The MIDI
Converter Help Page
This is the help page for the MIDI converter
tool, which is part of the KarVCD toolset. The purpose of this tool is to
convert MIDI or KAR files to WAVE, using its internal Sound Font based
softsynth.
To
get help on a specific topic, jump to one of the sections bellow:
The MIDI Converter Dialog
Let us take
a look at the MIDI converter window fields and buttons:
At the top
of the MIDI converter dialog there is the Files group of controls. In
this group there are two identical sets of controls, one for the MIDI/KAR file
and another for the WAVE file. Each set has the following elements:
¨
File name. This field shows the file name.
¨
Browse. This button lets you select
another file.
Bellow the Files
group, to the left, there is the MIDI tempo group of controls. These let
you change the speed at which the output WAVE file will play. You specify the
speed as a percentage of the original speed. You can set the speed value either
directly on the edit control or use the thumbwheel.
Bellow the Files
group, to the right, there is the MIDI transposition group of controls.
These let you shift the pitch of all the notes in the MIDI/KAR file in
half-tone steps. You can set the number of half tones either directly on the
edit control or use the thumbwheel.
Follows a
description of the remaining elements:
¨
Show MIDI error messages. When this check box is active, the
program will show messages about error conditions that it finds during
conversion.
¨
Normalize WAVE file. When this check box is active, the
program will scale all the values in the output WAVE file in order to use all
the available dynamic range.
¨
Progress bar. This control shows the progress as
the file is being converted.
¨
Convert. This button initiates the
conversion process.
¨
Abort. This button stops the conversion
or playing process.
¨
Play. This button lets you hear the output file
that was created during the conversion process.
¨
Status. This field shows you the time
already converted versus the total time.
¨
Defaults. This button sets all the
conversion parameters to their default values.
¨
Help. This button shows you the file that you are
now reading.
¨
Close. This button closes the MIDI
Converter Dialog and returns you to the Main Window.
Operation
The operation of the MIDI converter is very
simple: You select the MIDI/KAR file to convert, the name of the output WAVE
file, choose the conversion parameters and hit Convert.
The
conversion uses the Sound Bank specified in the Options
Dialog. To get the best results, you should use the Sound Font that is the
most appropriate for the instruments used in your MIDI/KAR file. Using the mute
buttons in the MIDI mixer, you can render each
instrument to a separate WAVE file using the best Sound Font available and
then, using the Audio Mixer combine all the WAVE
files into one.
The MIDI
tempo group of controls lets you change the speed at which the output WAVE
file will play. By default, the speed of the WAVE file is the same as the
MIDI/KAR file from which it derived. You can change this default and make the
file play faster or slower as a percentage of the original speed.
The MIDI
transposition group of controls let you shift the pitch of all the notes in
the MIDI/KAR file in half-tone steps. The shift can be upwards or downwards.
This is especially useful when the WAVE file will be used to accompany a singer
or group of singers, to adjust the WAVE file to the voice range of the singers.
When the Show MIDI error messages is checked,
the program will show messages about error conditions that it finds during
conversion. This can range from the use of a non-standard control to a missing
instrument in a Sound Font. This feature is very useful when you are not
getting the results that you expect, to determine what might be wrong with the
input or Sound Font files.
When the Normalize WAVE file is checked, the
program will scale all the values in the output WAVE file in order to use all
the available dynamic range. This not only provides a better sound, but also
provides some equalization among several WAVE files so they play with the same
loudness. This feature is particularly useful when converting several files to
record on an Audio-CD.
Modulators
In this section we will take a look at some of
the MIDI commands and parameters that are processed by the synthesis engine and
how the sound generated will be affected by them. The next section will deal
exclusively with Continuous Controllers.
To fully
understand the concepts described in this section it is helpful to have an idea
of the synthesis engine architecture, as described in the KarVCD
technical page.
¨
Key Velocity. MIDI key velocity affects both the
attenuation of the sound and the filter cut-off frequency. As far as
attenuation is concerned, key velocity will affect the initial attenuation
(before other modulators, namely the envelope, are applied) in an inverse way.
