[M4IF Technotes] B-frames in Simple? Which Levels?

[Rob Koenen]

>     Anything happening with including a profile descriptor in a MIME type
so
> that web-based content could be more accurately steered to an appropriate
> player?

That's all in the Initial Object Descriptors, and MP4 files
support those. Also the Visual and AUdio streams themselves
can contain this information.
Furthermore, there is a profile_and_level_indication field in 
the Visual bitstream (and also in the AUdio bitstream)
Rob