14832 views

 

33% damifortune

::|CONTENTS

1. Amigamod on BotB
2. Quirks of the format
3. Effect details
4. Tools
5. Restrictions on submit
6. Playback (for voting)
7. See also

The .mod filetype was the tracker module file for Protracker, originally developed for the Commodore Amiga. The original filetype had 4 channels of playback with 15 sample-based instruments, though later versions upped the sample limit to 31 samples (which is supported by BotB). Protracker was one of the first and most popular examples of software, and the .mod format saw extensive use in the demoscene and in video game development.

While the .mod format originated with Protracker, these days there is a wide variety of software that can import and/or export the module.

Amigamod on BotB

---

Most folks on BotB use the modern standard OpenMPT

for writing amigamod, though other tools are listed in the "Tools" section below.

In OpenMPT, make sure to enable the "Amiga Frequency Limits" option in View -> Song Properties. This prevents you from exceeding the (somewhat harsh) frequency limits of samples in the format - notes outside the range of C4 to B6 will turn red, and they won't play back properly, as they wouldn't on the original hardware. Bb6 and B6 are also somewhat flat, so it's best to stick to the traditional range of C4-A6.

Also in OpenMPT, "Resampling" on the General tab should be set to "Amiga Resampler". This is the default behavior.

Quirks of the format

---

The format has a characteristic hard-panned sound where the 4 channels are panned as follows:
Left / Right / Right / Left

The available note range for the Amiga is approximately C3 to A5, depending on the tracker, with higher notes distorting on a real Amiga. (Some trackers, such as OpenMPT, have this offset by an octave, i.e. C4 to A6.)

Unlike some of the other classic module filetypes, .mod files must have a pattern length of 64 (40 in hex).

As you might gather from the fairly limited note range, samples may have to be re-tuned to different octaves to utilize them where you want. This also means something like a bass sample might not be able to also be used as a high-pitched lead unless you duplicate and resample it.

Sample loop points are available in limited capacity: there is only the regular "forward" loop point, and loop points must be located on even numbers. They will be rounded down 1 if they are odd. (In OpenMPT this behavior won't occur until you've saved and reloaded your .mod, so be careful!) If both values fall on odd numbers consider adding a single point of silence at the beginning of the sample.

Effect details

---

You may recognize many of these effects from other trackers and formats like FamiTracker, DefleMask, Furnace or .XM.

Note that unlike other trackers and formats, there is only one column for effects, and there are no volume effects. The volume column in MPT and other trackers is entirely unused when editing .mod files. Volume is set via the Cxx effect instead.

Unlike e.g. FamiTracker, effect commands aren't "toggled off/on" and have to be used on each row you desire their effect.

Effects allowed:
0xy - Arpeggio
1xx - Portamento up
2xx - Portamento down
3xx - Portamento to specific note
4xy - Vibrato
5xy - Volume Slide (Axy) + Portamento (3xx)
6xy - Volume Slide (Axy) + Vibrato (4xy)
7xy - Tremolo
9xx - Sample offset
Axy - Volume Slide
Bxx - Jump to pattern
Cxx - Set volume (00 - 64 [40 in hex])
Dxx - Pattern break to row XX (up to 63 [3F in hex])
E1x - Fine Porta up
E2x - Fine Porta down
E3x - Glissando Control
E4x - Vibrato Waveform
E5x - Finetune
E6x - Pattern Loop
E7x - Tremolo Waveform
E9x - Retrigger Note
EAx - Fine Volume Slide Up
EBx - Fine Volume Slide Down
ECx - Note Cut
EDx - Note Delay
EEx - Pattern Delay
EFx - Invert Loop
Fxx - Set Speed (from 0 to 32 [20 in hex])
Fxx - Set Tempo (anything higher than 20 [hex] will set the BPM instead of speed)

Tools

---

- OpenMPT (the modern standard)
- Protracker
- MilkyTracker

Restrictions on submit

---

Your submission should be a 4-channel .mod file, 256KB or less.

As mentioned above, in OpenMPT, be sure to have "Amiga Frequency Limits" enabled under View -> Song Properties, and "Amiga Resampler" chosen (this is default) for the Resampling option in the General tab. This ensures your file will be hardware compatible, which is the goal of the BotB format.

Playback (for voting)

---

Use the tools mentioned above. Also, Winamp and many other media players play .mod files.

XMPlay can also play .mod files, but be sure to turn interpolation off for the format in the XMPlay options.

See also

---

- Protracker module format spec

- Tracker
- demo scene
- Complete list of ripped chiptunes repositories