diff --git a/sys/man/3/audio b/sys/man/3/audio index 520cbcec6..ccfb023e7 100644 --- 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 @@ -12,49 +12,23 @@ audio \- SoundBlaster or ESS1688 audio controller 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 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 @@ connected to .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