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Knob Shelf

What's the Knob Shelf?

MidiVid GPU offers an easy way to tweak plugin parameters, called the Knob Shelf. Any plugin parameter which can be set to a range of values will show up here. Knob controls can be used to change the value of a parameter during playback, or assign a MIDI continuous controller to a parameter.

The knobs for a given plugin will display when you select the note in the notes list. If the Active Note Selector box is checked, the last note played with the keyboard or a MIDI device will be selected, and its parameter knobs will display.

Above each knob is the name of the paramter that knob effects, and below it is the parameter setting. If you left-click a knob and drag it with the mouse, you can change the value of the parameter the knob is attached to.

Assigning Controllers

If you right click a knob, the knob will toggle between Parameter Mode, Controller Mode, LFO Mode, and Bass Mode. In Parameter Mode, the knob directly affects the parameter it represents. In Controller Mode, the knob chooses which MIDI Continuous Controller is assigned to this parameter, and whether the controller uses coarse or fine mode. In LFO Mode the knob chooses which LFO generator is assigned to this parameter. In Bass Mode the knob chooses which of the audio-in bass analyzers to use. Bass 1 through Bass 3 represent bass, but with increasingly smoothed amounts. Bass 4 through 6 are the same as 1 to 3, but respond 'backwards', IE when more bass is present, the control value goes down.

In the image above, the three right-most knobs are assigned to different controllers. The "Scale" knob is attached to the "Pitch" controller, also known as the pitch wheel, or pitch bender. The "PatSpin" knob is attached to continous controller #6, and the "Src Spin" knob is attached to continuous controller #1.

To simplify assigning MIDI controllers, Midivid knobs have a 'MIDI learn' mode. When a knob is in 'Controller' mode, press the left mouse button on the knob, and while holding it, click the right mouse button. The knob will assign itself to the MIDI controller that was moved last. So move the knob or slider on your MIDI controller that you want to assign, then left-click + right-click the Midivid knob to assign to that controller.

Coarse and Fine Controllers

When assigned to a controller, the knob display will be prefixed with either CC, for Coarse Controller, or FC for Fine Controller. A coarse controller has a range of 0 to 127, while a fine controller has a range of 0 to 16383. It is worth mentioning that fine controllers are made by "attaching" two coarse controllers. Each fine controller gets its value by taking the value of two coarse controllers that are 32 indexes apart, and adding their values together like this:

Fine[index] = (Coarse[index] x 128) + Coarse[index+32]

MIDI deals with this for you, so you don't really need to know how it works, but if you ever find a coarse controller and fine controller interfering with each other, they likely overlap.

Each parameter that a plugin exposes to the knob shelf will know its range of values. For example, color knobs generally have a range of 0 to 255. If you assign a controller to a knob value, the range of the controller will be mapped to the possible range of knob values. You should assign a fine controller only if the parameter has enough range or precision to warrant it. Using a fine controller for color parameters, for example, would use 16384 possible input values to specify only 256 output values, wasting most of the precision in the control, and taking up two coarse controllers when one would do.