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

Kieran O Leary kieran.o.leary at gmail.com
Wed Jul 25 16:10:08 EEST 2018


Hi,

On Thu, Feb 22, 2018 at 4:15 PM, Philip Langdale <philipl at overt.org> wrote:
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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.
>

I am hoping to test out this patchset in the hopes that it could
rectify the issue we're having with colour metadata in a MOV/ProRes
file not being migrated over to Matroska:
https://ffmpeg.org/pipermail/ffmpeg-user/2018-July/040717.html

I have two questions as I'm a bit confused:
1. Does this patchset require Paul's patchset to be merged? I can't
tell if it has already or not.
2. I see that this thread describes a series of 4 patches, but there
also seems to be
a set of three patches from February - do the set of 3 supercede this
set of 4? https://patchwork.ffmpeg.org/patch/7694/

Best,

Kieran O'Leary
IFI Irish Film Archive


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