why libva over ffmpeg

Reinhard Tartler siretart at tauware.de
Sun Dec 25 11:01:51 UTC 2011

On Di, Dez 13, 2011 at 19:34:05 (CET), Andres Cimmarusti wrote:

> Mmm. Forgive me for pressing the issue, why did Debian chose libva
> over ffmpeg? I've read the "history" behind the libva fork. It seems
> one of the main issues was that to get patches and/or features into
> ffmpeg was very very hard. They had to be the perfect solution or they
> would otherwise be rejected by the project leader. It feels
> counter-intuitive now, with the fork, that they release less often...
> meaning less features...

I agree that there is a lot of confusion going on here. First of all,
please keep in mind that FFmpeg is not the project that it used to be a
year ago. With the fork, the majority of the more conservative
developers, including me, went to create Libav. FFmpeg on the other hand
started to develop in a way more aggressive way.

> Don't get me wrong, from what I've read, I side more with the stance
> of the libva developers, but Debian has always been very pragmatic
> about many of its decisions.
>> To be honest, I also begin to wonder more and more. Sure, version
>> numbers are all hollow words, but it appears to me that the original
>> ffmpeg project is more vital than its fork - at least in term of
>> releases.

I can assure you that Libav is much more a continuation from what FFmpeg
used to be compared to what it is now.

> I agree version numbers mean nothing, but what about number of
> features? I'm not well versed in the many uses of ffmpeg/libav, so
> when reading the changelogs between versions I get no feeling for how
> their features compare. I'm asking the mailing list for this.

Well, are you talking about point releases of release branches or of the
latest new features in the respective 'master' branches?

As for the point releases, if you look at the (admittedly much more
frequent) FFmpeg point releases, you also see a much larger amount of
non-security related changes. I cannot follow most of these changes,
mostly because of very terse descriptions. I do not know if they are
terse on purpose so that I as Libav release manager have a hard time to
assess them or if it is just carelessness. In any case, to me that alone
is a reason to prefer the Libav point releases.

As for the 'master' branch, in my experience, all new important features
are developed in Libav trunk properly first. While FFmpeg indeed gets
more drive-by contributions (and they sell them as features that make it
superior to Libav), please note that Libav developers regularly review
them and integrate improved versions on a regular basis. Sure, FFmpeg
merges all change of Libav each day, but the diff between the forks is
constantly growing, and these differences get more complicated (and
therefore, more error-prone) each day. I conclude that Debian is still
much better off with Libav anyways.

> In any case, why has the name ffmpeg been kept?, shouldn't it all
> renamed to libav? (I'm aware some of the packages are already).

That's a rather ugly story that includes a lot of mud-throwing. Please
let's not re-iterate the details. Suffice to say that from the Debian
POV, tracking Libav instead of FFmpeg is the more conservative choice.

> I understand the debian multimedia maintainers is probably a group
> composed mainly of volunteers, and thus have very limited time, but
> have you consider packaging both ffmpeg and libav? and give the user
> the freedom to choose?

While that indeed sounds like the right decision if it was about the
front-end programs 'ffserver', 'ffplay', 'ffprobe' and 'ffmpeg' only, I
fear that won't be possible for the shared libraries. While sharing the
same SONAMEs, the two forks are not binary compatible, which means that
each package maintainer needs to decide against which fork he wants to
compile his package(s).

I think packaging both FFmpeg and Libav simultaneously would be an
irresponsible situation for both Debian's users and other package
maintainers. Therefore, I'd strongly object to any action that would
lead to have FFmpeg's libraries as shared objects in Debian¹.

I hope this mail clears things up,

Merry Christmas,

1: I know that debian-multimedia.org provides such FFmpeg packages. These
packages are known to subtly break packaged applications in debian, and
I expect this to become much worse for the upcoming 0.8 release. Please
note that we do not accept bug reports for Debian packages that got
broken because of this situation.

Reinhard Tartler, KeyID 945348A4

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