[FFmpeg-user] Levels and Primaries

Robert Krüger krueger at lesspain.de
Thu Feb 13 15:14:42 CET 2014

On Thu, Feb 13, 2014 at 1:55 PM, Thomas Worth <dev at rarevision.com> wrote:
> 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
> problems.


> 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.

As someone working in the exact same area, I would be interested in
the details. The mov muxer does have a few shortcomings indeed (e.g.
colr, clap handling, correct muxing of XDCAM material, used codec
strings, default interleaving patterns differ from apple's muxer) but
nothing, I am aware of, that could not be fixed with reasonable
effort. The question is, what you do if you run into those. Your
option always is to sponsor development. Have you tried that? If not I
would be interested in what kept you from doing that. I am asking this
because there has been a lot of discussion recently about how to make
it easier for companies to sponsor development and you are a perfect
example for someone to whom this should be an attractive option.

> 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

At the moment this does not seem likely as Baptiste has not appeared
in this project for a while. I think it's actually a handful of issues
(I mentioned some of them above) that won't take months to fix if
someone is interested but I may be missing something.

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