[Matroska-general] Re: help on libmpdemux usage (Modifié par Jérôme Cornet)

ChristianHJW christian at matroska.org
Sat Jan 17 09:32:42 CET 2004

D Richard Felker III wrote:
> On Tue, Jan 13, 2004 at 04:48:39PM +0000, Adam Rice wrote: 
>>D Richard Felker III wrote:
>>>QuickTime itself is non-free. Making a derivative work of MPlayer
>>>which is linked in as a component of non-free code (QuickTime) is not
>>>permitted by the GPL, as far as I can tell. LGPL would be required for
>>>something like this, and MPlayer is intentionally GPL rather than
>>>LGPL. Whether you release source is irrelevant.
>>As far as I know, QuickTime loads codecs at runtime. Thus the codec is 
>>not linked into QuickTime. So the only two relevant questions are:
>>a) Does Apple place restrictions on the licenses under which third-party 
>>QuickTime codecs may be distributed?
>>b) Is binary code under a GPL-incompatible license linked into the codec?
>>I would expect the answer to both of these questions to be "no". In some 
>>circumstances it could be legal even if the answer to the second 
>>question was "yes", as QuickTime is an OS component under MacOS, and the 
>>GPL has a specific exception for that.
>>As an aside, the GPL places no restrictions on "Making" anything. It 
>>only places restrictions on distribution, and only on binaries at that.
>>I should point out that these comments apply to GPL v2. Some people 
>>consider the ability to make GPL'd plugins for proprietary software to 
>>be a loophole that needs to be fixed in a future version. It seems to me 
>>this can't be done without placing restrictions on use, which would make 
>>the GPL no better than the proprietary software licenses it seeks to 
> Not at all. Someone is perfectly free to make a plugin for a
> proprietary system out of GPL code for their own private use, but the
> GPL does not give them permission to distribute this derived work
> since it is linked (even dynamically) to proprietary code.
> Rich

Hmmm, interesting discussion. I have to think through this a second 
time, but it seems Richard has just been proving to me that a GPL 
license is basically incompatible with *M$ DirectShow* also, and thus we 
presently dont allow anybody else to make and release a DirectShow 
parser filter for our stuff, as long as we have this license type for 
our main lib. Have to check if QPL would maybe allow, but i dont think 
it will be less restrictive in this respect.

Of course, this is currently no issue as we, the license holders, are 
distributing our own DShow parser/muxer filters, but to stress the same 
example as discussed here, if anybody wanted to make a Quicktime plugin 
using libmatroska/libebml, he'd violate the GPL doing so :O !! And 
jcsston is just working on a Helix/RealNetworks muxer for matroska, and 
using libmatroska for that ! As Helix itself is not GPL, but using a 
different license style to the best of my knowledge, you basically cant 
use any GPL plugins with it without violating GPL itself ?

I was actually never aware of that, and at first i was scared to death 
when thinking about FFdshow, Milan Cutka's great DirectShow decoder 
filter based on FFMPEG, but then of course the latter is using L-GPL, so 
Milan is fine and not violating anything. But, i will really start 
watching now how many DShow filters out there are using GPL'ed stuff, 
there may be a few and authors think they are fine by releasing their 
work under GPL also, but in fact they are not. After all, i was 
promoting since a long time now to change our license to L-GPL, as BBB's 
C lib is available under this license and there are allogether 6! 
different matroska implementations existing ( but most under GPL ), 
usage of the main lib should not be restricted to GPL apps any longer IMO.

Richard, thanks for pointing this out in detail, i honestly was not aware !

matroska project admin

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