Hello Colin, Thank you for your answer , So I fear that it is not possible to have several "fake" sinks (one per VM).... Unfortunatly when I load a other fake one, got 'failed' see above administrateur at 23390hd61252:~$ pacmd load-module module-null-sink sink_name=fake Welcome to PulseAudio! Use "help" for usage information. >>> Module load failed. >>> administrateur at 23390hd61252:~$ So... I fear that I have to ask for a sound card (it is a server "in box" , can be not easy) Is it right ? 2010/10/19 Colin Guthrie <gmane at colin.guthr.ie> > 'Twas brillig, and Fabrice Beauvir at 19/10/10 10:41 did gyre and gimble: > > On a Ubuntu 9.04 server running pulse audio without any sound card I run > > 2 Windows XP virtual box . > > > > Sound is Ok and on both of them , I am playing on the current virtual > > sound card (mapped on each vbox instance) and stream directly using > > virtual card as input on each . > > > > but.... > > > > On both stream sound is mixed , I heard the 2 sounds mixed out on each > > one !!! > > Ahh right, yes this is simple to explain, but rather more complex to fix. > > Ultimately PulseAudio uses a "module-null-sink" when no real hardware is > found. This means that a dummy sound card is essentially provided. This > is created automatically by module-always-sink so that applications > generally find "somethign" to output to (as without this, alsa > applications going via alsa->pulse bridge often got, erm, "confused" is > a nice term :D) > > Anyway, the point is that this module only provide a virtual null > *output*, and there is no virtual null *input*. > > Well, I say there is no null input but there *is* a "monitor" input for > the virtual output (a monitor basically acts as a pretend input that > allows you to record what is being currently played - think of how bands > perform at live gigs - they use monitors there to make sure they don't > sound crap!) > > > Anyway, when VirtualBox is recording it has to record form some source > in PA. As a side effect of the virtual output, the *only* input it can > record from is the montitor of this virtual input. As both VMs output to > the same virtual null sink in PA, their sound is mixed. Therefore when > either of them record, they get the product of the mixed audio from the > monitor. > > So that explains things. How to fix? > > Well there is no module-null-source (there arguably should be on written > but no one has done this yet). > > So a trick here would be to load a second null sink and set *it's* > monitor source as the default source, but never actually play anything > on it. This way you can happily "record" the silence inside the VMs and > that should be OK. > > Hope that makes sense! > > > You'd have to do something like: > > pacmd load-module module-null-sink sink_name=fake > pacmd set-default-source fake.monitor > > (you can also put this in your default.pa so it's done automatically) > > You'll likely need to restart your VMs to make sure they then use the > right devices. > > Hope that helps. > > Col > > -- > > Colin Guthrie > gmane(at)colin.guthr.ie > http://colin.guthr.ie/ > > Day Job: > Tribalogic Limited [http://www.tribalogic.net/] > Open Source: > Mageia Contributor [http://www.mageia.org/] > PulseAudio Hacker [http://www.pulseaudio.org/] > Trac Hacker [http://trac.edgewall.org/] > > _______________________________________________ > pulseaudio-discuss mailing list > pulseaudio-discuss at mail.0pointer.de > https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20101019/d0d38c0e/attachment.htm>
