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

[Robert Nagy]

On a side note. Shouldn't ffprobe also report the detect alpha mode if
the decoder/container supports it?

On Tue, Aug 5, 2025 at 11:16 AM Nicolas George <george at nsup.org> wrote:
>
> Nicolas George (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.
>
> Just an extra point:
>
> Imagine we had done it opt-out as you suggest, and you were looking at
> the list of >300 video filter source files.
>
> Would you have thought to set the opt-out flag to drawbox?
>
> I know you have the integrity to do so, so please take the time to think
> about it and answer honestly.
>
> Regards,
>
> --
>   Nicolas George
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