[FFmpeg-devel] Reintroducing FFmpeg to Debian

[wm4]

On Fri, 8 Aug 2014 15:06:20 +0100
Alessio Treglia <alessio at debian.org> wrote:

> Hi,
> 
> On Fri, Aug 8, 2014 at 12:13 PM, Matthias Urlichs <matthias at urlichs.de> wrote:
> > That leaves the question of the "official" opinion of the libav
> > maintainers (pkg-multimedia-maintainers at lists.alioth.debian.org).
> > Did none of them write anything in "defense" of libav, or have I simply
> > missed it?
> >
> > IMHO the best idea at this point would be to toss out libav, and rebuild
> > the rdeps with ffmpeg. Now, before it's too late for jessie.
> 
> This is an eminently bad idea. As I said before, it's too late for
> Jessie already.
> 
> Many Jessie's multimedia framework and packages have been developed
> and QA'd with libav.
> 
> We've spent a lot of time over the past months talking to upstreams,
> forwarding them our patches and make sure their programs and libraries
> work with libav.
> We've spent ***months*** in making the whole thing work, and dropping
> libav in favour of FFmpeg at this point, roughly few weeks from the
> freeze deadline, would be definitely insane.

I'm very interested in why packages would work with Libav, but not with
FFmpeg. I know for a fact that FFmpeg API is more compatible in general
(deprecated functionality is generally kept longer than in Libav, not
all API Libav removed is removed from FFmpeg). And also, FFmpeg's API
is a superset of Libav. So it could happen that a project doesn't work
with Libav because it uses FFmpeg-exclusive API, but not the other way
around.

The only real incompatibilities I know are:
- avfilter_graph_parse() function signature (can be fixed with some
  ifdeffery)
- libavresample disabled by default (FFmpeg being trapped by their own
  bullshit, wonderful)

Also, if does happen that software written for Libav works with the
latest Libav release, but not the latest FFmpeg release. This is simply
because Libav doesn't release as often, which increases the likelihood
that this project didn't update to newer APIs yet. But since Libav 10
was released relatively recently, and Libav 11 is planned to be
API-compatible, that should not be an issue currently.