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 many lawyers, including official representatives of the FSF to help us ensure we cover as much as possible as correctly as possible. The advice contained in here is meant for 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 properietary software or people distributing GStreamer might also find this document useful in order to understand how GStreamer works in a licensing context.

Licensing of code contributed to GStreamer itself

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

To keep this viable the GStreamer community has made a few licensing rules for code to be included in GStreamer or GStreamer's central modules like our official plugin packages. The first rule is that we demand that all new code written is licensed under the LGPL. Plugins can use other licenses like MPL or BSD if they are based on older code under these licenses. Plugins can use GPL libraries, but we ask that the plugin developer mail the library developer(s) and ask if a relicensing to LGPL is possible. The actual plugin code put into GStreamer would have to be LGPL even if it it is utilizing a GPL licensed library. The reason for this is because other developers might want to use the plugin code as a template for plugins linking to LGPL libraries and similar.

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 utilize 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. What complicates things with regards to GStreamer is its plugin based nature and the heavily patented and proprietary nature of multimedia codecs. And 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 with the very central place the US hold in the world economy and the computing industry especially, software patents are hard to ignore wherever you are.

Many companies, like major GNU/Linux distributions, who want to offer their customers out of the box support for patented formats would need to do this in a proprietary way or risk heavy litigation and punishment from patent owners. This leaves them the choice of either using special proprietary applications or try to integrate the support into the general multimedia infrastructure provided by GStreamer. Faced with one of these two evils the GStreamer community of course prefer the second option.

The problem which arise is that most Free 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. Because if they include proprietary plugins in GStreamer to support patented formats in a way that is legal for them, they do risk running afoul with the GPL license of the applications. We have gotten some conflicting reports from lawyers of whether this is actually a problem, but the official stance of the FSF is that it is a problem so that is what we go by as our measuring stick.

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 properietary plugins to be bundled with GStreamer and your applications in order to make sure that as many people 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 Ogg 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. Another suggested option is adding a statement of interpretation to your GPL license stating stating that you don't interpret the GPL to block anyone from shipping your GStreamer based application together with non-free plugins. We have made a example of such statement available here

If you do not want proprietary plugins to be used with your application you are of course free to use the GPL for it. And distributions not targeting the US market will of course still be able to combine your application with open source plugins implementing the codecs in question, like our ffmpeg based plugin. Distributions who do not want to distribute any non-free formats, only free formats like the Ogg ones, will of course also be likely to distribute your application if it ends up among the best of its kind.