Musical Instrument Digital Interface, - Hol.gr

Musical Instrument Digital Interface,
Antony’s Web Site: http://users.hol.gr/~antony07
is a digital communications protocol. In August of 1983, music manufacturers agreed on a document that
is called "MIDI 1.0 Specification". Any device that has MIDI capabilities must adhere to this specific data
structure to ensure that all MIDI devices are capable of working together. This protocol is a language that
allows interworking between instruments from different manufacturers by providing a link that is capable
of transmitting and receiving digital data. It is important to remember that MIDI transmits commands, but
it does not transmit an audio signal.
The MIDI specification includes a common language that provides information about events, such as note
on and off, preset changes, sustain pedal, pitch bend, and timing information. The specification has been
updated more recently with specific data structures for handling sample dumps, MIDI time code, general
MIDI and standard MIDI files. To see a complete listing of all MIDI data, go to: Types of Data
Transmitted through MIDI
MIDI information is transmitted through a MIDI cable that has DIN-type male plug connectors with five
pins. Two of the pins are used to transfer digital binary information (MIDI Code). One of the pins issues a
steady stream of five volts, while the other pin alternates between 5 volts and 0 volts to represent binary
information (on and off). The third pin is a ground and the remaining two pins are currently not in use.
The MIDI data is sent down the cable one
bit at a time as a stream of information,
which is called a serial interface. A
parallel interface allows the information
to be sent down separate wires so that the
message reaches the device at the same
time, making it faster than a serial
interface. Computer chips communicate
via a parallel interface.

The serial interface
was chosen by MIDI
manufacturers because
it is less expensive and
more efficient than a
parallel interface. The
speed of a MIDI serial
interface is 31,250 bits
per second. There are
10 bits needed for
every MIDI digital
word or 3125
messages per second.
Snap your finger and
think about how many
many events could be
transmitted during that
time. Consequently,
the serial interface
speed is more than
adequate for most
music applications.
There are many different
types of MIDI connections.
The MIDI Out sends
digital messages from one
MIDI device and into the
MIDI In of another MIDI
device.
In order to really
understand the concept
of digital information,
we must be familiar
with the decimal, binary
and hexadecimal
counting systems.
Understanding Decimal,
Binary,& Hexadecimal,
will help us to learn
about the three counting
systems and how they
are applied to MIDI
The MIDI Thru connector receives a copy of any digital message coming into the MIDI In connection
and sends a duplicate of this information out of the MIDI Thru port into the MIDI In of a third MIDI
device. This allows the user to have more than two MIDI devices connected as a studio. The MIDI Out
port from the second or third device in the diagram below would not work because it is sending MIDI
information from that particular synthesizer. The MIDI Thru port is receiving the MIDI In information
and passing it on to the next device.
When MIDI devices are linked together by a series of MIDI In and MIDI Thru connections, it is referred
to as a Daisy-Chain Network.
A MIDI interface may only
have two connections, a
MIDI In and a MIDI Out.
Copies of MIDI In information may be sent to numerous
devices by using MIDI Thru Boxes, known as Star
Networks.
Example of a MIDI Echo / MIDI
Merger

This gives the user the
ability to send information
to a computer, while the
computer sends MIDI
information out from a
software program. Some
music software programs
will have a MIDI Echo
device that allows a copy of
the information to be
merged with the information
that is leaving the computer
from the MIDI Out ports.
This enables the sequencing
software to simultaneously
record the information that it
is receiving at the MIDI In
port, while sending a copy
of that information out of
the MIDI Out port along
with previously recorded
tracks of MIDI events.
Return to MIDI Connections Menu
Now it is time to try connecting a few different MIDI studios. After each example there is a answer page
to see the complete connections.
All three keyboards have
MIDI connections.
Synthesizer A is the
Master keyboard and
Synthesizer B & C are the
MIDI slave devices.
Studio A
Studio B
Both keyboards have
MIDI connections.
Synthesizer A is the
Master keyboard and
Synthesizer B is the
MIDI slave device.
Which connections
would you use so that
synthesizer A is
sending MIDI
information to
synthesizer B.
To see the Answer

Which connections would
you use so that synthesizer
A is sending MIDI
information to synthesizer
B and synthesizer C.
To see the Answer
Studio C
In this example we have added a computer and MIDI interface. The
first order of business is to connect the master keyboard to the computer
so they can communicate with each other.
Next connect the three tone generators (synthesizers without keyboards)
The MIDI Out on the MIDI interface may also act as a MIDI Thru that
relays a copy of the MIDI In information. This will allow the keyboard
to communicate with the computer and the three tone generators. Use
the concept of the daisy-chain network set-up from the MIDI Thru
port of the keyboard.
To see the Answer
Studio D
A multi-port Star Interface receives MIDI data at the MIDI In ports
and then copies the information and sends it out to two or more Thru
ports. Each MIDI In port may be assigned to specific MIDI Thru ports.
Again, try connecting the keyboard controller so that it sends
information to the MIDI interface.

Then connect the MIDI interface to the Keyboard. Finally, connect the
three remaining Tone Generators using a star set-up. Do not use a daisychain
set-up for these connections.
To see the Answer
Return to MIDI Connections Menu
MIDI Interfaces
The pictures below are MIDI interfaces for the
Macintosh computer. Interfaces may be
purchased in many different styles and varying
degrees of complexity.
pictures from Opcode and Apple Computer
The pictures below
are MIDI interfaces
for Windows based
computers. Possible
interfaces may be
an external device
or inserted into the
computer as an
add-on card.
pictures from Music Quest Inc. and Dell Computer Corporation

We will explore three basic numbering systems, called decimal, binary, and hexadecimal.
A base 10 number system, the decimal system, is based on ten numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
The next number in the sequence is a combination of two digits, where the second digit is multiplied by
10. 10 is equal to (1 X 10) + 0. Two digits may go as high as 99, and then a third digit is needed for the
next number. The third digit is multiplied by 100. This concept continues with the next digit multiplied by
1000, the next by 10,000, and so on. A number like 6594 would be calculated as (6 X 1000) + (5 X 100) +
(9 X 10) + (4 X 1). This concept is easy to grasp, because we use the decimal system in every day
applications.
Computers work in a digital environment that
has only two variables, 0 and 1. All numbers in
the decimal system may be translated into 0's
and 1's of the binary system. By having only
one digit or box, there are two possibilities.
This binary system is a base 2 numbering
system that uses only two numbers, 0 and 1.
By having two digits or boxes, there are four
possibilities. The upper number is the decimal
counting system and the bottom numbers
represent the binary counting system. In binary,
the first digit (right box) corresponds to a
decimal value of 0 or 1, while the second digit
(left box) corresponds to a decimal value of 0 or
2. The multiples of the decimal counting system
are 1, 10, 100, 1000, etc. The multiples of the
binary counting system are 1, 2, 4, 8, 16, 32, 64,
128, etc.
By having three digits or boxes, there are eight possibilities. The upper
number is the decimal counting system and the bottom numbers
represent the binary counting system. The first digit (right box) may
have a value of 0 or 1. The second digit (middle box) may have a value
of 2 or 0 and the last digit (left box) may have a value of 4 or 0.

(Remember that 0 is a number, 0-15) The upper number is
the decimal counting system and the boxes represent the
binary possibilities.
This is the
same diagram,
but now you
only see the
binary
representation.
By having
four digits
or boxes,
there are
sixteen
possibilities.
The first digit (right box) may have a value of 0 or 1, and the second
digit may have a value of 2 or 0, the third digit may have a value of 4 or
0, and the last digit (left box) may have a value of 8 or 0.
Finally, we see all the combinations, with the upper numbers
representing the decimal counting system followed by the
[hexadecimal counting system]. The bottom number is the binary
equivalent of the upper numbers.
The hexadecimal counting system is a base 16 system. Each digit or slot may be represented by sixteen
possible numbers. Hexadecimal uses the first ten numbers of the decimal system: 0, 1, 2, 3, 4, 5, 6, 7, 8,
and 9. The number 10 has two digits so in hexadecimal it is represented by the letter A. The number 11,
by B, 12 by C, 13 by D, 14 by E and 15 by F.
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1A, 1B,
1C, 1D, 1E, 1F, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 2A ........etc.
Two digits or slots are needed to represent the next number in the sequence. The decimal number 16
would equal 10 in hexadecimal. (1 X 16) + 0. Continuing in the series, 17(decimal) would equal
11(hexadecimal), 18(decimal) would equal 12(hexadecimal), and so on until 31(decimal), which would
equal 1F(hexadecimal). The next hexadecimal number would be 20, (2 X 16) + 0, which would equal 32
in decimal. The hexadecimal number 9C would equal (9 X 16) + 12 = 156 in decimal.

