ref: d21de87db1e6068d35f66da7411a98231c361a70
dir: /man/3/audio/
.TH AUDIO 3 .SH NAME audio \- digital audio input and output .SH SYNOPSIS .B bind -a '#A' /dev .PP .B /dev/audio .br .B /dev/audioctl .SH DESCRIPTION The .I audio device serves a one-level directory containing two files, giving access to the host or native audio device in a platform-independent way. .PP .B 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. .PP .B Audioctl is the associated control file, which sets the characteristics of the device. Reads return lines of the form .TP .B "\fIsource\fP [in out] \fIvalue\fP" .TP .B "\fIsource\fP in \fIvalue\fP out \fIvalue\fP" .TP .B "\fIsource\fP [in out] left \fIvalue\fP right \fIvalue\fP" .TP .B "\fIsource\fP in left \fIvalue\fP right \fIvalue\fP out left \fIvalue\fP right \fIvalue\fP" The qualifiers .BR in , .B out and .BR left , .B right are omitted if they are not applicable or if the input/output and/or left/right values are the same. The .I source is one of .BR audio , .BR aux1 , .BR aux2 , .BR line , .BR mono , .BR mic , .BR rate , .B chans or .BR bits . If .I source is one of the ports .BR audio , .BR aux1 , .BR aux2 , .BR line , .B mono or .BR mic , .I value represents the volume on a scale of 0 (quiet) to 100 (loud). The default volume is 50 for the .B audio port and 0 for the remainder. If the .I source is .BR rate , .I value represents the rate at which the data was recorded in Hz. The default is 22050. If the .I source is .BR chans , .I value is the number of channels of audio data - 2 (the default) for stereo, otherwise mono. If the .I source is .BR bits , .I value is one of 4, 8 or 16, the sample size in bits. .TP .B [in out] enc \fIformat\fP Outputs the recording format on the input and/or output channels. .I Format is one of .BR ulaw , .BR alaw , .BR pcm , .B pcm16 or .B adpcm .TP .B loop \fIvalue\fP .I Value is 0 or 1 to disable or enable loopback respectively. .PP Writes control the device with strings of a similar format as that for reads. .TP .B "\fIsource\fP [in out] \fIvalue\fP" .TP .B "\fIsource\fP in \fIvalue\fP out \fIvalue\fP" .TP .B "\fIsource\fP [in out] left \fIvalue\fP right \fIvalue\fP" .TP .B "\fIsource\fP in left \fIvalue\fP right \fIvalue\fP out left \fIvalue\fP right \fIvalue\fP" Set the corresponding value/volume for the particular .I source. The same conventions apply as in the read case above. The default value of .I source is .BR audio . .TP .B reset Set all attributes to their default value. .TP .B loop \fIvalue\fP Enable (1) or disable (0) loopback mode. .TP .B [in out] enc \fIformat\fP Set the recording format on the input and/or output channels to .I format. .I Format is one of .BR ulaw , .BR alaw , .BR pcm , .BR adpcm . .TP .B [left right] dev \fIinput\fP Set the input source of the left and/or right ADCs. .I Input is one of .BR mic , .BR line , .BR aux1 , .BR loop . .SH SOURCE .B /emu/port/devaudio*.c .br .B /emu/*/devaudio.c .br .B /os/*/devaudio.c .br .B /os/*/devcs4231.c .SH SEE ALSO .IR auplay (1) .br .IR audio (6) .SH BUGS The device has not been implemented on every platform that could provide it, particularly hosted implementations. .br .B /os/port/devaudio.c (a driver for the SB16) implements an older interface of broadly similar form, but using .B volume not .BR audioctl , and supports a subset of the commands described above. .br The device is exclusive-use and cannot mix streams from several clients.