How does your video look within the Preview window? also with black borders everywhere?
Did you try the “no black bands” (or whatever it is called in English version of Vegas) option in the render settings? (as far as I remember, it only applies to some output formats).
This problem may come from so many things, it would help to post your .VEG file.
Hope this helps,
Frederic
—
Want to match colors between clips? new plug-in here.
Check FBmn Software plug-ins to fix white balance and exposure issues.
Want to learn on Sony Vegas Event Pan/Crop tool? Watch my video tutorial:
https://library.creativecow.net/baumann_frederic/Sony-Vegas_event-pan-crop-tool/1
Or about Keyframes? https://library.creativecow.net/articles/baumann_frederic/Animating-with-Keyframes-in-Sony-Vegas.php
French version: https://geo.creativecow.net/fr/a/12999