Help in rendering in After Effects!

[surferadi96]

I was trying to render a video with an alpha channel(as a pre-keyed footage).
I saved it as a quicktime file with RGB+Alpha(as h.624 doesn't have an option to keep the alpha channel) with the h.624 codec(so as to keep the file size as low as possible).
After the rendering when i used the footage, it didn't have the transparency.
The black background was still there.

Any Suggestion/Solutions ?

[poisondeathray]

What type of quicktime file? There are dozens of different types of compression

Most people using quicktime for RGBA would use "animation" or png in MOV

Did you select RGB+A specifically for the output?

How are you determining that alpha wasn't rendered ? Did you try re-importing the footage into AE (do you have the transparency grid enabled) ?

[surferadi96]

Its a usual .mov file.

Yes, I did select RGB+Alpha specifically for the output.

When i imported the file in AE it appeared with a black background and i tried enabling the transparency grid too,but, that too didn't work.

[poisondeathray]

Did you choose animation codec ? or something else?

You can try other formats, like uncompressed AVI . Even lagarith (lossless compression) supports RGBA.

On windows, AVI is more compatible container than MOV

Are you sure there is alpha in you comp prior to rendering? Do you see the checkerboard background in the transparency grid before rendering ?

(the reason I'm mentioning toggling the transparency grid, is the alpha channel won't be seen in normal media players - it will look black)

[surferadi96]

Did you choose animation codec ? or something else?

You can try other formats, like uncompressed AVI . Even lagarith (lossless compression) supports RGBA....

I chose H.264 under the codec.
Yes the comp does have an alpha and i did check it by toggling the transparency grid switch.

AVI files rendered using AE take a lot of space that is why i don't use that format anymore.
I generally use the h.264 format but since the H.264 doesn't support rendering with alpha i had to choose quicktime.

BTW's
what is your profession !?
Because you have such a HUGE knowledge in this stream!
You always have an appropriate answer to everybody's question!

[poisondeathray]

I chose H.264 under the codec.
Yes the comp does have an alpha and i did check it by toggling the transparency grid switch.

h.264 doesn't support alpha channel

Only a few quicktime formats that support alpha are prores4444, animation codec, png, very few others support alpha

AVI files rendered using AE take a lot of space that is why i don't use that format anymore.

You can use lossless AVI compression , e.g. lagarith , it will cut filesize about 1/2, and still be lossless

I generally use the h.264 format but since the H.264 doesn't support rendering with alpha i had to choose quicktime.

But "quicktime" includes about 100 different types of formats and compressions. h.264 in quicktime doesn't support alpha. That's why its not working for you.

The other options are image sequence (e.g. png + alpha, tiff + alpha)

The only lossy, small filesize format that supports alpha is VP6A in FLV (lowish quality). It's meant for distribution, like in flash videos . You don't want to use this for pre-keyed footage for use in other applications