2

I'm trying to convert a video file exported from Blackmagic Fusion as DNxHR with Alpha checked to WebM or PNG. FFMPEG seems to ignore the alpha and the background is black. Is there something I need to do? This is what I'm currently using:

ffmpeg -ss 0.5 -i DNxHR444A.mov -vframes 1 test.png

or

ffmpeg -i DNxHR444A.mov -c:v libvpx-vp9 -crf 30 -b:v 0 test.webm

I can upload my test video if that helps. But it's quite large.

Andy Jazz
  • 49,178
  • 17
  • 136
  • 220
Castles
  • 897
  • 1
  • 10
  • 29

1 Answers1

1

FFmpeg's DNXHD/R decoder does not support alpha. Either use another codec on export, or export alpha separately (it will be a grayscale picture). With the 2nd method, ffmpeg can combine the main image and the alpha for onward processing.

Gyan
  • 85,394
  • 9
  • 169
  • 201
  • Thanks. I've managed to get it working using your suggestion and this post: https://stackoverflow.com/a/46937409/313272 – Castles Aug 28 '18 at 01:02