How was MIDI developed

MIDI and notation? (Musical Instruments Digital Interface)


by Jürg Hochweber

Midi was developed in the early 1980s, before the actual computer age, to exchange data between electronic musical instruments. Midi is a code, a language, that tells the addressed device or program what it should do. For example, MIDI reports:
Now play a F sharp '' at volume 64, with the nylon guitar sound, for 2 seconds.

A MIDI file does not directly contain music like a CD or an mp3 file, but only instructions on what to do. How the addressed device (e.g. the computer's sound card) interprets these instructions is up to him.
So MIDI is actually more of a kind of notation in tabular form. Put simply, the 'columns' of this virtual table contain elements such as:

Working time end volume sound panorama channel Etc.

Other elements are pitch bend, vibrato, chorus, instrument changes and more.
The 'lines' contain the values ​​for these elements.
From what has been said so far, it is also clear that a MIDI file sounds different on different computers. The volume balance of different instruments is particularly tricky. While a 'trumpet sound' sounds much louder on one computer than a 'guitar sound', both sound almost equally loud on another computer.
Differences between a loud and a soft tone on the same instrument can also be much more blatant on one computer than on another.
MIDI files are very easy to edit (tempo, pitch, etc.) and they are usually more than a hundred times smaller than mp3 files.

MIDI files can be created, read and also edited by almost all notation programs and so-called sequencer programs.

In the program 'Cakewalk' I can see and edit the MIDI data in different windows, for example in the 'Piano Roll' window. Here the length of the bar represents the duration of the tone, the vertical lines below the volume of the individual tones.


Guitar tabs and MIDI

When I've created a sheet of music with FINALE (or another notation program) and saved it as a MIDI file, I usually have to do a lot of post-processing to make it sound more realistic. In the following example, an unedited file would sound quite dry, since the notes only sound exactly as long as they are written down. In reality, however, it is clear that these are chords whose notes should continue to sound.

Other changes that are often necessary:

Shorten the note length in staccato,
Volume must be adjusted for individual tones
Slight shifting of notes for chords that should sound arpeggiated.
Incorporation of slight pitch bends.
Special effects for glissando and percussive elements.
Slight fluctuations in tempo so that it doesn't sound too mechanical.

The notation programs and especially the sequencer programs provide a lot of tools for this purpose, but it is still a very time-consuming work, and in the end a MIDI file will never sound exactly like a live recording (that's a good thing). But MIDI files are very useful because they are small and very flexible.

The MIDI files on my website are quite different. Some are more or less left in their raw state, others I have upgraded quite finely.


Questions about MIDI

Can MIDI files be converted into audio files (wav, mp3 etc.)? Yes, many sequencer programs can do this, the sound, the tempo, etc. are then 'frozen' according to the sound card or soft synth used.
Can audio data be converted to MIDI?No, not good anyway. A natural sound contains a multitude of individual parts and noises that can hardly be filtered out. It would be like trying to create a plain text file from a conversation in the station hall.
There are programs that can recognize sounds in simple cases, but I haven't seen any that are really useful.
Can you play a piece on the midi keyboard or on the midi guitar and transfer it directly to the notation program?You can, but the result is seldom or never satisfactory. MIDI files do not contain any information about the type of beam setting, note stems, type of articulation, etc. In addition, the program cannot know which notes are assigned to which voice. And the program will first of all note down the smallest rhythmic impurities with great precision. This can be corrected by ingenious rounding methods (quantize), but the program will also round where it is not desired. So especially with guitar music it is usually faster to enter the notes step by step.


© Copyright 2002 by Jürg Hochweber