[FFmpeg-devel] [PATCH] VP8 de/encode via libvpx

[Uoti Urpala]

On Thu, 2010-05-20 at 10:12 +0200, Diego Biurrun wrote:
> On Wed, May 19, 2010 at 02:28:10PM -0400, James Zern wrote:
> > 
> > --- /dev/null	2010-02-26 16:50:52.000000000 -0500
> > +++ libavcodec/libvpxdec.c	2010-05-17 23:46:16.000000000 -0400
> > @@ -0,0 +1,168 @@
> > + * 
> > + *  Subject to the terms and conditions of the above License, Google
> > + *  hereby grants to You a perpetual, worldwide, non-exclusive,
> > + *  no-charge, royalty-free, irrevocable (except as stated in this
> > + *  section) patent license to make, have made, use, offer to sell, sell,
> > + *  import, and otherwise transfer this implementation of VP8, where such
> > + *  license applies only to those patent claims, both currently owned by
> > + *  Google and acquired in the future, licensable by Google that are
> > + *  necessarily infringed by this implementation of VP8. If You or your
> > + *  agent or exclusive licensee institute or order or agree to the
> > + *  institution of patent litigation against any entity (including a
> > + *  cross-claim or counterclaim in a lawsuit) alleging that this
> > + *  implementation of VP8 or any code incorporated within this
> > + *  implementation of VP8 constitutes direct or contributory patent
> > + *  infringement, or inducement of patent infringement, then any rights
> > + *  granted to You under this License for this implementation of VP8
> > + *  shall terminate as of the date such litigation is filed.
> 
> Ah, so the patent grant only covers this implementation!  Once we come
> up with our native and faster decoder, we will be liable again.  Good
> job Google!
> 
> Also note the language about "necessarily infringed" - if Google comes
> up with some clever tricks to speed up this implementation tenfold and
> then go on to patent it, you are *not* granted a license.  You can,
> after all, implement VP8 the slow way...

Well what else would you expect such a patent license to say? It could
hardly specify that it'd cover any patent in any code whatsoever as long
as that code managed to decode VP8 as one of its functions.

However having that license text in FFmpeg code could be a problem. It
talks about Google granting a patent license for "this implementation of
VP8". The code is glue code and it's questionable whether it can be said
to really "implement VP8". And more importantly it could be changed and
distributed by parties other than Google. "This implementation" becomes
a questionable term after modifications by people not associated with
Google - after all Google probably doesn't intend their patent grant to
cover all code that could possibly be placed in the same file by anyone
else.