GSS

GSS, short for General Sound Set, is the name of DMX's support for using MIDI sound effects. Instead of using the standard MIDI format, GSS use DMX formats 1 and 2 (format 0 is used for PC speaker sound effects, format 3 is used for digitized sounds).

The standard, a superset of  introduces the concept of instrument banks, which is used in these GSS sound formats; thanks to them there can be separate sound effect banks and melodic banks, so MIDI sound effects could be used without affecting the instruments used by MIDI music.

Format 1
This format allows to have simple sequences of notes played by a single instrument.

The sample rate is 140 Hz. A sample with value zero is a note off, otherwise each sample value determines both the note and the pitch bend. The note and pitch bend portions are bitpacked into a single byte:
 * note is equal to 28 plus the top 7 bits of the byte.
 * pitch bend depends on the lowest bit of the byte: a value of 0 maps to a MIDI pitch bend of 159, while a value of 1 maps to a pitch bend of 127.

Format 2
This format only defines a single note.