[Kdenlive-devel] 3d effects and transitions with blender

[Alberto Villa]

hi list!
since i like big proposals, i come here with another one :P

some time ago someone wrote on the forums about a project, 
gvfx.blogspot.com, which is actually a python script to embed images and 
videos in blender animation
i had a talk with one of the two guys behind this, and i'd like to discuss 
this feature with you all

1. how does it work?
here's the script: http://gvfx.blogspot.com/2008/01/script-gfvx-firts-
version.html
with the new coming version of the script (i would contribute to it, it's 
quite easy), you would have to supply one or two video files, select the frame 
range for the clip(s) (the duration of the effect/transition), and choose 
export parameters as well as the effect/transition you want

2. how to implement?
here's what i think: we could add a "3d transition" in the transition dialog 
(and list available effects in their list - the way to detect them should be 
defined - but i'll focus on transitions now) and list (like in the luma 
transition) all available 3d transitions (we could have the big "official" 
.blend file and lots of user contributed small files)
blender does take a long time to render, but it's about 5-10 seconds with a 
80x60 animation, so we could show a preview (maybe with just A and B images) 
of that size (only in the dialog, not in the timeline!)
those transitions should then be saved as kdenlive special ones; when 
rendering, we should:
1. warn the user about the long long time it could take
2. render all the timeline with melt alone (there will be rough cuts where 3d 
transitions are)
3. render the 3d transitions (think about slowmotion clips, or effects... 
blender needs a plain video)
4. join the clips (with melt, i guess)

3. pros and cons
pros:
- i can't think of any other way to implement 3d in kdenlive (maybe you can)
- it would be easy to contribute custom transitions (i'd start making lots of 
them!). and effects, of course. you can have a look at some of them on that 
website (testing them is quite funny)
- blender can also apply complex color filters and/or uv distortions (they're 
working on this), or... titles?
cons:
- it depends on blender (we already depend on other software like 
recordmydesktop or dvdauthor, but blender is big...)
- it takes a lot of time to render (they're talking about using the game 
engine to make it faster, but i guess it wouldn't work with every animation)
- you have to render the project 2-3 times
- the worst one, i think: you're limited to blender video export capabilities. 
unless we export to png and then join every single image to match the project 
profile (they say it should be faster then rendering to video), there's only 
avi and mp4 i think (dan could put light on this maybe)

well, that's it, to begin
if you are interested, i can write a patch to test it (for the list eyes only)

regards
-- 
Alberto Villa <villa.alberto at gmail.com>