From the ALSA wiki
What is a Sound Font
A SoundFont bank (or SoundFont-compatible bank) contains both the digital audio samples which have been captured from a sound source, and the instructions to the wavetable synthesizer on how to articulate this sound based on the musical or sonic context as expressed by MIDI (called articulation data). A SoundFont bank also contains information about the creation and intended use of the particular bank. Josh Green has a good introduction to the SoundFont technology here and an FAQ is at soundfont.com. The free technical specification for the 2.01 version of DLS SoundFonts can also be downloaded from soundfont.com.
SoundFont 2.0 License
E-MU / ENSONIQ and Creative Technology are actively promoting SoundFont 2.0 as an open standard. We have worked diligently on getting complete, unambiguous documentation and a suite of tools available for developers who might want to use the SoundFont 2.0 format. After a year of experience with SoundFont 1.0, E-MU / ENSONIQ and Creative Technology realized there had been a number of omissions in the SoundFont 1.0 realization of the original SoundFont concept. Rather than sticking to the SoundFont 1.0 format and putting up with these inadequacies, E-mu/Creative determined that the public release of the SoundFont standard would be a good time to make a clean sweep and revised the format to include all the necessary features.
It seems the actual PDF specification cannot be redistributed but the content and spirit of the specification is free for use by all. In other words, we cannot include the PDF file in open source distributions but we can link to it and freely use the standard. (If anyone has any views on this, either way, please say so).
Retrieved from "http://alsa.opensrc.org/SoundFont"