Operating system: Linux-4.18.0-25-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: Mesa DRI Intel(R) UHD Graphics 620 (Kabylake GT2) Intel Open Source Technology Center 4.5 (Core Profile) Mesa 18.2.8
Broken: version: 2.81 (sub 2), branch: master, commit date: 2019-08-14 22:18, hash: rBcb7ead2e3b62
Short description of error
The mask modifier in the VSE displays mask animations one frame too early when "Mask Time" is set to "Absolute".
Exact steps for others to reproduce the error
- Create a mask in the Movie Clip Editor with a shape key animation.
- Add a Color strip in the Video Sequence Editor.
- Add a Mask modifier to the strip and set the "Mask Input Type" to "Mask", select the mask created in 1. and set the "Mask Time" to "Absolute".
- Go through the animation frame by frame. In the VSE the mask will be animated one frame ahead of the actual shape keys. Other keyframes (like the mask layer opacity) will be timed correctly.