Unfortunately, the Work Group Note you referenced is nascent without even any prototype code being involved yet. But even though it is vapor, the ideas are really cool!
Even though it is not using just HTML5, I designed a system early this summer to stream audio content from a large venue event to people watching the facilities remote parking areas up to a mile away using easily available tools. The audio program would be fed into a notebook computer sound card input. The notebook streams the program material via the Internet to a server through a Sprint 4G hotspot. The server captures the stream and rebroadcasts (or actually re-encodes it) to multiple streams so listeners could connect with their smart phones. Although it was not used for the event it was designed for, I did build out the system and tested it fully. It worked really well. It would not be limited to smart phones either; any computer with a Web browser and media player could also listen in which is one of the reasons it was not utilized for the event (security of the program material).
The parts you would likely be interested in is the notebook to server connection. On the notebook at the event location I used the BroadWave
application from NCH Software in Australia. At the server end I utilized butt (broadcast using this tool) from SourceForge.net to capture the stream and pass it to the broadcaster. Then I used IceCast which is a broadcasting server that can re-encode audio streams to different bit rates on the fly.
By the way, butt can record streams as well as just passing them off to another broadcaster if you'd rather do that. Note that these apps are either free, usable under GPL, or free to use if you place a link to their site on the page linking to the streams.
Marty
BroadWave