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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

Operation

Modulators

Controllers

 


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

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