2017-07-31 14:00 GMT+02:00 Paul B Mahol <one...@gmail.com>: > On 7/31/17, Jon bae <jonba...@gmail.com> wrote: > > 2017-07-31 10:30 GMT+02:00 Paul B Mahol <one...@gmail.com>: > >> > >>> > >>> What exactly you tried? > >>> > >>> Perhaps you want premultiply filter? > >>> > >>> Yes I have a video and a lower third, and I want to overlay the lower > >> third. But my alpha channel from the lower third is not pre-devided with > >> the alpha channel, so I need to do a channel division in ffmpeg. > >> Something like: > >> > >> ffmpeg -i video.mp4 -i lowerthird.png -filter_complex > >> [1:v]geq=r=r/a:g=g/a:b=b/a[gq];[0:v][gq]overlay ... output.mp4 > >> > >> I see that you wrote a filter for this, but can you please give me an > > example of how it works? I don't get it to run. > > "I don't get it to run" means nothing to me. > > I'm not sure if I use the filter correct... But with this:
ffmpeg -i video.mp4 -i image.png -filter_complex "[0:v]format=rgba[a];[1:v]format=rgba[b];[a][b]premultiply" My result is, that everything what had alpha = 0, in my image, is now black. Mybe I understand the use case wrong, but how you would use this filter? _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
