Closed source is fine, but there are a few other things that are required of LGPL, some of which are
- Provide links to the source of the version of ffmpeg you used in your code
- User should be able to replace the ffmpeg libs with his own compatible builds if you're using dynamically linked libs. For statically linked libs, you need to provide the tools to re-link against a compatible build.
I went through an LGPL review recently so some of this is fresh in my memory, but please correct me if I'm wrong.
I knew about the soft copyleft (the source code requirements) but didn't know there was the requirement to have libs be replaceable. Now I want to know how useful that would be in reverse engineering closed systems (particularly nintendos, since I've always had an interest in the homebrew scene there)
iirc, the video player application VLC used to come without any mpeg support, and you had to go through a process to download ffmpeg separately ...not sure how easy it made it to replace individual libs, but I'm also not sure the license requires you to make it easy.
Dynamically and statically linked libs is hilarious in the context of webassembly running in the browser.
You can have multiple WASM modules communicating with each other (though you would probably need extra interop code?), or statically link them into a single module, the concepts work mostly the same