Re-releasing LGPL code as AGPL : need advice on how to phrase license

Question

I have written a compression codec that I am releasing under the AGPL.

I would like to link it with FFmpeg, a video streaming application. FFmpeg is licensed under the LGPL, but since it supports some GPL v2 codecs, it can also be licensed under GPLv2. But not GPLv3.

So, in order to link my codec with FFmpeg, I will re-release FFmpeg under AGPL.

My question is : how to set up the license for this.

FFmpeg has two different license files to cover both LGPL and GPLv2.

I will now add a third AGPL license, which shall apply to all of the code (Of course, the LGPL and GPLv2 licenses continue to be in force)

So, how do I word the AGPL to acknowledge the other two licenses ?

Thanks!!

Answer 1

Quoting https://www.gnu.org/licenses/license-list.en.html#AGPLv3.0 :

Please note that the GNU AGPL is not compatible with GPLv2. It is also technically not compatible with GPLv3 in a strict sense: you cannot take code released under the GNU AGPL and convey or modify it however you like under the terms of GPLv3, or vice versa. However, you are allowed to combine separate modules or source files released under both of those licenses in a single project, which will provide many programmers with all the permission they need to make the programs they want. See section 13 of both licenses for details.

Emphasis mine. According to http://ffmpeg.org/legal.html, ffmpeg is licensed under "GNU General Public License (GPL) version 2 or later." So, I believe it is possible to make the bolded line relevant. Quoting the GPLv2 license,

Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation.

I am not a lawyer and I make no promises that anything I said or emphasized is accurate, relevant, or trustworthy. Consult a lawyer for legal advice.

Answer 2

You may not re-release Ffmpeg under AGPL, as doing so imposes new restrictions on distribution, which is in violation of the original GPL license the software was distributed to you by.

Only the copyright holders of ffmpeg may create an AGPL licensed release.

Answer 3

FFmpeg is released under the LGPL, however some optional parts are GPL licenced, so you have a choice as a user of FFmpeg: to use the LGPL parts in a LGPL product, or to incorporate the GPL parts in a GPL product.

If you release under AGPL your codec will become part of the GPLd parts of FFmpeg, and will possibly confused the bejeesus out of people. This is probably not a good thing at all (just see the answers you've gotten already!)

I would say the nest approach would be to licence your codec as LGPL and then it will fit nicely into FFmpeg without any hassle. GPL would be clearer but then you'd be in the same category as x264 codec etc. AGPL will just cause confusion - is it really worth insisting on AGPL licencing given this?

Note if FFmpeg takes your codec, they will have to modify the build to exclude your codec when someone builds it in its default LGPL state.