term% cat index.txt AUDIO(3) Library Functions Manual AUDIO(3)
NAME
audio - audio device
SYNOPSIS
bind -a #A /dev
/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 sam‐
ple first. Each sample is a 16 bit little-endian two's complement in‐
teger; the default sampling rate is 44.1 kHz.
The length of the audio file as returned by stat(2) represents the num‐
ber 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 au‐
dio 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 ALSO
nusb(4)
AUDIO(3)