ref: 38c14a17f6d77b4a2523f8d897947e59d23eb1fa
parent: 24ef1b6a102dee58a93c5a0a7a5d49669ca1f80c
author: cinap_lenrek <cinap_lenrek@localhost>
date: Fri Aug 26 01:45:30 EDT 2011
audio(3): remove out of date information
--- a/sys/man/3/audio
+++ b/sys/man/3/audio
@@ -1,6 +1,6 @@
.TH AUDIO 3
.SH NAME
-audio \- SoundBlaster or ESS1688 audio controller
+audio \- audio device
.SH SYNOPSIS
.nf
.B bind -a #A /dev
@@ -12,12 +12,10 @@
The audio device serves a one-level directory,
giving access to the stereo audio ports.
.B Audio
-is the data file, which can be read or written to use the port.
+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 sampling rate is 44.1 kHz.
-Some implementations only support audio output
-and return a zero length when read.
.PP
The length of the
.B audio
@@ -24,37 +22,13 @@
file as returned by
.IR stat (2)
represents the number of bytes buffered for input or output.
-This provides some control over record or playback latency.
.PP
-The file
-.B audiostat
-provides additional timing and latency control. When read, it returns
-lines of the form
-.IP
-.B "bufsize \f2s\fP buffered \f2b\fP offset \f2o\fP time \f2t\fP
-.PP
-reporting number of bytes
-.I s
-used for DMA operations (i.e., the minimum useful size for reads and writes),
-the number of bytes
-.I b
-currently buffered, and the time
-.I t
-at which offset
-.I o
-was reached. Using
-.I t
-and
-.IR o ,
-it is possible to calculate at what time a byte with a different offset will
-be recorded or played back.
-.PP
.B 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 controls.
+latency control and for any tone controls.
Reads
return lines of the form
.IP
@@ -80,49 +54,6 @@
.BR audio .
.PP
Writes accept the same format with same abbreviations.
-Writing the string
-.B reset
-sets all of the attributes to their default value,
-and if no attribute is supplied,
-.B audio
-is assumed.
-.PP
-The Sound Blaster 16 (or MCD) is half-duplex and accepts the following controls on its
-.B volume
-file,
-in the format shown above for reads.
-.TF "\fLspeaker in out"
-.TP
-.B audio out
-Data written to audio.
-.TP
-.B synth in out
-MIDI synthesizer.
-.TP
-.B cd in out
-CD player.
-.TP
-.B line in out
-Line-level input.
-.TP
-.B mic in out
-Monaural microphone input.
-.TP
-.B speaker in out
-Monaural internal speaker connection.
-.TP
-.B treb out
-Stereo treble tone control.
-Values less than 50 decrease the treble,
-those greater increase it.
-.TP
-.B bass out
-Stereo bass tone control.
-.TP
-.B speed in out
-Sampling rate for the D/A and A/D converters,
-expressed in Hz.
-Defaults to 44100.
.SH SOURCE
.B /sys/src/9/port/devaudio.c
.SH SEE ALSO
--
⑨