synchronized music playback across multiple renderers

[Jonathon Conte <anotherjonathon gmail com>]

Hello, all.

I am looking for free software alternatives to the proprietary and
expensive music streaming offered by Sonos. I'm specifically
interested in software and standards that allow for synchronized music
playback to multiple clients on a wireless network. Logitech Media
Server has this capability but it relies on its own non-standard
protocol. From what I've read, VLC also offers client synchronization
although I have not tested it on a WiFi network.

My understanding is that the UPnP AV specification includes
synchronization across renderers as one of its features. Does Rygel or
GUPnP implement this functionality? If not, are there any other UPnP
projects that do?

Thanks in advance!

Jonathon