License problems

[jacereda]

Nice project, but a HN user posted some concerns regarding the license:

https://news.ycombinator.com/item?id=44809541

IANAL, but AFAICS this leaves 2 options, switching the license or removing that dependency.

[akx]

Given this project only uses phonemizer's Espeak backend, it wouldn't be too difficult to replace the phonemization call with direct use of the Espeak API.

EDIT: Espeak itself is GPL licensed, so that doesn't fly.

[jeethu]

Given this project only uses phonemizer's Espeak backend, it wouldn't be too difficult to replace the phonemization call with direct use of the Espeak API.

ICYMI, Espeak is also GPL-3.0 licensed.

[Const-me]

IANAL but I think another option is replacing Python library with phonemize command-line tool from the same package.

Just test carefully with non-English inputs and outputs on different operating systems. Windows may require some OS-specific tweaks to send/receive Unicode text to/from standard input/ output of child processes.

[akx]

ICYMI, Espeak is also GPL-3.0 licensed.

Thanks, yeah, I missed that. Good point! 😄

[phhusson]

There are two problems with depending on espeak-ng:

1. yes this makes KittenTTS GPLv3.0, but can be worked-around (I personnally think that a dlopen/dlsym makes it okay, but I can understand that legally it is actually the cli that is required)
2. Even if that's work-arounded, the project still can't be used in various commercial endeavors. (For instance embedded systems that require secure boot)

[nukeop]

If you use a GPL-licensed dependency, it doesn't mean your whole project must now be GPL-licensed. That would apply if this was a fork. Bunch of armchair lawyers

[jeethu]

There are two problems with depending on espeak-ng:

1. yes this makes KittenTTS GPLv3.0, but can be worked-around (I personnally think that a dlopen/dlsym makes it okay, but I can understand that legally it is actually the cli that is required)

2. Even if that's work-arounded, the project still can't be used in various commercial endeavors. (For instance embedded systems that require secure boot)

Dynamic linking (dyopen()/dlsym()) doesn't circumvent GPL.
https://www.gnu.org/licenses/gpl-faq.en.html#GPLStaticVsDynamic

[hbeskow]

If you use a GPL-licensed dependency, it doesn't mean your whole project must now be GPL-licensed. That would apply if this was a fork. Bunch of armchair lawyers

Once your code touches GPL licensed code your code becomes GPL licensed, via linking, or as any other form of dependency.
You seam to misunderstand that for the LGPL which allows linking without your code becomming gpl licensed.

[nukeop]

It doesn't "become" GPL licensed. You'd need to first release it under that license yourself. Import is not linking btw.

[hbeskow]

import is even worse. its literally copying code into your project.

[akx]

Import is not linking btw.

The phonemizer library used here (well, phonemizer-fork, via a transitive dependency) opens the espeak .so, and calls a function from it to phonemize a string. Dynamic linking (dlopening the .so) is still linking for GPL purposes.

[akx]

All this said, btw, there's this interesting bit in the GPL FAQ (paraphrased here):

If a whole software package contains very little code—less than 300 lines is the benchmark we use—you may as well use a lax permissive license for it, like Apache 2.0.

This repo seems to be Apache 2.0 licensed (aside from the conflicting mention of MIT in setup.py that #24 fixes), so that's fine – but in a larger project using this, the dependency on espeak tends to stick GPL's conditions to the entire project. IANAL.

[nukeop]

That is just an FSF interpretation, not law. There is room for doubt if dynamic (or even static) linking constitutes a derivative work.

https://www.linuxjournal.com/article/6366

[joshuaissac]

It's possible that the source code itself can be Apache-licensed if it does not include any GPL code, but the combined work can only be released under the GPL.

[PeterReid]

The phonemizer for kokoro TTS, called misaki, is already imported by this project and can phonemize English without espeak as of this PR: hexgrad/misaki#74 . That seems like a pretty easy option.