-
Quicktime Pro .avi export Alpha problem on Mac OS X
I’m having some problems keeping the alpha channel when exporting some smaller .avi movies out of Quicktime Pro on my Mac. I’m using Quicktime 7.6. I have a movie around 500px by 500px, around 20 seconds in length with an embedded alpha channel and the animation codec. I need to export it to an .avi movie and keep the alpha channel. When I export this 500×500 movie, the alpha channel exports fine. When I shrink the original .mov file down 45% to an SD size and try and export it again, it won’ t keep the alpha channel, it seems to be premultiplying it with black. I think this may be a new issue with Quicktime 7.6. I have been exporting small .mov files with alpha channels to .avi movies for years with no problem but the smaller sized movies won’t work. I also cannot find another piece of software for Mac that can export to .avi and keep the alpha channel (RGBA). I solved the problem by opening the .mov and exporting using a Windows version of Quicktime Pro. It kept the alpha channel. Does anyone else know of a solution to this problem? If someone would like to try it on a Mac using Quicktime Pro 7.6, let me know if you get different results. Try 150×150 pixels with embedded alpha and see if you can get it to work. Is there Mac software that can export with alpha channels to .avi?
Thanks!
Michael Barrett
Sr. Broadcast Designer -
2 Replies
-
Unfortunatelly you are right. I have the same results. No problem with 500×500, but with 150×150 – complete mess. There is not only alpha issue, but also the size has changed. Instead of source 150×150 – it’s 260×259.
???
The solution I found is to export AVI straight from AE. Make a composition of required size, and instead of adding it to render queue, just hit file – export, choose AVI, compression – none, millions of colors+ and go.
It works fine.
After Effects CS3.Bartek Skorupa
Warszawa, Poland -
Bartek,
Thanks for checking this out. Exporting the AVI out of After Effects CS3 totally solves the problem. Thanks for the info and response. There is still the basic problem that remains unresolved with Quicktime Pro 7.6 that should probably be reported to Apple, but I’m not sure where or how. If anyone knows where to send Quicktime Mac bugs in version 7.6 to, we should probably forward the links to this thread for fixes in future releases. Again, thanks for your help Bartek.
Michael
Reply to this Discussion! Login or Sign Up