The key velocity values of 0®127 will map to an attenuation of
96dB®0. As far as filter cut-off frequency is
concerned, key velocity will affect the initial value (before other modulators
are applied). The key velocity affects filter cut-off frequency in an inverse
way – As the velocity increases the filter cut-off frequency decreases. The key
velocity values of 0®127 will map to a frequency change
of 0®-2400 Cents.
¨
Channel Pressure. Both Polyphonic Key Pressure and
Channel Aftertouch will affect Vibrato LFO pitch depth. This is a modulator
that affects the digital oscillators included in the Sound Generator blocks.
The Channel Pressure values of 0®127 will cause a frequency change of
0®50
Cents relative to the maximum excursion of the vibrato modulator.
¨
MIDI CC1. Like Channel Pressure, MIDI
continuous controller 1 (Modulation) will affect Vibrato LFO pitch depth. The
maximum amount of modulation will also be 50 Cents.
¨
MIDI CC7. MIDI continuous controller 7 (Main
Volume) affects initial attenuation of the signal in an inverse way. MIDI CC7
values of 0®127 will map to attenuation values of 96dB®0.
¨
MIDI CC10. MIDI continuous controller 10
(Panorama) will affect the position of the sound generated in the stereo field.
Value 0 corresponds to the extreme left, 64 to centre and 127 to the extreme
right.
¨
MIDI CC11. Like MIDI CC7, MIDI continuous
controller 11 (Expression) affects the initial attenuation, by the same amount.
MIDI CC7 should be used at the beginning of a track to set overall volume, and
CC11 should be used locally to highlight small passages of the music.
¨
MIDI CC91. MIDI continuous controller 91
(Reverberation) controls the percentage of signal that is routed through the
reverberation unit. CC91 values of 0®127 will map to values of 0®100%.
¨
MIDI CC93. MIDI continuous controller 93
(Chorus) controls the percentage of signal that is routed through the chorus
unit. CC91 values of 0®127 will map to values of 0®100%.
¨
MIDI Pitch Wheel. Pitch Wheel values are bipolar and
range from 0® +/-8192. The pitch value sent to the
oscillators depends on the value set for the Pitch Wheel Sensitivity parameter.
By default the pitch wheel excursion is set to 2 semitones (200 cents).
Controllers
In this section we will take a look at some of
the MIDI Continuous Controllers that are processed by the synthesis engine. The
difference between these controllers and the modulators referred to in the
preceding section consists mainly in the fact that the controllers herein
described do not directly affect the sound generated, being more of an
housekeeping nature.
¨
MIDI CC0 – Bank Select. Selects one of the banks of the
Sound Font file.
¨
MIDI CC32 – Bank Select LSB. This controller is ignored.
¨
MIDI CC64 – Sustain. Active when the value associated
is greater than or equal to 64. When active, all notes in the key-on state
remain in this state regardless of whether a key-off command for the note
arrives. The key-off commands are stored and when sustain becomes inactive all
stored key-off commands are executed.
¨
MIDI CC66 – Sostenuto. Active when the value associated is
greater than or equal to 64. Unlike the Sustain command, the Sostenuto function
prolongs only the notes that are played after the function becomes active.
¨
MIDI CC67 – Soft. Active when the value associated
is greater than or equal to 64. This causes the notes to be played at half
strength.
¨
MIDI CC120 – All sound off. When received with any data value,
all notes playing in the key-on state immediately enter release phase,
regardless of their Sustain or Sostenuto status.
¨
MIDI CC121 – Reset All Controllers. Resets all continuous controllers
to their default values.
¨
MIDI CC123 – All notes off. When received with any data value,
all notes playing in the key-on state immediately enter release phase, pending
their Sustain or Sostenuto status.
Feedback
Comments, suggestions and bug reports are welcome and should be sent to fadevelop@clix.pt
This page last modified 2003-07-28 - Copyright
© 2000-2003 ACE