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

[Nicolas George]

Niklas Haas (HE12025-08-11):
> I still think this series overall is a step in the wrong direction; and that
> our goal should be to move towards negotiation, and not towards some IMO hacky
> flag that is already deprecated on arrival.

In terms of work, this patch series is 5% trivial code easily removed
and 95% work that is necessary for real negotiation.

Which means this patch series is a step in the right direction anyway.

> However, I decided I would rather just implement the full negotiation at this
> point, to save ourselves the continued discussion; especially in light of the
> TC's inaction / radio silence.
> 
> Can you confirm that, if we implement full negotiation (thus allowing every
> filter to decide for itself which alpha modes it can ingest), your remaining
> your remaining objection to this series would be withdrawn?

Of course. I suspect you widely underestimate the amount of work
necessary for real negotiation, but I would be happy to be proven wrong
on this issue.

As I said multiple time, work on negotiation in libavfilter must start
with adding test coverage to avoid breaking the myriad of corner cases
that have been implemented over the years. I would be happy to review
your patches in this direction. Feel free to take over the old
preliminary ones I had posted a few years ago and never pushed.

But whatever you choose, negotiation or hackish flag, I will stand firm
on the fact that the default must be to protect users from creating
invalid output. 

Regards,

-- 
  Nicolas George