Openpipe creates a non-blocking pipe from stdin.

There may be a simpler way to accomplish this, but I wanted to get audio from pianobar (https://github.com/PromyLOPh/pianobar) into forked-daapd (https://github.com/ejurgensen/forked-daapd), and this works.

To use, set up an ALSA alias in ~/.asoundrc or /etc/asound.conf:

pcm.writePipe {
    type file
	slave {
		pcm null
	}
	file "|openpipe /srv/music/Pandora"
	format "raw"
}

Create a named pipe with mkfifo and make sure the write permissions are appropriate.

Then, send the ALSA audio to "writePipe". For pianobar, add a line to /etc/libao.conf:

dev=writePipe

To build:

$ git clone "https://github.com/b-fitzpatrick/openpipe"
$ cd openpipe
$ make openpipe
$ sudo cp ./openpipe /usr/local/bin/ (optional)