What should be taken into account when licensing software that generate video?

Question

For the context, I am involved in Manim Community which develop Manim (originally published by Grant Sanderson), a Python library for creating explanatory math videos. Users of the library write Python code which creates videos that look like this.

We were discussing with a member how to license a Manim video in a way that creates a good open-source culture. The answer turned out not to be as straightforward as we hoped, because the software and the video are directly connected, and we would want the same terms to apply to both the video.

Example case that could cause a dispute: I license the code for an animation as GPLv3, but unless I state a license for the generated video, someone could take the code and sell the generated video. (Correct me if I'm wrong in this example)

Question 1: Should the code always be accompanied by a creative commons license (i.e. dual licensing)? If so, how should it be chosen? E.g. what licenses would each of GPL, LGPL or MIT would require?

Question 2: The community member I was speaking to would like to allow for reusing parts of the code, but not copying it verbatim. Is there a license that ensures such a thing?

Question 3: Our main concern is to encourage sharing and for what is free to remain free. What principles should be considered for that?

I have found previous answers which are related to this but none that mentions Manim, so I think this post would be a good reference for others searching the same thing.

Answer 1

I license the code for an animation as GPLv3, but unless I state a license for the generated video, someone could take the code and sell the generated video. (Correct me if I'm wrong in this example)

You are, at least, not completely right. Unless the manim program is copying parts of its own source into the output, the output video is a derivative of the input instructions (the python code), not of the manim program (see, eg, this question for a more detailed discussion of this point). That given, a video that arises from GPLv3 python code (as interpreted by manim) is a copyright derivative of that python code, and so must itself be licensed under GPLv3, if it's made by someone other than the rightsholder in the code.

That doesn't mean it can't be sold. The FSF are very clear that selling free software is fine. But it means it has to come with freedoms, so the purchaser may use the video as (s)he pleases, copy it without restriction, modify it, and distribute modified works based on it - under GPLv3.

Question 1: any copyleft-licensed python code will lead to video that must be similarly licensed. Permissively-licensed python code will lead to video with very few license restrictions, which certainly could be distributed under a proprietary license.

Question 2: there is no such free license, as the right to make verbatim copies is one of the four freedoms.

Question 3: a copyleft license on the python code will ensure that recipients of the resulting video have the right to do with as they would like. If you don't want that to include selling it, you have a problem.

Answer 2

I quote part of the FAQ of GNU licenses below:

Is there some way that I can GPL the output people get from use of my program? For example, if my program is used to develop hardware designs, can I require that these designs must be free?

In general this is legally impossible; copyright law does not give you any say in the use of the output people make from their data using your program. If the user uses your program to enter or convert her own data, the copyright on the output belongs to her, not you. More generally, when a program translates its input into some other form, the copyright status of the output inherits that of the input it was generated from.

So the only way you have a say in the use of the output is if substantial parts of the output are copied (more or less) from text in your program. For instance, part of the output of Bison (see above) would be covered by the GNU GPL, if we had not made an exception in this specific case. .....

In what cases is the output of a GPL program covered by the GPL too?

The output of a program is not, in general, covered by the copyright on the code of the program. So the license of the code of the program does not apply to the output, whether you pipe it into a file, make a screenshot, screencast, or video.

The exception would be when the program displays a full screen of text and/or art that comes from the program. Then the copyright on that text and/or art covers the output. Programs that output audio, such as video games, would also fit into this exception.

If the art/music is under the GPL, then the GPL applies when you copy it no matter how you copy it. However, fair use may still apply.

Keep in mind that some programs, particularly video games, can have artwork/audio that is licensed separately from the underlying GPLed game. In such cases, the license on the artwork/audio would dictate the terms under which video/streaming may occur. ....

Can I use the GPL for something other than software?

You can apply the GPL to any kind of work, as long as it is clear what constitutes the “source code” for the work. The GPL defines this as the preferred form of the work for making changes in it.

Question 1:

This is answered by the third answer from the FAQ quote above, assuming we intend to use the GPL license to cover both software and video/ artwork.

Question 2:

All open source licenses (based on the Open Source Definition by the Open Source Initiative) allow copying, redistribution and sale verbatim. However, copyleft licenses require modified source to remain open.

Question 3:

"Encourage sharing and for what is free to remain free" is essentially what copyleft is all about.

GPL and MPL are copyleft licenses. I'm not sure if MPL can be applied to video or artwork or not, but GPL can be.

I think if you apply the GPL to your software and your source videos or artwork that is used to generate the output video, then it fulfills most of your open sourcing goals under a single license.

MIT and BSD are free, permissive licenses, not copyleft.