SSG-EG

SSG-EG is a feature of the OPN soundchip that uses the ADSR envelope to create a wave shape as the final envelope. It works similarly to an amplitude LFO, except it can get to frequencies high enough to be perceived as a note pitch and modify the base sine wave. This allows for creating more complex sounds with the FM channels.

However it's a pretty complex feature that not even many musicians used before the 2000's. It wasn't even implemented into PMD properly until KAJA updated it in 2020.

Because of this, currently there are only 1 player and 1 emulator that support it:

Player	SSG-EG	Comment
pmdwin.dll	Yes	Versions released after 2020
NekoProject II fmgen	Yes	use genpfm.dll
98fmplayer	No
DOSBox-X	No
PMDDotNET	No	Dev prefers keeping to the original version
MML2VGM IDE	No	Dev prefers keeping to the original version

pmdwin.dll refers to the library used by FMPMD2000, inFMPMD and foo_input_fmpmd.

Usage

SSG-EG is a complicated feature that you have to build your instrument speficically to use, or else it won't work. Using an instrument editor such as YM2608 tone editor on Windows or VEDSE on DOS will allow you to test the values properly.

After creating a instrument and putting it in the script, call the instrument with @ and then use the command SE<operator>,<value>:

@0 0 0 31 19 31 15 2 29 0 7 7 0 31 11 31 15 1 28 0 0 3 0 24 11  0 15 2 29 0 2 0 0 27 13 12 15 2  2 0 2 0 0

A   @0 l8 o3 [c4gc2.<g16g16>[c<g]3]4  ;Instrument without SSG-EG
A   SE3,8    [c4gc2.<g16g16>[c<g]3]4  ;Activating SSG-EG changes the sound to a timpani-like sound

<operator> indicates which FM slots the SSG-EG applies to. The expected value is similar to other individual-slot commands. 0 is not a valid value. Note that any slots not specified are not changed.

<value> indicates the mode of the SGG-EG. Its range is 0–15. The following table is a summary of all modes.

Mode	Result
0–7	Disables SSG-EG
8	Repeats the ADSR envelope upon the volume reaching 0
9	As if SSG-EG was disabled, though it is enabled
10	Repeats the ADSR envelope forward and backward, reversing when the volume reaches 0 or maximum respectively
11	Uses the ADSR envelope, then stays at maximum volume
12–15	The same as the respective type minus 4, but inverted so that volume 0 is maximum and vice versa

A difference to the ADSR envelope when using SSG-EG is that AR is fixed at 31 regardless of the instrument definition. Furthermore, because SSG-EG expects the ADSR envelope to reach 0, if it does not (due to DR, SL, or SR not allowing it), then SSG-EG can't apply.

It's important to note that the SSG-EG won't reset on instrument change, so you need to deactivate it with SE15,0 when changing to an instrument that doesn't use it.

If you don't know how SSG-EG works and how to make instruments that use it, this video has a quick look into it at the first part. The software is different, but it works the same.