MOD (file format)
Encyclopedia
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
where the original trackers instead use a “mod.” prefix scheme, e.g. “mod.echoing”. A MOD file contains a set of instruments in the form of 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.
; tracker software released for the Amiga
computer in 1987http://www.soundtracker.org/. The format has since been supported by hundreds of playback programs and dozens of other trackers.
The original version of the MOD format featured four channels of simultaneous audio playback, corresponding to the capabilities of the 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 PCM
format ready to be played on the Amiga DAC
, and pattern data is not packed. Playback required very little CPU time on an Amiga, and many games used MOD files for their background music.
A common misconception is that the 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.
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 as well.
as a table with one column per channel, thus having 4 columns; one for each Amiga hardware channel. Each column has 64 rows.
A cell in the table can cause something to happen on its column's channel when its row's time is reached:
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.
) or 60 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.
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
used primarily to represent music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...
, and was the first module file
Module file
Module files are a family of music file formats originating from the MOD file format on Amiga systems used in late 1980s...
format. MOD files use the “.MOD” file extension, except on the Amiga
Amiga
The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...
where the original trackers instead use a “mod.” prefix scheme, e.g. “mod.echoing”. A MOD file contains a set of instruments in the form of sample
Sampling (music)
In music, sampling is the act of taking a portion, or sample, of one sound recording and reusing it as an instrument or a different sound recording of a song or piece. Sampling was originally developed by experimental musicians working with musique concrète and electroacoustic music, who physically...
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 SoundtrackerUltimate Soundtracker
Ultimate Soundtracker, or Soundtracker for short, is a music tracker program for the Commodore Amiga. It is the creation of Karsten Obarski, a German software developer and composer at a game development company; sources differ as to the name of the company, recorded it as reLINE, whereas ...
; tracker software released for the Amiga
Amiga
The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...
computer in 1987http://www.soundtracker.org/. The format has since been supported by hundreds of playback programs and dozens of other trackers.
The original version of the MOD format featured four channels of simultaneous audio playback, corresponding to the capabilities of the 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 PCM
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...
format ready to be played on the Amiga DAC
Digital-to-analog converter
In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...
, and pattern data is not packed. Playback required very little CPU time on an Amiga, and many games used MOD files for their background music.
A common misconception is that the magic number
Magic number (programming)
In computer programming, the term magic number has multiple meanings. It could refer to one or more of the following:* A constant numerical or text value used to identify a file format or protocol; for files, see List of file signatures...
"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.
After the Amiga's production ceased, the MOD format has had continued popularity in the Demoscene
Demoscene
The demoscene is a computer art subculture that specializes in producing demos, which are non-interactive audio-visual presentations that run in real-time on a computer...
and as background music for independent video games and Chiptune
Chiptune
A chiptune, also known as chip music, is synthesized electronic music often produced with the sound chips of vintage computers and video game consoles, as well as with other methods such as emulation. In the early 1980s, personal computers became cheaper and more accessible than they had previously...
s. It is not uncommon to hear MOD music in keygen
Keygen
A license or product key generator is a computer program that generates a product licensing key, serial number, or some other registration information necessary to activate for use a software application.-Software licensing:...
s as well.
Format overview
A pattern is typically represented in a sequencer user interfaceUser interface
The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...
as a table with one column per channel, thus having 4 columns; one for each Amiga hardware channel. Each column has 64 rows.
A cell in the table can cause something 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 "vertical blanking" (VSync) interval, because the original software used the VSync timing of the monitor running at 50 Hz (for PALPAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
) or 60 Hz (for NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
) 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.
Other MOD formats
MOD is the file extension for several other applications:- The video file format used on many digital camcorderCamcorderA camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...
s, such as the JVC Everio, the Canon FS100 and the Panasonic D-Snap SD-card camcorders. - Game modules in Neverwinter NightsNeverwinter NightsNeverwinter Nights , produced by BioWare and published by Infogrames , is a third-person perspective computer role-playing game that is based on third edition Dungeons & Dragons and Forgotten Realms rules. It was originally to be published by Interplay Entertainment, but the publisher's financial...
. - AMPLAMPLAMPL, an acronym for "A Mathematical Programming Language", is an algebraic modeling language for describing and solving high-complexity problems for large-scale mathematical computation AMPL, an acronym for "A Mathematical Programming Language", is an algebraic modeling language for describing and...
module files. - Old phpBBPhpBBphpBB is a popular Internet forum package written in the PHP scripting language. The name "phpBB" is an abbreviation of PHP Bulletin Board...
modification templates. - Module files in FemapFemapFemap is an engineering analysis program sold by Siemens PLM Software that is used to build finite element models of complex engineering problems and view solution results...
- The extension for the binaryBinary fileA binary file is a computer file which may contain any type of data, encoded in binary form for computer storage and processing purposes; for example, computer document files containing formatted text...
variant of the Wavefront .obj format. - The extension for some games using the Vassal game engine.
- The extension for FortranFortranFortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
module files.
See also
- Mod (disambiguation)
- MOD and TOD (video format)MOD and TOD (video format)MOD and TOD are recording formats for use in digital tapeless camcorders. The formats are comparable to XDCAM EX, HDV and AVCHD.-Overview:...
- Module fileModule fileModule files are a family of music file formats originating from the MOD file format on Amiga systems used in late 1980s...
- Tracker (music software)
- List of Amiga music format players
- MIDI