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

Christian HJ Wiesner chris at
Sun Jan 18 15:08:06 CET 2004

Steve Lhomme wrote:

> ChristianHJW wrote:
>> D Richard Felker III wrote:
>>> 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.
> Don't worry, you're not the first person to ask about this. And if 
> there was a definitive answer noone would need to question it again. 
> But actually there is *no* answer to this... My opinion is that a DSF 
> is just a standalone piece of code, that could be used by a DirectShow 
> clone that could be GPLed. So it's not hard linked in any kind to 
> anything proprietary. Sowe don't mind about it. 

Even this question seemed to be discussed within the FSF in great 
detail, and they finally seemd to have agreed that DirectShow is  part 
of the OS, and as such falls under the exception the FSF has made for 
the usage of OS related libraries etc.

>> 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 ?
> The license for Helix is compatible with the GPL. It's stated on 
> Real's site. Of course Quicktime may be another problem...

Steve, the reason i was copying the helix-general list on this email was 
obvious :

I wanted to see if anybody from them has the balls to comment. I know 
they made Helix GPL, but dont you see that they are violating the GPL 
with this ? Helix is linking to proprietary code, i.e. the codecs, and 
this is strictly forbidden by the GPL license. The argument that there 
'.... may be a similar plugin/framework which happens to have the same 
interface, and is GPL ...'  is void. If its released under the GPL, it 
must be released. If you have the sources on your HDD, and dont release 
them, you cant apply the GPL to them, as GPL strictly regulates the 
*DISTRIBUTION* of code, so a code that is not released can not comply 
with the GPL.

In short, as long as there is no GPL or L-GPL RealVideo/Audio 
de/encoder, the complete Helix framework can not be released under GPL, 
and is a contradiction in itself. In return, we have to make 
libmatroska/libebml L-GPL, or we violate the GPL ourselves, now that we 
know this.


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