AUDIO(3)AUDIO(3)
NAME
audio – audio device
SYNOPSIS
bind -a #A /dev
unhandled troff command .sp
/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 sampling rate is 44.1 kHz.
The length of the
audio
file as returned by
stat(2)
represents the number of bytes buffered for output.
Audioctl
is driver specific control file and left undocumented 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 controls 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.
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
nusb(4)