GSTFS is a filesystem for on-demand transcoding of music files between
different formats.  It utilizes the gstreamer library for conversion so any
formats supported by gstreamer should also be supported by gstfs.  The
filesystem's only requirement is that the gstreamer pipeline begin with a
filesrc with the name "_source" and end with an fdsink with the name "_dest".
The filesystem will automatically substitute the filename and fd number in
these pipelines.