[media file] A demultiplexer for digital media files, or media demultiplexer also called a file splitter by laymen or consumer software providers, is software that demultiplexes individual elementary streams of a media file, e.g., audio, video, or subtitles and sends them to their respective decoders for actual decoding. Media demultiplexer... Found on http://en.wikipedia.org/wiki/Demultiplexer_(media_file)