Musical Instrument Digital Interface (MIDI)
In this video I will look at MIDI. MIDI is a communication protocol that provides an interface between different musical instruments. This video will look at the basics of how MIDI works.
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Musical Instrument Digital Interface (MIDI)
MIDI or Musical Instrument Digital Interface is a protocol for musical instruments to communicate with each other. The MIDI standard was first published in 1993 and continues to be updated and supported today.
Rather than trying to explain how it works, let’s consider an example of how MIDI can be used. Firstly, I have a keyboard that supports MIDI. The MIDI connection allows the keyboard to be plugged into a computer.
The computer can now record the keys that are pressed on the keyboard. This includes a value that represents how much force or how rapidly a key was pressed. There is a limit to what can be achieved on a keyboard, so you may want to add additional instruments like a drum machine. You want to be able to control the drum machine like the keyboard using the computer; however, you want them also to be in sync with each other. In order to do this, a MIDI connection is run from the keyboard to the drum machine.
You can also add additional devices, for example an FX device could be added to the drum machine. The MIDI cables connect each device in a daisy-chain like fashion. This allows each device to be controlled. MIDI also allows the devices to be run in sync with each other.
The advantage of this is not only control, but also the output from these devices can be recorded to the computer. The computer can then save this output to a MIDI file. Since MIDI only saves information such as which instrument was played, how long each key was pressed and how loud the music was, MIDI files are very small. For example, approximately seven minutes of a Beethoven symphony can be recorded onto a 60 Kilobyte file. However, if this was converted to a high-quality audio file, it would be approximately 80 Megabytes in size.
A MIDI file can be copied between different computers and played on those computers. For example, this is an example of a MIDI file being played.
As you can hear, there are sounds for piano and drums. The MIDI file essentially only contains the notes that are played, which allows the file to be quite small. However, there are limitations to this. Let’s have a look.
MIDI Format
A MIDI file essentially contains all the notes that are played, the instruments that are played, the length of the notes and their loudness. Think of the MIDI file like a sheet of music. A sheet of music is essentially a printed document that represents music by the use of symbols. The musician can read these symbols and know when to play the required notes. MIDI is essentially the same concept as it contains all the notes and when they are to be played.
In order to play a MIDI file, you need a device that is able to play them. In this case, I will use a computer to play the MIDI file. The computer will read the MIDI file and output it to some speakers. Essentially the computer is reading the notes in the MIDI file and changing them to a sound. The problem with this approach is that the sound is limited by the reproduction ability of the output device.
In the old days of DOS, this was more of a problem. This was because sound hardware was not as good as it is today. In the old days, MIDI could potentially sound very different depending on what hardware it was played on. Nowadays, basic MIDI files sound pretty much the same regardless of which device you play them on.
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References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 5 Paragraph 209 - 213
“CompTIA A+ Certification exam guide. Tenth edition” Page 420
“MIDI” https://en.wikipedia.org/wiki/MIDI
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“(.mid) Standard MIDI File Format” http://faydoc.tripod.com/formats/mid.htm
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“MIDI sample.mid” https://commons.wikimedia.org/wiki/Fi...
“Picture: Folder” https://unsplash.com/photos/pONH9yZ-wXg
“Picture: Music notes” https://pixabay.com/illustrations/mus...
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