I'm in a situation where I've got some DLS format (http://www.midi.org/techspecs/dls/dls.php) soundfonts that I'd like to use in, say, MuseScore, which only supports SF2/SF3. And after spending some time searching around, the only software I've found capable of importing DLS and exporting SF2 has been limited or defunct proprietary trial-ware with super-confusing UI (i.e. Awave and Vsamp3). Would be cool to be able to use a decent open-source program like Polyphone to do the job!
I also second with this request. DLS is de facto Soundbank to be embedded in RIFF MIDI (.rmi) and Extensible Music Format (.xmf). If we want portable MIDI file that include its own sound bank, DLS is the solution.
AFAIK the only open source library supporting this format is from OpenMPT that use it for mapping soundfont to module format.
Here is the link https://source.openmpt.org/browse/openmpt/trunk/OpenMPT/soundlib/Dlsbank.h