multiple of each digit 1286432168421
binary counting system 1 0 1 1 0110
The binary number 10110110 is the equivalent of 182 in decimal. That is, (128 x 1) + (64 x 0) + (32 x 1)
+ (16 x 1) + (8x0) + (4 x 1) + (2 x 1) + (1 x 0).
multiple of each digit 256 16 1
hexadecimal counting system 1 A F
The hexadecimal number 1AF is the equivalent of 431 in decimal. That is (256 x 1) + (16 x 10) + (1 x
15). The multiples of the digits in the hexadecimal counting system are 1, 16, 256, etc.
So why do we have to learn all these numbers to understand MIDI?
Remember that MIDI digital information is transmitted using the binary system. The serial interface
translates musical actions or events into binary numbers that it receives and sends one at a time down a
MIDI cable. By understanding the binary counting system, we can look at MIDI information and
understand what is being transmitted through a MIDI cable. The binary number 10010000 is not easy to
calculate, but reading the number in the hexadecimal equivalent 90 makes more sense when it is applied to
a MIDI message.
10010000, 00110111, 01111011 = 90, 37, 7B, which may be interpreted as;
Note ON, MIDI channel 1, play the 55th note, at a velocity of 123 out of 127 possibilities.
multiple of each digit 1286432168421
binary counting system 1 0 1 1 0110
If we look at the binary number above there is an easier way to add up the number. Instead of counting the
binary number as (128 x 1) + (64 x 0) + (32 x 1) + (16 x 1) + (8x0) + (4 x 1) + (2 x 1) + (1 x 0) = 182
(Decimal), split the binary number into two sections.
multiple of each digit 8421 8421
binary counting system 1011 0110
hexadecimal counting system B 6
(8 X 1) + (4 X 0) + (2 X 1) + (1 X 1) = 11 or B in hexadecimal
(8 X 0) + (4 X 1) + (2 X 1) + (1 X 0) = 6 in hexadecimal
B6 hexadecimal number (11[B] x 16) + 6 = 182 in decimal
If we use eight binary digits we have 256 possible numbers. 00000000 to 11111111. We can use two
hexadecimal numbers to represent 256 numbers, 00 to FF. All MIDI events may be represented with eight
binary or two hexadecimal numbers.
You may download a document,Conversion of Numbers, that was created using the program Max. This
document compares the similarities between the decimal, binary and hexadecimal counting systems.By
clicking on the document your browser should download the file. The document may be changed back to

its original version by using the program StuffIt Expander. If your browser is set up to recognize StuffIt
Expander, it may have already unstuffed the document. If not, you will need to obtain a copy of the
program StuffIt Expander from Aladdin.
The program MAXplay is needed to run the document Conversion of Numbers. If you would like
information about the application Max, please contact Opcode Systems, Inc.. You may download a free
copy of this application by clicking on the MAXplay icon below. This is a run-time only version of the
application Max; it may not be used to create new Max documents. MAXplay will work only on a
Macintosh computer.
Specific examples of MIDI data structures
The MIDI language is represented with binary code. Each 0 or 1 is called a bit. Four bits equal a nibble
and eight bits equal a byte.With MIDI, each digital word consists of a total of 10 bits: 8 bits (1 byte) plus
one start bit. (The MIDI messages in this program will not display the start and stop bits.)
When we look as a digital word, 10010110, the bit at the far left is considered the Most Significant Bit.
The remaining seven bits, 10010110, are considered the Least Significant Bits. Most MIDI messages
consist of one, two or three bytes. Each byte may be classified as a status or data byte.
A MIDI processor will look at the Most Significant Bit to see if it is a 1 or a 0. Status bytes start with a
1, while data bytes start with a 0. A status byte is the first word in a digital MIDI message, and it is used
as an identifier or an instruction.
Channel messages are composed of status bytes that are followed by one or more data bytes. The data
bytes are information that is pertinent to the status byte. Because a data byte starts with a 0 in the binary
number, 01101100, there are 128 possible values. In hexadecimal, the values range from 00 to 7F. You
may want to download the MAXplay program, Conversion of Numbers, to better understand the
relationship of a MIDI slider with binary and hexadecimal information.
You may download a document,Conversion of Numbers, that was created using the program Max. This
document compares the similarities between the decimal, binary and hexadecimal counting systems.By
clicking on the document your browser should download the file. The document may be changed back to
its original version by using the program StuffIt Expander. If your browser is set up to recognize StuffIt
Expander, it may have already unstuffed the document. If not, you will need to obtain a copy of the
program StuffIt Expander from Aladdin.
The program MAXplay is needed to run the document Conversion of Numbers. If you would like
information about the application Max, please contact Opcode Systems, Inc.. You may download a free
copy of this application by clicking on the MAXplay icon below. This is a run-time only version of the
application Max; it may not be used to create new Max documents. MAXplay will work only on a
Macintosh computer.
• Conversion of Numbers(MAXplay document) (17k)
• MAXplay 3.0 (Application) (644k)

To look at some specific examples of MIDI binary information, you may want to download two more
MAXplay programs that demonstrate what occurs when a note is turned on and the relationship of the
keyboard notes to hexadecimal, decimal and binary information.
• MIDI Note On(MAXplay document) (17k)
• MIDI Note Conversion (MAXplay document) (17k)
Specific examples of MIDI data structures
Turning on a MIDI Note
Binary code 10010000 00111100 01110010
Hexadecimal 9 0 3 C 7 2
9 0 Status Byte Note On with MIDI channel 1.
3 C
Data Byte, that is the actual note which is the 60th note on a range of 0 to 127, which is
Middle C.
7 2
The key velocity information on how fast the note was pressed. This data byte also has a
range of 0 to 127. A higher velocity will create more volume with the sound.
Creating a Program Change
Binary code 11001111 00011010
Hexadecimal C F 1 A
C F Status Byte Program Change on MIDI channel 16.
1 A
Data Byte that is the actual program number that was pressed on the synthesizer. The
program would be the 26th program setting. That is (1 x 16) + (A, which is 10)
Using the Sustain Pedal
Binary code 10110111 01000000 01111111
Hexadecimal B 7 4 0 7 F
B 7 Status Byte Control Change on MIDI channel 8.
4 0 Data Byte that selects sustain pedal as a controller.
7 F Data Byte that turns on the sustain pedal.

Using the Volume Pedal
Binary code 10111010 01000000 00000101 00000110 ......
Hexadecimal B A 0 7 0 5 0 6 ......
B A Status Byte Control Change on MIDI channel 11.
0 7 Data Byte that selects volume as a controller.
0 5, 0 6, ..... Data Bytes that increase the volume.
There are four main categories of MIDI data. The following charts represent information on the current
hexadecimal numbers that are used in MIDI transmission. Each MIDI message includes a Status Byte. If
they are required, Data Bytes will follow each Status Byte. Some of the example below have links that
may be clicked for more detail about the MIDI event.
MIDI Message
• Channel
Messages
• System
Exclusive
Status
Byte
• System
Common
• System Real-
Time
Channel Messages
Data Byte Data Byte
Note Off 8n Note Number Velocity
Note On 9n Note Number Velocity
Polyphonic
Aftertouch
An Note Number Pressure
Control Change Bn Control Number Data Information
Control Change Bn 01 Modulation Wheel Data
Control Change Bn 02 Breath Controller Data
Control Change Bn 04 Foot Controller Data
Control Change Bn 05 Portamento Time Data
Control Change Bn 06 Data Entry Slider Data
Control Change Bn 07 Main Volume Data

