I'm using the latest kdenlive package and associated mlt, frei0r from sunab's svn repo, on Kubuntu 12.10.
What I want to achieve with kdenlive is this: a sequence of short clips is playing inside a fake polaroid image. This whole animated polaroid should then coming flying in and rotating at the same time until it reaches the center of the canvas where it sits still, but the animated minature clips in the polaroid still play.
My first attempt was to create the static polaroid containing the playing clips as a separate kdenlive project, say PolProj.
Next, I create the main project and add PolProj as a clip. I'm dragging this clip into the timeline and add an affine transition to it, setting the keyframed position and rotation. When I preview this in kdenlive, everything looks as expected. When I'm rendering (to H.264) it is all messed up: there are only the playing minature clips visible but not the static polaroid around it. The affine translation does not get applied at all.
Okay, so I went back to PolProj and rendered it into an mp4 file using the H.264 codec. Project and output resolution is 1920x1080. Next, I drag the final mp4 clip into my main project (and remove the kdenlive project clip from my first attempt above). When I add an affine effect to the clip in my timeline and add the keyframed translation and rotation, everything seems to be okay.
However rendering gives a strange effect: the polaroid has been magnified by maybe 5 or 10% and now stretches past the project canvas. This happens only in the rendered output.
Even more strange, adding a second rendered H.264 kdenlive clip and adding an affine effect to it does not cause any visible effect on this second clip at all.
Another strange thing I'm observing is that the rotation actually causes distortion, as if the pixel size is not square. Locking at the clip meta data does not reveal any problems: 1920x1080, pixel ratio 1:1.
Forcing the ratio to 16:9 now causes just the proxy clip to change it's aspect ratio, but when deleting the proxy clip, the original clip retains its proper aspect ratio. So the force causes the proxy to look different in aspect ratio compared to the original clip.
I'm totally lost at the moment at how to achieve my original idea using kdenlive. Any help is greatly appreciated.