[FFmpeg-devel] ProRes 4444 with Alpha Channel

Robert Krüger krueger at lesspain.de
Wed Aug 7 17:41:14 CEST 2013


On Wed, Aug 7, 2013 at 5:29 PM,  <Andy_Copeland at scee.net> wrote:
> Hash: SHA256
> Hi there,
> We are currently investigating an automated process of generating ProRes
> assets from PNG image sequences but need some help with getting the Alpha
> Channel working with ProRes 4444 on FFMPEG.
> We're running FFMPEG on Windows 7 x64 machines and we are sure that the
> Alpha Channel is preserved when the output PNG's are generated from our
> various different pieces of motion graphics software.
> The command we're using is as follows:
> ffmpeg -r 30 -i "c:\Users\<username>\Desktop\Cube Vibrate\results
> \Cube%04d.png" -vcodec prores_ks -profile:v 4444 -pix_fmt yuva444p10le
> - -alpha_bits 8 -acodec copy "c:\Users\<username>\Desktop\Cube Vibrate
> \results\cube_vibrate_10.mov"
> Any help that can be given on this will be SOOOOO appreciated as it's been
> stumping us for a day or so now! I'm pretty sure it's just me being stupid
> - - but want to know for sure!
> Thanks in advance!!
> ac
> Kind Regards,
> Andy Copeland
> Virtualisation Specialist | World Wide Studios Europe
> T. +44 (0)20 7859 0269
> Sony Computer Entertainment Europe Limited.
> http://uk.playstation.com/

this question should rather go to the ffmpeg-user mailing list, so
when you reply to this, it probably makes sense to use or cc to the
ffmpeg-user list (not sure what the correct process is, someone with
more experience?).

Please write what the actual problem is, i.e. what is not working and
then provide uncut console output of your ffmpeg run.

My gut-feeling is that you may be using an older ffmpeg version that
is from the time before alpha support was added to the prores encoder
(not so long ago). AFAIK what you want to do should work. I have
tested preserving alpha from a PNG to an ffmpeg-generated prores file

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