Control Change Bn 08 Balance Controller Data
Control Change Bn 0A Pan Controller Data
Control Change Bn 0B Expression Controller Data
Control Change Bn
40 Sustain Pedal
(Damper)
00: Off 7F: On
Control Change Bn 41 Portamento 00: Off 7F: On
Control Change Bn 42 Sostenuto 00: Off 7F: On
Control Change Bn 43 Soft Pedal 00: Off 7F: On
Control Change Bn 45 Hold 2 00: Off 7F: On
Control Change Bn
5B External Effects
Depth
00: Off 7F: On
Control Change Bn 5C Tremelo Depth 00: Off 7F: On
Control Change Bn 5D Chorus Depth 00: Off 7F: On
Control Change Bn
5E Celeste (Detune)
Depth
00: Off 7F: On
Control Change Bn 5F Phaser Depth 00: Off 7F: On
Control Change Bn 79 Reset All Controllers Data to reinitialize
Control Change Bn 7A Local Control 00: Off 7F: On
Control Change Bn 7B All Note Off 00
Control Change Bn 7C Omni Off 00
Control Change Bn 7D Omni On 00
Control Change Bn 7E Mono On 00-0A Number of Channels
Control Change Bn 7F Poly On 00
Program Change Cn
Program Number 00 to
7F
No second data byte
needed.
Channel Aftertouch Dn Note Number Pressure Value
Pitch Wheel En Least Significant Bit Most Significant Bit
n=MIDI Channel Number [ Hexadecimal numbers 0 to F = 1 to 16 MIDI channel number)
Return to Types of Data Menu

MIDI Message
System Exclusive F0
System Exclusive
Universal
System Exclusive
Universal
System Exclusive
Universal
System Exclusive
Universal
System Exclusive
Universal
Status
Byte
System Exclusive
Data Byte Data Byte
Manufacture ID
Code
F0 7E Sample Dump
Manufacture Data
Data on sample, bits, length, rate,
and loop points
F0 7F MIDI Time Code Data on Complete Message
F0
MIDI Machine
Control
Data commands
F0 MIDI Show Control Data commands
F0
Return to Types of Data Menu
MIDI Message Status
Byte
MIDI Time Code
Quarter Frame
Song Position
Pointer
Standard MIDI
Song File
System Common
F1 Frame Number Data
F2
Data for Song File
Data Byte Data Byte
Data on number of SSP 6
Bytes everyQuarterNote
No second data byte. F1 status
byte is repeated with data byte.
Data on number of SSP 6 Bytes
everyQuarterNote
Song Select F3 Song Number No second data byte.
Tune Request F6 Data to change tuning Data to change tuning
End of Exclusive F7 No data bytes No data bytes
Return to Types of Data Menu

System Real-Time
MIDI Message Status Byte Data Byte Data Byte
TimingClock MIDISync F8 No data bytes
No data bytes. 24
Status bytes per
quarter note.
Start FA No data bytes No data bytes
Continue FB No data bytes No data bytes
Stop FC No data bytes No data bytes
Active Sensing FE No data bytes No data bytes
System Reset FF
Sets instrument to
default
• MIDI Channels
• MIDI Reception Modes
• Multi-Timbral Instruments
MIDI Channels
No data bytes
All MIDI devices receive MIDI information at the MIDI In port. All MIDI channel message information
has an identification of a specific MIDI channel. The second nibble of a MIDI byte has sixteen
possibilities that identify the MIDI channel. In the example below, the first four digits (1100) represent a
program change and the last four digits (1111), refer to MIDI channel 16.
Binary code 11001111
Hexadecimal C F
Consider the analogy of a television set that has sixteen channels. All sixteen may be viewed, but only one
channel may be on the screen at any given moment. A MIDI device may be set-up to respond in a similar
fashion. It may receive information on all sixteen channels, but it only responds to one MIDI channel at
time. The MIDI device will ignore all channel messages that do not correspond to the same MIDI channel.
This type of reception mode is called Omni-Off Poly. Now, let's look at the four types of MIDI reception
modes.
Return to MIDI Channels & Modes Menu
MIDI Reception Modes
Mode 1 - Omni-On Poly - The receiving device listens and responds
to all incoming MIDI channel data. The device will ignore the channel
destination of each status byte and attempt to play all MIDI messages.

Poly, is dependent on the number of voices that a MIDI device can play
at any given moment in time. Some devices may only have eight note
polyphonic capabilities, while other devices may play up to sixty-four
voices simultaneously.
Mode 2 - Omni-On Mono - The receiving device listens and responds
to all incoming MIDI channel data in the same fashion as Mode 1,
though the instrument will only play one note at a time. The mode is not
very practical and has little use in most MIDI applications.
Mode 3 - Omni-Off Poly - This is the most frequently used mode. The
MIDI device will listen to all incoming channel data but only responds
to information set to one particular channel. Poly is dependent on the
number of voices that a MIDI device can play at any given moment in
time. Some devices may only have eight note polyphonic capabilities,
while other devices may play up to sixty-four voices simultaneously. If
a device is multi-timbral, then it may be set-up to have more than one
instrument playing simultaneously, and each instrument will play the
notes polyphonically up to the device's limit.
Mode 4 - Omni-Off Mono - The MIDI device will listen to all
incoming channel data but only responds to information set to one
particular channel. It will only play one note at any given moment. A
typical use for this mode is a MIDI Guitar Controller, where each string
of the guitar is assigned to a separate MIDI channel and each string will
play only one note at a time.
Return to MIDI Channels & Modes Menu
Multi-Timbral Instruments
A multi-timbral MIDI device is able to respond to two or more different sounds simultaneously. It is like
having two or more synthesizers combined into one device. A multi-timbral instrument can be set-up to
play a piano sound on channel 1, a bass sound on channel two, a string sound on channel 3, and a solo
instrument sound on channel 4. This type of device works well with a sequencer program that has specific
information assigned to separate tracks, because each timbre ( program) will only respond to a specific
MIDI channel.
In the example on
the left, a sequencer
application in the
computer can send
multiple tracks of
MIDI notes on
channels 1 through
10. The keyboard is
set-up to respond to
MIDI information on
channels 1 through
3, while the multitimbral
device on the
right is responding to
MIDI information on

A MIDI controller is a device that is
able to transmit performance related
MIDI events. The most common type
of controller is a MIDI device with a
keyboard. There are keyboard
controllers without sound modules.
The instrument produces no sound of
it own, rather it generates MIDI
events from the keyboard. A
keyboard controller usually will have
weighted keys that have the "feel"
and "response" of a piano. Keyboard
controllers usually have 76 or 88
keys.
channels 4 through
10.
Listed below is an overview
of different MIDI controllers.
• Synthesizers
• Percussion
Controllers
• Guitar Controllers
• MIDI Pedal
Controller
• Wind Controllers
• Disklavier Piano
• MID Grand Piano
Using a keyboard is not the only way to control a MIDI device.
There are alternate controllers than include drumpads, keyboard
mallets, wind controllers, guitar and bass controllers, and MIDI
pedals. Experimentation with MIDI controllers has led to the
development of muscle controllers that are attached to the body,
glass plate harps, violin controllers, and many other imaginative
devices.
Many synthesizers include keyboard
controllers. Tone Generators are synthesizer
modules without the keyboard.
pictures from Alesis Studio Electronics and Yamaha Corporation of America
Return to MIDI Controllers Menu

The picture on the right is a MIDI
Percussion Controller. It resembles
a vibraphone but has the added
flexibility of MIDI.
Return to MIDI Controllers Menu
A MIDI Guitar
Controller may either
resemble a guitar in
appearance (as in the
upper picture) or may
be an actual guitar
with a special MIDI
pickup installed (as in
the lower example).
MIDI Drum-Pad Controllers give the
percussionist added flexibility. Each pad
may be assigned to a certain drum
sound, special effect or other MIDI
parameters.
pictures from KaT, Inc.
Guitar Controllers may be set-up to
control a different MIDI device on
each string. The ability to combine the
guitar's expressiveness with MIDI
controls gives the user unlimited
potential.
pictures from Yamaha Corporation of America and Roland Corporation
Return to MIDI Controllers Menu

Below is a MIDI
footpedal board,
which is often used
as an auxiliary
controller to switch
between patches or
effects.
MIDI Wind
Controllers are
designed to mimic
the expressive
articulation of a
woodwind or brass
instrument. They
usually have a very
dynamic feel and
may have a more
humanistic effect on
the sounds or
samples.
pictures from Yamaha Corporation of America and Music Industries Corporation
Return to MIDI Controllers Menu
Inside the
disklavier
are optical
sensors
and key
solenoids
for
recording
and
playback.
The Yamaha Disklavier is an acoustic
piano which also functions as a MIDI
controller and player piano.
pictures from Yamaha Corporation of America

