did some reading on the web, some searching, but seeking someone who actually knows!
if making an HD Blu-Ray or a digital 2K/4K for playback at a theater, does one render the file WITH black bars top and bottom or just make the Project the Widescreen size, NO black bars? Like say 1920x800 or so?
usually the video is 1920x1080 but I always add black bars to mask it to theater aspect 2.40:1 so, the viewable video is only 1920x800, or in 4K case: 3840x1600
what happens if I just make that the project size? does burning bluray then fail?
more importantly (and I don't know anything about this gear) would theater projection not accept it?
Take a look at this recent thread to see if any of these points address your question. The main thing to consider is whether the theater (as in some film festivals) are projecting from a BluRay source or if they require a DCP package. That introduces a whole new set of issues. http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=869035&Replies=12
Vegas can't. Whole different color space, for one thing. WIth the do-it-yourself DCP creators I've looked at, you would need to render a tiff sequence, then import into an app that can convert to JPEG2000 sequence, then feed that to the app that creates the DCP. Also, to comply with older digital projection systems (in US, at least) you would have to conform to a true 24fps sequence (not 23.976). I decided against a DIY approach for now, but things are changing rapidly. It might be feasible soon.