AUDIO(3)						      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 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)
	  represents 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 content 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.

	  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)