Installer, default installation
The installer (Microsoft Windows and MacOSX) and the default installation (GNU/Linux) contain and install the minimal default installation. At install time or later, the downloading of optional components is also possible, but read on for certain legal cautions you might want to take. All downloads are from the freedesktop.org website.
Licensing of SDK
Gstreamer SDK minimal default installation only contains packages which are licensed under the GNU LGPL license v2.1. This license gives you the Freedom to use, modify, make copies of the software either in the original or in a modified form, provided that the software you redistribute is licensed under the same licensing terms. This only extends to the software itself and modified versions of it, but you are free to link the LGPL software as a library used by other software under whichever license. In other words, it is a weak copyleft license.
Therefore, it is possible to use the SDK to build applications that are then distributed under a different license, including a proprietary one, provided that reverse engineering is not prohibited for debugging modifications purposes. Only the pieces of the SDK that are under the LGPL need to be kept under the LGPL, and the corresponding source code must be distributed along with the application (or an irrevocable offer to do so for at least three years from distribution). Please consult section 6 of the LGPL for further details as to what the corresponding source code must contain.
Some portions of the minimal default installation may be under different licenses, which are both more liberal than the LGPL (they are less strict conditions for granting the license) and compatible with the LGPL. This is advised locally.
There are two types of optional packages (GPL and Patented), which are under a different license or have other issues concerning patentability (or both).
Part of the optional packages are under the GNU GPL v2 or v3. This means that you cannot link the GPL software in a program unless the same program is also under the GPL, but you are invited to seek competent advice on how this works in your precise case and design choices. GPL is called “strong copyleft” because the condition to distributed under the same license has the largest possible scope and extends to all derivative works.
Certain software, and in particular software that implements multimedia standard formats such as Mp3, MPEG 2 video and audio, h.264, MPEG 4 audio and video, AC3, etc, can have patent issues. In certain countries patents are granted on software and even software-only solution are by and large considered patentable and are patented (such as in the United States). In certain others, patents on pure software solutions are formally prohibited, but granted (this is the case of Europe), and in others again are neither allowed nor granted.
It is up to you to make sure that in the countries where the SDK is used, products are made using it and product are distributed, a license from the applicable patent holders is required or not. Receiving the SDK – or links to other downloadable software – does not provide any license expressed or implied over these patents, except in very limited conditions where the license so provides. No representation is made.
In certain cases, the optional packages are distributed only as source code. It is up to the receiver to make sure that in the applicable circumstances compiling the same code for a given platform or distributing the object code is not an act that infringes one or more patents.
Software is as-is
All software and the entire SDK is provided as-is, without any warranty whatsoever. The individual licenses have particular language disclaiming liability: we invite you to read all of them. Should you need a warranty on the fact that software works as intended or have any kind of indemnification, you have the option to subscribe a software maintenance agreement with a company or entity that is in that business. Fluendo and Collabora, as well as some other companies, provide software maintenance agreements under certain conditions, you are invited to contact them in order to receive further details and discuss of the commercial terms.
Frequently Asked Questions
What licenses are there?
The SDK containst software under various licenses. See above.
How does this relate to the packaging system?
The packaging is only a more convenient way to install software and decide what's good for you. GStreamer is meant to be modular, making use of different modules, or plugins, that perform different activities.
We provide some of them by default. Others are provided as an additional download, should you elect to do so. You could do the same by finding and downloading the same packages for your own platform. So it is entirely up to you to decide what to do.
Also, we note that SDK elements are divided into different packages, roughly following the licensing conditions attached to the same. For instance, the codecs-gpl package contains GPL licensed codecs. All the packages installed by default, conversely, are licensed under the LGPL or a more liberal license. This division is provided only for ease of reference, but we cannot guarantee that our selection is 100% correct, so it is up to the user to verify the actual licensing conditions before distributing works that utilize the SDK.
Can I / must I distribute the SDK along with my application?
You surely can. All software is Free/Open Source software, and can be distributed freely. You are not required to distribute it. Only, be reminded that one of the conditions for you to use software under certain licenses to make a work containing such software, is that you also distribute the complete source code of the original code (or of the modified code, if you have modified it). There are alternative ways to comply with this obligation, some of them do not require any actual distribution of source code, but since the SDK contains the entire source code, you might want to include it (or the directories containing the source code) with your application as a safe way to comply with this requirement of the license.
What happens when I modify the GStreamer SDK's source code?
You are invited to do so, as the licenses (unless you are dealing with proprietary bits, but in that case you will not find the corresponding source code) so permit. Be reminded though that in that case you need to also provide the complete corresponding source code (and to preserve the same license, of course). You might also consider to push your modifications upstream, so that they are merged into the main branch of development if they are worth it and will be maintained by the GStreamer project and not by you individually. We invite you not to fork the code, if at all possible.
How does licensing relate to software patents? What about software patents in general?
This is a tricky question. We believe software patents should not exist, so that by distributing and using software on a general purpose machine you would not violate any of them. But the inconvenient truth is that they do exist.
Software patents are widely available in the USA. Despite they are formally prohibited in the European Union, they indeed are granted by the thousand by the European Patent Office, and also some national patent offices follow the same path. In other countries they are not available.
Since patent protection is a national state-granted monopoly, distributing software that violates patents in a given country could be entirely safe if done in another country. Fair use exceptions also exist. So we cannot advice you whether the software we provide would be considered violating patents in your country or in any other country, but that can be said for virtually all kinds of sofware. Only, since we deal with audio-video standards, and these standards are by and large designed to use certain patented technologies, it is common wisdom that the pieces of software that implement these standards are sensitive in this respect.
This is why GStreamer has taken a modular approach, so that you can use a Free plugins or a proprietary, patent royalty bearing, plugin for a given standard.
What about static vs. dynamic linking and copyleft?
We cannot provide one single answer to that question. Since copyright in software works as copyright in literature, static linking means basically that the programmer includes bits of code of the original library in the bytecode at compile time. This amounts to make derivative code of the library without conceivable exceptions, so you need a permission from the copyright holders of the library to do this.
A widespread line of thinking says that dynamic linking is conversely not relevant to the copyleft effect, since the mingling of code in a larger work is done at runtime. However, another equally authoritative line of thought says that only certain type of dynamic linking is not copyright relevant. Therefore, using a library that is specifically designed to be loaded into a particular kind of software, even through API, requires permission by the copyright holder of the library when the two pieces are distributed together.
In all cases, since most of the software we include in the SDK is under the LGPL, this permission is granted once for all, subject to compliance with the conditions set out by it. Therefore, the problem only arises when you want to use GPL libraries to make non-GPL applications, and you need to audit your software in that case to make sure that what you do is not an infringement. This is why we have put the GPL libraries in a separate set of optional components, so you have a clearer view of what is safely clear for use, and what might need better investigation on a case-by-case basis.
Please be reminded that even for LGPL, the recipient of the software must be in a position to replace the current library with a modified one, and to that effect some conditions apply, among which that for static linking you must also provide the complete toolchain required to relink the library (“any data and utility programs needed for reproducing the executable from it”, except the “major components”) and that the license of the conditions of the resulting program must allow decompilation to debug modifications to the library.