Experiencing something similar, though not involving black bars. Just the images themselves. Everything looks fine in preview, but the final rendered video is decidedly darker.

Is it darker in an external player or in the Vegas Pro preview?

Marco, is darker in external players: VLC, Windows Media photo video whatever, old Media Player. Is like my 16-235 on the tracks - seen in preview - are not pushed to file. All my old stuff rendered this was used to be, with VLC displaying 16-235 correctly, and Windows Media being natively darker, but still proper.

The pic I posted above shows the Preview screen on the right, and VLC on the left. The background on the right is a dark gray, not black, like the black bars at top and bottom.

A couple details possibly, but doubtfully related, I'm running nvideo 10bit mode, and in vegas, rendering from 32bit floating point video. I did try rendering a second from 8bit mode and it made no difference.

I understand external players can and do play back things differently, which is why I use 3 or 4 of them to test. But usually I can make a render out to 16-235.

Also have tried changing "COLOR SPACE" in the render part to rec709, but that changed nothing.

May be the black bars overlay is yanking everything back up to FULL 0-255, but the preview does not show that even at BEST/FULL SIZE settings.

That's what my guess was. The Vegas rendered files actually aren't darker. Instead the players do a studio swing/full swing adoption.

It was always like this. If preview is not on separate monitor, it does not show you "proper levels" (you can use SemW extension to apply required StuduiRGB to ComputerRGB conversion).

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