v1.12.0

ASS typesetting now follows the picture under Fill and Stretch.

The subtitle renderer laid its canvas out as the video's letterboxed box and always had — which is exactly right under Fit, and why this looked correct for as long as nobody touched the aspect control. Under Fill the browser crops the picture to fill the screen, and under Stretch it distorts it; in both, the picture stopped being where the subtitles had been drawn. A sign pinned to a shop front landed somewhere else in the frame, and the dialogue sat inside a letterbox that was no longer there.

All three modes centre the picture on the same point, so the subtitles are now scaled about that centre onto wherever the picture actually is. Verified against a picture rectangle worked out independently of the code: all three modes line up to the pixel, and on a heavily typeset frame every sign stays on the object it labels when the aspect changes.

This was previously documented as a reason to turn typesetting off. It no longer is.

One trade-off worth knowing: the subtitles are drawn at the letterboxed size and scaled up, so Fill and Stretch soften the text a little — imperceptible at ordinary aspect mismatches, more noticeable at extreme ones.