[Libav-user] License Compliance Checklist

Robin Stevens rdstevens at gmail.com
Sat Jun 27 21:25:17 CEST 2015

On Saturday, June 27, 2015, Info || Non-Lethal Applications <
info at non-lethal-applications.com> wrote:

> Hi,
> > if I read http://ffmpeg.org/legal.html there is #18 which says "Make
> sure
> > your program is not using any GPL libraries (notably libx264)."
> >
> > Could anybody please elaborate on this. How can a caller know if it
> opens a
> > file and tries to decode it, if Ffmpeg uses LGPL or GPL code?
> >
> > I know that Ffmpeg can be built without --enable-gpl resp.
> --enable-nonfree,
> > but what if the user replaces LGPLed shared Ffmpeg libraries with GPLed
> > shared Ffmpeg libraries? Now it could happen that an application -
> without
> > wanting to do so - is using GPL code inside Ffmpeg libraries and thus
> > infringing GPL.
> >
> > What can an application do (mean which Ffmpeg functions can be called) to
> > prevent this?
> I personally wouldn’t consider the improbable cause where a user exchanges
> a shared lib because this is - honestly - not my problem.
> If you are really concerned about this (but I really think you shouldn’t),
> you can put some special notice in your license agreement.
> I don’t know which platforms you’re targeting but on the Mac, I’d just put
> the libs inside my app bundle and make sure that they are loaded from there.
> Only my two cents ...
The GPL only has effect if you distribute software licensed under it.

If someone substitutes your lgpl libs with gpl versions, no distribution
has taken place.

If they were subsequently to redistribute (assuming they had that right in
your software)... Hmmm, that's tricky but I'd suggest they can't do that.

If you give them the right to distribute your software, you should limit it
redistribution of an unmodified copy, which would avoid this (and other)

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