MIDI messages
March 2001 – Edition 1.4
MIDI messages
MIDI messages
(For MIDI specialists only!)
MIDI is that most rare of beasts, a standard set by a number of different manufacturers that
is universally implemented and supported. This sounds too good to be true, and it is,
because in order to understand exactly how MIDI works, you need to be able to speak
Martian.
MIDI instruments (such as your computer’s sound card or external sound module) send
and receive MIDI messages, which consist of a status byte and one or two data bytes. MIDI
bytes can have a decimal value of 0-127, which is their most human-readable form (they
can also be addressed in terms of seven decimal bits – e.g. 1111111 – or hexadecimal up to
7F, but unless you’re a computer, you won’t want to think about this for too long).
In order to be device-independent, numbers in MIDI messages (including program
numbers) always count from 0, even if your MIDI device’s manual counts from 1.
MIDI messages are classified either as channel messages, which affect a single channel (in
Sibelius, this translates to the staff to which they are attached), and system messages, which
affect all channels (in Sibelius, all staves).
Channel messages carry the majority of the musical data (e.g. which notes to play, how long
they should last, which sound to use), while system messages are used for other arcane
things like synchronization with other MIDI devices.
Sibelius supports most MIDI messages (e.g. pitch bend, SYSEX), and can also send just raw
data.
Entering MIDI messages in Sibelius
In general, you’ll only need to enter channel messages manually in Sibelius in very specific
circumstances, because Sibelius reads almost all markings in your score and automatically
turns them into appropriate MIDI messages when playing back. You can also define words
and phrases and what their effect on playback is using the playback dictionary.
However, you can also tell Sibelius to send any MIDI message you like at any point, by
typing it in as text using the simple MIDI message language described below. These MIDI
messages can be appended to ordinary text and can be hidden, so if you write mute
~P59 in a trumpet part, Sibelius will send program change 59 to produce a muted
2
MIDI messages
trumpet sound at the exact point where ‘mute’ appears on the print-out. The ~P59 can be
hidden. (Clever, eh?)
If the trumpet mutes often, you can of course copy mute ~P59 using z-click or
Alt+click to save you retyping, or you can add it to the word menu obtained when you
Control-click (Mac) or right-click (Windows) ( Word menus and special
characters), and assign it a keyboard shortcut at the same time.
When you import a MIDI file, you can choose to have MIDI messages in the file written into
your score, in which case any control changes etc. will appear as if you’d typed them in
yourself.
Should I use the dictionary or MIDI messages?
Many situations are more conveniently dealt with using the playback dictionary. If you want
to send a MIDI message which is always associated with a particular word in your score,
then just define it as a new word in the dictionary.
For instance, if trumpet is the only instrument in your score which is ever told to ‘mute’,
then just define ‘mute’ to send program change 59 in the dictionary, and you won’t have to
keep typing ~P59 all over the place.
However, if your score uses muted strings as well as trumpet, then using the playback
dictionary would make the strings also produce a muted trumpet sound wherever they were
told to ‘mute’.
In this case, you should use MIDI messages, so you can send a muted trumpet program
change wherever the trumpet mutes, and turn the volume down (say) wherever the strings
mute.
Syntax
You can type MIDI messages into your score using any staff text style – typically Technique
or Expression text. MIDI messages can be written on their own, or put at the end of any
other text (such as ‘mute’).
Messages take the form: ~ followed by a single command letter, followed by one or more
numbers, which are usually separated by commas.
E.g. ~C64,127
(~ is informally called a ‘tilde’ or ‘swung dash’, but the technical term is ‘twiddle’.)
3
MIDI messages
Numbers can be written in decimal (e.g. 0-127), binary preceded by b (e.g.
b01111010), or hexadecimal preceded by h (e.g. hA8).
Note that:
•
•
•
MIDI messages are case sensitive (i.e. you must type capitals or small letters as
indicated), except for hex digits – so ~P123 is correct but ~p123 won’t work
You can write multiple messages in the same piece of text, separated by a space or
Return (on the main keyboard), and with just one twiddle at the start, e.g.: ~P43
A65 C64,127
If you like you can also put spaces or Returns around commas and numbers.
Channel messages
Channel messages are split into two types: channel voice messages, which carry the musical
data; and channel mode messages, which affect how the MIDI device responds to the
musical data.
Let’s examine each of the channel messages in turn:
NoteOn/NoteOff
These messages control which pitch is played, how loud the note is, and how long it lasts
for. These cannot currently be entered manually in Sibelius. They consist of two data bytes
(MIDI key number – e.g. 60 is middle C – and velocity), although the second byte is usually
ignored in NoteOff messages.
