View source for MOD (file format)

{{Short description|Audio tracker file format}}
{{For|the video file format used on many digital camcorders|MOD (video format)}}
{{Other uses|Mod (disambiguation){{!}}Mod}}
{{unfocused|date=September 2017}}
{{Infobox file format
| name          = MOD
| icon          = 
| logo          = 
| screenshot    = 
| caption       = 
| extension     = .mod
| mime          = audio/mod, audio/x-mod
| type code     = 
| uniform type  = 
| magic         = 4 bytes "M.K." at offset 0x438
| owner         = [[Karsten Obarski|Karsten "Obi" Obarski]]
| genre         = Video/music
| released      = 1987
| extended to   = [[XM (file format)|XM]]
}}
'''MOD''' is a computer [[file format]] used primarily to represent [[music]], and was the first [[module file]] format. MOD files use the “.MOD” [[file extension]], except on the [[Amiga]] which doesn't rely on filename extensions; instead, it reads a file's header to determine filetype. A MOD file contains a set of ''instruments'' in the form of [[sampling (music)|sample]]s, a number of ''patterns'' indicating how and when the samples are to be played, and a list of what patterns to play in what order.

== History ==

The first version of the format was created by [[Karsten Obarski]] for use in the [[Ultimate Soundtracker]], [[tracker (music software)|tracker]] software released for the [[Amiga]] computer in 1987.<ref name=Driscoll2009>{{cite journal|url=http://journal.transformativeworks.org/index.php/twc/article/view/96/94 |author1=Driscoll, Kevin  |author2=Diaz, Joshua  |name-list-style=amp |title=Endless loop: A brief history of chiptunes|doi=10.3983/twc.2009.0096 |quote=''Most importantly, Soundtracker provided an environment in which nonprogrammers could access the sophisticated music tools in their home computers without needing to learn a programming language.''|year=2009|journal=Transformative Works and Cultures |number=2 |access-date=2011-02-13|doi-access=free}}</ref><ref>[http://www.soundtracker.org/ www.soundtracker.org] same named later clone of Obarski's soundtracker</ref> The format has since been supported by hundreds of [[List of Amiga music format players|playback programs]] and dozens of [[List of audio trackers|other trackers]].<ref>{{cite book
 | last = Sweet
 | first = Michael
 | title = Writing Interactive Music for Video Games
 | publisher = Addison-Wesley
 | year = 2014
 | isbn = 978-0-321-96158-7
 | pages = 272–273}}</ref>

The original version of the MOD format featured four channels of simultaneous audio playback, corresponding to the capabilities of the [[original Amiga chipset#Paula|original Amiga chipset]], and up to 15 instruments.

Later variations of the format have extended this to up to 32 channels and 31 instruments.

The format was designed to be directly playable on the Amiga without additional processing: for example, samples are stored in 8-bit [[Pulse-code modulation|PCM]] format ready to be played on the Amiga [[Digital-to-analog converter|DACs]], and pattern data is not packed.  Playback required very little [[CPU]] time on an Amiga, and many games used MOD files for their [[video game music|background music]].

A common misconception is that the [[magic number (programming)|magic number]] "M.K." in the 0x438 offset of MOD files are the initials of Mahoney and Kaktus, two prominent Amiga demomakers at the time, who played an important part in the popularity of the format. They in fact stand for the initials of [[Michael Kleps]] a.k.a. Unknown / DOC, another developer of the format.<ref>{{cite web|url=http://io.debian.net/~tar/debian/xmp/xmp-2.7.1/docs/formats/Ultimate_Soundtracker-format.txt |title=Ultimate Soundtracker module format description |archive-url=https://web.archive.org/web/20100921225940/http://io.debian.net/~tar/debian/xmp/xmp-2.7.1/docs/formats/Ultimate_Soundtracker-format.txt |archive-date=2010-09-21 |access-date=2014-07-02}}, by Michael Schwendt, 1997; distributed in the source of the [http://packages.debian.org/stable/xmp xmp] module player; published at io.debian.net</ref>

{{demoscene}}

After the Amiga's production ceased, the MOD format has had continued popularity in the [[Demoscene]] and as background music for [[independent video games]] and [[Chiptune]]s. It is not uncommon to hear MOD music in [[keygen]]s either.

