This is the documentation of the library that stands behind mp3splt (version >= 2.2) and mp3splt-gtk.
Libmp3splt is licensed under the GNU General Public License version 2.
Source code and binaries can be found on the mp3splt-project home page.
Some of the library features include:

losslessly split of mp3 (using libmad), ogg vorbis (using libvorbis), FLAC files
extensibility to other audio formats using plugins
querying tags from tracktype.org
split on silences
trim using silence detection
split by a fixed time or equal time length
CDDB, CUE, audacity labels import
CUE export
extract tracks created with Mp3Wrap or AlbumWrap

In order to use the library in another project:

Start with the Initialisation of the main state section, continue with Input filename and paths and Registering callback functions and then finish with Splitpoints handling and Split functions.
A minimal example on how to use this library can be found in minimal.c
For any other example or question, contact Alexandru Munteanu at m@ioa.nosp@m.lex..nosp@m.net.

For writing a plugin to support other file type:

Look at the splt_plugin_func from the Creating libmp3splt plugins.

A list of all modules is also available.