Hi there,
I created a video from an animation in Blender of a mobile phone that has a completely unicoloured (i.e. green) screen, because I want to edit a video onto it afterwards using a green screen effect.
This does work using the chroma key effect to an extent, but I would like to e.g. tilt the animated phone and the video mapped onto it should follow that movement. So the video would have to be stretched into a trapezoid shape, but I would like that to happen automatically, so no keyframes. Basically, the video should be mapped onto a green trapezoid dynamically.
I have definitely seen this before, however I would like to know if it can be done in kdenlive.

Thanks for any ideas

I am afraid this is not possible in kdenlive.

kdenlive treats the video from Blender just like any other video and has no clue about any object nor its position in 3D space. Any green area is treated like a mask through which an underlying clip can be seen. Other video editors like Davinci Resolve have planar trackers that can be used for what you want to achieve, but kdenlive doesn't have that.

So you need to use the Corners effect to make your video clip follow and conform to the tilting and rotating object. This is fairly easy to do in kdenlive, and with a few keyframes you should be able to achieve your effect.

Hope this helps ...

Thanks for answering, this helps in multiple regards:
- At the very least I now know the name: planar tracking
- Good to know it doesn't work in kdenlive
- The Corners effect will definitely come in handy in some situations. For some reason, it wasn't available in my 21.08, therefore I didn't find it. But after updating to 21.12 it was back.

I since have figured out that one can also apply a video as material in Blender. This makes the green screen part unnecessary for this particular use case.
I still appreciate your help, the new knowledge will surely come in handy one day