Return to MIDI Controllers Menu
The Yamaha MIDI Grand is the ultimate MIDI
controller.
It gives the performer the feel and
sound of a grand piano with the
control of multiple MIDI devices.
pictures from Yamaha Corporation of America
The following files are QuickTime Movie clips of concert footage that incorporates a Yamaha MIDI
Grand Piano in a few compositions. The performances were presented by the faculty and students of the
Electronic Music Class at Santa Barbara Community College in Santa Barbara, California.
Excerpt from: Animus Vivére (Will to
Live) by Peter Raschke
Music for Vocal Chant, MIDI Grand
Piano, Synthesizer, and Percussion
Ensemble.
Text is from "The Liturgy of the Hours".
Performance from Santa Barbara City
College Sonic Sequences Concert, May 26, Excerpt from: Animus
1995.
Vivére QTM (6.8MB)
@1995 Copyright Protected
Excerpt from: Tone Poem
Mov.I QTM (9.7MB)
Excerpt from: Tone Poem
Mov.II QTM (9.2MB)
Excerpts from: Tone Poem by Peter
Raschke
[ Spiritual - Mystical - Enchanted -
Tempestuous ]
Music for MIDI Grand Piano,
Synthesizer, Timpani, Wind Chimes,
Cymbals, Gong and Tubular Chimes.
Performance from Santa Barbara City
College Sonic Sequences Concert,
December 17, 1993. @1993 Copyright
Protected

Excerpt from: Building Blocks by Peter
Raschke
Music for Soprano Saxophone, two
Flutes, MIDI Grand Piano, Synthesizer,
and Timpani.
Performance from Santa Barbara City
College Sonic Sequences Concert, May
28, 1993.
Performance from Santa Barbara City
College Faculty Concert, October 24,
1993.
@1993 Copyright Protected
Excerpt from: Building
Blocks QTM (11.7MB)
General MIDI is an addition to the original MIDI specification. It follows a standard that assigns 128
instrument sounds that are assigned to specific numbers. There are sixteen specific families or types of
instruments and eight instruments within each group. A separate group of percussion sounds is usually
available on MIDI channel ten, and they are assigned to specific notes on a MIDI keyboard.
Piano Bass Reed Synth F/X
Chromatic Perc. Strings Pipe Ethnic
Organ Ensemble Synth Lead Percussive
Guitar Brass Synth Pad Sound F/X
Any MIDI device that conforms to the General MIDI Standard will assign each instrument to a specific
number and will allocate at least a 24 note polyphonic capability. The General MIDI Standard was created
so that generic Standard MIDI Files created on a sequencer or notation application may be played back
on another device while preserving the integrity of the original selection.
This Standard has also been integrated into the Quick-Time Movie format in the form of the Musical
Instruments Extension. This program allows the tracks from a Standard MIDI File to be loaded as a
Quick-Time movie that may be played back without a MIDI module. Plug-ins on a web browser will use
the same extension to play MIDI files on the web. Quick-Time 3.0 now supports all 128 voices. Listed
below is the complete list of the General MIDI Instruments. Some of the voices below are programmed to
play a MIDI file with the selected sound by pressing on the link.
1.Acoustic Piano
General MIDI Instrument List
Piano return to the top
2.BrtAcou Piano 3.ElecGrand Piano 4.Honky Tonk Piano
5.Elec.Piano 1 6.Elec.Piano 2 7.Harsichord 8.Clavichord
Chromatic Percussion return to the top
9.Celesta 10.Glockenspiel 11.Music Box 12.Vibraphone

13.Marimba 14.Xylophone 15.Tubular Bells 16.Dulcimer
Organ return to the top
17.Drawbar Organ 18.Perc. Organ 19.Rock Organ 20.Church Organ
21.Reed Organ 22.Accordian 23.Harmonica 24.Tango Accordian
Guitar return to the top
25.Acoustic Guitar 26.SteelAcous. Guitar 27.El.Jazz Guitar 28.Electric Guitar
29.El. Muted Guitar 30.Overdriven Guitar 31.Distortion Guitar 32.Guitar Harmonic
Bass return to the top
33.Acoustic Bass 34.El.Bass Finger 35.El.Bass Pick 36.Fretless Bass
37.Slap Bass 1 38.Slap Bass 2 39.Synth Bass 1 40.Synth Bass 2
41.Violin
Strings return to the top
45.Tremelo Strings
42. Viola 43.Cello 44.Contra Bass
46.Pizz. Strings
47.Orch. Strings 48.Timpani
Ensemble return to the top
49.String Ens.1 50.String Ens.2 51.Synth.Strings 1 52.Synth.Strings 2
53.Choir Aahs 54. Voice Oohs 55. Synth Voice 56.Orchestra Hit
Brass return to the top
57.Trumpet 58.Trombone 59.Tuba 60.Muted Trumpet
61.French Horn 62.Brass Section 63.Synth Brass 1 64.Synth Brass 2
Reed return to the top
65.Soprano Sax 66.Alto Sax 67.Tenor Sax 68.Baritone Sax
69. Oboe 70.English Horn 71.Bassoon
72.Clarinet
Pipe return to the top
73.Piccolo 74.Flute 75.Recorder 76.Pan Flute
77.Blown Bottle 78.Shakuhachi 79.Whistle 80.Ocarina
Synth Lead return to the top
81.Lead1 Square 82.Lead2 Sawtooth 83.Lead3 Calliope 84.Lead4 Chiff
85.Lead5 Charang 86.Lead6 Voice 87.Lead7 Fifths 88.Lead8 Bass Ld
Synth Pad return to the top
89.Pad1 New Age
90.Pad2 Warm 91.Pad3 Polysynth 92.Pad4 Choir
93.Pad5 Bowed 94.Pad6 Metallic 95.Pad7 Halo 96.Pad8 Sweep
Synth F/X return to the top
97.FX1 Rain 98.FX2 Soundtrack 99.FX3 Crystal 100.FX4 Atmosphere
101.FX5 Brightness 102.FX6 Goblins 103.FX7 Echoes 104.FX8 Sci-Fi

105.Sitar
Ethnic return to the top
106.Banjo 107.Shamisen 108.Koto
109.Kalimba 110. Bagpipe 111. Fiddle 112. Shanai
Percussive return to the top
113.TinkerBell 114.Agogo 115.SteelDrums 116.Woodblock
117.TaikoDrum 118.Melodic Tom 119.SynthDrum 120.Reverse Cymbal
Sound F/X return to the top
121.Guitar Fret Noise 122. Breath Noise 123.Seashore 124.BirdTweet
125.Telephone 126.Helicopter 127.Applause 128.Gunshot
Standard MIDI File is the protocol that is used to transfer MIDI information from one type of device to
another. A MIDI sequencer file could be transferred to another sequencer or to a notation program. In the
example below a MIDI sequence file is converted to a Standard MIDI file and then imported into a
notation program.
This standard was added to the MIDI specification in 1988. It is a universal language that saves all MIDI
notes, velocities, and controller codes as a generic file that may be interpreted by any program that
supports the Standard MIDI File. In music applications that support Standard MIDI Files, the user may
access and create Standard MIDI Files with the import and export commands. Standard MIDI files have
the extension .mid added to the end of the document name.

There are three types of Standard MIDI Files, that include:
• Type 0 - which combines all the tracks or staves in to a single track.
• Type 1 - saves the files as separate tracks or staves for a complete score with the tempo and time
signature information only included in the first track.
• Type 2 - saves the file as separate tracks or staves and also includes the tempo and time signatures
for each track.
The internet is an excellent source for Standard MIDI Files. Because the files are MIDI information, they
are usually fairly compact is size and they may also be compressed before they are sent over the internet. I
have listed a few sites that have Standard MIDI Files available for the user. Please use the comment area
in Program Information and Comments page for more sources that should be added to this page.
Links to some sites that have Standard MIDI Files available on the WWW
• Classical MIDI Archives
• The Internet Piano Page
• Monster MIDI Links
• Twin Cities MIDI Home Page
• Harmony Central
• MIDI File Central
• Abundant Legal MIDI Files
• The MIDI Farm
• The Ultimate TV & Movie MIDI Page
• The Music Room
• The Cool Crescendo Site of the Day
• My Mega Midi Archive
• Complete MIDI File Directory
• Standard MIDI Files on the Net
Once you have downloaded some MIDI files, they may be played back with any sequencer or music
notation software. Usually you have to use the Import command to bring up the MIDI File on you
computer program. If you are interested in playing MIDI Files on a Web site, go to Using MIDI on a Web
Site for more information on MIDI Files and MIDI Plug-ins.

