[Ffmpeg-devel] Patch for dynamic liba52.so loading

Rich Felker dalias
Sat Jun 11 21:23:54 CEST 2005

On Sat, Jun 11, 2005 at 04:53:56PM +0200, M?ns Rullg?rd wrote:
> Rich Felker <dalias at aerifal.cx> writes:
> >> > Of course there are multiple codec contexts. Is there a good reason
> >> > for dynamic loading support? IMO it's unnecessary complexity that
> >> > should just be removed..
> >> 
> >> There is no technical reason for dynamic loading.  It allows
> >> libavcodec to be distributed under the LGPL, and still use liba52,
> >> even if you believe the lies being perpetrated by the FSF.
> >
> > As long as the party setting it up for this use is not also
> > distributing liba52 or outerwise doing something for it that requires
> > accepting the GPL on liba52 I agree. On the other hand, if someone
> > makes a proprietary program that needs to decode ac3, and distributes
> > it with libavcodec compiled for dynamic liba52 loading, then offers a
> > separate download of liba52 under GPL terms, they ARE infringing on
> > liba52. Making them separate downloads or separating them in other
> > ways does not get around the fact that they have prepared a non-GPL
> > derivative work of liba52, thus invalidating their rights to
> > distribute liba52 under the GPL.
> The point is that linking against liba52 (or any other library) does
> not create a derived work.  There is a fair amount of evidence that
> making use of a library through its API, does not amount to creating a
> derived work.  The bits from the library that end up in the executable
> linking to it (names of functions, mainly), are not subject to
> copyright protection.  This is analogous to writing an article, in
> which references to various books are made.  This does in no way
> infringe on the copyright of the books referenced.
> If APIs were protected by copyright, then creating a compatible
> implementation would also be creating a derived work, and would

The legal definition of "derived work" is totally irrelevant to what I
said. If the vendor is distributing copies of liba52 WHATSOEVER, they
must have permission to do so. Otherwise they are infringing
copyright. The GPL __ONLY__ allows them to make copies under certain
conditions, one of which is that any "derivative work" (according to
the GPL's definition, not the copyright definition) MUST be licensed
under the GPL.

Naturally if the vendor refrains entirely from distributing liba52,
they need not care about the GPL as it pertains to liba52.

This is all plainly obvious. Anyone who does not understand should go
enroll in logic 101.


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