[Bf-vfx] Problems and bugs regarding VFX editing in Blender

[maciej.szczesnik at autograf.pl]

Hello there,

I'm working a lot in VFX recently and I mostly use Blender for all my work. I have some ideas and thoughts, I'd like to share here. 

I have one, really big problem with making VFX with Blender - there is no live preview. The node system is quite amazing and really powerfull. Combined with render layers makes a ready to use tool for VFX editing, but editing becomes painful if someone wants to make an effect with strict time constraints, e.g. an explosion, muzzle flash, and so on. My workflow for such effects is to place pre-made movies or image sequences with alpha channel on a plane in 3d viewport, assign the plane to a render layer, render the plane and compose with nodes. It works just fine, but the tricky part is to match the effect with the movie. You can preview each frame quite fast (you have to render though), but there is no way to preview a part of the movie. You have to render each time you want to see what you get. That makes tweaking things a lot more complicated and time consuming. I guest that live preview is not easy to achieve, when 3d rendering is used for placing video elements onto another video element. I know what I'd like to be able to achieve, that is a great and short example: http://www.videocopilot.net/tutorial/blast_wave/. Maybe it would be possible to have After Effects like tools inside the new video clip editor (used for camera tracking) one day?

I think, I've also found some issues that I'd like to tell about (I'm not quite sure if that is the right place though, so if I'm mistaken, please tell me where I should post such things):

1. Crash on movie preview in 3d window. If you have a movie assigned as background in a 3d view, Blender often crashes when scrubing through timeline (I've noticed it especially when I scrubed frame by frame, using current frame counter). It's one crash per 30 - 60 minutes, when using 720p mp4 video. I'm using nVidia GeForce 9800 GT 1GB, Win XP 32 Bit, intel Quad Core Q8200, 233Ghz, 4GB RAM. I have the latest video drivers from nVidia. 

2. There is a problem with transparent quicktime videos. These are quite often used as source video files for various VFX (for example, I've bought Action Essentials 2 from videocopilot.net). It seems that in some cases Blender isn't able to read the alpha channel from quicktime video. It recognizes the file, as RGBA quicktime movie with premultiplied alpha, but it looks like alpha channel is white. What is interesting, in other cases it works as it should. I have several examples on the Action Essentials DVD for working, and not working alpha channels. If I open the movie file in quicktime pro - it works just fine. For now the only method for me is a workaround - I use quicktime pro, to export movies to PNGs with alpha channel, and then import the image sequence to Blender. But anyway it looks like some kind of a bug and probably should be adressed in some way. 


Best regards,
Maciej Szczesnik