libopenmpt is a BSD-3-clause-licensed, cross-platform C and C++ module playback library. It is based on the player code of the Open ModPlug Tracker project.
Since libmodplug, which is based on an earlier version of the original ModPlug code base, had been released, the code bases of other ModPlug descendants (most notably Schism Tracker and Open ModPlug Tracker) had diverged significantly from the libmodplug code base. libmodplug did, in our opinion, not maintain pace all that well - especially regarding playback accuracy in corner cases.
Over the last year, OpenMPT developers refactored the OpenMPT code base in a way such that a player library can be built separately from the tracker GUI again, as it had been possible with the original ModPlug Tracker source code drop by Olivier Lapicque.
In order to avoid possible future source code fragmentation, libopenmpt is, and will continue to be, developed together with OpenMPT itself in the same source code repository.
libopenmpt comes together with a stand-alone command-line/terminal-based player called openmpt123 as well as player plugins for XMPlay (xmp-openmpt), Winamp (and compatible) (in_openmpt) and foobar2000 (foo_openmpt). A gstreamer plugin, gst-nonstream-audio, is currently in the works at https://github.com/dv1/gst-nonstream-audio. A Debian package is also being worked on.
Get more information at the libopenmpt website at lib.openmpt.org.