[FFmpeg-devel] [PATCH 1/3] avfilter: Add support for colour range as a link parameter

[Philip Langdale]

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On Thu, 22 Feb 2018 12:39:16 +0100
Nicolas George <george at nsup.org> wrote:

> Philip Langdale (2018-02-21):
> > Negotiation is part of Paul's larger changeset, and will be a useful
> > feature. My change is still a strict improvement over the current
> > state of the world - where range is not propagated at all,
> > regardless of compatibility. In those situations where negotiation
> > is required, the status quo will essentially continue, with the
> > range value not accurately reflecting the frame contents.  
> 
> I am not comfortable with what you write here.
> 
> I am afraid that adding negotiation on top of this would be more work
> than adding negotiation on top of the current code.
> 
> I am also afraid that an incorrect value is worse than an unspecified
> one.
> 
> But it all depends on what filters and codecs actually do with the
> color range, and that I do not know.
> 
> Could you perhaps make a little summary of that issue: where the color
> range comes from, which filters and encoders do not care, which ones
> only work with one, which ones do something special with it? Maybe as
> a longer doxy comment for enum AVColorRange in libavutil/pixfmt.h?

You can go back and read through Paul's patchset from december, which
implements negotiation. My changes here are a strict subset of those,
so empirically, merging this subset on its own does not make
negotiation harder. You are also welcome to recommend merging his full
patchset now; it never got the reviews it needed, but that doesn't mean
it can't.

Thanks,

- --phil
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