Re: LilyPond, LilyPond snippets and the GPL

[Carl Sorensen]

On 10/29/19, 5:46 PM, "David Kastrup" <address@hidden> wrote:

    Karsten Reincke <address@hidden> writes:
    
    > By my last post, I, unfortunately, evoked a discussion concerning
    > LilyPond, LilyPond snippets, and the GPL which actually did not belong
    > to the original topic. During this discussion Harm stated, that „maybe
    > LSR should better use GPL 3, not this deprecated one (Public Domain)“.
    > Urs asked whether anything has to be done with respect to the Lilypond
    > Snippet Repository. And Andrew asked whether I apprehend not to be able
    > to use lilypond due to the fact that it is licensed under the GPL.
    >
    > I owned these comments by my statement, that I will not be able to use
    > and to support the development of LilyPond snippets or libraries (as
    > OpenLilyLIb) as long as they are licensed under the GPL. Meanwhile, I
    > have written a thorough analysis of the situation. It is published
    > under the title „LilyPond, LilyPond Snippets and GPL: About some bad
    > side effects“. https://fodina.de/en/2019/lilypond-snippets-and-the-gpl/
    >
    > For those, who do not want to read such an exhaustive document – I need
    > this depth of detail due to my work as the open-source compliance
    > officer of a Germany company – let me briefly summarize the line of
    > argumentation:
    >
    > [1] The LilyPond language (interpreted by the LilyPond program which
    > creates nice music sheets in the form of PDFs or PNGs) is a programming
    > language.
    >
    > [2] The LilyPond interpreter is licensed under the GPL.
    >
    > [3] None of the existing Lilypond snippets is licensed under the GPL
    > because the interpreter is licensed under the GPL (= no copyleft effect
    > from the engine to its input/output). If they are licensed under the
    > GPL, then it is a decision of the snippet authors, who also could have
    > chosen one of the other open-source licenses.
    >
    > [4] But if a GPL licensed LilyPond snippet is used by another LilyPond
    > code (either by a functional call into the included snippet or by
    > literally copying the snippet into the other code), then the copyleft
    > effect of the GPL is triggered.
    >
    > [5] The copyleft effect does not distinguish between distributing the
    > source (the LilyPond code) or the compilation (the PDFs, the PNGs): it
    > simply requires that the resulting work (the derivative work) has to be
    > distributed (published) under the terms of the GPL too.
    
    I disagree with your assessment that calling any code/function makes the
    work doing so a derivative of that code (that would concern using
    OpenLilyLib code).  I do agree that including/using/changing LSR
    snippets as part of your work means deriving from them.  That's why I
    would agree that using the GPL for the LSR snippets would not be
    desirable since it would introduce a licensing regime where it seems
    exaggerated.

I agree with this comment only to the extent that you are distributing the 
source code for your music.  If you only distribute the PDF and/or MIDI output, 
the GPL does not apply, according to the FSF:

" In what cases is the output of a GPL program covered by the GPL too? 
(#WhatCaseIsOutputGPL)
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. See also: Can I use the GPL for something 
other than software?" [1]
    

Carl Sorensen

1. https://www.gnu.org/licenses/gpl-faq.html#WhatCaseIsOutputGPL