Dragon Player in kdereview, proposed move into kdemultimedia

[Dirk Mueller]

On Thursday 31 January 2008, Ian Monroe wrote:

> > > So I suppose we should remove phonon-xine because its useless too?
> > No, it is LGPL. Also all the other phonon engines, at least those
> > maintained by Trolltech.
> No, libxine is GPL v2+.

You were asking about phonon-xine though. It is true that xine has this 
license, but then again, there are other playing frameworks out there that 
have different licenses. Mostly those from the GNOME side of things, because 
they apparently have already understood the issues involved. The goal would 
be IMHO to be able to support those frameworks as well. 

> > That is correct, but not relevant as long as it is under GPLv2. It is at
> > least questionable if patent licensing is disallowed under the GPLv2 (it
> > is explicitely forbidden in GPLv3).
> I don't know what this means. Are you saying that if I add a media
> codec exemption it makes no difference for now but might in the
> future?

It depends on the whole software stack. GPLv3 disallows patent relicensing, 
which is needed to be able to ship certain software patent protected 
algorithms to countries that enforce software patents. When it comes to the 
uesrs, they can't decide on that: they live in such a country, and they want 
to listen to such media, and they will not move to a different country or 
switch to another media just because our default player does not support it: 
They will choose a different media player. 

Regarding your particular question: If any part of the stack (the definition 
depends on which lawyer you ask: some say its what you're linking against, 
what you're loading, what you're building against, what is used together to 
define the derived work etc) is e.g. only GPLv3 compatible, then nothing can 
use it anymore: Thats the drawback of using a copyleft based software. 

In your case: if you combine (essentially, not optionally by user interaction) 
a library that is GPLv3, Qt and your application, then any of those can only 
be distributed under the terms of GPLv3. It is different in the case of mere 
aggregation (e.g. the components are not or only loosely coupled, just happen 
to be shipped together). 

So obviously in that case your exception statement does not change anything. 
In the other case, where the software stack is (L)GPL and your application is 
GPLv2/v3, there is a clear benefit from using an exception statement. 

In the end it comes down to your personal decision: Do you want people to be 
able to use your software by default on a distribution that has purchased 
licenses for video or audio codecs? Do you want them to switch to a different 
player? The sooner you decide the less problems you have with finding the 
agreement over all copyright holders to your project. the longer you wait the 
more contributions you'll get from all sorts of places. 

The Qt/Free edition is currently under plain GPL, so in cases where the 
license agreements for such codecs would be GPL incompatible (!) (I don't 
know of any such agreement existing up to my best knowledge so far, but it 
could be the case in the future), Qt/Free is a limiting factor. Something 
that can be fixed with the non-free Qt license, or by asking TT to reconsider 
their licensing. If that succeeds or not I cannot judge, but the discussion 
has a lot more power _if_ Qt is actually the limiting factor, and not the 
licensing of the software stack itself. 

> I do share your concern about parts of trunk/KDE becoming a wasteland
> of mostly unmaintained software. This is kind of what happened to
> kdemultimedia in KDE3. We should be more aggressive in pruning
> software in trunk/KDE. This shouldn't scare us into a situation of
> just keeping everything in extragear, even software being released on
> the KDE schedule. Kind of just shuffles the issue around.

I agree about that, but it still leaves the question of the default player 
open :)

> The only way (currently) to make a phonon video player that meets
> Novell and Redhat's criteria would be for someone to buy a Qt license
> and develop a video app with it. 

Wrong, actually. It is not the only choice, and it is neither the safest one 
(but I don't know the Qt/Commercial licensing terms, so I can't judge nor 
care). 

There is a very strong reason for Qt/Free being good enough if the media 
player has a codec exception. I don't think I'm allowed to say, but it should 
be pretty easy to guess if you read the flow of reasons given above. 


Greetings,
Dirk