Over the past few years the use of MIDI on the internet has gone through many changes. To make things
even more complicated, all browsers do not process MIDI files the same way. There are different HTML
tags that are needed for specific browsers. For an overview of a brief history of the use of MIDI options on
a web site, I recommend "MIDI Options for Web Authors", at the Crescendo web site. Currently, the best
support for playing MIDI files over the internet is to use a plug-in. There are many different companies
that have created plug-ins and I am not recommending any specific plug-in.Currently this page is using the
html embed tag that brings up a Quicktime movie file. The Quicktime movie file is a MIDI file that is
saved as a movie file with the (.mov) extension.
On the Standard MIDI Files page is a list of recommended web sites that have MIDI files. Some of the
sites have links to more MIDI file sites and by no means does this list cover all MIDI files on the web. A
MIDI file will contain note and performance information as well as instructions for the type of sound for
each track of the MIDI file. The actual sound is not included in the MIDI file, instead a program change
recommending a certain type of sound in the General MIDI format. If your browser is set up properly with
a MIDI enhanced plug-in, then the sounds that you are hearing on this web site are from your computer.
Below are examples of "Solfeggio", by Carl Philipp Emanuel Bach . Each MIDI file is exactly the same in
notes and performance instructions. The only event that is different is the program change to play various
sounds from your computer.
Solfeggio, with piano
Solfeggio, with
Harpsichord
Solfeggio, with sitar
Solfeggio, with
Orchestral Harp
Here are examples of a "Walt in Ab" by Johannes Brahms, first with a piano sound and then with a
vibraphone sound.
Waltz in Ab with piano.
Waltz in Ab, with a vibraphone
sound.
Finally, the Prelude in e minor by Frederic Chopin played as the original solo piano composition. A
synthesizer voice is used in the MIDI file immediately below and the two arrangements on the right take
the upper piano voice and double the part with one of the following instruments.
Prelude in e minor, solo piano
Prelude in e minor, synth piano
version
Prelude in e minor, piano with
violin
Prelude in e minor, piano with
clarinet
The sound quality of these MIDI Files is limited by the sound set-up that you have on your computer.
Transferring the MIDI Files to a sequencer and a favorite synthesizer may enhance the sound quality. The
purpose of this exercise is to show you the possibilities of using MIDI Files on a web page. The nice thing
about MIDI Files is that they take up very little memory in the computer and they download relatively fast
compared to digital sound files (Audio vs. MIDI Files).
Plug-ins, such as QuickTime Movie(MoviePlayer) from Apple, LiveAudio by Netscape, Beatnik by
Headspace, Crescendo Plus by LiveUpdate, MacZilla by Knowledge Engineering and MIDIPLUG, by
Yamaha are located at Netscape Products for free downloads.

On this page we will look at computer software applications that use MIDI. This page in no way
encompasses the vast use of MIDI in computer programs. Included are examples of some programs that
demonstrate the wide variety of uses with the MIDI specification. Different types of software include:
Sequencers Music Patch Editors and Librarians
Digital Audio with MIDI
Object-Oriented Programming
sequencers
Music Notation MIDI in Multimedia Applications
Computer Aided Instruction for
Music
Sequencers
When you first glance at an interface of a MIDI sequencer, it has the
similar look of a tape recorder. You have the typical transport controls as
well as tracks of music information. The big difference is the actual
information that is recorded. With an analog tape recorder the acoustic
waveform is recorded on a magnetic tape. With a digital tape recorder
digital numbers are recorded to represent the acoustic signal. A MIDI
sequencer records MIDI events. There are MIDI sequencers that also
have the capability of recording digital audio and they will be discussed
later.
The diagram below displays eight MIDI tracks of information with each
track sending notes, program changes, controller parameters to the
individual instruments. The sequencer does not playback the actual
sounds, but sends MIDI information to the synthesizers that generate the
sounds. Once the MIDI information is stored in a sequencer there are
many ways to manipulate the data. The diagram below is an overview,
but the user can get a more detailed look at the information by clicking on
certain icons.

The picture to the right
represent about ten
measures of MIDI notes for
one track. The analogy of a
player piano roll is used in
that the sequencer is
sending note information to
a synthesizer in the same
way that a piano roll sends
note information to the
player piano. An attractive
feature about a MIDI
sequencer is that if the
performance has a few
mistakes the notes may be
moved, made shorter or
stretched instead of having
to re-record the entire
section.
To the right is an
example of an
event listing of
note information.
Here the notes are
listed with their
location in each
measure as well
as position in
absolute time.
MIDI sequencers
include timing
information on
the tempo of the
composition.
MIDI events may
Another attractive feature of a
MIDI sequencer is the ability to
add control changes after the
recording. In the example to the
left the key velocity for each note
is represented in a graph. The user
may change the velocities with the
stroke of a pencil using a mouse.
Other control options include
program changes, pitch bend,
fader controls, modulation wheel,
panning, and many more.
Piano roll editing and graphic
editing is one way to manipulate
the MIDI data. It is possible to
view the same information in
notation form or in an event
listing.

e recorded at a
slow tempo and
then played back
at a faster speed.
To get a better
understanding of
time and tempo
features I
recommend MIDI
Timing Concepts
Another important feature of MIDI
sequencers is the input options.
Advanced sequencers will give the
user three options for inputting data.
Real Time Recording - Incoming
data is recorded as the performer
plays on a MIDI controller.
So far this
demonstration
has centered
on Computer
Based MIDI
sequencers
(right image).
Other types of
MIDI
sequencers
include:
Step Time Recording - Allows
the performer to input notes of
events one step at a time from the
controller, or with the computer
keyboard or mouse.
Loop Recording - Allows the
user to decide on a specific
amount of measures with a repeat
mode to enter data. It is very
similar to a drum machine tap
mode.
Dedicated
Sequencers -
are multitrack
recorders of
MIDI digital
information.
They are
called
dedicated
because their
only
function is to record MIDI information. An excellent choice for a sequencer if
you move your equipment around a lot for "gigs", and they usually cost less
than a computer.
Workstation, On Board Sequencers - Many work stations (synthesizers,
drum machine, sequencer), now have small sequencers built in that allow
multi-track recording of MIDI information.

eturn to the menu
Digital Audio with MIDI sequencers
A powerful
combination is MIDI
sequencing and digital
audio. This allows the
user to have MIDI
files playing
synthesizers in sync
with digital audio
tracks. The programs
are more expensive
than a MIDI sequencer
and the computer need
to have fast
microprocessors as
well as large amounts
of memory to store the
digital files.
To the right and below
are examples from the
program ProTools by
digidesign.
Highlighted in yellow
are digital audio tracks
as well as MIDI tracks.

eturn to the menu
Music Notation
It was during the mid-
1980's that music
notation became
accessible to anyone
that had a computer
and quality printer
with the beginning of
desktop music
publishing. Laser
Printers with
PostScript music fonts
are able to create highquality
music
manuscript.
There is a wide range of
notation programs
available depending on
the price range. Most
programs allow the user
to input data in step time
or real time. Incoming
data is recorded as the
performer plays on a
MIDI controller in Real
Time Mode. Step Time
Mode allows the
performer to input notes
of events one step at a
time from the controller,
or with the computer
keyboard or mouse.
There is usually a graphic interface that gives the user many options on
note and rest values as well as musical marking symbols, text, musical
expressions, etc.
Files may be saved as a document file or exported as a Standard MIDI
file that could then be read by another notation program or a MIDI
sequencer program. Some programs will allow the user to create a full
score of a composition as well as extracting the individual parts with
transposition for individual instruments. The graphic interface is usually
very intuitive and in little time a composition can appear as a
professional copy.

eturn to the menu
Computer Aided Instruction for Music
Computer programs that involve music instruction have advanced to new levels in recent years. There are
four main categories of software and the range is from the very beginning user to the advanced user. The
categories include:
Flexible Practice - works on music
aural skills and music theory
applications as well as
performance skills. This type of
program allows the student and
teacher to customize the program
by entering new material.
Drill and Practice - work on music
aural skills and music theory
applications. The software is
customized for specific tasks and
instructional support but new
material may not be added to the
program.
Simulation - exciting because they
allow the user to interact with the
computer program. The user may
play practice a melody or
improvise with an accompaniment
pattern.
Multimedia - offer a combination
of sound, graphics, text, and
hypertext in a learning
environment. There are many
programs available, but most of
them do not use MIDI support.
Most Web Browsers and some
HyperCard programs do have
MIDI support.
The programs that are listed below have MIDI capabilities. There are many excellent CAI music programs
that do not use MIDI, but they are not discussed on this page. I recommend the book Experiencing
MUSIC TECHNOLOGY for a complete review of CAI music software programs.
Flexible Practice
Practica Musica is an in depth Flexible Practice program that teaches music
theory and aural skills. When the software is connected with a MIDI
interface the program becomes very powerful with input from a MIDI
controller. If the user doe not want to use MIDI sounds the internal sounds
in the program are also an excellent option. For a college level aural skills
course an instructor may enter their own melodies with the an editor
selection.

