What is MIDI?
MIDI, or Musical Instrument Digital Interface is a collection of performance data that tell the electronic keyboard or computer what to play. A MIDI file contains a particular set of “instructions” to tell how an instrument should be played, when it should be played, and how loud it should be played. MIDI devices such as drum machines, music synthesizers, sound generators and sound cards can control the music and talk to each other using MIDI files.
The closest comparison to MIDI is the piano roll, a roll of paper that has “reading” holes to tell a player piano what notes should be played and when. A MIDI synthesizer is more advanced in terms of being able to play any sound recording, and can even create synthesized sounds from scratch. The MIDI format is universally accepted and can be easily modified by another synthesizer or MIDI device. A MIDI filename extension is .MID or .MIDI.
MIDI files have an advantage over digital audio files in size (often being 10k or less), but the same MIDI file can play differently on other sound cards. It is worthy to note that in order to play MIDI files on mp3 or CD players, you will need to create a digital audio recording of MIDI instruments playing the MIDI sequences. This process is called a “mixdown”, from which you can convert it to an audio format that a CD player can recognize.
What is Digital Audio?
Digital Audio is somewhat like a container that can record and play back sound. Think “tape recorder” in an electronic format, and you will have a good idea of what digital audio is. They can store all kinds of sounds (not just from MIDI devices), then reproduce the same sound when you play it on machines that recognize these digital audio files. A digital recording is a high fidelity recording of sounds that happened in the real world, and not just a string of commands instructing a sound generator what to play.
Digital Audio files can be modified in a way that you can change the overall tone quality. You can make them sound softer or louder on playback; you can edit or even add in some sounds along the way. You can’t, however, change the instrument sounds recorded (for example, you can’t modify a recording of an electric guitar and change it to a saxophone).
Digital audio files are great for reproducing music and sounds faithfully, but sound fidelity comes at a price- they have large file sizes and can take a while to download.