[MPlayer-dev-eng] Small talk on the GPL by laymen (was: Re: help on libmpdemux usage)

[Romain Dolbeau]

D Richard Felker III wrote:

> That's not the question. The question is whether a binary _containing_
> libmpdemux is a derived work of MPlayer, and the answer is of course
> YES!

Obviously.

 > Distributing that derived work is not legal if it doesn't meet
> the conditions of the GPL.

Obviously. Well, 'til the GPL has been tried in
court, anyway.

 > And if that derived work is linked, even
> dynamically, to QuickTime, then it's not meeting the conditions of the
> GPL.

I disagree. But then, I'm not a lawyer (one in the family
is more than enough :-

PMlayer *is* linked to QuickTime, yet the mplayer authors
can't re-licence QuickTime under the GPL, so dynamic
linking better be OK....

> You can't breach the GPL on code to which you hold copyright, since
> you don't need to accept it yourself. Obviously for all code written
> by MPlayer developers, they're implicitly giving their permission to
> make binaries that use QuickTime codecs by putting that functionality
> in the source to begin with. This does NOT imply that they're giving
> their permission for parts of MPlayer source to be used in the (highly
> proprietary) QuickTime framework.

MPlayer uses QuickTime for audio and video (through the SDL)
output, not for codecs (well maybe for codecs too)
And there's only one QuickTime framework.

What makes mplayer calling QuickTime legal, but QuickTime
calling mplayer illegal ?

> If one really wanted, one could built 2 MPlayer binaries: one with
> QuickTime but not libmpeg2, and the other with libmpeg2 but not
> QuickTime. So for all practical purposes, the two aren't linked.
> There's certainly no dependence between them, unlike the example we're
> dealing with of incorporating libmpdemux into QuickTime.

W/o quicktime, mplayer has no sound and almost no video
(X11 would still work). So on MacOSX, no, you can't
build mplayer w/o QuickTime (<rant> w/o Troll Tech
I'd put QT, faster to type... </rant>) for any
useful purpose. mencoder yes, but not mplayer.
So on MacOSX, mplayer is dependant on proprietary
QuickTime...

> ROTFL, this shows your ignorance. The shell has nothing to do with
> program loading.

Once upon a time, shell used to do fork()/exec()
to load a new program in the system. I guess
this changed and you can't load new program
by using a shell ? I still could 2 minutes ago.
Or maybe "program loading" doesn't mean the same
thing to you and me. That's the trouble of speaking
a foreign language...

Anyway, I like to spread sweetness and light around
me, so I hope you enjoyed your laugh :-)

>>but not if it is QuickTime Player ? What if the module
>>was a wrapper that simply launched mplayer via exec() ?
> 
> Then it wouldn't work. :)

Don't bet on it. I've seen worse thing done in
my life. With enough stuborness, a good programmer
can do almost anything, no matter how stupid
it seems at first.

> Yes, the purpose of the GPL is political: to keep code free and ensure
> that it's not taken for the purpose of enhancing proprietary software
> while providing no benefit to free software.

The very reason the GPL is perfect for hobbyist
and terrible to establish standards. Apache,
TCP/IP, X11... But I disgress, sorry.

> It's not possible to be more restrictive than the GPL in this area.
> It's the maximum allowed under the law (in most countries at least).

Well, I'd say that the average software company
uses licenses that are a lot more restrictive than
the GPL :-)

-- 
Romain Dolbeau
Not speaking for my employer