[Libav-user] What are my license responsibilities?

[Carl Eugen Hoyos]

Am Mo., 24. Mai 2021 um 23:22 Uhr schrieb Anderson, M. Paul
<Paul.Anderson at jhuapl.edu>:

> I’d like to understand your license requirements as they apply to
> software my team is creating.

I don't think they are different from any other software using the GPL or
LGPL as their license, and both are very common.

Note that "creating" software often has no requirements under these
licenses other than "no warranty" which is even required for "using"
the open source software.

> For a little background, the Johns Hopkins University Applied Physics
> Laboratory is a non-profit organization

This is interesting but has no relevance for the license in question.

> and our project creates desktop training software for the Navy.

Great!

> This is a very limited software distribution

I am not a native speaker; Is there a difference between a
"distribution" and a "limited distribution"?

> with the sole purpose of training sailors that operate a specific class
> of submarine. Due to the classified nature of the program, this
> training software cannot, and will never be, distributed commercially.

For the (L)GPL It is completely irrelevant if your software is distributed
commercially or not.
I am a little surprised though that Johns Hopkins works for free for the
US Navy.

> We use the FFmpeg binaries unmodified, linked into our software
> executable.

I believe we have made a very readable explanation for such cases.

> I am unclear on what license requirements we must abide by for
> this limited use.

Again: What does "limited" mean in this context?

> Can you provide guidance on your license expectations, as well as an
> online reference I can read?

https://www.ffmpeg.org/legal.html

> Because of our unique project, I am unclear how your license
> requirements apply.

Could you elaborate on why your distribution of binaries based on
FFmpeg source code is different from others?

> I have viewed the License Compliance Checklist on this page,
> however, I am unclear on which of the 18 items are “good ideas”
> and which are “required”.

Usually, when people try to make this distinction, the reason is that
they do not want to fulfill the obligations of the (L)GPL.
(It should be completely trivial to fulfill them, except for
providing the source code which clearly is "required".)
If this is your reason, please do not use FFmpeg in any way.

> Since we are using the libs unmodified, I’d like to understand how to
> ensure compliance.

I am not sure why you believe that modification (or not) makes a difference:
Just provide the source code together with the binaries and follow the
other guidelines, as said I believe all are trivial to fulfill.
If you want to use static linking you have to provide object files that
allows the recipient of your software to relink if he wishes
to do so, the other requirements do not change.
If you compiled FFmpeg with "--enable-gpl" you have to open-source
your whole "software executable".

Carl Eugen