Alpha over Video In Sequence

Anyway to get a Alpha mapped PNG to “sit over top” of a Video AVI or anything like that?

I plan to use subtitles, but I can only add them when I get my timing right, which is last, so, can it be done?

Hi, yeah it sure is possible.

I guess there’s a a couple of ways of going about it. You could do it in the sequencer or the node editor. I’ve done it in the node editor.
Here’s a node setup that will chuck an image ontop of a video. I’ll leave it to you to animate the fading in and out of the image, or whatever transition you choose.

Try having a play with the factor of the AlphaOver node. This is what you’ll animate with the time node to effect a fade-in/out

There’s some videos here that should have all that you need. The 2nd last vid in the compositing section will show you all about the time node and using it to animate things…



if you want to use premultiplied alpha, with the alpha strip selected, push the N key, and from the popup menu select ’ use premul alpha ’ ( i think it’s still the same, allthough i vaguely recall reading about some minor change in this, somewhere in the release notes )

So where do these “extra” new node sytles come from?

Alpha Over and Composite are not in my list when I press the space bar in the nodes window.

Do I have to install more software to get these “new” nodes?

Alright, the Alpha thing in the Sequence editor isn’t working, and for the node thing, how do I set the amount of time it stays there, since I need many subtitles a clip. Coming and going at different times.

if the sequencer isn’t doing it, it might be that you have to switch the stacking order of the strips. the correct procedure is:
add strip A to ‘slot’ one ( shift A and drag )
add strip B to ‘slot’ two ( shift A and drag )
select strip A, shift select strip B, and add an alpha over strip to ‘slot’ three ( shift A and drag )
to switch stacking order, select the alpha over strip, and press ‘C’ and from the menu that appears, press ’ switch A - B ’


I forget which one now, though those screen shots came from either 2.44 or 2.45. (on linux) Both of these (standard issue) copies of Blender have the nodes available.

Composite is found in Add->Output->Composite, and is the node that blender gets it’s rendered frame from (the one that’s shown on screen, or output to a file) I’d be surprised if this node was any newer than the Node Editor tbh.

Alpha Over is found in Add->Color->AlphaOver

Hope this helps mate.

I finally found the nodes.

You have to click “Do Composite” in the F10 menu.
You have to also open a nodes window. Then click composite nodes. (The little portrait icon). then you have to click “Use Nodes”.
Until you do that, none of the compositing nodes show up in the Add menu because it defaults to Material nodes.