Data AcQuisition And Real-Time Analysis
Scope - Spectrum - Spectrogram - Signal Generator
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Voice Velocity Track

Controls: Sgram/PT Dialog >> Pitch-to-MIDI >> Setup
Changes: tv=n

MIDI velocity refers to the speed or force with which a note is hit on a piano keyboard. On a real piano the tone color as well as the loudness is affected. On a MIDI synthesizer, a particular instrument may or may not change tone color with velocity, but the effective volume always changes.

When Velocity Track is off, the MIDI velocity of a voice is controlled by the character specified in the Velocity Pattern. If no pattern is supplied, each note defaults to an effective pattern character of '8', which is maximum velocity (MIDI velocity = 127).

When Velocity Track is active, the specified or default Velocity Pattern is scaled proportional to the current Pitch Track amplitude, relative to full scale for the current Spectrogram/Pitch Track range.

You can use Velocity Track with any signal, but to get the maximum tracking range the loudness range of the input signal should be a good "fit" to the full-scale range of the input volume control, as well as to the Spectrogram range. (If you are using the Generator to provide the Pitch Track signal, the Stream Level settings are relevant, but the Wave and Master Volumes are not.)

Adjusting for optimum Velocity Track range:

The input volume should be adjusted first. Toggle Spectrum display on, and make sure Y-log is active so you see a dB range on the Y axis. Provide the same input signal you intend to use (sing, whistle, play an instrument, etc) at the same maximum loudness.

Adjust the Input Line and/or Input Master level controls (in the Input Control dialog) as high as possible without distortion. (Remember that these values are negative, so you are raising toward 0.) Distortion will become apparent as a sudden rise in spectrum harmonics as you raise the level.

If you are not sure, toggle Spectrum off to see the waveform... it should be near full scale when distortion starts. (But some sound cards start showing obvious distortion when the signal is only around half scale, so if you are still not sure, trust the Spectrum result.)

Now adjust the Track Threshold, which is in the Track Limits dialog that you access from the Spectrogram Control dialog, or from the Track button of the Spectrum Control dialog. Set this higher than the softest sound you want to track, which must be above the maximum in-band noise (any unwanted sounds between the Max and Min Frequencies).

Make a note of the dB value of the highest peak that you see in the Spectrum display. Now toggle Spectrogram on and adjust the upper limit of the color bar on the right end of the spectrogram so that the peak dB value is near the top. To do this, hold down the SHIFT key while dragging the color bar with the mouse.

You may then adjust the bottom of the range by dragging without the SHIFT key to suit your preferences.

Spectrogram range (color bar) changes affect the Track Threshold Color indicator, but they do not affect the specified Track Threshold itself.

MIDI Changes Script:

Use tv=n to set Velocity Track for Voice v to the state indicated by the value of n, which may be any unsigned integer or valid expression, including current MIDI control values, random values, current computer keyboard states or mouse position, input or buffered notes, or oscillators. If the value is zero, Velocity Track is off; any other value sets it on.

Alternatively, you can use x instead of a value to toggle the current state. For example, t2=x toggles the current Velocity Track state for Voice 2.

You can use "voice" 9 to set or toggle all 8 voices at once.

See also MIDI Voice Setup Dialogs, Pitch-to-MIDI dialog, Pitch Track Toolbox - Overview


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