An audio file on your hard drive, such as a WAV file, consists of a small header indicating sample rate and bit depth, and then a long series of numbers, one for each sample. These files can be very large. For example, at 44,100 samples per second and 16 bits per sample, a file requires 86 KB per second—about 5 MB per minute. That figure doubles to 10 MB per minute for a stereo CD, which has two channels.

In contrast to a digital audio file, a MIDI file might be as small as 10 KB per minute, so you can store up to 100 minutes of MIDI per megabyte. For more information, see Understanding MIDI data and VST instruments.