Full Sound Tracker ZX-Spectrum compilled module description
Updated 07.12.2015
STC format of Sound Tracker for ZX-Spectrum is simple according with other tracker formats.
STC file structure:
Offset Size Name Description
+0 1 Delay Global delay in interrupts
+1 2 Positions Pointer
+3 2 Ornaments Pointer
+5 2 Patterns Pointer
+7 18 Identifier 'SONG BY ST COMPILE' or anything else
+25 2 Size Full length in bytes (may be incorrect)
+27 99*X Samples Pointer Samples, 99 bytes per sample
the first byte is sample number
may be in wrong order, so you must check
sample numbers of each sample to find correct,
X = 1-16
+27+99*X Data Other data
Sample format
Samle length is 99 bytes (32 positions)
Off Size Name Description
+0 1 Sample Number
+1 32*3 Data samples data (3 bytes per each)
- byte 0 - bits 0-3 volume,
bits 7-4 for low bits of high byte of pitch
- byte 1 -
- bit 7 noise mask (0 - enabled, 1 - disabled)
- bit 6 tone mask (0 - enabled, 1 - disabled)
- bit 5 +- determines the direction of pitch shift
(1 +, 0 -)
- bits 0-4 noise value
- byte 2 - pitch (low byte)
+97 1 Repeat Position - sample & ornament repeat position
(if equal to 0, the channel is disabled at the end of sample)
+98 1 Repeat Length - the length of repeat
PS: if Repeat Length is higher then sample positions left then position starts from zero
Ornament format
Full ornament length is 33 bytes (32 positions changed together with sample)
Off Size Name Description +0 1 Ornament Number +1 32byte Data each byte is value of 12 half tones (1 octave) signed!
Pattern Format (for each channel)
Values in pattern
0x00-0x5f - note number after receive should finish position
0x60-0x6f - sample number -0x60
there are no zero sample
0x70-0x7f - ornament number -0x70
disable envelope
if zero value - disable ornament
0x80 - command R (pause) (disable channel and finish position)
0x81 - empty note (do nothing but finish position)
0x82 - disable envelope and ornament
0x83-0x8e - envelope value -0x80 (3 - 14)
(next byte is low byte of envelope period)
also disable ornament
0x8f-0xa0 - impssible values in pattern
(for future developement)
0xa1-0xfe - delay between notes in channel (in interrupts) - 0xa1 0xff - end of pattern
Patterns table format
Each pattern record is 7 bytes
Off Size Name Description
+0 1 Number Pattern number
+1 2 Address Ch A Pattern of channel A offset
+3 2 Address Ch B Pattern of channel B offset
+5 2 Address Ch C Pattern of channel C offset
Positions table format
Off Size Name Description +0 1 Count Number of positions in table +1 Count*2 Positions Positions data
Each position record is 2 bytes
Off Size Name Description
+0 1 Transposition Global Tone offset for pattern
+1 1 PatternNum Pattarn Number for this position
Note frequency table
static ushort[] ST_Table = {
0xef8, 0xe10, 0xd60, 0xc80, 0xbd8, 0xb28, 0xa88, 0x9f0, 0x960, 0x8e0,
0x858, 0x7e0, 0x77c, 0x708, 0x6b0, 0x640, 0x5ec, 0x594, 0x544, 0x4f8,
0x4b0, 0x470, 0x42c, 0x3f0, 0x3be, 0x384, 0x358, 0x320, 0x2f6, 0x2ca,
0x2a2, 0x27c, 0x258, 0x238, 0x216, 0x1f8, 0x1df, 0x1c2, 0x1ac, 0x190,
0x17b, 0x165, 0x151, 0x13e, 0x12c, 0x11c, 0x10b, 0x0fc, 0x0ef, 0x0e1,
0x0d6, 0x0c8, 0x0bd, 0x0b2, 0x0a8, 0x09f, 0x096, 0x08e, 0x085, 0x07e,
0x077, 0x070, 0x06b, 0x064, 0x05e, 0x059, 0x054, 0x04f, 0x04b, 0x047,
0x042, 0x03f, 0x03b, 0x038, 0x035, 0x032, 0x02f, 0x02c, 0x02a, 0x027,
0x025, 0x023, 0x021, 0x01f, 0x01d, 0x01c, 0x01a, 0x019, 0x017, 0x016,
0x015, 0x013, 0x012, 0x011, 0x010, 0x00f
};
Format features
Number of octaves: 8
Number of positions: 1-256
Number of patterns: 1-32
Number of positions in pattern: 1-64
Number of samples: 16
Number of ornaments: 16