Program and bank change
A program change controls which sound is used to play a particular note. Sibelius
automatically sends the correct program change when it starts playing, so that a violin staff
plays with a violin sound. However, if you want to change the sound a staff plays with
midway through your score, you can use a program change message.
The syntax of a program change is ~P program e.g. P76
Sibelius also allows you to change the bank and program in the same MIDI message. If your
playback device only supports GM sounds, you’ll never need to use a bank and program
change together, but if it has a wider selection of sounds, you may want to use a sound
from a different bank.
The syntax of a bank and program change is: ~P bank/program e.g. P2/76
4
MIDI messages
Note that program numbers here always start from 0, and bank numbers are always
represented as (MSB x 128)+LSB. This is not necessarily how the values appear in the
Sounds dialog box (Play/Flexi-time menu).
Pitch bend
Pitch bend normally allows you to alter the pitch of a note by up to two semitones up or
down (although there are a couple of ways to increase its range – see below).
The syntax of pitch bend is ~B0,bend-by, e.g. ~B0,64 means normal pitch, ~B0,0
means bend two semitones downwards, and ~B0,127 means bend two semitones
upwards. (In other words, values lower than 64 flatten the note, and values higher than 64
sharpen it.)
If you want finer control over the pitch bend, you can change the initial byte, also in the
range 0-127, which gives very small deviations in temperament, so e.g. ~B127,64 will
sharpen the written note by a small amount.
You can use the pitch bend control to create a portamento or glissando effect by inserting a
number of MIDI messages one after another.
You can also use this control to make a note play back sharp or flat without inserting an
accidental, e.g. if you want to make ficta – editorial accidentals above the staff – play back,
you can insert the accidental from the Symbols dialog box, and then use a MIDI message
of e.g. ~B0,96 to play the note a semitone sharp. Don’t forget to use ~B0,64 to return
the channel to its normal tuning on the next note!
To create a pitch bend effect over an interval wider than two tones, you can either use the
portamento control change (see Control changes below) to make a pitch bend, or use
the following method:
•
•
First, set up the range over which the pitch bend can operate. Insert the MIDI
messages ~C101,0 ~C100,0 ~C6,semitones in your score, where semitones
is the total range of the pitch bend in semitones, from 0-12. For example, to set up
pitch bend with a maximum range of an octave, use ~C6,12.
(It’s best to put these messages at the start of your score.)
When you want to add a pitch bend to your score, insert a ~B0,bend-by
command as usual, except that now you must divide the bend-by parameter into
the number of semitones set up with your ~C6 command, e.g. if you enter
~C6,12, each semitone adds or subtracts 5.3 (64 divided by 12) to bend-by. So
to bend upwards by four semitones, you would enter ~B0,85.2.
5
MIDI messages
Note that this method requires that your MIDI device supports standard ‘Registered
Parameters’, which is common but not universal.
Aftertouch
Aftertouch refers to the amount of pressure used when e.g. a key on a MIDI keyboard is
pressed. This information can be used to control some aspects of the sound produced by
the synthesizer, e.g. vibrato on a violin sound. The precise effect of this controller is
dependent on the sophistication of the MIDI device used.
Aftertouch can be applied either on a particular note (polyphonic aftertouch), or on a
channel as a whole (channel aftertouch). Polyphonic aftertouch is not as widely
implemented in MIDI devices as channel aftertouch.
The syntax is as follows:
•
•
Channel aftertouch: ~A pressure e.g. A64
Polyphonic aftertouch: ~a pitch,pressure e.g. a60,64
Control changes
Control changes are used to control a wide variety of functions in a synthesizer. Although
the function of each control change is clearly defined, not all MIDI devices support every
control change. These are split up into groups, including:
•
•
•
•
•
•
Control changes 0-31: data from switches, modulation wheels, faders and pedals
on the MIDI device (including modulation, volume, expression, etc.)
Control changes 32-63: optionally send the LSB for control changes 0-31
respectively
Control changes 64-67: switched functions (i.e. either on or off) such as
portamento, sustain pedal, damper (soft) pedal, etc.
Control changes 91-95: depth or level of special effects such as reverb, chorus, etc.
Control changes 96-101: used in conjunction with control changes 6 and 38 (Data
Entry), these can be used to edit sound patches
Control changes 121-127: channel mode messages (see Channel mode
messages below).
The syntax for control changes is ~Cbyte1,byte2, where byte1 is the number of the control
change (from 0-127) and byte2 is the control value (also from 0-127).
For full details of the control changes supported by your MIDI device, consult the
manufacturer’s manual.
