Hello everyone,
I was doing a little experimenting with MLT and ran into the following
problem: both the affine and composite transitions do not seem to follow
proper alpha handling. Industry standard in video is to use premultiplied
alpha, however these two transitions seem to expect straight alpha. To use
an example: I have a few clips (QTRLE with alpha) that I want to combine
using the composite transition with a "background" clip that has all-solid
alpha. What i get is this:
http://s30.postimg.org/60jrz8qpt/alpha_black_outline.jpg
However, I should not get these black outlines around the edges. I think
this is because the mixing done by the affine and composite transitions
seems to assume, that the source is "straight alpha".
Am I doing something wrong, or is this just a weak spot in MLT? This would
seem like something that needs fixing, as this affects everything that
doesn't use fully opaque or fully transparent alpha.
I would really like to fix this, however I would like some clarification:
the composite transition works line by line and the SSE2 acceleration is
only used for "Over" (default) line compositing function, correct? So if I
wanted to fix it, what I would need to do is create a new line compositing
function, right?
I hope this is not an issue that has already been covered, however I found
no such mention in the list archives.
Kind regards,
Jan Starzak
------------------------------------------------------------------------------
Learn Graph Databases - Download FREE O'Reilly Book
"Graph Databases" is the definitive new guide to graph databases and their
applications. Written by three acclaimed leaders in the field,
this first edition is now available. Download your free book today!
http://p.sf.net/sfu/NeoTech
_______________________________________________
Mlt-devel mailing list
Mlt-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mlt-devel
