On Wed, Jul 22, 2020 at 08:55:02AM +0200, Gerd Hoffmann wrote: > Hi, > > > IIUC, QEMU can expose multiple sound devices to the guest too. > > > > I think this means that we can have a M:N relationship between > > a sound device, and an audio backend, not just 1:1. > > It's 1:N. Sound devices have a single backend, but a backends can > service multiple sound devices.
Sigh yes, of course, wasn't thinking right. > > Assuming I'm right about the M:N relationship, I assume that > > of multiple cards all do playback concurrently, something > > will have todo mixing of the streams ? > > In general it is a good idea to go with 1:1 if possible. With > pulseaudio this works fine. You'll have two streams to pulseaudio > then, pulseaudio does the mixing, and you'll see both streams in > mixer apps. > > OSS devices tend to not like being opened multiple times, so you > have to go with 1:N if you want multiple sound devices. qemu mixes > the playback streams then. Not fully sure what happens with > recording, probably all sound devices see the very same stream. Ok, so it sounds like we need the XML schema I illustrated. Even though we'll recommend 1:1 for general use, we'll want the option to supoort 1:N setups. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
