Bug#694657: closed by Reinhard Tartler <siretart at tauware.de> (Bug#694657: fixed in libav 6:9.1-1)

Jonas Smedegaard dr at jones.dk
Wed Jan 9 20:10:06 UTC 2013

Hi Francesco,

Quoting Francesco Poli (2013-01-09 19:18:02)
> On Wed, 09 Jan 2013 06:51:10 +0000 Debian Bug Tracking System wrote:
> [...]
> >    [ Jonas Smedegaard ]
> >    * Rewrite copyright file using copyright format 1.0.
> >      Closes: bug#694657. Thanks to Francesco Poli.
> You're welcome, Jonas!
> Thanks to you, indeed.
> I have a question, though.
> At the beginning of the new debian/copyright file, I read the following
> comment:
> | Comment:
> |  Because the libavcodec-extra-* package (since libavcodec-extra-54)
> |  links against libraries licensed under Apache-2.0 (not compatible with
> |  LGPL), effective license of that package and libav-dbg is GPL-3+.
> This does not look too clear to me.
> Which license is the libavcodec-extra-* package released under?
> LGPL-2.1+ or GPL-2+ ?

GPL-2+.  I fail to understand how that can be misunderstood from that 

> By looking at the rest of the debian/copyright file, it seems to me
> that the answer is LGPL-2.1+ : can you confirm, please?

What a debian/copyright file covers is _source_ licensing.  That's why 
it is merely a comment.

The effective license of a binary package is that license among the many 
many licenses involved in that binary work which is compatible with all 
the other ones.  This not only involves the source parts of that same 
project, but also the parts linking in during build.  So even if you 
cannot find a single GPL-3+ licensed piece anywhere in this project, the 
very purpose of libavcodec-extra-* (as compared to libavcodec-*) is to 
link against GPL-licensed parts.

...and even if none of those _other_ GPL-licensed parts are explicitly 
GPL-3+, ome parts are Apache-2.0 which is incompatible with GPL-2, 
rendering GPL-2+ licensed parts essentially equal to GPL-3+.

Whew.  Hope that whole pile made sense. :-)

> If this is really the case, then, although it's true that Apache-2.0 
> is not compatible with GPL-2, I don't think it's accurate to say that 
> Apache-2.0 is not compatible with LGPL...

Correct.  One need to check the long description and build-dependencies 
of libavcodec-extra-* to get an epiphany here.

> Moreover, why should the effective license of the libavcodec-extra-* 
> package be considered GPL-3+ ?

How is this question different from the previous parts?

> This seems to imply that I cannot distribute a program under a 
> GPL-3-incompatible license (for instance, BSD-4-clause) linked with 
> libavcodec-extra-*: I don't see any reason why such a program should 
> be considered as legally undistributable...

Not sure what you are trying to say here.

It is legal to distribute libavcodec-extra-* and it is legal to 
distribute GPL-3-incompatible code.

Purpose of that comment is to make (developer) users aware that despite 
Licenses listed in this copyright file, that binary package (and the 
-dbg package) has been "infested" with strong copyleft licenses.

> Please clarify the situation, and let's see whether we can find a 
> clearer formulation for the above-quoted comment.

I don't mind us discussing it here, but do find this a different matter 
than the issue you filed this bugreport about.

Kind regards,

 - Jonas

 * Jonas Smedegaard - idealist & Internet-arkitekt
 * Tlf.: +45 40843136  Website: http://dr.jones.dk/

 [x] quote me freely  [ ] ask before reusing  [ ] keep private
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