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What is a parameter curve ?
Parameter curves are a fast and accurate
way to change the sound of an instrument while music is playing.
As you could read in previous chapters,
general digital effect settings, in the "Play tools" palette, enables to
change the global volume of a document, as well as bass boost, noise reduction,
etc...
These settings apply to the whole
instruments of the document. If you change the volume, for example, it
affects the whole piece.
Then on each staff, digital effect processors can be inserted in order to add specific effects : Distortion, Flanger, Chorus, Reverb, etc. These are "Effect processors" objects.
From Harmony Assistant version 8.0
(Melody Assistant 6.0), several curves can be related to each staff. Each
curve defines the way a parameter evolves during time. The curves are processed
in priority in regard to effect processors, but you can use both on the
same staff.
A curve enables to control more
finely the variation of this parameter.
For each time position in the written
music, you can select precisely the parameter value, or make the parameter
vary smoothly betwee two time positions.
Here are some samples of use :
We saw that in scroll mode (the only
display mode available in Melody Assistant) or in page mode with control
handles enabled (Harmony Assistant only), little icons are displayed on
the left of the staff. The third icon from the top is a green arrow. When
clicking this icon, a pop-up menu opens.
You can select the curve to be edited.
When a curve is currently edited, the staff is grayed out in order to ease
the layering between notes and the parameter curve values.
The first menu item resets the standard
display and editing mode for notes on the staff.
The next one enables to edit note
velocities (power). A red curve joins the notes. The bigger value for
note velocity, the higher curve point. By clicking in "Editing" (pencil)
mode, you can change graphically the velocity value of each note.
Then, with Harmony Assistant only, you can adjust delay and pressure time for each note. A blue horizontal line shows the delay (offset from the note head) and the pressure time (line length). As for velocity, you can can change graphically these values in "Editing" (pencil) mode.
A second section in the menu grants
you the access to other parameters, like volume, panning position, frequency,
chorus level...
You can also define parameters that
are dedicated to MIDI output management.
Parameters in this second section, contrarily to velocity, delay and pressure time, are not related to the notes, but to the staff itself. Deleting or moving note won't change the curve. It is therefore preferable to adjust curves after having input all notes.
When a curve exists for a parameter, the curve name is displayed in bold in the pop-up menu.
Then, the third section of the menu
enables to configure the curves, or to apply changes to existing
curves.
How to edit a curve ?
A curve is made of segments (coloured lines) between control handles (little squares). On the left side of the staff, the minimum and maximum value of the parameter, as well as its name. You can configure the parameter, in order to change its minimum and maximum value, as well as its display color.
To add a control handle, click the
staff in "Editing" (pencil) mode.
To move a control handle, drag it
in "Editing" (pencil) or "Select" (lasso) mode.
To move a curve, drag its first
control handle while Shift key is down.
To change several values at a time,
include the group of control handles to change in the selection range,
the drag one of these control handles.
To split a curve into two parts,
click a segment with the delete tool (bolt)
To delete a control handle, click
it with the delete tool (bolt)
To delete a curve completely or
partially, select the staff then Edit>Erase
You can copy/paste parts of a curve
on the same staff, or from a parameter to another.
You can add or subtract a value
to the selected range through the apply option in the pop-up menu.
You can fill the selection range
(or the whole staff if nothing is selected) with triangle or square curve
through the apply option in the pop-up menu.
How the parameters are applied ?
Values of parameters that are displayed as a curve are applied in real-time while music is playing, 200 times each second. The value is read at the required time position in the written score, and eventually calculated to perform smooth changes between two control handles. If, at a given position, there is no segment (that can occur for example if you splitted a curve by deleting a segment), the parameter is not applied.
Some parameters are specific to digital
output, some other to Midi only, or to both digital and Midi output.
The array below shows each possible
parameter curve as well as its field of action.
If you define your parameter curve
to be applied to all staves in the document, it will be applied to any
staff EXCEPT if a curve also exists for this parameter in the staff.
It enables to define global curves
that are replaced by specific curves in some time ranges in some staves.
To ease the reading, it is recommended (but not needed) to group all global
curves in the first staff of the document.
MIDI parameter curves
These parameters are specific to
your MIDI device and enables to control the non-standard features of your
synthesiser.
You can define up to 5 MIDI parameter
curves in each staff.
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To define this kind of parameter, open the parameter setting window and select the parameter in the list. Then input a text that defines the command to be sent to your synthesizer. The manual provided with your MIDI hardware should describe these specific items.
Command input is made in hexadecimal
(16-based digits, each digit being a valued between 0..9, A..F). The value
read on the curve replaces characters 'm' and 'l' in the command line.
'll' represents the less significant
bits (LSB) of the value, 'mm' represents its most significant bits (MSB).
Channel number replaces the 'n'
character?
All other characters, like space
or comma, are ignored and can be used as separator.
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Let's take an example :
On my Roland JV-30 synthesizer manual,
I read a specific command, part of the NRPN (Non-registered parameter number)
section, can be used to manage the internal filer cutoff frequency. Values
for this command can be in a range from de 0 to 127.
I open the configuration box from
the curve pop-up menu, and select the first MIDI parameter curve. I enter
the minimum (0) and maximum (127) valuer. The value will therefore be represented
in the command text by 'll'.
I input the command text "Bn 63
01 Bn 62 20 Bn 06 ll" (by refering to the synthesizer manual)
I just have now to draw the curve
shape to send commands to my synthesizer. Character 'n' will be substituted
by the channel number, and 'll' by the value that has been read on the
curve.
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