Is there a way to use object masks while also changing the speed of the clip (for example with time remapping)? When I try to just add an object mask (via Shape Alpha) to a clip that is not on 100% speed, the mask is applied second and thus doesn’t match the object in the clip anymore.
No, anything that analyses the raw clip, like motion tracking, doesn’t get its keyframes transformed by time remapping.
The only way at present to use them together is to render the clip at its original speed, reimport the result of that, and then apply the time remapping.
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Or use a second sequence which you re-import into the original sequence (nesting).
Apply the mask you want. Create a new sequence from that clip and re-import the sequence. Now you should be able to adjust the speed of the sequence-clip.
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I thought I’d tried that and not had any joy, but whatever fell over for me last time I did, I can’t reproduce it with current kdenlive … the indirection seems to work exactly as it should. \o/
Maybe I misunderstand what you mean, but when I move the clip into it’s own sequence where I then apply the object mask, and then put that sequence back into my main sequence, it loses the transparent background and just has a black background.
What does work for me is doing it the other way around:
- Move the clip into it’s own sequence
- Apply the time remapping (if not already done)
- Put that new sequence back where the clip was originally
- Make an object mask for the sequence and apply it to it
This works and I will use it, so thank you for that. But it also comes with a small workflow issue, which is that kdenlive doesn’t allow me to select “Create Sequence from Selection” when I only have a single clip selected.
This is probably a function of the same issues with which codecs do and don’t support transparency that have been discussed elsewhere in the forum.
Importing a sequence as a clip isn’t quite the same as compositing two clips with an alpha mask in the same sequence. And I’m not quite sure what we’d need to do to declare that a sequence should have alpha when nested.
As you note, you can work around it by swapping the order of operations, but that means that if you ever tweak the time mapping, you’ll need to regenerate the mask - which isn’t the ideal situation in terms of overhead.
kdenlive doesn’t allow me to select “Create Sequence from Selection” when I only have a single clip selected.
Normally, that’s quite reasonably a feature, since creating a sequence from a single clip is the same as just using that clip, and probably not what you intended - but if this remains the expected way to do this, it also seems reasonable to lift that restriction.