Summary

Use of Mask Line transform crashes FFMPEG stage on trigger.

Steps to reproduce

1. Quick project, NTSC
2. Add Mask Line
3. Configure it with A:0-71,208-300
4. run with ffv1

Expected behavior

All cinemascope letterbox lines are blacked, as expected (ffmpeg sink preview proves it).

What happened instead?

Crash, segfault, but "after a while" (between quasi immediate and 2 minutes later)

• OS: Ubuntu 24.04
• Build/commit: 758a9d3
• Component: orc-core