Hi there,

recently I had to find how to convert the incoming 'speed' midi messages from a djing controller's jog-wheels in order to get 'classical' [0-127] 'position' values.

To be more explicit, a 'normal non-infinite knob' gives a [0-127] value, and can be used as is. But some 'infinite knobs' or 'jogwheels' provide values that are in fact related to the 'turning speed' : mine gives me speed values between 1 and 30 (after removing an offset and retreiving the 'sign' of it).

I actually managed to convert these [0-30] speed values to position values, using a basic integration scheme, and using a quadratic function to 'shape' these speed values (this had to be introduced to avoid the position beeing dependent of the turning speed). So now everything works, using a semi-empirical patch.

My question is : does anybody knows if there exist a document explaining how this 'turning speed' is coded to give me numbers between 1 and 30 ? Of course this is rather naïve to hope there is some kind of 'standard' used by different manufacturers, I know

It's obvious when you test it that a value of 20 does not correspond to twice the 'turning speed' related to a value of 10. (that's why I used a 'shaping func").

This information, if it exists, could help me to better my empirical patch.

Thank you,

Nau

I could be wrong, but I think that this is going to vary depending on the manufacturer of the MIDI DJ controller. I don't think that there is a standard way of doing this. I have an ION Discover DJ controller and its values do seem to directly represent rotational velocity (so, on my controller, 20 does seem to be twice the turning speed of 10) except that it never gives 0, just always 1 or -1 (127) depending on which way it was last spinning. Which MIDI DJ controller are you using?

Thanks for your interest, KeithIrwin.
I use a U-mix control pro controller. It sends a "zero" when not spinning (whatever the last turning direction was).