Ah, I just finished what I considered a half-decent attempt at solving the issue: https://github.com/oottppxx/en…/master/plugins/budweiser
It seems I'm about 10 months late w/the idea (or even more, if any other plugins out there do the same), I'll update the README.md to point to this thread, well done.
From the comments, it seems you're also using gstreamer (how else), now I need to go look at your code to see how it was done :-) I see the gst1-0-ipaudio mentioned in the comments, but that command doesn't seem to exist (at least by default) in openatv 6.2.
BTW, I "solved" the VU+ OpenATV 6.4 audio issue by utilizing alsasink w/an explicit device (hw:0) - from gst-inspect-1.0 it didn't seem to have osssink, and autoaudiosink would select dvbaudiosink which is obviously not what we want.
P.S. - Ok, now that I've looked at the code, I see you're using a specific binary, while my code tries to make do with existing packages; so very similar idea, but quite distinct implementations; again, well done!