The first quicktime (test.mov) is a test with annotations composited over the image. The second quicktime (test_letterbox.mov) is the same script + cropping of the image to 1920817(exporting the quicktime at 19201080). When the annotations is added to the letterbox, the new text is added on top of the text of the previous frame without clearing it first.
I’d like to make sure I understand: in test_letterbox.mov, you’re cropping the image, and then compositing it over a black background image, right?
It looks like the background image needs to be reset to black at the beginning of each frame. You can do this using the SetToColor function:
img.SetToColor(Draft.ColorRGBA(0, 0, 0, 1.0))
If I misunderstood the problem, it may be helpful if you could please send me a copy of the Draft script you’re using. You can send us files using our ticket system. I think you’ll need to ZIP the script, otherwise it will be filtered out.