Alternate Alpha Programmatically

Hi, how can I … set alpha to increase and decrease programmatically. For instance:
3 sec increase from 20 to 100,
then hold for 3 sec,
then 3 sec decrease from 100 to 20
… and to continue like this for 10 minutes.
??
Thanks

Hi @TRS7

Maybe this discussion would help?

Except that instead of using keyframes on a Brightness filter, you would use them on an Opacity filter.

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Thanks but … perhaps you consider it for the future.
Programmatic multi-step alternation of property.

@TRS7 maybe we are not on the same wavelength :thinking:

So by Programmatically you mean that instead of adding keyframes manually, you would give instructions to Shotcut so it could add the keyframes for you?

Yes say you had a 2 hr long timeline and you want the opacity to fade in and out according to a particular pattern. 0% for 30 seconds, then fade to 80% over 2 seconds, hold on 80% for 3 minutes, fade to 0% over 10seconds. Repeat …

It sounds like you are editing the same length of clips and video each time.

Perhaps consider a different approach.
Create an opacity MLT project to place above your video editing tracks.
2024-02-08_10-47-26

shotcut_2024-02-08_10-21-24
Example video:

Important note: Both your project and the MLT XML Clip must match the exact resolution and fps.

Keyframe example:
shotcut_2024-02-08_10-53-19

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