Bug#698019: libav: the effective GPL-licensed status of the binary packages should be clearly documented

Francesco Poli invernomuto at paranoici.org
Mon Jan 14 22:45:56 UTC 2013

On Mon, 14 Jan 2013 11:13:48 +0100 Jonas Smedegaard wrote:

> Quoting Charles Plessy (2013-01-14 02:55:38)
> > On Sat, Jan 12, 2013 at 11:43 PM, Francesco Poli (wintermute)
> > > > 
> > > > I think that the effective licensing status of the binary packages 
> > > > (GPL-2+ or GPL-3+) should be explicitly and clearly documented in 
> > > > the comment at the beginning of the debian/copyright file and, 
> > > > probably, in the binary package long descriptions, as well.
> > 
> > Le Sun, Jan 13, 2013 at 09:50:58AM +0100, Reinhard Tartler a écrit :
> > > 
> > > I am not happy at all with cluttering the binary package description 
> > > with license blabla. I would do so only as last resort
> > 
> > Dear Reinhard, Francesco and everybody,
> > 
> > I think that the Debian copyright file of libav 6:9.1-1 is clear 
> > enough with its comment in the header, and that it is best to keep the 
> > license information out of the description of the package.
> Newest progress(?) on this is commit e3731d with this commit message:
> > Document all licensing of binary packages in README.Debian (not partly 
> > as comment in copyright file), to avoid confusing source
> That change has not yet released but sits in our VCS.  Could you please 
> comment on that?
> Sorry, I can't figure out how to reference it at our public anoncms URL, 
> but it is commit e3731d at git.debian.org:/git/pkg-multimedia/libav .

I think it is:

And the commit diff is:

I am not too convinced this is a progress: it's true that it
consolidates all the considerations about the effective licenses of the
binary packages in one place. This is indeed good.
But I think it chooses an unfortunate place: not where I would look at,
when searching for licensing information...

I am afraid that those useful considerations would be read by very few
interested people, as long as they are buried deep in a README.Debian

> > Note that the machine-readable format also allows License fields in 
> > the header paragraph to give the license information for the package 
> > as a whole.
> I am aware of that.  But I am not convinced that *any* of the licensing 
> formally covered by the copyright file format 1.0 are about the 
> licensing of _binary_ packages.  It is my understanding that they all 
> are about sources only, not effective reasoned licenses.

This is generally true, as far as I know, in the sense that only the
licenses for the source files are _required_ to be documented in a
debian/copyright file.
But I think that some additional considerations about the effective
licenses of binary packages are not forbidden, if placed in a Comment

Since currently there is no better place (at least, not one I am aware
of) to carry these considerations and since I am convinced that such
considerations are important, I still think that the comment should be
kept in the debian/copyright file and clarified.

Something along the lines of

| The effective license for all the binary packages is the GPL, not the
| LGPL, because GPL-licensed parts of ffmpeg were enabled and some binary
| packages link against GPL-licensed libraries.
| Additionally, some binary packages directly or indirectly link against
| libraries that are licensed under the Apache License v2.0: these binary
| packages are effectively distributed under the GPL v3 or later (rather
| than GPL v2 or later).
| Binary packages under GPL-2+ :
| libav-doc (apart from one stylesheet under Apache-2.0),
| libav-source, libavcodec-dev, libavutil-dev, libavutil*, libavcodec*,
| libavresample*, libavresample-dev, libswscale*, libswscale-dev
| Binary packages under GPL-3+ :
| libav-tools, libavcodec-extra-*, libavdevice*, libavdevice-dev,
| libavformat*, libavformat-dev, libavfilter*, libavfilter-dev
| Transitional packages :
| ffmpeg-doc, libavdevice-extra-*, libavfilter-extra-*,
| libavformat-extra-*, libavutil-extra-*, libswscale-extra-*
| The libav-dbg package includes debug symbols from all the other
| packages.

Please fix any inaccurate part, of course.

In http://bugs.debian.org/694657#120 you say:

[to determine effective licensing of binary packages]
> One needs to examine the combined licensing of all parts of the chain - 
> which is a huge job, I agree.  First step in imporving that job is to 
> make _source_ licensing machine readable *without* changing anything 
> else, and a later step is to hopefully make a tool that traverses all 
> build-dependencies to warn about potential incompatibilities.

This future scenario is really interesting and desirable, but, although
I am a perfectionist myself, I think we should acknowledge that we have
nothing of the kind right now.
Hence, while striving to achieve that great goal, we should implement
an admittedly imperfect solution to enhance the current situation for
the libav package.
In Italy we have a proverb that says "Il meglio è nemico del bene",
which more or less translates into "The perfect is the enemy of the

I hope I clarified my opinion.

 New GnuPG key, see the transition document!
..................................................... Francesco Poli .
 GnuPG key fpr == CA01 1147 9CD2 EFDF FB82  3925 3E1C 27E1 1F69 BFFE
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