All PulseAudio source files are licensed under the GNU Lesser General Public
License. (see file LGPL for details)
-However, the server side links to the GPL-only library 'libsamplerate' which
-practically downgrades the license of the server part to GPL (see file GPL for
-details), exercising section 3 of the LGPL.
+However, the server side has optional GPL dependencies. These include the
+libsamplerate and gdbm (core libraries), LIRC (lirc module) and FFTW (equalizer
+module), although others may also be included in the future. If PulseAudio is
+compiled with these optional components, this effectively downgrades the
+license of the server part to GPL (see the file GPL for details), exercising
+section 3 of the LGPL. In such circumstances, you should treat the client
+library (libpulse) of PulseAudio as being LGPL licensed and the server part
+(libpulsecore) as being GPL licensed. Since the PulseAudio daemon, tests,
+various utilities/helpers and the modules link to libpulsecore and/or the afore
+mentioned optional GPL dependencies they are of course also GPL licensed also
+in this scenario.
-Hence you should treat the client library ('libpulse') of PulseAudio as being
-LGPL licensed and the server part ('libpulsecore') as being GPL licensed. Since
-the PulseAudio daemon and the modules link to 'libpulsecore' they are of course
-also GPL licensed.
+In addition to this, if D-Bus support is enabled, the PulseAudio client library
+(libpulse) MAY need to be licensed under the GPL, depending on the license
+adopted for libdbus. libdbus is licensed under either of the Academic Free
+License 2.1 or GPL 2.0 or above. Which of these applies is your choice, and the
+result affects the licensing of libpulse and thus, potentially, all programs
+that link to libpulse.
--- Lennart Poettering, April 20th, 2006.
+Andre Adrian's echo cancellation implementation is licensed under a less
+restrictive license - see src/modules/echo-cancel/adrian-license.txt for
+details.
+
+Some other files pulled into PA source (i.e. reference implementations that are
+considered too small and stable to be considered as an external library) use the
+more permissive MIT license. This include the device reservation DBus protocol
+and realtime kit implementations.
+
+Additionally, a more permissive Sun license is used for code that performs
+u-law, A-law and linear PCM conversions.
+
+While we attempt to provide a summary here, it is the ultimate responsibility of
+the packager to ensure the components they use in their build of PulseAudio
+meets their license requirements.