Update README.md

README.md

@@ -4,3 +4,17 @@ This is a port of the original Dexed engine (see https://github.com/asb2m10/dexe
 
 The current state is: work in progress... 
 
+## License
+Dexed is licensed on the GPL v3. The msfa component (acronym for music synthesizer for android, see msfa in the source folder) stays on the Apache 2.0 license to able to collaborate between projects.
+
+## Credits & thanks
+
+* Dexed engine by Pascal Gauthier (asb2m10)
+* DX Synth engine (as part of Dexed): Raph Levien and the msfa team
+* PPPlay : Great OPL3 implementation, with documented code :D
+
+## Dexed comes with 3 engine types :
+
+* Modern : this is the original 24-bit music-synthesizer-for-android implementation.
+* Mark I : Based on the OPL Series but at a higher resolution (LUT are 10-bits). The target of this engine is to be closest to the real DX7.
+* OPL Series : this is an experimental implementation of the reversed engineered OPL family chips. 8-bit. Keep in mind that the envelopes stills needs tuning.