AUDIO(3)						     Library Functions Manual							  AUDIO(3)

NAME

       audio - digital audio input and output

SYNOPSIS

       bind -a #A /dev

       /dev/audio
       /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 read or writ-
       ten to use the port.  Audio data is a sequence of stereo samples, left sample first.  Each sample is a 16 bit little-endian  two's  comple-
       ment integer; the default sampling rate is 44.1 kHz.  Some implementations only support audio output and return a zero length when read.

       Volume  is  the control file associated with the audio port.  Each input and output source has an associated stereo volume control, ranging
       from 0 (quiet) to 100 (loud).  In addition, there are controls for the sampling rate of the D/A and A/D converters and for  any	tone  con-
       trols.  Reads return lines of the form

	      source in left value right value out left value right value

       possibly  abbreviated  if  the  values  are  shared or non-existent.  For example, if all of the values are shared, the form degenerates to
       `source value'.	Valid sources depend on the particular audio device, though all devices have a audio stereo  source,  which  controls  the
       output volume from the D/A converter connected to audio.

       Writes  accept the same format with same abbreviations.	Writing the string reset sets all of the attributes to their default value, and if
       no attribute is supplied, audio is assumed.

       The Sound Blaster 16 (or MCD) is half-duplex and has the following controls.

       audio out
	      Data written to audio.

       synth in out
	      MIDI synthesizer.

       cd in out
	      CD player.

       line in out
	      Line-level input.

       mic in out
	      Monaural microphone input.

       speaker in out
	      Monaural internal speaker connection.

       treb out
	      Stereo treble tone control.  Values less than 50 decrease the treble, those greater increase it.

       bass out
	      Stereo bass tone control.

       speed in out
	      Sampling rate for the D/A and A/D converters, expressed in Hz.  Defaults to 44100.

       Indigo audio is full-duplex and has the following controls.

       audio out
	      Data written to audio.

       line in out
	      Line-level input.

       mic in out
	      Microphone input.

       aes in out
	      Digital input.

       Nextstation audio is output only and has the following controls.

       audio  Data written to audio.

       deemp  A value of zero turns off the stereo de-emphasis filter, any other value turns it on.

SOURCE

       /sys/src/9/*/devaudio.c

																	  AUDIO(3)