| Offset | Bytes | Description |
| 0 | 20 | Songname. Remember to put trailing null bytes at the end... |
Information for sample 1-31:
| Offset | Bytes | Description | ||||||||||||||||||||||||||||||||||
| 20 | 22 | Samplename for sample 1. Pad with null bytes. | ||||||||||||||||||||||||||||||||||
| 42 | 2 | Samplelength for sample 1. Stored as number of words. Multiply by two to get real sample length in bytes. | ||||||||||||||||||||||||||||||||||
| 44 | 1 | Lower four bits are the finetune value, stored as a signed four bit number. The upper four bits are not used, and should be set to zero.
| ||||||||||||||||||||||||||||||||||
| 45 | 1 | Volume for sample 1. Range is $00-$40, or 0-64 decimal. | ||||||||||||||||||||||||||||||||||
| 46 | 2 | Repeat point for sample 1. Stored as number of words offset from start of sample. Multiply by two to get offset in bytes. | ||||||||||||||||||||||||||||||||||
| 48 | 2 | Repeat Length for sample 1. Stored as number of words in loop. Multiply by two to get replen in bytes. |
Information for the next 30 samples starts here. It's just like the info forsample 1.
| Offset | Bytes | Description |
| 50 | 30 | Sample 2... |
| 80 | 30 | Sample 3... |
| . | | |
| . | | |
| . | | |
| 890 | 30 | Sample 30... |
| 920 | 30 | Sample 31... |
| Offset | Bytes | Description |
| 950 | 1 | Songlength. Range is 1-128. |
| 951 | 1 |
Well... this little byte here is set to 127, so that old trackers will search through all patterns when loading. Noisetracker uses this byte for restart, but we don't. |
| 952 | 128 |
Song positions 0-127. Each hold a number from 0-63 that tells the tracker what pattern to play at that position. |
| 1080 | 4 |
The four letters "M.K." - This is something Mahoney & Kaktus inserted when they increased the number of samples from 15 to 31. If it's not there, the module/song uses 15 samples or the text has been removed to make the module harder to rip. Star trekker puts "FLT4" or "FLT8" there instead. |
| Offset | Bytes | Description |
| 1084 | 1024 | Data for pattern 00. . . . |
| xxxx |
Number of patterns stored is equal to the highest pattern number in the song position table (at offset 952-1079). |
Each note is stored as 4 bytes, and all four notes at each position inthe pattern are stored after each other.
00 - chan1 chan2 chan3 chan4 01 - chan1 chan2 chan3 chan4 02 - chan1 chan2 chan3 chan4 etc. Info for each note: _____byte 1_____ byte2_ _____byte 3_____ byte4_ / \ / \ / \ / \ 0000 0000-00000000 0000 0000-00000000 Upper four 12 bits for Lower four Effect command. bits of sam- note period. bits of sam- ple number. ple number. Periodtable for Tuning 0, Normal C-1 to B-1 : 856,808,762,720,678,640,604,570,538,508,480,453 C-2 to B-2 : 428,404,381,360,339,320,302,285,269,254,240,226 C-3 to B-3 : 214,202,190,180,170,160,151,143,135,127,120,113
To determine what note to show, scan through the table until you find the same period as the one stored in byte 1-2. Use the index to lookup in a note names table.
This is the data stored in a normal song. A packed song starts with thefour letters "PACK", but i don't know how the song is packed: You canget the source code for the cruncher/decruncher from us if you need it,but I don't understand it; I've just ripped it from another tracker...
In a module, all the samples are stored right after the pattern data. To determine where a sample starts and stops, you use the sample info structures in the beginning of the file (from offset 20). Take a lookat the mt_init routine in the playroutine, and you'll see just how itis done.
Lars "ZAP" Hamre/Amiga Freelancers
Mark J Cox
Bradford, UK
PS: A file with even *much* more info on MOD files, compiled by LarsHamre,
is available from ftp.cwi.nl:/pub/audio/MOD-info.
Enjoy!
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