Licensing your applications and plugins for use with GStreamer

This document is the result of many discussions both inside the GStreamer community and with stakeholders outside the community. It includes the results of discussions with lawyers, including official representatives of the FSF, to help us ensure we cover the legal issues as correctly as possible. This does not mean the FSF or anyone else endorse the opinions in this page. The opinions only represent the rough consensus of the GStreamer community. The advice contained in here is meant as information and guidance for people developing free and open source software using the GStreamer library, so they are aware of the consequences of their choices. People developing proprietary software or people distributing GStreamer might also find this document useful in order to understand how GStreamer works in a licensing context.

For more information on licensing you can check out our legal FAQ.

Licensing of code contributed to GStreamer itself

GStreamer is a plugin-based framework licensed under the LGPL. The reason for this choice in licensing is to ensure that everyone can use GStreamer to build applications using licenses of their choice.

To keep this policy viable, the GStreamer community has made a few licensing rules for code to be included in GStreamer's core or GStreamer's official modules, like our plugin packages. We require that all code going into our core package is LGPL. For the plugin code, we require the use of the LGPL for all plugins written from scratch or linking to external libraries. The only exception to this is when plugins contain older code under more liberal licenses (like the MPL or BSD). They can use those licenses instead and will still be considered for inclusion. We do not accept GPL code to be added to our plugins module, but we do accept LGPL-licensed plugins using an external GPL library. The reason for demanding plugins be licensed under the LGPL, even when using a GPL library, is that other developers might want to use the plugin code as a template for plugins linking to non-GPL libraries.

We also plan on splitting out the plugins using GPL libraries into a separate package eventually and implement a system which makes sure an application will not be able to access these plugins unless it uses some special code to do so. The point of this is not to block GPL-licensed plugins from being used and developed, but to make sure people are not unintentionally violating the GPL license of said plugins.

Licensing of applications using GStreamer

The licensing of GStreamer is no different from a lot of other libraries out there like GTK+ or glibc: we use the LGPL. What complicates things with regards to GStreamer is its plugin-based design and the heavily patented and proprietary nature of many multimedia codecs. While patents on software are currently only allowed in a small minority of world countries (the US and Australia being the most important of those), the problem is that due to the central place the US hold in the world economy and the computing industry, software patents are hard to ignore wherever you are.

Due to this situation, many companies, including major GNU/Linux distributions, get trapped in a situation where they either get bad reviews due to lacking out-of-the-box media playback capabilities (and attempts to educate the reviewers have met with little success so far), or go against their own - and the free software movement's - wish to avoid proprietary software. Due to competitive pressure, most choose to add some support. Doing that through pure free software solutions would have them risk heavy litigation and punishment from patent owners. So when the decision is made to include support for patented codecs, it leaves them the choice of either using special proprietary applications, or try to integrate the support for these codecs through proprietary plugins into the multimedia infrastructure provided by GStreamer. Faced with one of these two evils the GStreamer community of course prefer the second option.

The problem which arises is that most free software and open source applications developed use the GPL as their license. While this is generally a good thing, it creates a dilemma for people who want to put together a distribution. The dilemma they face is that if they include proprietary plugins in GStreamer to support patented formats in a way that is legal for them, they do risk running afoul of the GPL license of the applications. We have gotten some conflicting reports from lawyers on whether this is actually a problem, but the official stance of the FSF is that it is a problem. We view the FSF as an authority on this matter, so we are inclined to follow their interpretation of the GPL license.

So what does this mean for you as an application developer? Well, it means you have to make an active decision on whether you want your application to be used together with proprietary plugins or not. What you decide here will also influence the chances of commercial distributions and Unix vendors shipping your application. The GStreamer community suggest you license your software using a license that will allow proprietary plugins to be bundled with GStreamer and your applications, in order to make sure that as many vendors as possible go with GStreamer instead of less free solutions. This in turn we hope and think will let GStreamer be a vehicle for wider use of free formats like the Xiph.org formats.

If you do decide that you want to allow for non-free plugins to be used with your application you have a variety of choices. One of the simplest is using licenses like LGPL, MPL or BSD for your application instead of the GPL. Or you can add a exceptions clause to your GPL license stating that you except GStreamer plugins from the obligations of the GPL.

A good example of such a GPL exception clause would be, using the Muine music player project as an example:

Our suggestion among these choices is to use the LGPL license, as it is what resembles the GPL most and it makes it a good licensing fit with the major GNU/Linux desktop projects like GNOME and KDE. It also allows you to share code more openly with projects that have compatible licenses. As you might deduce, pure GPL licensed code without the above-mentioned clause is not re-usable in your application under a GPL plus exception clause unless you get the author of the pure GPL code to allow a relicensing to GPL plus exception clause. By choosing the LGPL, there is no need for an exception clause and thus code can be shared freely between your application and other LGPL using projects.

I have above outlined the practical reasons for why the GStreamer community suggest you allow non-free plugins to be used with your applications. We feel that in the multimedia arena, the free software community is still not strong enough to set the agenda and that blocking non-free plugins to be used in our infrastructure hurts us more than it hurts the patent owners and their ilk.

This view is not shared by everyone. The Free Software Foundation urges you to use an unmodified GPL for your applications, so as to push back against the temptation to use non-free plug-ins. They say that since not everyone else has the strength to reject them because they are unethical, they ask your help to give them a legal reason to do so.