Is there ANY reliable A/V IM/Streaming protocol? Especially audio!

I have spent weeks testing all sorts of servers, protocols, you name it, trying to find the most reliable A/V streaming protocol. Everything seems to have it's limitations of course but which is the most reliable even with those limitations? I have tried; Asterisk and other PBX's which allow h.264 streaming. These work the best so far, all of them seem to be using h.264. Openfire, jabberd with various A/V plugins. Good video, always out of sync audio. Countless flash based applications, all of them have pretty good video but the audio is always crummy. I have even tried an AIR based application which again, has pretty good video but crummy audio. I tried all of these things on a variety of hardware, all windows based because the end users use windows so it's gotta do win. Hardware ranged from quad 3.0/4GB machines to duo-3.0 machines, to android cells and tablets. A few weeks ago, android wasn't able to access the front facing camera but we seem to have gotten past that. So it seems there are plenty of 'almost' there applications but are there any which are there for sure? What I am looking for is basically a way for two (or more) people to connect together by picking someone's avatar and going directly into an A/V connection, no text chatters etc. I'm not quite sure what else to include at the moment but happy to post more if someone wants more info.

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