Originally Posted by Ireland
I don't know if that's entirely true. I don't remember this in QuickTime with AVI files prior to Mavericks.
It just hangs here (no beach ball, it's just questionable if it's actually moving). This screenshot is of embedded HUD within the QuickTime X Player
When I say files should still open in Quicktime, I mean the last useful version of Quicktime - Quicktime Pro, not Quicktime X; I always append the X to the useless version. If that's a screenshot of what happens when you open a .avi in QTX, it may be trying to auto-convert the movie from .avi to another format. It shouldn't hang like that but they maybe didn't bother testing to see if 3rd party plug-ins worked properly.
It looks like they've deprecated the core system Quicktime components and moved to AV Foundation and there's not much sense in Quicktime X linking to a deprecated set of frameworks. When it comes to the next version of OS X, I'd guess Quicktime Pro will stop working as they'll remove all the core Quicktime support from the OS and Perian etc will not be usable. One positive is that AV Kit does seem to support plug-ins, see the last comment here:
So rather than components going into /Library/Quicktime, they go into /Library/Video/Plug-ins. This should mean it's possible for a Perian rewrite to work with AV Kit but there's not much chance of that happening given that the developers stopped working on it. This guy suggests AV Foundation isn't meant to be extended that way:
but he makes a comparison to Battlestar Galactica and talks about his anime movies so he might not be the best source. FCPX is based on AV Foundation and it supports media plug-ins for 3rd party formats but it likes to convert everything to ProRes. This kind of setup would prevent you from opening a movie, chopping it and saving without encoding.
Going forward, what I would like to happen is for Quicktime Pro to be wrapped up into a standalone application along with the OS frameworks it needs that will be removed later on and then it can still be used with old plug-ins for conversion, even if this functionality is merged into Compressor, that would be ok. If the old plug-ins are easy enough to port, they will need to be moved to AV Kit.