How to make paths in *.m3u playlists relative?

As you know users can put all songs from a directory in a order they like and save the playlist (with
the order) into a *.m3u playlist file.

This works fine as long as all songs in the *.m3u playlist are inside the current folder.

If I want to group songs from many different (sub) folders into one and the same *.m3u
then this is only possible with an FULL ABSOLUTE PATH (that means with prepended drive letter).

Since I want to put all my .mp3 on an USB flash drive and play it on various devices (e.g. Hifi stations
at friends or notebooks or whatever) the drive letter may change.

Furthermore I want to be able to move the whole .mp3 folder tree to another location without
destroying the location information.

So what I need is an audio player which let me save RELATIVE path information into *.m3u playlists.

Does someone know such a tool which can play songs AND save relative pathes?

Thank you
Peter

Relative to what?

DD.20140820.1824.CEST

Mp3tag can do this.
Use an action "Format value" on the pseudo tag-field _DIRECTORY.
Search the forum for examples.

DD.20140820.1830.CEST

Obviously to the position of the playlist *.m3u file

If you want to move the playlist about freely, you would have to use absolute paths.

In case of the original playlist file has absolute filepathnames, then use a text editor, load the copy of the playlist, and change all filepathnames, replace "DriveLetter:" with one dot character ".".
Then all filepathnames are named relative to the current folder of the playlist.
You have to make sure, whether players can work with this path information.

See also ...
http://en.wikipedia.org/wiki/Path_(computing)

... and have a look into the dialog ...
Mp3tag>Extras>Options>Playlist

DD.20140824.1153.CEST