Dear André, The frei0r effects have to be added to /usr/lib/frei0r-1 The xml UI has to be written as described at the link you told me: https://invent.kde.org/multimedia/kdenlive/-/tree/master/data/effects and it has to be added to /usr/share/kdenlive/effects/
For the rest, I read what you are needing, and I can tell you that something similar already exists. It's the frei0r.bgsubtractor which is now blacklisted - to show it again you have to edit the blacklisted_effects.txt in the "data" folder of the Kdenlive source code. Actually, this effect works pretty well, and it could be used for achieving your goal. The issue is that it takes the “reference” frame automatically, and it refreshes in several situations (eg. if you change preview resolution it reloads the frame by taking the one you are on when you do the operation, or if you move the clip to another track, or you trim, cut, etc). It could be fixed if we can set the “reference” by using a frame in the clip through an absolute position . I've reported this issue here https://invent.kde.org/multimedia/kdenlive/-/issues/350 but nobody has tried to fix it yet so far. Maybe you can go forward with your effect and/or try to edit the frei0r.bgsubtractor too and make it finally work. This second option could be really great news. Cheers. Massimo. ----Messaggio originale---- Da: andre.em.cal...@gmail.com Data: 15-ago-2021 13.58 A: "Massimo Stella"<maxs...@tin.it> Cc: "kdenlive"<kdenlive@kde.org> Ogg: Re: Registering frei0r plugin. Dear Massimo, First of all... by the way... if anyone wants to contribute, I would be glad. I would probably publish it as GPL. > can you explain in details what this mixer2 is supposed to do? It compares track A and track B. Copies track B to output D and sets D[alpha] to transparent whenever A and B are "equal". I am a professor of mathematics. I have recorded some classes I edited with Kdenlive. I know nothing about video editing. :-) For example: https://www.youtube.com/playlist?list=PLMG2ETzS-iy80kspoqaE2bgLWvZFf9i3u I am recording a new set of lectures for a different subject. Now, that I am a little savier, I want to be able to erase my background. I have asked a question here https://video.stackexchange.com/questions/34264/kind-of-chroma-key-using-a-key-frame on how to do that, but I got like 7 views in a few days. So, I decided to write a plugin. :-( I realized it would be easy to implement a simple version of that but that would not work very well due to already known issues with "chroma keying". I got it working roughly some 8 hours ago. Shadows are the biggest problem right now. But maybe I can fix it with better illumination. It is not really usable, but much better than I expected. I used "melt" to test it. I can share the resulting video if you want. Not a Kdenlive issue... but now I realize it would be better to write an MLT plugin, so I could use a better color scheme, and also chain some other processing. I can publish my code, if you want. The method to determine if two pixels are the same needs to be improved. I have thought of a dozen things that could be done, but I think it would have to be an MLT plugin to do more advanced processing. I will also need to "erase" the ink on the whiteboard. Also, a different version of the plugin could be an "MLT filter" instead of a "mixer2". It could compare to a specific keyframe, instead of comparing to a track. But I would probably not be able to do it with frei0r, and I am not really confident there is a GUI for the "keyframe" value. So, by now, it is a "mixer2". I would be a nice approach, and the image to be compared with could "evolve/adapt" for the next keyframes. > BTW: to add a frei0r plugin to Kdenlive, you have to add it to the > frei0r plugin folder and create an xml ui file for it. I have read a lot since I made this question. Following an advice I got on MLT mailing list, I have added it to ~/.frei0r-1/lib/ I guess I need to provide an XML as described here: https://invent.kde.org/multimedia/kdenlive/-/tree/master/data/effects And I should probably put it in here: ~/.local/share/kdenlive/effects/ Cheers, André Caldas.
