[FFmpeg-user] HD > SD Down-Convert Prores Color

Kevin Wells kevwells at hotmail.co.uk
Fri May 15 17:29:18 CEST 2015

> Date: Fri, 15 May 2015 15:04:54 +0100
> From: kevin.j.wheatley at gmail.com
> To: ffmpeg-user at ffmpeg.org
> Subject: Re: [FFmpeg-user] HD> SD Down-Convert Prores Color
> I should have paid more attention to your command line, in that case
> you are going between the same pixel format and I'm not sure that the
> use of the scalar for converting between different colour difference
> encodings will actually do anything as I believe it only considers
> using the matrices if the pixel formats go between a difference
> encoding and RGB.
> Going between two encoded video signals you might have to use the
> colour matrix filter, to get 'correct' behavior.
> Still won't stop some decoders making assumptions, though.
> Kevin
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Hi Kevin, that is what I started this thread with:

ffmpeg -i HD_BARS.mov -map 0:v -vf colormatrix=bt709:bt601,scale=720:576:flags=lanczos -vcodec prores -profile:v 3 -vtag apch -vendor ap10 -f mov SD_BARS.mov

Which produces lots of tiny artefacts, hard to see normally, but easily seen when you apply a gamma filter and turn it up.


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