[FFmpeg-devel] avfilter/vf_premultiply : use full range for RGB input

Martin Vignali martin.vignali at gmail.com
Sun Mar 18 14:57:32 EET 2018

> If you pre-multiplty the alpha and then save it as a file, how it is
> supposed to know that you did that? :)
This is a common trouble in post-production, like some software output by
default in premult
and some in straight.

For Mov file, Adobe set an UDTA for alpha.
Never see another way to store this information.

I post a patch (in discussion avformat/mov : add support for read/write
Adobe Alpha Udta)
This patch add support for read and write this metadata.

Maybe we can add support for reading/writing this metadata in
vf_premultiply/unpremultiply filter.

Patch for unpremultiply_offset pushed.


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