I'm having some (a lot actually) trouble exporting a transparent... something from After Effects. I have created a button with some sparks flying by behind it, and the background of the project is transparent. I intend to use it in Flash as the mouse over animation for a button. However, I can't seem to export it properly. I exported it as a Quictime with RGB+ and Million+ colors for setting, and tried exporting it as an FLV later as well, but unfortunately, that doesn't work. When I open the file in Flash, Windows Media Player or Flash Video Player, the background is just grey.
The only thing I can imagine that could cause the problem, would be the 32 bpc setting, but that is something that is needed for the effect. Not quite sure if it matters, but the effect is created with CC Particles. I'm using After Effects CS3.
Thanks very much in advance for your answers, any help would be great :)
"I exported it as a Quictime with RGB+ and Million+ colors for setting"
You didn't leave the comp in the render queue so the AEP doesn't show what's wrong with your Render Settings or Output Module.
In any case, you have to use a codec that supports alpha channels (Animation, PNG, ProRes, Uncompressed, etc.). Also note that media players can't display transparency even if it's there ... they generally show it as black, but in your case, you've changed your comp's background color to grey so that's what will be used to represent the alpha channel. The only way to see it as transparency is in other media creation (versus playback) software.
Everything is right in the render settings and output module ... try changing your AE background to black (CNTRL B) and re-rendering ... I'm not a Flash guy so I don't recall this about Flash, but many programs that aren't specifically video programs won't interpret an alpha channel if it's represented by any color other than 100% black.
Changing the background to black didn't help unfortunately. Also, the 32cbt setting isn't causing the problem either, because the background still isn't transparent when I change it to something lower.
It's been a while, but I found the solution and am posting it here for reference.
The point where it went wrong, was in Flash apparently. When importing the video into Flash, you have to explicitly tell Flash that it has an alpha channel. Something quite simple, but easy to forget/look over.