Written by jester firstname.lastname@example.org
Modules are digital music files, made up of a set of samples (the instruments) and sequencing information, telling a mod player when to play which sample on which track at what pitch, optionally performing an effect like vibrato, for example. Thus mods are different from pure sample files such as WAV or AU, which contain no sequencing information, and MIDI files, which do not include any custom samples/instruments. Mods are extremely popular in the demo world and offer a way of making music of an acceptable level of quality rather cheaply. With the advent of high-quality sound hardware, new generations of mods may even rise to a sound quality nearing that of professional equipment.
Mods' sequencing information is based on patterns and tracks. A pattern is a group of tracks with a certain length, usually 64 rows (see 1.3). The tracks are independent of each other, meaning that a four track mod can play four voices or notes simultaneously. The patterns can be sequenced in a playlist, so that repeating the same sequence of patterns doesn't require rewriting of them.
This makes mods a hybrid between pure sample data files such as WAV, VOC or IFF/8SVX and pure sequencing information files like MIDI. One of the most frequently asked questions is "how do I convert a WAV to MOD?". This can be done, but is rather senseless. The other way around might be interesting for people with enormous hard drives, so they could listen to what used to be a mod at higher quality than before at the cost of several megabytes of drive space (10 MB/min. at 16 bits, 44.1kHz, stereo), or for those who want to show off a mod to others who don't have a mod player (or worse, can only play 8kHz AU files..
Numerous mods have been released that were basically huge samples off a CD (is there a connection to CD-ROM drives gaining increasing popularity?), the only parts actually sequenced were the chorus bits. Most of these mods were some form of top ten hit. These are, in effect, WAV to MOD conversions. I don't mind them floating around, but it is a widely acknowledged opinion that these kinds of mods defeat their own purpose. I therefore don't recommend their making (but this is my opinion). Note that this is NOT the same as using sampled drum loops or riffs in mods. While I don't like these myself either, these do require a lot more sequencing than huge 64KB chunks of a complete song.