License question

[JarbasAl]

Piper is licensed as MIT

Espeak-ng is licensed as GPL

https://github.com/rhasspy/piper/blob/master/src/cpp/phonemize.hpp#L13 <- doesnt this mean MIT license is invalid, piper needs to also be GPL

[synesthesiam]

Piper depends on an espeak-ng fork, which is available under GPL here: https://github.com/rhasspy/espeak-ng

[JarbasAl]

IANAL but my question is exactly that, Piper depends on GPL so it can't be licensed as MIT, having a GPL dependency (non-optional) means you must keep the license

[synesthesiam]

I'm not a lawyer either, so I don't see the point in speculating. Like any piece of modern software, users of Piper will need to evaluate the licenses of all its dependencies and consult the appropriate legal counsel. Pull most any package from PyPI and you will be in the same situation.

If I'm ever advised by a relevant lawyer to change the license, I definitely will.

[JarbasAl]

well, i would not consider this speculation as this kinda is the entire point of GPL, as a developer it is you responsibility to comply with the license, users aren't affected by this directly and do not need to evaluate licenses as they wont be breaking any license clause by just being users

in OVOS we have automations to ensure license complicance, so the pypi issue you mention is something I am deeply familiar with, accidents happen, pretending there is no issue is a whole another thing once it is flagged to you

I opened this issue out of concern for the project, as this is currently my favorite TTS.

a quote from gnu.org GPL FAQ

A system incorporating a GPL-covered program is an extended version of that program. 
The GPL says that any extended version of the program must be released under the GPL if it is released at all. 

thanks for looking into this

[synesthesiam]

I believe the point of the GPL is to prevent companies from using open source software without contributing back to the community. Everything I create is open for others to view and modify, and I encourage upstream contributions.

I say "I believe" because, again, I'm not a lawyer and I'm not qualified to interpret legal code. If someone from the espeak-ng project actually has an issue and would like to chat about it, I'm all for it. I appreciate the concern, but I think we can all be good open source citizens without the threat of legal boogeymen.

[ChanceNCounter]

Came to my attention because I’m the OVOS license compat nerd, and this analysis includes our Piper plugin in addition to Piper itself (heritable licensing is a big headache)

The threat of legal boogeymen in this situation is exactly why Steve Penrod moved MycroftAI away from copyleft, and it’s what warned us off those Mycroft components that were relicensed in the Dinkum era.

OVOS has gratefully ported a whole bunch of that work, but not the copyleft stuff, because we also prefer the MIT and BSD licenses, and we don’t want to inherit the copyleft restrictions. We have bots digging for missed hard deps, license policy compat checks in our CI. This stuff keeps me up at night.

The “good” news is that rendering the dependency optional would probably be sufficient. I haven’t actually sunk my teeth in yet, but that’s the usual situation. Throw in a bit of API that would make it possible to import some other lib in its place, and a way to make that configurable, and you’re (probably, again, haven’t dug in) GPL compliant.

[JarbasAl]

I'm not gonna rehash the old debate of permissive vs copyleft licenses, but any search around those keywords will show this is not some boggeyman i'm making up... complying in spirit is not complying with the license. Countless internet debates show you this is a real concern. But my intention is not to discuss merits of either, just to point out the issue

"i didnt mean too" is not a good argument, but if your stance is you don't care until a lawyer comes up there's not much else I can say....

With that said, I will no longer be using the license as an argument to recommend piper over mimic3 like I have been doing and will point to this discussion when the subject does come up

[jamesmyatt]

I haven't investigated the exact situation, but I expect that the following are true:

• Piper is not a derivative of espeak-ng: it's only dynamically linked
• https://github.com/rhasspy/espeak-ng is a derivative of espeak-ng: it's modified code

GPL only requires derivatives to be GPL-licensed, so piper can choose its own licence, while https://github.com/rhasspy/espeak-ng cannot. If espeak-ng used AGPL, then it would be a different matter.

[JarbasAl]

I haven't investigated the exact situation, but I expect that the following are true:

* Piper is _not_ a derivative of espeak-ng: it's only dynamically linked

* [rhasspy/espeak-ng](https://github.com/rhasspy/espeak-ng) _is_ a derivative of espeak-ng: it's modified code

GPL only requires derivatives to be GPL-licensed, so piper can choose its own licence, while rhasspy/espeak-ng cannot. If espeak-ng used AGPL, then it would be a different matter.

the dynamically linked argument would be valid for LGPL only, not for GPLv3

it is precisely point 1 that is the concern, if the user is able to replace this lib with a non-GPL equivalent then there wouldnt be an issue as espeak would just be a plugin among countless others, just empowering users to change it

as is, users can not install this without espeak so it is not optional

[ChanceNCounter]

The question with respect to Piper, and I’m still commenting pre-analysis, would be if it’s a combined work, not whether it’s derivative. The static vs. dynamic linking distinction hasn’t been properly settled in court; rms and the FSF contend that it’s all the same, and it all amounts to a combined work.

Philosophically and logically, I disagree. As a representative of a nonprofit on a shoestring budget, I can’t afford to argue with the FSF’s legal theories about its own licenses.

[jamesmyatt]

I understand that lots of people have differing opinions on this (which is one of the big issues with GPL), but I believe the most widely held is that only static linking with libraries creates a GPL'd work. The dynamic linking, especially of the kind that Python does, is generally allowed.

[JarbasAl]

I understand that lots of people have differing opinions on this (which is only of the big issues with GPL), but I believe the most widely held is that only static linking with libraries creates a GPL'd work. The dynamic linking, especially of the kind that Python does, is generally allowed.

in regards to python, I couldn't articulate the concerns better than Steve Penrod did https://softwareengineering.stackexchange.com/questions/119436/what-does-gpl-with-classpath-exception-mean-in-practice/326325#326325

the link above pretty much explains why we avoid even LGPL in python libs under OpenVoiceOS

EDIT: glad to see this issue reopened instead of swept under the rug