Hello,
I have a prores footage with alpha and I need to apply alpha premultiply rather than straight alpha. How to do it in kdenlive?
Thanks!

Shotcut has an unpremultyply alpha effect which works perfectly, just FYI.

Could you perhaps describe a little more specifically what it is that you are trying to do and what it is that you are not succeeding with Kdenlive?

More preciely:
Kdenlive requires an alpha changing mode in footage properties or an effect to unmult the alpha channel.
In vfx world some footage comes with straight alpha, some come as premulitplied alpha. Kdenlive I guess by default treats all alpha footage as straight alpha.

We got some prores 4444 with alpha, which requires to treat it as alpha premultiplied. Which Kdenlive can't do. Shotcut has an alpha unpremultiplied effect. Which is working perfectly.
The work around was converting the footage to qtrle with PNG.

Oh, I'm afraid I'll have to pass. I see that I had never dealt with this issue.
Let's hope that another user who knows about it will have something to say about it soon. Sorry.

Hi,

There is a frei0r plugin for that : https://www.mltframework.org/plugins/Fi ... emultiply/ but it has been blacklisted in Kdenlive in the category "# WORKING BUT NEED CHECKS"
https://invent.kde.org/multimedia/kdenl ... s.txt#L174

Could you compile Kdenlive with this line removed and test it with your footage ?

Cheers,
Camille

kde-camillem wrote:Hi,

There is a frei0r plugin for that : https://www.mltframework.org/plugins/Fi ... emultiply/ but it has been blacklisted in Kdenlive in the category "# WORKING BUT NEED CHECKS"
https://invent.kde.org/multimedia/kdenl ... s.txt#L174

This one should work. Shotcut is using it. Will compile it after finishing the project. Thanks.

mickae wrote:Oh, I'm afraid I'll have to pass. I see that I had never dealt with this issue.
Let's hope that another user who knows about it will have something to say about it soon. Sorry.

Maybe these links help:
http://dvd-hq.info/alpha_matting.php
https://en.wikipedia.org/wiki/Alpha_compositing

kde-cgvirus wrote:

kde-camillem wrote:Hi,

There is a frei0r plugin for that : https://www.mltframework.org/plugins/Fi ... emultiply/ but it has been blacklisted in Kdenlive in the category "# WORKING BUT NEED CHECKS"
https://invent.kde.org/multimedia/kdenl ... s.txt#L174

This one should work. Shotcut is using it. Will compile it after finishing the project. Thanks.

Did a quick test and it seems to work fine. Would you like to send me some sample footage that you are using for me to test?

frdbr wrote:

kde-cgvirus wrote:

kde-camillem wrote:Hi,

Did a quick test and it seems to work fine. Would you like to send me some sample footage that you are using for me to test?

Here is a test file
https://drive.google.com/file/d/1nzrN2K ... sp=sharing

kde-cgvirus wrote:https://drive.google.com/file/d/1nzrN2K ... sp=sharing

Looks fine right?

https://imgur.com/a/k7j4Kjl

frdbr wrote:

kde-cgvirus wrote:https://drive.google.com/file/d/1nzrN2K ... sp=sharing

Looks fine right?

https://imgur.com/a/k7j4Kjl

Yes, this is exact. Thanks for checking it out!

Issue Created:
https://invent.kde.org/multimedia/kdenl ... ssues/1381