MIDI
What it is, how we use it
MIDI is a
term which you'll see a lot in music, and we use the term in reference
to some of the keyboards we use in our concerts. The word is pronounced
like "middy" and it is actually an acronym for the term Musical
Instrument Digital
Interface. There's a lot
we could write about MIDI, but fortunately there's a lot on the Internet
as well about it so if you really want to pursue MIDI in depth, do a Google
search on it. Although it is a complicated technology that is evolving
into new forms, essentially it is a protocol or a means by which various
electronic musical instruments can communicate with each other and also
with a computer.
MIDI is in a sense a special language or
file system (although the two terms are not really synonymous) by which
information gets transferred between and among various electronic musical
instruments, signal processors, sound modules, drum machines, sequencers
and computers. Songs can be stored in sequencers and computers as MIDI
files and then played back on any other MIDI compatible equipment that
is capable of synthesizing MIDI sounds. MIDI is also standardized, so
that all MIDI equipment should operate and sound the same way regardless
of who manufactured it. There are considerable differences in imitational
accuracy between high- and low-end equipment, however, ranging from imitations
that sound like imitations to some that are essentially indistinguishable
from the real thing. It is reasonably safe to say, however, that the accuracy
of even low-end MIDI imitations is better than that of the best electronic
organs of the analog era. New electronic organs however use the new technology
also and thus their imitations are as good as those of any other MIDI
equipment.
MIDI makes it possible for a person who
is knowledgeable about its implementation to create elaborate, flawless
orchestral arrangements of even the simplest of songs. It allows a person
sitting at one MIDI compatible keyboard to control and play simultaneously
a number of other MIDI compatible instruments, and it also allows a person
to add numerous different instrumental parts to songs, fix up any errors,
and select from a wide variety of instrumental effects and sounds whatever
he wishes to incorporate in the final production. MIDI can be used in
real time playing, and it can also be used to produce complex arrangements
which then get played back later on in their entirety after the MIDI musician
has first "laid down" tracks or the various parts of his final
arrangement.
With the right computer software installed,
you can play a song on a MIDI keyboard, and then have the computer's printer
print it out as sheet music. If you hit a wrong note or have slightly
sloppy fingering, this is not a problem either as MIDI allows complete
editing and error correction. If you meant to hit Middle C but instead
you nicked D by mistake, you can go in and move D down to C. If after
you listen to the MIDI playback and you decided you would like to have
the song play in a different key from the key you played it in, you can
type in a simple command and instantly the song is shifted up or down
as necessary to the key of your choice. This is a boon for those keyboard
players who play everything in the key of C but can't transpose to other
keys by normal playing.
If you wish to play a polka at a fast tempo
but your fingering is not up to par, no problem. Just play it as slowly
as you want, and then set the tempo to as fast as you would like and instantly
the song plays at the new tempo. With all of these wonderful capabilities,
it is no wonder that MIDI has become a very important part of music production
today. It is safe to say that probably at least ninety percent of the
musical scores that accompany movies and TV programs today are, in spite
of their big, lush orchestral sound, probably the work of just one or
two musicians using MIDI equipment in a studio. And when the time comes
to play this music and have it sound like it was being played in an acoustically
correct concert hall instead of a bedroom sized studio, modern digital
signal processors come to the rescue, creating room and hall ambience
at the touch of a few buttons. [Digital signal processing will be the
subject for a different article.]
MIDI keyboards and other related equipment
which are capable of generating musical sounds have achieved an incredible
level of realism in their instrument sounds. Some of the best equipment
available can mimic various instrumental sounds so well that on a recording
it is virtually impossible to distinguish between the MIDI instrument
sounds and the actual instruments that they are imitating.
When you press a key on a MIDI keyboard,
this action sends out some information. It tells a compatible synthesizer
or tone generator to start playing a certain note. It also tells it what
pitch to make the note, and what it should sound like and perhaps even
how loud it should be depending on how hard you hit a key, just like a
piano. When we let go of the key, this tells the note when to end. All
of these "instructions" are bits of information. This is fundamentally
very different from the operation of earlier electronic organs, such as
the Hammond, where pressing a key applies an existing audio frequency
or frequencies ultimately through an amplification system and to loudspeakers.
The signals coming out of a MIDI keyboard are not musical signals at all.
If you converted MIDI signals directly to sound, the result would not
be even remotely recognizable as music, because the signals from the MIDI
keyboard are not audio signals but coded bits of digital information.
When the MIDI keyboard signals arrive at
the synthesizer or tone generating section of the system, which may be
entirely remote from the keyboard and possibly even the sound card in
a computer, then the synthesizer responds to the MIDI information signals
by generating the required instrumental sounds which it usually recalls
from an electronic memory that holds samples of the various sounds. In
most cases, these MIDI sound samples have been taken from actual musical
instruments which is why the realism of MIDI equipment is so much better
than that of the earlier analog technology of electronic organs.
This separation of time is something that
takes a little getting used to. For example, we could set up a MIDI keyboard,
play a song and hear absolutely nothing as the MIDI keyboard sent its
information to a computer. Then, we could store the MIDI file in the computer,
and perhaps even a week or a month later, we could have the MIDI file
operate on the computer's sound card, and then we would finally hear what
we played previously. This is totally different of course from conventional
instruments where you hear what you play when you play it, but then a
MIDI keyboard may not even have the capability of producing any musical
sounds at all, although most of them have on board synthesizers so that
you can indeed hear what you are playing. So, how do we use MIDI at the
NSHOS? Next page.
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