What is MIDI?

What is MIDI?

Put simply, MIDI is a data transfer standard that allows easy and comprehensive control among electronic/digi- tal music instruments and other devices. To get a better idea of what MIDI does, let’s first consider acoustic instruments, such as a grand piano and a classical gui- tar. With the piano, you strike a key, and a hammer inside hits some strings and plays a note. With the gui- tar, you directly pluck a string and the note sounds.

But how does a digital instrument go about playing a note?

Recording and play back the performance of a digital instrument (MIDI data)

Recording

Playback

 

USB storage

USB storage

 

device

device

Controller (keyboard, etc.)

 

 

 

Tone Generator

 

 

Sequencer

Acoustic guitar note production

Pluck a string and the body resonates the sound.

Digital instrument note production

Internal amp

Tone generator

Internal amp

L

R

(Electric circuit)

 

 

Playing the key board

Based on playing information from the keyboard, a sampled note stored in the tone generator is played through the speakers.

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In the case of digital instruments, the audio signals are sent through output jacks (such as [AUX OUT]) on the instrument.

The “controller” and “tone generator” in the illustration above are equivalent to the piano in our acoustic exam- ple. Here, the player’s performance on the keyboard is captured as MIDI song data (see illustration below). In order to record the audio performance on an acoustic piano, special recording equipment is needed. How- ever, since the PSR-OR700 features a built-in sequencer

Instrument with

Other Devices

Using Your

 

As shown in the illustration above, in an electronic instrument the sampled note (previously recorded note) stored in the tone generator section (electronic circuit) is played based on information received from the key- board.

Now, let’s examine what happens when we playback a recording. When you play back a music CD (for exam- ple, a solo piano recording), you’re hearing the actual sound (vibration in air) of the acoustic instrument. This is called audio data, to distinguish it from MIDI data.

Recording and playing back the performance of an

acoustic instrument (audio data)

RecordingPlayback

In the above example, the actual acoustic sounds of the pianist’s performance are captured in the recording as audio data, and this is recorded to CD. When you play back that CD on your audio system, you can hear the actual piano performance. The piano itself is not neces- sary, since the recording contains the actual sounds of the piano, and your speakers reproduce them.

that lets you record performance data, this recording equipment is unnecessary. Instead, your digital instrument allows you to both record and play back the data.

Tone generator

Sequencer

Keyboard performance (MIDI data)

However, we also need a sound source to produce the audio, which eventually comes from your speakers. The tone generator of the instrument fills this function. The recorded performance is reproduced by the sequencer, playing back the song data, using a tone generator capable of accurately producing various instrument sounds — including that of a piano. Looked at in another way, the relation of the sequencer and the tone generator is similar to that of the pianist and the piano

—one plays the other. Since digital instruments handle playback data and the actual sounds independently, we can hear our piano performance played by another instrument, such as guitar or violin.

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Even though it is a single musical instrument, the PSR-OR700 can be thought of as containing several electronic components: a con- troller, a tone generator, and a sequencer.

174 PSR-OR700 Owner’s Manual