I have seen in commercial DVD's that when you hit the "play movie" button sometimes there is a short video clip or transition effect that moves you from the main menu to the movie or or other parts of the DVD (as opposed to just a straight cut). Does DVDA have this capability and how is it done?
Yes and no. To really implement this with as little chance of delay as possible, DVDA needs to implement not only menu loop points (intro and body that loops), but menu out points as well. AKA multi-cell menus, where the cell count is >2.
However, in the absence of this capability you can simply insert your transition as a separate movie; you change the link on the menu item to link to the transition movie and then the end action of the transition movie links to the actual movie clip you want to play.
What i've always wondered in these cases is, why not just render that little intro clip right into the main movie file? That way it would be included automatically with absolutely zero effort when laying out the DVD. As an added benefit, there would be no gap or pause in playback when transitioning from the intro to the movie.
"why not just render that little intro clip right into the main movie file?"
Commercially my guess would be that it might be seen as more efficient when the title vid is 24p with pulldown added, & the created video is NTSC or PAL. OTOH I suspect for many that it just hasn't occurred to them. Practically speaking, I imagine some might feel it's some shortcoming when the viewer's hitting the Prev button on the remote when at the real video start, though *maybe* you could fix that editing the IFOs?
When it comes to using a loop point vs. separate intro, I've personally encountered more of a pause when the menu loops, but that could just be the players I test on. The way DVDA puts menu & intro vids in VTS_01_0.VOB & VTS_01_1.VOB respectively, it *might* be quicker to play start than seek a loop point? Anyway my logic [which may be wrong, or even illogical] is that you'll only see the intro transition once, whereas you might see the menu loop several times if you pop the DVD in & wait for everyone to gather.
Multiple cells per menu vid would probably help minimize a pause before playing an outro (?) clip, but I think the usefulness would depend on having only one button or choice or place to go to -- I think of it as an intro, or rather separate intros that transition into a new view rather then *BAM - here you are*. But on the downside [there's always at least one] integrating it into another menu using a loop point can be a pain for the viewer who might not want to wait for the pretty intro he/she's seen several times all ready.