[FFmpeg-user] Levels and Primaries

Thomas Worth dev at rarevision.com
Thu Feb 13 13:55:58 CET 2014

On Thu, Feb 13, 2014 at 12:45 AM, Robert Krüger <krueger at lesspain.de> wrote:
> Did you file bug reports with reproducible cases were you had
> incorrect numbers (just asking, no subtext intended)? I mean it is
> completely legitimate to come to the conclusion to do it yourself and
> build a product upon that competitive advantage but I would be
> surprised if such a bug report proving that swscale did indeed produce
> incorrect numbers (which may very well be the case) would be ignored
> but I may be wrong here.

To be honest Robert, I brought this up a while back on the list and got
resistance. The issue had something to do with Canon's DSLR cameras using
full-range scaling for H.264 video and FFmpeg doing something weird because
of this. In fact, if you look through the list archives you can probably
find the conversation. I decided it would just plain be a better use of my
time to write my own scaler/color space converter to do exactly what I
needed rather than to try to convince others of the value in fixing these

I'll just add that there are issues beyond this color thing with FFmpeg
that unfortunately make it unsuitable for film work, primarily because its
output many times doesn't match what professional programs are generating.
I've had to rely on Apple's AVFoundation API for file writing, which I
would rather not do since I lose portability but that's the only reliable
option at this point. I suspect issues like these are what caused Baptiste
to fork. He is also here in Los Angeles and very likely works with film
industry people so perhaps his priorities differ from those of the general
FFmpeg population. In any case, I believe changes can be made to the
swscale and avformat libs that would make it much more useful to us. It
might even be worthwhile to request some guidance from Baptiste since he's
already done much of the legwork and is familiar with the codebase. And
I'll help in any way I can if there's genuine interest from the FFmpeg crew.

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