Every cell has an effect: a number from 0 to F in the low half of its third byte, and an 8-bit parameter in its fourth. Unlike the layout, the effects changed from one Soundtracker to the next, and the file does not say which program wrote it. The same number can mean different things in two files, so a player has to guess from the effects themselves.
Ultimate Soundtracker
Karsten Obarski’s Ultimate Soundtracker had two effects that changed the pitch:
| Effect | Name | What it does |
|---|---|---|
1xy | arpeggio | Cycles between the note, the note + x semitones and the note + y semitones. |
2xy | pitch bend | With y not 0: slides the pitch up by y a tick. With y 0: slides it down by x a tick. |
Other numbers did “modulation”, according to the Tracker History project; what each did is not recorded in the sources used for these pages.
The later Soundtrackers
The Soundtrackers that followed moved arpeggio to 0, used 1 and 2 for slides, and added more, one program at a time:
| Program | Date | Effects it added |
|---|---|---|
| TJC Soundtracker II | March 1988 | C set volume, D and E volume slides, tempo changes during play |
| Soundtracker III (Defjam) | March 1988 | F set speed |
| D.O.C. Soundtracker IX | July 1988 | 0 arpeggio, 1 and 2 slides, C volume, E filter, F speed |
| D.O.C. Soundtracker 2.0 | August 1988 | B position jump and D pattern break |
The effects of D.O.C. Soundtracker IX and after, with the ProTracker meanings the explorer gives them:
| Effect | Name | What it does |
|---|---|---|
0xy | arpeggio | Cycles between the note, the note + x semitones and the note + y semitones, tick by tick. 000 is no effect. |
1xx | slide up | On each tick after the first, takes xx from the period, raising the pitch. |
2xx | slide down | On each tick after the first, adds xx to the period. |
Bxx | position jump | After this row, goes on at position xx (from D.O.C. Soundtracker 2.0). |
Cxx | set volume | Sets the volume to xx, 0 to 64. |
Dxy | volume slide or pattern break | In some versions a volume slide; in the latest, D00 is a pattern break, going on at the next position (OpenMPT). |
E0x | filter | Switches the Amiga’s low-pass filter. |
Fxx | set speed | Sets the speed, ticks a row. Soundtracker reads only the low four bits, so the speed is 1 to 15 (OpenMPT). |
How the explorer plays them
Like OpenMPT, the explorer decides between the two sets from the patterns. If any
1xx or 2xx in the stored patterns has a parameter above
1F, the module is taken to be Ultimate Soundtracker’s. Then:
1xyplays as an arpeggio, and2xyas a slide up by y or, when y is 0, a slide down by x;- every other effect is ignored.
Otherwise the effects are read with ProTracker’s meanings, with two changes for the Soundtrackers:
- a
Dxywhose parameter is not00is a volume slide, up by x or down by y as ProTracker’sAxy;D00is a pattern break; Fxxkeeps only its low four bits, soF06andF16both set speed 6, and anFwhose low four bits are 0 does nothing.
The explorer’s summary of a module says which set it used. The guess can be wrong: an
Ultimate Soundtracker song whose 1xx and 2xx all stay at
1F or below is read with the later set, and a later song with a slide
above 1F is read as Ultimate Soundtracker’s.