Keep your ears open
It is not suitable for the FreePats project unless it is accompanied by a special exception. Please read Copyleft and ShareAlike for more information.
It is not suitable for the FreePats project. It would impose serious restrictions to any work built upon those sound samples. Please read Copyleft and ShareAlike for more information.
It is not suitable for the FreePats project. Any composition made with sound samples constitutes a derivative work of multiple pieces. If derivatives are not permitted, it would be impossible to make anything useful.
While it may make sense to license a whole composition under NoDerivatives condition, when someone licenses sound samples intended for musical production, it is usually by misundertanding. The author probably wants a proprietary license with no license fees instead of Creative Commons NoDerivatives.
It is not a free license under the open source definition. It places restrictions on commercial distribution and only allows modifications under certain limited conditions. It is rejected by the Debian Free Software Guidelines.
Moreover, Creative Commons has retired the Sampling Plus license and does not recommend it anymore. It has other drawbacks, as it is not compatible with any other Creative Commons license. Please don't use it for your works.
We highly recommend to always give credit to your sources, even in those cases which is not strictly required by the license. Your artistic content will also be enhanced when your audience is provided with background information about the work, like credits at the end of a movie. We believe that it is fair and useful.
However, some people may find cumbersome to maintain a list and properly credit every single sound sample that was combined on their work, and sometimes it can be difficult to find a place to include attribution, specially while streaming or during a live performance.
We always recommend attribution as a good practice, but we prefer licenses that don't require attribution for practical reasons. In certain cases we may avoid sound samples under licenses that require attribution, such as within General MIDI collections or combined sound banks. If you want to contribute your original sound samples, we suggest a permissive license like CC0 for easiest and widest usage.
The GNU General Public License (GPL) is a popular license for free software, it prevents a computer program to become proprietary because all modifications of the program are required to be licensed in the same terms. This concept is commonly referred as Copyleft. Some Creative Commons licenses use a similar concept, referred as ShareAlike.
Usually the output of a GPL program is not covered by the GPL itself, though there are exceptions, but sound samples are different than computer programs because they are mixed into the final work. It means that when someone creates a composition using GPL sound samples, the composition itself must be licensed under the GPL.
We encourage people to distribute their artistic works under a free license, but we definitely don't want to impose a particular license for their works. The FreePats project can only accept GPL licensed samples if they include a special exception, please read GPL+exception for more information. For the same reason, Creative Commons ShareAlike licenses are unsuitable for the FreePats project.
Things can become complicated if a single work combine sound samples from different sources or under different licenses. Not all licenses are compatible with each other, even if all of them are considered free. See the compatibility chart of Creative Common licenses for examples.
A project like FreePats combines sound samples from multiple sources, authors, and licenses. It would soon become a mess if some sounds are made incompatible with others, so we must reject any license that can create compatibility problems. That means that most Copyleft/ShareAlike licenses are unsuitable, even if they are considered free within other contexts.
Sometimes files do not carry a license, or they just say that were "taken from public domain sources". This is a quite common case with sound samples downloaded from the Internet or distributed with music magazines.
People may think that files with no license are automatically in the public domain. That is not true under today's copyright law. Absent a license to grant users freedom, they don't have any. This is explained with more detail in the FSF web site.
Due to the vast amount of sound samples extracted from proprietary libraries and incorrectly identified as public domain all over the Internet, we can only accept them if their sources are documented and verified.
Informal licenses such as "do whatever you want" may be subject to different interpretations and should be taken with caution. Sometimes it may be required to ask their authors for clarification.