All of this information has been accumulated over reading some sources. Made by RepellantMold, 2023/2024.
| Offset (decimal and hex) | Size of field (bytes) | Explanation of field (accumulated information from various documents) |
|---|---|---|
| 0 | 20 | Song title (in ASCIIZ) |
| 20/0x14 | 8 | Magic string, common value is "!Scream!" (this is not checked in either Scream Tracker 2 or 3 but other importers tend to be picky about this!) |
| 28/0x1C | 1 | 0x1A (checked in Scream Tracker 3 but not 2) |
| 29/0x1D | 1 | File type (song = 1, module = 2) |
| 30/0x1E | 1 | Major version |
| 31/0x1F | 1 | Minor version |
| 32/0x20 | 1 | Initial tempo |
| 33/0x21 | 1 | Number of patterns |
| 34/0x22 | 1 | Global volume |
| 35/0x23 | 13 | Reserved |
| 48/0x30 | Instrument header * 31 | Instrument information |
| 1024/0x410 | 128 | Order list (decimal 99 for blank entries) |
| 1168/0x490 | 4 * 64 * Number of patterns | Pattern data |
| after the pattern data | sample size, padded to 16 byte boundaries | PCM data |
| Offset (decimal and hex) | Size of field (bytes) | Explanation of field (accumulated information from various documents) |
|---|---|---|
| 0 | 12 | Sample name (in ASCIIZ) |
| 12/0x0C | 1 | 0x00 |
| 13/0x0D | 1 | Insrtument disk |
| 14/0x0E | 2 | Parapointer to sample data |
| 16/0x10 | 2 | Sample length |
| 18/0x12 | 2 | Loop start |
| 20/0x14 | 2 | Loop end (65535/0xFFFF denotes no loop) |
| 22/0x16 | 1 | Default volume |
| 23/0x17 | 1 | Reserved |
| 24/0x18 | 2 | C2 speed |
| 26/0x1A | 6 | Reserved |
The pattern format consists of the following...
byte 1: oooonnnn
byte 2: iiiiivvv
byte 3: VVVVeeee
byte 4: pppppppp
o = octave (valid range 0 - 4, all other values are invalid/garbage and 10 - 15 show up as garbage characters)
n = note (valid range 0 - 11 = C - B, other values are undefined)
i = instrument (valid range 0 - 31, 0 = blank cell)
Vv = volume (valid range 0 - 127, 65 = blank cell, 66+ = undefined, causes awful audio clipping and shows up as "??" in the editor)
e = effect (valid range 0 (no effect) - 15, they show up as A (1 internally) - O in the editor, however only A - J are defined with all other effects doing nothing and even bugging out Scream Tracker 3 when importing)
p = effect parameter
The effects have really strange/quirky behavior when compared to other trackers and even Scream Tracker 3.
| Effect | Function in ST2/STMIK - in ST3/others | Notes/Quirks (Effect memory does not exist in Scream Tracker 2, so a parameter of 0 will act like a no-op for any effect that normally has it like volume slide, porta slides, vibrato, etc.) |
|---|---|---|
| Axx | Set speed - Set ticks per row | It has a scaling factor alongside setting ticks per row. |
| Bxx | Set next order - Position jump | It does not perform an immediate pattern break unlike most other trackers. |
| Cxx | Pattern break | The parameter is ignored which is identical behavior to NoiseTracker. |
| Dxy | Volume slide | There's no fine slides, and y will take priority if both x and y are specified (which is backwards from how it's usually handled). |
| Exx | Portamento down | This effect can cause the note period to underflow, and there are no fine/extra-fine slides. |
| Fxx | Portamento up | This effect can cause the note period to overflow, ditto for fine/extra-fine slides. |
| Gxx | Tone portamento | It does not reset the sample volume unlike most other trackers. |
| Hxy | Vibrato | The depth is doubled compared to other trackers. |
| Ixy | Tremor | A parameter of 0 will be a very fast tremor which is identical to how it behaves in Scream Tracker 3 before v3.20. |
| Jxy | Arpeggio | The effect tends to skip to y halfway through a row if x was 0, it's not commonly implemented this way however. |
| Kxx | (No-op) - Vibrato + Volume slide | This can be entered into the editor but it does not do anything. |
| Lxx | (No-op) - Tone portamento + Volume slide | Ditto. |
| Mxx | (No-op) | Ditto. |
| Nxx | (No-op) | Ditto. |
| Oxx | (No-op) - Set sample offset | Ditto. |
Byte 1 can also have special meanings, specificially if it is...
| value | meaning |
|---|---|
| 251/0xFB | the next 3 bytes do not exist, and are 0 |
| 252/0xFC | the next 3 bytes do not exist, note = -0- (note cut) |
| 253/0xFD | the next 3 bytes do not exist, note = ... |
| 254/0xFE | note = -0- |
| 255/0xFF | note = ... |
Do note that these pseudocode examples does not handle the special note cases.
switch(byte1) {
default:
octave = byte1 & 0xF0;
pitch = byte1 >> 4;
note = octave * 12 + pitch;
break;
case 251:
instrument = 0;
volume = 0;
effect_type = 0;
effect_param = 0;
case 252:
case 253:
break;
case 254:
case 255:
note = byte1;
break;
}
instrument = byte2 >> 3; // 0=empty
volume = (byte2 & 0x07) | (byte3 >> 4); // 65=empty, 66-127=undefined
effect_type = byte3 & 0x0F;
effect_param = byte4;
octave = note / 12;
pitch = note % 12;
byte1 = pitch | (octave << 4);
byte2 = (instrument << 3) | (volume & 0x07);
byte3 = ((volume & 0x78) << 1) | effect_type;
byte4 = effect_param;
These pseudocode examples are made by cs127