Blender special effects?

I wasn’t quite sure where to put this…

anyways I know this has been asked like a lot but I was wondering how you would use blender to add special effects to a video… I can’t seem to get it to work…

Like what kind of special effects do you want to do? Or are you asking how you would composite the special effects into a video after rendering?

I’m wondering how you would like add fire to some one’s hand or some thing like that… I basically know how it’s done but I can’t really seem to get it to work… Like I would have it so the scene that I want to add to the video is added OVER the video but with the background transparent right? because I can’t seem to get that to work…

if you want to add the fire during compositing, you can use either composite nodes, or do it in the video sequencer. you will have to make sure your fire strip has an alpha channel, and you can enable premul alpha by clicking N in the video sequencer, to get the appropriate menu. another way would be to use a black background to the flame, put both strips in the video sequencer, add a cross, and set the cross to ‘add’. However, I would not bother with the compositing, and instead, use a particle emmitor to generate the flames.

so I did the thing with the black background and added a cross but how to I change it to add? in the sequencer buttons where the drop down menu to change it from ‘replace’ to ‘add’ but the only thing in it is ‘replace’… how do I change it to ‘add’?

sorry, with both strips selected, add a cross, then select the cross and hit the ‘C’ key to change it to add.

oh thanks!

another problem… my video clips don’t like to work… I get them in and they only show on the first frame… so when I hit alt-A it just goes blank after frame one… I can’t figure it out

It may be a codec ( avi format ) issue. try rendering an image sequence in png or jpg form, or to an avi codec that you know is supported.

Well what type of special effects are you thinking?