On Mon, 2010-01-18 at 15:41 +0100, Lennart Poettering wrote: > On Mon, 18.01.10 13:29, Grzegorz Kryza (gkryza at gmail.com) wrote: > > > Hello. > > > > I'm trying to figure out how to add a virtual source device. > > Virtual microphone available in all pulse enabled applications as a > > sound source. Voice data for this source should be provided by a third > > party application over a socket, pipe or any other inter process > > communication method. > > You'd have to write module that lives in the PA process first for > that. We do not provide anything like that out-of-the-box since audio > should best not be passed onto many other processes. For latency > reasons you want to keep your pipelines short and every further > context switch comes at a price, espeically if you serialize things > onto a socket for that. Also notice that if you do implement this its > substantially more work than simply providing a fifo a la > module-pipe-source, since you need to implement proper timing control > which is usually the most complex part of a feature like this. > > > This can be done using 'module-pipe-source' but it was recently removed > > from Fedora packages so I'm looking for alternative. > > This won't work, since that device does not really provide any kind of > timing control, and also also depends on apps on the other side > read/write data in the right speed. It's mostly a toy. Yes, but if a timing is done by a process on other side of a pipe? We have already implemented a solution based on pipe sink/source which takes care about providing a data in correct sample rate, format, etc. It works well on all Linux distros with PA we tested except Fedora 12. Writing a new PA module for sure is a better solution but it will makes problems with distributing a new module across different distros/PA versions. I'm also not sure if it will reduce a latency in our case... Audio data are send across network and handled (compressed/decompressed) by our process so some kind of interprocess communication is required even with a new module. Thanks for a answer. > Lennart Grzegorz Kryza
