Creative Music File
Encyclopedia
The Creative Music File (CMF) is a synthesised music file format
, similar to MIDI, designed by Creative Labs for use with their Sound Blaster
cards. The format actually stores its song data in MIDI format but it differs in that while MIDI instruments are standardised, CMF instruments are stored in the file itself in the same manner as MOD files
. This allows a large range of instruments to be used, and unlike MIDI the song should sound the same regardless of which synthesiser it is played through. While MOD files store their instruments as digital data ("samples
"), CMF instruments are stored as a set of register values that can be programmed into the OPL
chips that were part of all early Sound Blaster cards (a feature that made them compatible with competing Adlib
cards at the time.)
Because CMF music is played through these OPL chips, it has a distinctly synthesised sound. However in the early 1990s when the format first came out this allowed songs to be synthesised entirely in hardware, meaning the performance impact of using CMF music was very low. For this reason the music in a number of games from this era was in CMF format (such as Kiloblaster
and Jill of the Jungle
.)
. Files can easily be identified by looking at the first four bytes - they will be "CTMF" (Creative Technology Music File) if the file is in CMF format.
The instruments inside a CMF file are stored in an identical manner to that used in SBI files (Sound Blater Instrument), minus the SBI header. The music block is in standard MIDI format, allowing for easy conversion between .mid and .cmf files. The CMF format also assigned a new meaning to a handful of MIDI controllers, so they could be used to change different aspects of playback (such as switching between the OPL's 9-channel FM synthesis mode and its alternate 6-channel + 5-percussion "rhythm mode" synthesis.)
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...
, similar to MIDI, designed by Creative Labs for use with their Sound Blaster
Sound Blaster
The Sound Blaster family of sound cards was the de facto standard for consumer audio on the IBM PC compatible system platform, until the widespread transition to Microsoft Windows 95, which standardized the programming interface at application level , and the evolution in PC design led to onboard...
cards. The format actually stores its song data in MIDI format but it differs in that while MIDI instruments are standardised, CMF instruments are stored in the file itself in the same manner as MOD files
MOD (file format)
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”...
. This allows a large range of instruments to be used, and unlike MIDI the song should sound the same regardless of which synthesiser it is played through. While MOD files store their instruments as digital data ("samples
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...
"), CMF instruments are stored as a set of register values that can be programmed into the OPL
Yamaha YM3812
The Yamaha YM3812 also known as the OPL2 is a sound chip created by Yamaha Corporation in 1985 and famous for its wide use in IBM PC-based sound cards such as the AdLib and Sound Blaster.It is backwards compatible with the OPL aka YM3526, to which it is very similar – in fact, it only adds 3 new...
chips that were part of all early Sound Blaster cards (a feature that made them compatible with competing Adlib
AdLib
Ad Lib, Inc. was a manufacturer of sound cards and other computer equipment founded by Martin Prevel, a former professor of music and vice-dean of the music department at the Université Laval...
cards at the time.)
Because CMF music is played through these OPL chips, it has a distinctly synthesised sound. However in the early 1990s when the format first came out this allowed songs to be synthesised entirely in hardware, meaning the performance impact of using CMF music was very low. For this reason the music in a number of games from this era was in CMF format (such as Kiloblaster
Kiloblaster
Kiloblaster is a Space Shooter Video Game Trilogy written by Allen Pilgrim and published by Epic MegaGames in the early 1990s. It is based on the classic Galaxian game, with a few differences such as allowing greater player movement , much faster enemy movement, power-ups, enemies that take more...
and Jill of the Jungle
Jill of the Jungle
Jill of the Jungle is a trilogy of platform computer games released in 1992 by Epic MegaGames. It was intended to rival computer games from other shareware companies such as id Software and Apogee Software, Ltd....
.)
Technical specifications
The CMF format not surprisingly uses the .CMF filename extensionFilename extension
A filename extension is a suffix to the name of a computer file applied to indicate the encoding of its contents or usage....
. Files can easily be identified by looking at the first four bytes - they will be "CTMF" (Creative Technology Music File) if the file is in CMF format.
The instruments inside a CMF file are stored in an identical manner to that used in SBI files (Sound Blater Instrument), minus the SBI header. The music block is in standard MIDI format, allowing for easy conversion between .mid and .cmf files. The CMF format also assigned a new meaning to a handful of MIDI controllers, so they could be used to change different aspects of playback (such as switching between the OPL's 9-channel FM synthesis mode and its alternate 6-channel + 5-percussion "rhythm mode" synthesis.)
External links
- The CMF format article on the Game Modding Wiki has a detailed description of the CMF file format.