6
MIDI messages
The most commonly used control changes are as follows:
Modulation
Control change 1 controls the vibrato ‘wobble’ generated by a modulation wheel. For lots of
wobble, use ~C1,127; for no wobble, use ~C1,0.
Breath
Control change 2 is only recognized by certain MIDI equipment, such as wind synthesizers,
and corresponds to the ‘breath pressure’ used to play a note.
Portamento
Portamento is actually controlled by two control changes: ~C5,0-127 controls the length of
time taken to perform the portamento (0 is fastest, 127 is slowest), and ~C84,0-127
determines the distance of the portamento (values below 60 start below the note, values
above 60 start above the note).
So you must first ‘set up’ the portamento effect with a ~C5 message, and then attach the
~C84 message to the note on which the portamento occurs.
Note that this control change is not supported by all MIDI equipment.
Volume
Controller 7 determines the volume of a given note, e.g. ~C7,127 is the loudest and
~C7,0 is the softest.
You should only need to use this MIDI message if you want to achieve a change of dynamic
over the course of a held note – the Cresc./Dim. Playback plug-in enters these
messages for you.
Pan
Controller 10 determines the pan position of a particular channel, e.g. ~C10,0 is absolute
left, ~C10,64 is center, and ~C10,127 is absolute right.
You don’t need to use this MIDI message unless you need to change the pan position of an
instrument during playback – you can usually change this setting in the Sounds dialog box
(type I).
Expression
Controller 11 takes a fraction of the channel volume specified by controller 7, so
~C11,127 uses 100% of the channel volume, ~C11,64 uses 50% of the channel
7
MIDI messages
volume, and so on. Functionally ~C7 is intended to act something like a volume knob and
~C11 something like a pedal for tweaking the ‘main’ volume.
Sustain pedal
Sibelius automatically inserts MIDI messages for the sustain pedal if you use the Ped. lines
from the Lines dialog box ( Lines). However, if you want to make playback of your
score sustain without using these lines, use ~C64,127. Switch the pedal off again with
~C64,0. (Note that the sustain pedal control change is a switched function, i.e. it is either
on or off.)
Soft pedal
Controller 67 can be used to achieve the effect of using the una corda pedal on a piano: to
switch on the soft pedal, use ~C67,127; to switch it off, use ~C67,0. Note that this
control change does not work on all MIDI devices.
Channel mode messages
You’ll probably never need to use control changes 121-127 in Sibelius, but just in case:
•
•
•
~C121: reset all controllers
~C122: Local Control on/off
~C124-127: Omni mode on/off, Mono/Poly mode
System messages
These don’t need a channel, so the staff they are attached to only determines which MIDI
device they are sent to.
System messages are split into three types: system common messages, system real-time
messages, and system exclusive messages. Typically, only the latter are useful in Sibelius
(the former two are largely connected with synchronizing MIDI with clock-based MIDI
components, which is unsupported by Sibelius).
System exclusive messages are used to send data that is specific to the particular MIDI
device you are using, and they may vary from device to device.
To enter system messages in your score:
•
•
•
8
System exclusive: ~X bytes e.g. ~Xh40, h00, hf7. Note that normally you
should put hf7 at the end to terminate the system exclusive, unless you’re going to
follow it with a D command containing more data.
System common/system real time: use raw data (below)
Raw data (without any ‘command’ byte): ~D bytes e.g. ~Dh40, h00, h7f
MIDI messages
Hiding MIDI messages
You probably don’t want MIDI messages littered all over your score when you print it, so to
hide them, simply switch off Show text after tilde (~) on the Text page of the
House Style dialog box (File menu).
Only the ~ and the messages after it are hidden, so you can still read preceding instructions
to the players such as ‘mute’ which are meant to be visible. MIDI messages still play when
hidden. When you edit the text the ~ message reappears.
Dynamics
It’s worth dwelling for a moment on the specific case of dynamics in the playback dictionary.
When you enter a dynamic using Expression text ( Text), it derives its playback
characteristics from the appropriate entry in the dictionary – e.g. fff equates to a MIDI
velocity of 127. However, the actual velocity of the note will be determined by the Balance
parameter in the Sounds dialog box ( Sounds), which is a scale factor applied to the
note’s velocity – e.g. if the Balance of a staff is set to 50%, a fff dynamic in that staff will
produce a MIDI velocity of 64.
But this isn’t quite the end of the story – the actual playback velocity of a note also depends
on the level of Espressivo and any articulations (such as accents) present.
Further information
If this topic hasn’t exhausted your appetite for strings of letters and numbers, you can find
more information on MIDI messages at the web site of the MIDI Manufacturers’ Association
(MMA), www.midi.org.
9
Open as PDF
Similar pages