audio – SoundBlaster or ESS1688 audio controller|
bind –a #A /dev |
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 written 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 complement integer; the default sampling rate is 44.1 kHz.
Some implementations only support audio output and return a zero
length when read. |
The length of the audio file as returned by stat(2) represents the number of bytes buffered for input or output. This provides some control over record or playback latency.
The file audiostat provides additional timing and latency control.
When read, it returns lines of the form
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. Reads return lines of the form
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 accepts the following
controls on its volume file, in the format shown above for reads.