Qt5 QtMultimedia video playback - what backends, formats, etc.

Hello,
I'd like to know more details about QtMultimedia video playback in Qt 5.0. I couldn't find these specifics in the online documentation.

I understand with Phonon the supported media types were platform specific depending on the backend used, e.g. DirectShow on Windows, QuickTime on Mac OSX, etc.

With QtMultimedia in Qt 5.0 is this still the case? Is there anywhere I can get a list of backends supported by platform?

Or, if QtMultimedia integrates its own video playback engine, is there any info on what this is based off of (e.g. ffmpeg, libav, VLC, gstreamer, etc.) and what video types are supported?

Thanks!