== Format overview ==
A pattern is typically represented in a sequencer [[user interface]] as a table with one column per channel, thus having four columns – one for each Amiga hardware channel. Each column has 64 rows.

A cell in the table can cause one of several actions to happen on its column's channel when its row's time is reached:
* Start an instrument playing a new note in this channel at a given volume, possibly with a special effect applied on it
* Change the volume or special effect being applied to the current note
* Change pattern flow; jump to a specific song or pattern position or loop inside a pattern
* Do nothing; any existing note playing in this channel will continue to play

An instrument is a single sample along with an optional indication of which portion of the sample can be repeated to hold a sustained note.

== Timing ==
In the original MOD file the minimum time frame was 0.02 seconds, or a "[[Analog television#Vertical_synchronization|vertical blanking]]" (VSync) interval, because the original software used the VSync timing of the monitor running at 50&nbsp;Hz (for [[PAL]]) or 60&nbsp;Hz (for [[NTSC]]) for timing.

The rate at which pattern data is played is defined by a ''speed setting''. Each row in the pattern data lasts one vertical blanking (or 0.02 seconds) times the current speed setting. The speed setting varied from 1 to 255.
In later versions of the format, the vertical blanking was replaced with an adjustable time period staying in the range [0.01, 0.078] seconds. The old speed setting command was replaced with a new one that was used to change both the old speed setting and the new adjustable time period. Unfortunately, some of the old functionality was broken, because the new speed setting command had an identical code value to the old command. Values in the range [1, 31] were interpreted as the old speed settings, but other values were regarded as modifications to the adjustable time period. Hence, values in the range [32, 255] used in some old songs broke in new versions of the player.

Further information on the MOD format can be found at the alt.binaries.sounds.mods FAQ.<ref>{{cite web|url=http://cd.textfiles.com/darkdomain/faqs/faq-mod_v28-part1.txt |title=The alt.binaries.sounds.mods FAQ on the MOD format |access-date=2020-04-15}}</ref>

== Other formats that use the MOD extension ==

MOD is the [[file extension]] for several other applications:

* The [[MOD (video format)|video file format]] used on many digital [[camcorder]]s, such as the JVC Everio, the Canon FS100 and the Panasonic D-Snap SD-card camcorders.
* Game modules in [[Neverwinter Nights (2002 video game)|Neverwinter Nights]].
* [[AMPL]] model files.
* Old [[phpBB]] modification templates.
* Module files in [[Femap]]
* The extension for the [[binary file|binary]] variant of the [[Wavefront .obj file|Wavefront .obj format]].
* The extension for some games using the Vassal game engine.
* The extension for [[Fortran]] module files.<ref>{{cite web|url=http://parallel.ksu.ru/docs/Intel/f_ug/fced_mod.htm |title=Fortran Programs with Modules}}</ref>
* The extension for [[Visual Basic (classic)|legacy Visual Basic]] module files, for versions before the release of [[Visual Basic .NET]].
* The extension for [[Go (programming language)|Go]] module files, used for package versioning.
* Module for ABB Robotics IRC5 and S4 robot controllers. Contains robotic motion programs written in the language RAPID.
* [[Lanner Group Ltd|Lanner]] WITNESS simulation software model files
* [[Paradox Development Studio]] uses a ".MOD" format for user-created modifications of their games.
* DND adventure modules for [[Fantasy Grounds]], a virtual tabletop application.
* [[GNU GRUB]] boot modules (when found in /boot)

== See also ==

{{Portal|Amiga}}
* [[Module file]]
* [[Tracker (music software)]]
* [[Mod (disambiguation)]]
* [[MOD and TOD (video format)]]
* [[List of Amiga music format players]]
* [[MIDI]]

==References==
{{reflist}}

== External links ==
* [http://www.textfiles.com/programming/FORMATS/mod-form.txt Noisetracker/Soundtracker/Protracker Module Format - 3rd Revision]
* [http://www.aes.id.au/modformat.html Noisetracker/Soundtracker/Protracker Module Format - 4th Revision]
* [http://aminet.net/tree?path=mods Music data index site]
* [https://modarchive.org Modarchive]

{{AmigaOS}}

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[[Category:Amiga music formats]]
[[Category:AmigaOS]]
[[Category:Module file formats]]
[[Category:Video game music file formats]]