[Libav-user] Licensing question

Carl Eugen Hoyos cehoyos at ag.or.at
Sat Dec 14 01:30:46 CET 2013

Ioan Stan <Ioan.Stan at ...> writes:

> 1.      Let’s suppose that I own a library named "a.dll"

I already fail to parse the word "own" in this sentence;-(

Let me try it differently:
If you distribute binaries that contain code from the FFmpeg 
project, you have to tell your users that they install FFmpeg 
and you have to tell them about their rights (you have to 
show them the LGPL). You have to offer them the exact source 
code that you used to compile, that means that the users 
have to be able to download the source code from your server 
(not from the FFmpeg server). You should add some information 
on how you compiled the source code.
Note that all the above is not related to static or dynamic 
The idea is now that if your users wish to change something 
about the FFmpeg library that you installed on their computer, 
it has to be possible: That means that either - if you provided 
FFmpeg as a dynamic library - they must be able to make 
modifications to the source code you provided, and replace 
the binary that you installed with one that they compiled.
If you used static linking, you have to provide object files 
(of your code, not the FFmpeg code) that allow them to relink.

For technical reasons, the above requires you not to forbid 
your users to reverse engineer your software (it is needed 
for debugging if the above process fails).

Now, if you ask yourself "is it possible that my users update 
FFmpeg without additional help" and the answer is yes, then 
I suspect you comply with all requirements. If you asked to 
find a way around it, you are probably wrong here.

We made a page to simplify the process, if you consider it 
unclear, please tell us: http://ffmpeg.org/legal.html

Please remember that I am not a (and not your) lawyer!

Please do not top-post here, it is considered rude.

Hope that helps, Carl Eugen

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