
of stereo samples, left sample first. Each sample is a 16
bit little-endian two's complement integer; the default sam-
pling rate is 44.1 kHz.
The length of the audio file as returned by stat(2) repre-
sents the number of bytes buffered for output.
Audioctl is driver specific control file and left undocu-
mented here.
Audiostat is a read only status file. The first line has a
length of 32 bytes including the newline and starts with the
string bufsize followed by the preferred write unit (in
bytes) and the string buffered followed by the number of
bytes currently queued for output. The numbers are decimal
and right-padded with spaces to fit. After this fixed
header, the contents of the file is driver specific.
Volume is the control file associated with the audio port.
Each source has an associated stereo volume control, ranging
from 0 (quiet) to 100 (loud). In addition, there are con-
trols for the sampling rate, latency control and for any
tone controls. Reads return lines of the form
source left right
or
source value
Valid sources depend on the particular audio device, though
all devices have an audio stereo source, which controls the
output volume from the D/A converter. Values for speed set
the sampling frequency of the audio device and delay limits
the audio data output buffering to a number of samples.
9
Page 1 Plan 9 (printed 11/23/24)
AUDIO(3) AUDIO(3)
Writes accept the same format except that for stereo sources
left and right can be abbreviated to a single value if both
should be set the same.
SOURCE
/sys/src/9/port/devaudio.c
SEE ALSO
nusb(4)
Page 2 Plan 9 (printed 11/23/24)