NAME

audio − digital audio input and output

SYNOPSIS

­bind -a ’#A’ /dev

­/dev/audio
­/dev/audioctl

DESCRIPTION

The ­audio device serves a one-level directory containing two files, giving access to the host or native audio device in a platform-independent way. 

­Audio is the data file, which can be read or written to exchange data with the device. Audio data is a sequence of stereo samples, left sample first, each of which is a 16 bit little-endian two’s complement integer. 

­Audioctl is the associated control file, which sets the characteristics of the device.  Reads return lines of the form

­source [in out] value

­source in value out value

­source [in out] left value right value

­source in left value right value out left value right value
The qualifiers ­in , ­out and ­left , ­right are omitted if they are not applicable or if the input/output and/or left/right values are the same.  The ­source is one of ­audio , ­aux1 , ­aux2 , ­line , ­mono , ­mic , ­rate , ­chans or ­bits.  If ­source is one of the ports ­audio , ­aux1 , ­aux2 , ­line , ­mono or ­mic, ­value represents the volume on a scale of 0 (quiet) to 100 (loud). The default volume is 50 for the ­audio port and 0 for the remainder. If the ­source is ­rate , ­value represents the rate at which the data was recorded in Hz. The default is 22050.  If the ­source is ­chans , ­value is the number of channels of audio data - 2 (the default) for stereo, otherwise mono. If the ­source is ­bits , ­value is one of 4, 8 or 16, the sample size in bits. 

­[in out] enc format
Outputs the recording format on the input and/or output channels. ­Format is one of ­ulaw , ­alaw , ­pcm , ­pcm16 or ­adpcm

­loop value
­Value is 0 or 1 to disable or enable loopback respectively. 

Writes control the device with strings of a similar format as that for reads. 

­source [in out] value

­source in value out value

­source [in out] left value right value

­source in left value right value out left value right value
Set the corresponding value/volume for the particular ­source.  The same conventions apply as in the read case above. The default value of ­source is ­audio. 

­reset
Set all attributes to their default value.

­loop value
Enable (1) or disable (0) loopback mode.

­[in out] enc format
Set the recording format on the input and/or output channels to ­format.  ­Format is one of ­ulaw , ­alaw , ­pcm , ­adpcm. 

­[left right] dev input
Set the input source of the left and/or right ADCs. ­Input is one of ­mic , ­line , ­aux1 , ­loop. 

SOURCE

­/emu/devaudio∗.c
­/os/∗/devaudio.c
­/os/∗/devcs4231.c

SEE ALSO

auplay(1)
audio(6)

BUGS

The device has not been implemented on every platform that could provide it, particularly hosted implementations. 
­/os/port/devaudio.c (a driver for the SB16) implements an older interface of broadly similar form, but using ­volume not audioctl, and supports a subset of the commands described above. 
The device is exclusive-use and cannot mix streams from several clients.

Plan 9  —  June 08, 2000