midi xml mapping Invert option doesn't work with Pitch Bend Change midi messages with 14-bits values

[Sébastien BLAISOT]

The Invert option in controls mapping of XML midi mapping is documented as:
Invert: Subtracts the value from 127, giving an inverted control (-127..0)

This doesn't work with Pitch Bend Change (PBC) midi messages because they have 14-bit values sent in byte 2 and 3 of the midi message.

So basically, you can not map an inverted pitch slider in pure XML and you need to script it to reverse it. Without that, the physical controller slider is inverted versus the on-screen slider. Using the pitch reverse option doesn't change anything, the physical and on-screen sliders remain inverted.

we should either extend the invert option to be compatible with PBC messages or add a new option to handle this situation.

[ronso0 (ronso0)]

Took a while until I found the proper workaround there
http://www.mixxx.org/wiki/doku.php/midi_scripting#available_common_functions
> script.midiPitch(LSB, MSB, status)

Mapped pitch slider to this function in MyController.js:
TerminalMix.pitchSlider = function (channel, control, value, status, group) {
    engine.setValue(group,"rate",-script.midiPitch(control, value, status));
}

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/8615