How do i make the background of my composition transparent?

[Mylenium]

Transparency preview (checkerboard pattern as in Photoshop) while working (it’s one of the little switches on the lower edge of the composition window), Export with Alpha channel when rendering (e.g. PNG 24).

Mylenium

[Pour Myl

[Tbucki]

yea i was able to see and select the checkered box in the lower corner it makes the back ground go away…that is exactly what i want to see when i play the video once it is rendered!!! but…what do i need to do in the render precess to make it that way…??? I selected the checkered box…the background goes away…now i am ready to render the video as is…but are you saying i need to select the alpha channel instead of rgb for the color output?? Where in the render view is the option to make background of composition transparent?

[Steve Roberts]

You need to render to RGB+alpha, millions+ colours. Once you choose “make movie” for your composition, the settings are in the render queue.

The background will then be transparent when opened in an app that can view transparent backgrounds.

Look in the AE help for more info.

[Mylenium]

Huh? You just choose “RGB + Alpha” on the Output module settings and choose a file format that can handle it. That’s it. The rendered file will still show you the black background if you view it standalone, though, since in computer graphics there is no real transparency. Alpha channels only determine how the background info is used and you should be able to do just that once you import your stuff in Flash.

Mylenium

[Pour Myl

[Tbucki]

so once i get the animated text how i want it, i select the checkered box, which remover the background, then i drag and drop the composition to the render cue, from there select rbg+alpha–millions of colors–and export file type as flash?? and thats it…when the video completes it will take into account that i selected the checkered box and the only thing being viewed is my text and not the black background?

[Tbucki]

Basically what i have done i loaded one of Adobe after effect’s preset animations. from there i have modified the text that they had to match the text that i want…the composition’s background is black but when i click the checkered button below the preview space, the background goes away and only the text shows. when i select alpha instead of rgb, the background is still there but what i want to see is the same thing i see when i select the transparency grid button ( the checkered button), which is only the text and no background, the background is gray and white checkers, which means that there is no background…now how would i set this up in rendering if i were rendering to a flash output?

[David Frisk]

You don’t even have to select the checkerbox. The black background (or whatever color your background is set to) doesn’t actually exist. It’s just there because I assume people don’t like always looking at the checkerbox background, so you can choose to have a solid color instead. So it’s not necessary to put the checkerbox background up.

As far as exporting with an alpha, I’m not sure whether the flash format your choosing supports it. I always use Quicktime Animation, and I know there are a few others that support alpahs too. I guess an easy way to find out is to pick a codec and then see if the “rgb+alpha, millions of colors+” is available for it. If it’s not, then you can’t export an alpha with that codec (Well, you could export it separaetly, just not all inclusive in one file with the rgb information).

[Steve Roberts]

Just to attempt to summarize what has been said:

1. To render a composition with transparency (alpha channel), select composition>make movie, then make sure that you render with RGB+alpha, millions+ colours.
2. You need to pick a codec/format in your output module that will allow you to render with those settings. PNG was recommended, if I recall. Animation is another codec, but it may not be appropriate for Flash.
3. The checkerboard switch doesn’t affect the render — it just makes the coloured background appear transparent while you’re working.
4. However, all this is well and good, but … you need to make sure that whatever app is receiving your rendered movie can actually import movies that have transparency. I don’t know if Flash can import those, but you need to find out which formats Flash wants, then make something acceptable in AE. That would be a question for a Flash forum: “I want to import a movie with transparency (alpha channel) into Flash. Which formats does Flash accept?”