To export video files with alpha channel in FCP7

[David Rowan]

This is the formula I use to export a clip from FCP7 with an alpha.

Change the timeline to the “Animation millions of colors +” codec. It can be any size or aspect ratio.

Do not render the timeline.

Export Quicktime as “Self-contained” but do not render all frames.

The final product will be a video clip in the animation codec where all the transparencies have been preserved by alpha channels.

Keep in mind that the animation codec is very large and demanding. Only very powerful systems can play it smoothly, if at all. I use this when creating a video element that I am going to edit in over other video repeatedly (Such as an animated corner “bub”)

DWR

[Pablo s. Herrera]

Hello Dave,

Thanks for your help, to answer your question, effectively the problem is the high bit rate, the server is unable to play it smoothly, in fact it hangs because the material is quite large …

I was hoping there was any other codec or format that would allow me to do, at least try it, but I have to keep doing chroma key, with the nasty problems that presents the keys at live events…

Thanks again for your time.

Pablo S. Herrera
Senior Editor
Espacio Virtual – Bogotá, Colombia

[Peter Hall]

Thank you David, yours was the only post that mentioned “not to render” in order to preserve alpha channel, the only post here that worked for me to enable me to use some Motion 3D text barrells around from front to behind some small images. Looks like I will have to finish that project in Motion. Thanks again for valuable tips.

Peter Hall

[Ken Seehart]

Seems like everyone, including myself, dreams of good compression in a codec that supports alpha channel. I’m not a video expert, but I can’t think of any technical reason why alpha channel support is so poor in the industry. Certainly I would expect the alpha channel to have favorable statistical properties for compression (e.g. correlations with nearby pixels and with color channels).

Perhaps certain kinds of lossy compression might cause artifacts if the alpha channel were treated exactly like color, but with hundreds of brilliant engineers, someone should be able to figure it out. I would try myself, but I can’t be an expert in every field 🙂

I’ve always been frustrated by poor alpha support in nearly all graphics libraries as well, where the alpha is handled rather badly (and sometimes not at all).