Rereleasing packJPG under a different license

[packDEV]

Hi everyone,


sorry if this is in the wrong section, I couldn't decide wether this belongs here or under data compression.

Anyways: a few months ago, I released packJPG under the GPL v3. However, some people pointed out that this will make packJPG incompatible with other projects such as 7-Zip. Because of this I've been thinking about a re-release under a different license, or maybe dual-licensing. Being no expert at all in licensing myself, I'll just ask you .

So, what do you think, what would be a good license to release packJPG under? I could use some help.

[Matt Mahoney]

BSD and MIT licenses are most popular.

[Piotr Tarsa]

But, AFAIK, none of them protects algorithms from being patented (by third party).

[m^2]

But, AFAIK, none of them protects algorithms from being patented (by third party).

Copyright and patents have little in common. No license can prevent such thing from happening, though patents that cover unoriginal inventions are invalid by definition.

As to license, GPL v3 is not technically incompatible with 7-zip (which is public domain) in the sense that anyone can mix both codes and use in any way that doesn't break GPL.
It is incompatible with GPL v2 though and there are many codecs that use it. Also, it's incompatible with CDDL and there's at least 1 codec covered by it. These can't be legally distributed in a mix with your code.

GPL was designed so a combination of GPL with other code is practically GPL and projects that chose notably different licensing schemes are unlikely to be willing to take your code. Using a less restrictive scheme is the only thing you can do to make the deal acceptable for them.

So I suggest that you consider 3 choices:
- Dual licensing under GPL v2 and v3. It solves the issue for GPL projects, doesn't for anyone else, but is the closest to what you have now.
- A permissive license. Matt listed 2 popular choices. Anyone can use your code in any way, but they have to mention that you're the author of your code. Might not solve the issue for some purists (7-zip?), but I guess it's good enough for 99% of projects.
- Public domain. Really, not much different from the second option, 99% of people will keep naming you as the author because it's the right thing and heck, why not.

[packDEV]

Copyright and patents have little in common. No license can prevent such thing from happening, though patents that cover unoriginal inventions are invalid by definition.

As to license, GPL v3 is not technically incompatible with 7-zip (which is public domain) in the sense that anyone can mix both codes and use in any way that doesn't break GPL.
It is incompatible with GPL v2 though and there are many codecs that use it. Also, it's incompatible with CDDL and there's at least 1 codec covered by it. These can't be legally distributed in a mix with your code.

GPL was designed so a combination of GPL with other code is practically GPL and projects that chose notably different licensing schemes are unlikely to be willing to take your code. Using a less restrictive scheme is the only thing you can do to make the deal acceptable for them.

So I suggest that you consider 3 choices:
- Dual licensing under GPL v2 and v3. It solves the issue for GPL projects, doesn't for anyone else, but is the closest to what you have now.
- A permissive license. Matt listed 2 popular choices. Anyone can use your code in any way, but they have to mention that you're the author of your code. Might not solve the issue for some purists (7-zip?), but I guess it's good enough for 99% of projects.
- Public domain. Really, not much different from the second option, 99% of people will keep naming you as the author because it's the right thing and heck, why not.

Thank you!

I read about the MIT and BSD licenses and I suspect that they don't require that source code changes are re-released under the same license and permits usage in closed-source projects, but this might be wrong. I don't mind usage in closed source projects that much, but I want any optimizations done by anyone to be open source again.

So, staying with the GPL but using v2 alongside v3 might be the best option. If I want an easier way to permit usage in closed-source (other than special permissions as previously intended by me) I could also use the LGPL (right?).

[Bulat Ziganshin]

I don't mind usage in closed source projects that much, but I want any optimizations done by anyone to be open source again.

it's called LGPL

basically:

GPL - one should open-source entire program where library was used
LGPL - one should open-source only modifications to the library itself
BSD/MIT/p.d. - full freedom

basically, GPL prohibits commercial library usage (allowing you to sell commercial licenses), LGPL prohibits to improve library to gain advantages over other library users

[m^2]

I read about the MIT and BSD licenses and I suspect that they don't require that source code changes are re-released under the same license and permits usage in closed-source projects, but this might be wrong. I don't mind usage in closed source projects that much, but I want any optimizations done by anyone to be open source again.

Correct.

If I want an easier way to permit usage in closed-source (other than special permissions as previously intended by me) I could also use the LGPL (right?).

Right.

BSD/MIT/p.d. - full freedom

No, BSD / MIT are quite restrictive licenses...not nearly as much as (L)GPL, but still fair bit from public domain.

And actually public domain may not be full freedom either, for example in many european countries there are perpetual 'moral rights' which say that you can't claim to be an author of sb. else's work. Just saying.

[Bulat Ziganshin]

what are bsd/mit restrictions?

[m^2]

Depends on the exact license version, but the least restrictive requires everybody who distributes the code either as source or compiled to provide a copy of the license together with a copyright notice.