Simulation
Vivace is simulation CAI music
program that provides Intelligent
Accompaniment for vocalists,
winds and brass instruments.
Vivace is an interactive system
that is able to listen to and follow
the musician by responding to the
sound source through a
microphone. As the musician plays
or sings their melody line, Vivace
will respond with an
picture from Coda Music
accompaniment that reacts
musically to the soloist's tempo
interpretations.
The company Coda provides over 4,200 titles with a wide range of
ability levels and a repertoire that includes selections from classical, jazz
and current pop and rock tunes. This program has been very successful
in educational programs from grade school through college. There are
now band method accompaniments that offer an exciting new approach
in encouraging the beginning student to practice their music lessons.
Vivace is a way for a student to practice with an accompaniment that
would not be available on a regular basis.
Simulation
Band in a Box is another simulation CAI music program that works as an
accompaniment for the musician. The program allows the user to program
in a wide variety of chords and rhythm style accompaniment. The
accompaniment may range from the standard piano, bass, and drums to a
more elaborate ensemble with guitar, strings, horns and a melody line. The
keyboard above will display the piano accompaniment and the bass line.
The user can adjust the tempo, transpose the key signature, and set up the
song to repeat a specific number of times to rehearse a selection. This
program is very helpful for the rehearsal of a jazz improvisation solo
without the jazz band, saving valuable time in a jazz band rehearsal.
return to the menu
Music Patch Editors and Librarians
The programs that are described here are applications that deal with MIDI. There are many Sound Editing
Programs that work with digital audio sound files. Examples would include Sound Edit 16, Alchemy,

Sound Designer, and Pro Tools. These programs allow the user to manipulate sound file samples, but they
do not use MIDI techniques to edit the sound file.
Music Patch Editors work directly with the sound patches within a synthesizer. Patch editors are
designed specifically for individual synthesizers because each company uses their own system exclusive
information to create their programs. First the hexadecimal code F0 is used to identify the status byte of
system exclusive. The status byte is followed by a data byte that identifies the manufacturer. All data bytes
that follow pertain to MIDI information created by that particular manufacturer. At the end of the system
exclusive message will be the hexadecimal code F7 end of exclusive command.
Patch Editors allow the user to change the size of envelopes, types of filters, samples, waveforms, panning
information, modulation effects and basically anything that changes the parameters of the patch. Each
manufacturer uses different techniques to create sounds for the synthesizer so each Patch Editor must be
designed for the specific synthesizer. Universal Patch Editors are programs that support many different
MIDI devices. That way a user may by one program that will support their studio that has products from
Roland, Yamaha, Korg or other manufactures.
The example on the left is the Universal
Patch Editor Galaxy. Here the user is able to
make changes to the envelopes, original
oscillators, filters and other effects.
Image from the book Experiencing MUSIC
TECHNOLOGY
Patch Librarian software allows the user to organize their sounds, but
they may not edit the sounds. Librarians are a great way to create a bank
of sounds for a specific composition or creating your top 64 or 128
sounds.
Sometimes a sound
from one synthesizer
may be layered with
MIDI to another sound
in a different
synthesizer to create a
new combined sound.
The librarian will
allow the user to move
patches so the
combination is on the
same number.
return to the menu
Image from the book
Experiencing MUSIC
TECHNOLOGY

The computer program
Max allows the musician to
use a graphical
environment to represent
musical events. This
program allows the user to
manipulate and control
MIDI events in new ways
that are not limited by the
conventions of a music
sequencer or notation
software.
The program can send
MIDI event information to
synthesizers as well as
performance event
information to a compact
disc or CD-ROM.
Object-Oriented Programming
Max creates a flexible design of
manipulating any type of MIDI
event in a random or structured
order. You may send commands
to a synthesizer, or create a
system exclusive parameter
change in a sound patch. Any
type of MIDI event may be
altered or changed with the
program. Max is an excellent
composition tool as well as an
excellent source for music
instruction. Go to Understanding
Decimal Binary & Hexadecimal,
or The MIDI Language to see
examples of Max using MIDI
data.
return to the menu

MIDI in Multimedia Applications
MIDI takes up less space than digital audio files which makes it a valuable option in many Multimedia
programs. Some programs use a combination of MIDI and digital audio files. MIDI may be used in the
HyperCard and SuperCard programs. It may be imported into the audio tracks of a QuickTime Movie and
sophisticated Multimedia program like Director may use MIDI files as well as sound files. The new
internet browsers have plug-in capabilities that allow MIDI files to played over a web site (see Using
MIDI on a Web Site).
Sometimes, this subject is a little confusing because both formats are referred to as digital information.
This page will try to explain the content of both signals and clear up some misconceptions about the two
formats.
• Digital Signal
Files
• Computation of Digital
Signals
Digital Signals
• MIDI Files
First let us start by describing an analog signal. The word analog implies a resemblance or similar
comparison of one thing representing another. An analog signal is a transformation of an acoustic signal,
movement of molecules in a medium such as air, to a voltage signal that travels down an electrical wire.
The voltage in the wire is an analog or representation of the acoustic signal. A typical set-up may be a
musical instrument that creates a tone. This tone energy creates a disturbance in the air particles by
pushing air molecules that condense and cause a rarefaction of the air when it returns. This movement is
happening at a fast rate that equals the initial source of the soundwave. This tone is then received by a
microphone that has a sensitive diaphragm that responds to the movement of air. At this point we use a
term called transducer, because the energy is converted from an acoustic signal to an electrical signal than
represents the same waveform. This voltage signal is then carried down a wire to an amplifier, where the
signal is amplified and then sent down another wire to a loudspeaker, which transforms the signal back to
acoustic energy that is received by the auditory system.
Another example of analog signals are the use of the older modular type synthesizers that use voltage to
carry the musical signal down a wire. Alterations to the signal, such as filters, ring modulators, simple
frequency modulation, sample and hold are modifiers that are used to alter the analog signal.
In the digital world, numbers are used to represent a digital waveform. An audio signal is represented in
digital memory with a binary code that stores a massive amount of numbers that are used to represent a
signal. An ADC (Analog to Digital Converter) is a computer chip that is used to convert an analog signal

into digital information. This process is called sampling and has changed the world of sound in a dramatic
fashion.
Once the signal is represented as binary numbers, it may be manipulated with processes like combining
sounds, splicing, truncation, looping, and reversing a sound and other digital signal processing. The signal
is then converted back to an analog signal through a DAC (Digital to Analog Converter).
In order to sample a sound event we must understand the process that is used to convert the acoustic
waveform to a digital sample.
The user has to determine the sampling period or rate and must also decide on the bit resolution. Let's use
a time period of one second for a sample. During that second of time, the sampling rate determines the
number of samples that will be taken during that one second. The bit resolution determines where to
represent the signal during that discrete moment in time. If the resolution is at 16 bits, then there would be
65536 locations to represent the waveform at each given sample. That would be a range from -32768 to 0
to 32767. If the resolution is 8 bits, there would be 256 possible locations. The term quantizing is when
the actual sample is shifted to one of the bit locations that best represents the signal at that discrete
moment in time. If we changed the sampling rate, the period of time or space between each sample is
changed. In the diagram below are four examples of different quantization and sampling rates.

