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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)
