[XviD-devel] License/legal discussions

charact3r charact3r at yahoo.com
Tue Dec 2 06:47:30 CET 2003

Hello gruel,

My understanding is different to yours:

> GPL forbids to include algorithms that are under
patent, unless they are
> free to use for everybody. 

GPL does not forbid the inclusion of patented
algorithms.  You can incorporate as many patented
algorithms as you like and still distribute under GPL.
 GPL is just a way of saying "I give you permission to
do X with my code provided you do Y".   You might into
trouble with the patent holders for saying this, but
that's a different matter. 

Clause 7 of the GPL just reinforces the point that if
you have other obligations that conflict with your
obligations under GPL, then you do not have an excuse
to break the GPL rules.  Example:

Let's say I want to use xvid in a computer game.  I go
to MPEGLA and they sell me a bespoke MPEG-4 patent
license which necessarily has a whole list of
conditions attached, including restricting the number
of copies I am allowed to produce.  When I come to
release my game I am in an impossible situation.  GPL
requires me to permit unlimited redistribution under
GPL.  MPEGLA requires that I place restrictions on
distribution and use.  I can't satisfy both sets of
constraints -- so I can't use xvid.

> There isn't anything about "paying for
> users" or so. 

No, but that's the practical upshot.  One way to break
out of the situation described above is to pay the
licensor a huge wad of $$$ and effectively buy the
patent(s).  Not going to work with MPEG-LA.

BTW, of course you were right on the GPL licensing of
the source.  My mistake.

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