Different Quantization and Sampling Rates
In diagram (A) and (B) the sampling rate is the same, but the quantization resolution is better in diagram
(B). In diagram (C) & (D), the sampling rate has been doubled and the bit resolution has been increased in
diagram (D). What a dramatic difference the sampling rate and bit resolution can make on recreating an
acoustic waveform.
The Nyquist Theorem determines that the bandwidth of any digital sampling length will always be onehalf
of the sampling rate. This means that a sample taken at a rate of 44k would have 22k (22,000)
pictures or snap shots of the waveform in one second of time. A higher rate will have more samples per
second and will also take up more computer memory. The Nyquist Frequency is the frequency of the
highest component of a sound and the Nyquist Rate is twice the Nyquist Frequency.
More computer memory is also used when the bit resolution is higher (16 bits to represent a number
verses 8 bits). Computer memory and the content that is being sampled will determine the sampling rate
and bit resolution to use. For example, sounds that do not have a high frequency content could be sampled
at a lower rate and still imitate most of the same fidelity as the original sound.
It is important that the signal that is being sampled does not have frequencies above the Nyquist
Frequency. Every time that a sample is made, there is also duplicates of the signal that are also created that
are called Folding Components.

When a sample goes beyond the sampling rate, the duplicate of the signal crosses over into the sampling
range and is considered the Folding Frequency. We use the term aliasing to describe the folding
frequencies which are doubles of the frequencies. In the sampling process filters are used before the ADC
to make sure that the folding frequency will not happen when the signal is sampled.
In digital sampling, the number
of bits per sample also determines
the signal to noise ratio. The
signal to noise ratio depends on
how loud the signal is. The
following ratio is used to
determine the decibel ratio.
Return to Audio vs. MIDI Menu
dB = 20 log 2 N / 1 or 2 N - 1 /
0.5
# Bits dB
2 12
4 24
8 48
12 72
16 96
24 144
Computation of Digital Signals
Clearly, digital sampling is a very complicated concept
and in order to truly capture an acoustic waveform, a
quality sample will need a large amount of computer
memory. Use the following formula to get a better idea
of how large the file size is of a sampled audio sound.
(# seconds) * (# channels) * (sampling rate) * (bit resolution) / 8 =
file size
Take the number of seconds and times it by the number of channels (mono or stereo). Times that by the
sampling rate and the bit resolution. Then divide the total by eight to get the file size.
Example 1- Sampling a four second sound of a speaking voice.
Because the voice is in the lower range of the audio spectrum we could sample the sound at 11kHz with
one mono channel and 8 bit resolution.
(4 secs.) * (1 chan.) * (11kHz) * (8 bits) / 8 = 44k
Example 2 - Sampling a four second sound of a musical selection.
First we need to change the sampling rate to 44kHZ to capture the spectrum of the complex musical sound
and we will record a stereo sample with 16 bit resolution.
(4 secs.) * (2 chan.) * (44kHz) * (16 bits) / 8 = 704k
Both examples are four seconds of sound, but the final output is very different in size (44k vs. 704k). If
we tried to take example 2 and record a minutes worth of sound, the sound file would expand to 10,560k
or 10.6megabytes, while a minutes worth of sound from example 1 would be 660k. Both examples are
one minute long, but the difference in the size of the files is 9900k or 9.9 megabytes.
Return to Audio vs. MIDI Menu

MIDI Files
It is important to understand that MIDI contains performance data or instructions for creating music. The
actual analog audio signal or digital audio signal, are not moving through a MIDI cable.
The type of performance data that is communicated by MIDI includes:
1. turning on and off notes
2. expressing the velocity of each note
3. sending program changes
4. use of the sustain pedal and other controller, such as pitch bend or modulation wheel
5. timing relationships of all MIDI notes and events
6. for others, go to Types of Data Transmitted through MIDI page
If we look at the hexadecimal and binary code of a MIDI file, we will discover that the amount of
information is drastically reduced in comparison with a digital audio file. A one second digital audio file
may be around 700k, while a one second MIDI file might contain 1 to 3k of information. With MIDI we
are not recording or sampling the actual note. Instead, we are sending information to turn on a MIDI
devices sound. Go to the MIDI Language for more detail.
Return to Audio vs. MIDI Menu
Explanation of Absolute and Examples of MIDI Time Code in a
Relative Time
Sequence
MIDI Timing Clock Studio design using SMPTE/MIDI
Time Code
Different types of Time Code Related Terms
• SMPTE Time Code
• MIDI Time Code
The first concept that needs to be understood is the difference between absolute and relative time. MIDI
Time Code and SMPTE Time Code are representations of absolute time in that they follow hours, minutes
and seconds just like your watch. Absolute time is always the same and you cannot speed it up or slow it
down. Relative time is a reference to a musical piece that has an inner tempo. A composition may take
three minutes to perform at a tempo of 80 bpm (beats per minute), but would take only a minute and a half
if the tempo was increased to 160 bpm. An advanced MIDI sequencer is able to work with both absolute
time and relative time and make adjustments when there are changes in the relative time of a composition.
In the chart below the upper line represents absolute time and includes an example of 17 seconds of time.
Both MIDI Time Code and SMPTE Time Code may be used to represent absolute time which is fixed and
may not be moved. Following the absolute time line are examples of repeated quarter notes at 3 different
tempos (relative time). Notice that 2 measures have passed at 4 seconds with a tempo of 120 bps, but it
would take 8 seconds for the same two measures at a tempo of 60 bpm and 16 seconds for the same two

measures at a tempo of 30 bpm.
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MIDI Timing Clock (MIDI Sync) is a status byte (F8) that is sent 24 times per quarter note for note
resolution. Advanced sequencers will also subdivided each MIDI clock twenty times for a resolution of
480 times per quarter note. Standard - 24 PPQ. Professional - 480 PPQ. If the tempo changes, the speed of
the MIDI Timing Clock will pass at a faster rate, but the number of status bytes (F8) per quarter note will
stay the same.
An F8 status byte is a system real time message that is
used in a MIDI sequence to connect all the different
rhythm values. The image above is a simple sequence
consisting of quarter notes in the 1st measure, half notes
in the 2nd measure, a whole note in the 3rd measure,
followed by eighth-notes and sixteenth notes in the 4th
and 5th measure, and finally a whole note in the last
measure.
To the left is a graph depicting the same information in an
event listing. Notice that the first number represents the
measure, followed by the beat and finally the F8 timing
clock resolution. In the first three measures each note
starts exactly on the beat which corresponds to a timing
clock reference of 0. Notice at the 4th measure that the
timing clock has changed to values of 240. Remember
that 480 times is the total for each quarter note and the
240 value is an eight note. In measure 5, the value
changes to 120 which now represents the sixteenth note.
If the tempo of this sequence was changed to a different
number, the numbers and values on these two charts

would not change. What would change is the location of
the notes in respect to absolute time. The value of the new
tempo would map out a new chart for placement along
the MIDI Time Code.
Now we will look at what MIDI Time Code and SMPTE
Time Code have in common (absolute time) and how it is
used in conjunction with MIDI Timing Clock (relative
time).
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A Time Code is an electrical or digital signal that gives a common timing reference for syncing MIDI
devices with other electronic devices. The evolution of timing references has changed dramatically since
the beginning of MIDI, from the use of click track, PPQ Clocks, FSK Clocks, to the more sophisticated
use of SMPTE Time Code and MIDI Time Code.
SMPTE Time Code (Society of Motion Picture and Television Engineers) Was originally developed
by NASA to sync computers together. SMPTE is a digitally encoded labeling system that strips a tape
with an exact timing reference. It is a 1200 Hz modulated square wave that uses a biphase modulation to
encode the signal on a tape. SMPTE is used to sync video with music, audio and sound effects. It may be
used with a multi-track tape recorder and a synchronizer to sync a MIDI sequence with the tape or to sync
two multi-track tape recorders. It is important to remember that a SMPTE Time Code signal is made up of
digital words that contain 80 bits. These bits are used to represent the type of SMPTE signal, the actual
location which includes hours, minutes, seconds, and frames, as well as user bits for dates and reel
numbers. This digital number is converted to an audio tone so that it may be recorded on to an analog
tape.
There are two different ways to record a SMPTE Time Code on to a tape. LTC Time Code
(Longitudinal Time Code) is SMPTE Time Code encoded on one of the audio tracks or in-between the
audio tracks of a video tape. This type of time code needs to be running in order to be read. A window
burn is used on a working copy of a tape with LTC in order to address the code in slow or paused position.
VITC Time Code (Vertical Interval Time Code) is SMPTE Time Code encoded on the Video signal in
the Interval between frames. This allows for the use of SMPTE at very slow speeds without the need of a
window burn or the loss of an audio track.
There are four different SMPTE formats in the standard. Each format refers to the number of frames per
second. In film there are 24 frames which corresponds to the number of pictures per second. In European
film and video the number of frames per second is 25. In the United States the original black and white
TV programs ran at exactly 30 frames per second. This changed with the advent of color to run at 29.97
frames per second. In order to compensate for this discrepancy, there is a SMPTE format called "drop
frame" at 30 frames per second. There are exactly 30 frames for every second, except two frames are
dropped at the beginning of every minute, except at minutes 0, 10, 20, 30, 40 and 50. A total of 108

