> 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. Martin _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
