This was asked already a couple of years ago but no solution was found. I would like to use an ALSA loopback device for my virtual machine. With the now deprecated soundhw/env parameter syntax everything worked. I'm specifying "-device intel-hda -device hda-duplex " which are fine I guess, but the -audiodev parameter is causing trouble:
-audiodev alsa,id=snd0,out.dev='hw:Loopback,0,4',in.dev='hw:Loopback,1,5' results in the following error: Invalid parameter '0' This is logical as comma is the parameter separator. But apparently it cannot be escaped in any way? I tried using the JSON form: -audiodev \"{ 'driver':'alsa', 'id':'snd0', 'out':{'dev':'hw:Loopback,0,4'}, 'in':{'dev':'hw:Loopback,1,5'} }\" but this resulted in the following error: qemu-system-x86_64: -audiodev "{: Parameter 'id' is missing This I do not understand, as there clearly is the id property for the audiodev. Is there a bug in the JSON parsing, is using the HW subdevices not possible, or am I missing something? Thank you!