• sintetici
  • MIDI (solo dati musicali) (.mid)
  • MIDI+SDS/SBK/SF2
  • MOD
  • XM
• solo audio
  • RealAudio (.ra)
  • Iwave
  • MP3 (.mp3)
• audio e video (utilizzo: solo audio, solo video, combinati)
  • QuickTime (.mov)

Un file MIDI di base consiste di comandi del tipo:

• Suona la nota x
• Smetti di suonare la nota x
• passa allo strumento #24 (non meglio identificato)
• Cambia il controller y al valore z

e così via.

Lo standard General MIDI stabilisce quali sono gli strumenti che corrispondono ai vari numeri (per esempio #1 è il pianoforte acustico, #24 è la chitarra a corde di nylon e #128 è il colpo di pistola). Contiene 128 strumenti predefiniti, ma nient'altro. Per esempio non indica il tipo di chitarra, il tipo di suono, il volume.

On the Mac, the most common instrument set is QuickTime Musical Instruments (with sounds licensed from Roland), which comes along with QuickTime (obviously). It's a separate extension, so if you have Quicktime installed and can't hear any music, check your extensions folder to make sure you have both.

If you are using QuickTime 2.5, you have 61 instruments and 47 percussion sounds at your disposal. If you have moved up to QuickTime 3.0 then you have more than 200 instruments available deploying the full set of GM instruments and some of Roland's extended GS set.

PC's are blighted by the fact that there is such a variety of sound cards, each with it's own implementation of General Midi. This in turn means that, although all the instruments might play, they will sound different from one machine to another. QuickTime 3.0 resolves this by installing the same set of instruments on all computers, so that the midi music will sound the same on any platform.

Esistono altri standard MIDI che comprendono anche il suono campionato degli strumento (MIDI +SBK, SP2, SDS ecc.).

Remember that midi files only sound as good as the synth that plays them back. There are numerous midi plug-ins, some of which include their own synth (eg: QT, Beatnik, Yamaha Midplug) whilst others use the inbuilt sounds on a PC sound card or, on the mac, QT instruments. If you want to make sure that what you created sounds the same on your visitor's browser as your own, you need to specify your favoured plug-in on the page, or export your file in an exclusive format - eg .mov for QuickTime or .rmf for Beatnik.

Midi files can also be converted into .mov files and embedded in web pages.