IzSound is distributed under a 3 clauses BSD-style license. Here are the exact terms of the license agreement:
IzSound - Copyright (c) 2003, 2004 Julien PONGE - All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the author nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
You must be aware that although IzSound is released under a BSD-style license, some DSP units might require a library which is released under a license which has more constraints. It may also use third-party code published on a more restrictive license. Those DSP units can be disabled by the configure script before you build IzSound. The following table sums-up the licensing constraints put on the applications that use IzSound.
Table 1.1. Licensing constraints, depending on the DSP that are built in IzSound
Your application license has to be compatible with the GNU GPL. The DSP unit source code is licensed under the terms of the IzSound license.
Your application license has to be compatible with the GNU GPL. The DSP unit source code is licensed under the terms of the GNU GPL.