On 7/31/17, Jon bae <jonba...@gmail.com> wrote: > 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?
Try harder to explain your use case? Like providing input and wanted output images and explaining in more detail how alpha should be manipulated. _______________________________________________ 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".
