Re: [FFmpeg-devel] [PATCH] lavfi: protection against premultiplied alpha (was: The patch series about premultiplied alpha)

From: Nicolas George <george@nsup.org>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] lavfi: protection against premultiplied alpha (was: The patch series about premultiplied alpha)
Date: Tue, 5 Aug 2025 11:05:54 +0200
Message-ID: <aJHJchHFpWBZVJWU@phare.normalesup.org> (raw)
In-Reply-To: <20250805105119.GD219179@haasn.xyz>

Niklas Haas (HE12025-08-05):
> I will repeat myself briefly here that such a flag should be an opt-out, not
> an opt-in. Supporting premultiplied alpha should be the default assumption
> unless provable otherwise.

Absolutely not.

Do you dereference a pointer when you can prove it cannot be NULL or
when you cannot prove it can be NULL? It is the same: if you cannot
prove a filter produces a valid result, then we protect by default. It
is already too much that it is not blocking when it is unspecified. On
this I will stand firm.

> On a side note, I don't think it's necessary to add a new "default" struct
> just for one particular combination of flags;

Of course it is not necessary, it just makes a dozen other patches much
much shorter.

>						especially not if your intention
> is (as you state) to have such flags for every other AVFrame property.

It does not make it either harder nor easier.

-- 
  Nicolas George
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