frames are dropped for each minute to adjust to the 29.97 frames per second. The standard that is used for
most applications is "30 drop frame" and listed below are some examples.
The number to the right
represents 23 hours, 59
minutes, 59 seconds, 29
frames, and 79 bits. By
adding one more bit to
this number would
change the number to 24
hours.
The number to the left
represents a specific
moment in time. The
number represents 1 hour,
6 minutes, 12 seconds, 9
frames and 6 bits. There
are 80 bits for every
frame.
When MIDI was invented there was no specific data for synchronizing with SMPTE Time Code. If a
musician was trying to use MIDI sequences to synchronize with a video tape they needed a sync device.
Song Position Pointer is a System Common status byte F2, that is generated every six MIDI clocks. It is
used as a reference to find a location in a song by counting the Song Position Pointer total and diving by
16 (4 per quarter note in a 4/4 time signature) to find the measure. A Tempo Map is used by a sequencer
to change tempo at certain locations in a sequence. In order to synchronize with Song Position Pointer, a
sync device is used to decide tempo and tempo changes in a song and the amount of measures in a song,
using SPP and tempo map. The sync device can then figure out the amount of SMPTE time that passes at
certain "hits". This was a very complicated way of synchronizing a MIDI sequence to a video tape, so in
1987, MIDI Time Code, was added to the MIDI specification in order to have a direct link of MIDI with
SMPTE Time Code.
return to the menu
MIDI Time Code is a digital conversion of the SMPTE Time Code that allows MIDI devices to lock to
the SMPTE Time Code in real time. Every frame of the SMPTE Time Code is broken down into 4 frames
of MIDI Time Code with an average of 120 times a second. There are System Common Quarter - Frame
messages which are used when the system is running and System Exclusive Full Messages to address any
location.
MIDI Time Code Quarter Frame Messages (QFM) are used when a system is running. It takes a total
of 8 QFM to address one SMPTE Frame. That means that SMPTE is updated every two frames. Each
QFM starts with the F1 Status byte, followed by a Data byte were the first nibble will be 0 through 7
followed by a nibble that is the actual number.
F1 - MIDI Time Code Quarter Frame Address - Status
Byte
nx - Data Byte

n= First nibble - 0 - Frame count LS nibble
n= First nibble - 1 - Frame count MS nibble
n= First nibble - 2 - Seconds count LS nibble
n= First nibble - 3 - Seconds count MS nibble
n= First nibble - 4 - Minutes count LS nibble
n= First nibble - 5 - Minutes count MS nibble
n= First nibble - 6 - Hours count LS nibble
n= First nibble - 7 - Hours count MS nibble and SMPTE
Type
x= Second nibble - Actual number of the Time Code 0
through 9
The
relationship
between the
SMPTE time
code numbers
and MIDI time
code quarter
frame message
is listed in the
example below.
0 1 1 6 2 5 1 2
F1
70
F1
61
F1
51
F1
46
Example of MIDI Time Code in a MIDI Sequencer
In the example to the right
are red arrows pointing to
specific MIDI time code data
in a sequencer track. The
upper right arrow is pointing
to a specific absolute time
number of 1 hour, 3 minutes,
7 seconds and 8 frames.
Below this arrow is an arrow
pointing to the music that is
being played at this location.
The arrow on the left is
pointing to an offset number.
Offset is a way of setting the
MTC time at a certain
number to begin a sequence
or cue.
F1
32
F1
25
F1
11
F1
02

There are red
arrows in the
diagram to the
right that are
locating a
highlighted
note in this
MIDI
sequence at
measure 5,
beat 2. The
tempo for this
sequence is set
at 220 bpm
and the time
code (upper
right arrow
indicates that
the note will
start at 4
seconds, 19
frames and 74
Here is an event listing of the
notes and the arrows are
pointing to an exact moment in
time. In the top arrows the note
D2 is played in measure 39,
beat 1, with a MIDI clock
resolution of 70. This note
occurs at 1 hour, 1 minute, 22
seconds, 6 frames and 51 bit
resolution.
In the lower arrows the note C2
is played in measure 48, beat 1,
with a MIDI clock resolution of
220. The time reference of this
note is 1 hour, 1 minute, 38
seconds, 29 frames, and 34 bit
resolution.
It is important to remember that
if the tempo of the music
changed, the time code
numbers would change, but the
value and placement of the
notes would stay the same. The
next two example clearly show
the relationship of the MIDI
time code with the MIDI timing
clock.

its and will
end at 5
seconds, 13
frames and 79
bits.
This example is
the exact same
sequence as
above with the
tempo slowed
down to 110
bps. Again the
same note at
measure 5, beat 2
is highlighted,
but with the
slower tempo the
time code
numbers have
changed. The
note will first
start at 9
seconds, 9
frames and 66
bits and end at
10 seconds, 27
frames and 78
bits.
The highlighted note would start 4 seconds, 19 frames, and 72 bits later in
the second example with the tempo cut in half. The duration of the
highlighted note in the second example would be for 1 second, 18 frames
and 12 bits, while the duration of the highlighted note in the first example
would only be 0 seconds, 24 frames and 5 bits. The use of MIDI Time
Code in a sequencer allows the user to make changes with the tempo of a
composition and all the timing information is automatically updated to
follow the new tempo marking. With the use of MIDI Time Code to sync
up to SMPTE Time Code, there is no need for a sync device and
synchronization with Song Position Pointer
This program, Exploring MIDI was
designed and created by Peter J.
Raschke.He is currently at Northwestern
University pursuing a Ph.D. in Music
Technology. He completed the Masters of
Music Technology degree in June, 1997.
As a member of the Northwestern
University School of Music Web design
team, Mr. Raschke helped to create its
Web pages.
He has taught a multimedia software
Email address is:
raschke@northwestern.edu

development class, Web Authoring, and
an Introductory to Technology class in the
Music Technology program at
Northwestern University, and he was an
instructor and music laboratory technician
at Santa Barbara City College prior to
beginning his graduate studies. Web sites
created by Peter Raschke are located at the
Northwestern University School of Music
projects Web page.
Publications and Papers Music Theory Online, The Online Journal of
the Society for Music Theory Volume 5, Number 2, March 1999.
"Review of Music-Theory Web Sites for the Beginner."
International Computer Music Conference, 1998, Paper Session, "Music
Technology as a Tool for Exploring the Creative Aspects of Music."
Other Web Sites created by Peter Raschke:
An interactive music theory web site, "Score Scan," provides practice in
reading the "tonal profile" of a music selection. Based on the 1989
HyperCard document created by Northwestern music theory professor
John Buccheri, the current version is a Java applet and Java application
that was created by the collaborative efforts of Michael Overman and
Peter Raschke.
3D Sound at Northwestern University, is an educational site covering
concepts and applications in 3-D Sound & Spatial Audio.
Current Web site for the Introduction to Technology class at
Northwestern University, School of Music. (Fall 1999)
Web Authoring course in Multi Media Software Development at
Northwestern University, School of Music.
Collaborated on the Web site 3D Sound at Northwestern University, an
educational site to help you learn more about 3-D Sound & Spatial
Audio.
The Web site, Gregorian Chant, Christmas Mass is a site for discovering
the sounds of Gregorian Chant by listening to a recording of selections
from the Proper and Ordinary of a Roman Catholic Mass.
• Link to Home page
• Philosophy of Music Education
(paper based on using technology as a tool in Music Education)
This web site, "Exploring MIDI" was recognized in the May 1999 issue of
Electronic Musician, in the article "Music Sites for Web Surfers"and in the May
1998 issue of Electronic Musician, in the article "Back to School Online." It is
also mentioned in the latest edition of How MIDI Works, Alexander Publishing,
and the 2nd Edition of Experiencing Music Techmology, Schirmer Books.

"Exploring MIDI" is
included in the
WannaLearn
directory, a directory
of the best free,
family-safe, online
tutorials, guides and
instructionally
oriented Websites on
the Net!
"Exploring MIDI"
received the Golden
Crane Creativity
Award (GCCA). This
award is given to
sites that provide free
instructional
information in arts,
crafts, music, and
other creative
activities.