[FFmpeg-devel] GPL version matter

Michael Niedermayer michaelni
Sun Jul 1 19:43:31 CEST 2007


On Sun, Jul 01, 2007 at 08:08:06PM +0300, Uoti Urpala wrote:
> On Sun, 2007-07-01 at 17:31 +0100, M?ns Rullg?rd wrote:
> > Actually, I believe that is exactly what they want.  They are
> > desperately holding on to the notion that by making patented
> > algorithms incompatible with the license, people will choose to
> > implement a different algorithm rather than use another license.
> > Of course reality is quite different from their utopian visions.
> Bullshit. The FSF is well aware that it's impossible in practice to
> write a program without violating a patent, and all programs are
> strictly speaking illegal in jurisdictions that allow software patents.
> The GPL is not meant to exclude programs covered by patents.

it is, and the FSF is claiming that even the (L)GPL2 is fundamentally
incompatible with patents, to quote carlo piana (FSF europe lawyer)
though he wrote the text below as lawyer of some company and not the
There is a short reply, for sure, but it would take too long. So here's
the long story.

The coexistence of sw patents and GPL/LGPL is very hard. Let's talk only
of LGPL, but the difference is tiny, as the LGPL differs from the GPL
mainly because of a weaker copyleft effect. i.e., what is considered a
derivative (which is a big issue, because one should remember that LGPL
was designed for libraries, not for fully working software applications).

As a rule of the thumb, you cannot take LGPL'ed code X, making changes
that are subject to a patent and distribute it under LGPL conditions.
That would be a copyright violation, or would it be claimed so with
sound grounds by the copyright holders of the original code. Despite
there is no patent retaliation clause in LGPL v.2, passing along a
modified version which the original author is not entitled to use unless
he takes a patent license, turns the Free Software "consideration" into
a "sham". So if you yourself have special rights to use the patented
principle and knowingly use the principle while relying on a special
clause of exemption, in order to be compliant you should make sure that
anybody in the downstream market has a free/gratis equivalent clause of
exception. The language of LGPL is quite clear:

    *11.* If, as a consequence of a court judgment or allegation of
    patent infringement or for any other reason (not limited to patent
    issues), conditions are imposed on you (whether by court order,
    agreement or otherwise) that contradict the conditions of this
    License, they do not excuse you from the conditions of this License.
    If you cannot distribute so as to satisfy simultaneously your
    obligations under this License and any other pertinent obligations,
    then as a consequence you may not distribute the Library at all.
    *For example, if a patent license would not permit royalty-free
    redistribution of the Library by all those who receive copies
    directly or indirectly through you, then the only way you could
    satisfy both it and this License would be to refrain entirely from
    distribution of the Library*.

IANAL, but the claim above is baseless IMHO, but it shows very nicely
what the FSF wants to achive, that is make the *GPL fundamentally
incompatible with patenets, and thats exactly what they did in the *GPL3

the GPL3 clearly says:
  If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients.  "Knowingly relying" means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient's use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.

to me this means, if you distribute ffmpeg and signed a patent license then
you must ensure that the source is available to anyone free of charge
under this patent license

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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