[pulseaudio-discuss] Virtual device in Pulseaudio

Colin Guthrie gmane at colin.guthr.ie
Thu Jul 1 08:14:05 PDT 2010

'Twas brillig, and 4ernov at 01/07/10 15:58 did gyre and gimble:
> Hello,
> I'm working at some global effect processing stuff, for example,
> equalizer which affects several my applications which output sound
> through Pulseaudio. I want to implement it using GStreamer and virtual
> soundcard which all the applications will output their sound to. E.g.
> we set some virtual PA device as output for every application, say
> "devproc" and some processing GStreamer application use this device as
> its input and transfers stream to 'real' PA device (which stands for
> real soundcard) through some effects.
> My question is: is it possible to create a virtual device in
> Pulseaudio which has one input and one output and transfers stream
> from its input to the output? I tried different solutions including
> module-loopback (no success) and module-pipe-sink/source (gstreamer
> wasn't able to stream through it due to very low speed as I guess) but
> I have no success at all.

While I don't know much about it, git master does have a kind of virtual
device that is used for the new built in equaliser stuff. It may be that
you could use that.

Alternatively you could simply use a null sink (call it what you want,
play your stuff to the null sink, then have a gst pipeline that records
from the monitor source of that sink, does it's processing and then
plays it back to a real sink. That should work OK if you can live with
all the delays and inefficiences etc. such an approach creates.



Colin Guthrie

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