[FFmpeg-devel] [PATCH 6/6] lavfi: make AVFilterLink opaque in two major bumps.

Michael Niedermayer michael at niedermayer.cc
Sun Dec 18 23:33:35 EET 2016

On Sun, Dec 18, 2016 at 07:41:14PM +0100, Nicolas George wrote:
> L'octidi 28 frimaire, an CCXXV, Michael Niedermayer a écrit :
> > How does this patchset relate to the open-ness of the API ?
> > you arent saying anything about the plans, goals, intend of this (or
> > i missed it or fail to associate it with the patchset)
> I am doing this to accommodate people who object to having a different
> view of AVFilterLink for the public API and the internal implementation,
> mostly Hendrik, Andreas and Clément.
> As for me, I am pretty happy with the current code that gives a
> different view of AVFilterLink to the public than the one used for
> implementation. Something like that is needed because some fields have a
> type that is not itself public.
> > Iam asking as it seems like this is moving libavfilter further away
> > from being "open" and centralizing control over filters more.
> > I most likely misinterpret this as i just see the change in the code
> > and dont know the whole story but IMO we should move toward a clean and
> > stable API that everyone can use.
> > That also implies to allow filters to only use public API.
> > while this patchset seems to make filters use more private api by
> > making more needed API private. I think a open API and external
> > filter support would drive developers and users towards libavfilter
> > while locking it down would likely do the opposit

> I am not sure I understand what you mean by openness. Do you mean
> applications writing their own filter and inserting it in a filter
> graph?

yes and ideally also installable filters like plugins
but really plugins are IMHO not hard, having an API that one can
access is the imortant part. Even without a true plugin API other
apps or users could link in filters build from a seperate package
quite easily

> If so, I can tell you it is not currently possible, and has not
> been since at least 2012-06-12 (9d0bfc5 lavfi: make AVFilterPad opaque
> after two major bumps.).

i know, but at the time all this closing down of the API happened it
was said that this was temporary (not by you and i dont remember who
said so and not limited to libavfilter) and now over 4 years later
temporary seems to be changing into the permanent end.

IMHO if you want libavfilter to be a success in the long term it needs
to be a open system with clean API that anyone can use and add filters

As it is libavfilter is limited to what ffmpeg developers want INSIDE
ffmpeg. If a filter doesnt fit into that it will likely be rejected.
Which makes sense if there are external filters / plugins. But if the
only way to use a filter in libavfilter is through it being accepted
into main ffmpeg git that just makes libavfilter unfit as a _general_
filter framework.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
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