[FFmpeg-user] FFmpeg licensing

[Carl Eugen Hoyos]

Matus Novak <matusnov <at> gmail.com> writes:

> My question is, if I compile shared FFmpeg libraries 
> *without* parameters "--enable-gpl" and "--enable-nonfree" 
> to make it LGPL compatible, then am I legally allowed to 
> make DDLs available on framework`s git repository?

I am not sure if I understand the question:
(I am not a native speaker.)

If you compile FFmpeg with --enable-nonfree, you are not 
allowed to distribute the resulting binaries. If you 
compile with --enable-gpl, you are allowed to distribute 
the binaries if you comply with the rules of the GPL.
If you use neither --enable-nonfree nor --enable-gpl, 
you may distribute the resulting binaries under the 
rules of the LGPL.
We have written a page that makes it - in our opinion - 
easy to check if you follow all LGPL requirements:
https://www.ffmpeg.org/legal.html

> If I understood right, I also need to make the source 
> code available on same repository from which DLLs were 
> compiled?

You have to make sure that users can (easily) download 
the exact sources that you used to compile the binaries 
based on FFmpeg source code (the "DLLs").
I am not sure what you mean with "same repository": If 
your binaries are not typically downloaded through a 
web browser (but through an installer program), then it 
is important that your users may click on a link to the 
source code. I believe we do explain this on our 
checklist: I suspect you somewhere (on a webpage) provide 
a link that will be used by the installation program. 
Just put a link to the source code next to the link to 
the app. (And you should of course mention that the 
source code is not needed to run your app.)
(And we believe that it makes sense to host the binaries 
and the source code on the same server, but this is of 
course no requirement, the requirement is that users may 
download the sources if they want to do AND that they 
can switch the "DLLs" you provided with DLLs they 
compiled themselves.

All the above is relevant no matter if the executable 
that calls the "DLLs" is licensed under LGPL or is 
proprietary and it makes no difference how much you 
charge for the executable.

Don't forget that you also have to tell your users about 
FFmpeg and the LGPL.

I am not a lawyer, it may be necessary that you consult 
your lawyer.

Carl Eugen