MIDI Kinetics Forum

Hello,

Im trying to make the monitor object show the DB for my gain knob in traktor. Right now it just displays the midi information. Any idea what the conversion is?

Formula is
20*Log10(x) so that 0.0 -> -inf, 1.0 ->0.0 db, 2.0 -> 6 db
When converting from MIDI often 0 -> -inf, 100 is 0 db and 127 is 6 db, but that's up to the app

Now I don't know what is the formula to make 0 = 0.0 (or a least close to 0), 100 = 1.0 and 127 = 2.0 as I don't think it's linear, maybe the easiest is to store some values in an array.

basically i have a fader and then above it a monitor to display the gain information.

How can I implement the formula into the text? Using a script? Im not so good with the scripting aspects so sorry if this is a really obvious question

If you have a fader called Fader, then just enter this into the monitor value field:

20*log10(Fader.x)

This will display values from -inf to 0.0 db
To display values from -inf to 6 db you can enter this

20*log10(Fader.x*2)

If you need something more fancy you may need a multiline script.

First, remove the formula you had in the monitor value.

Select your fader, add a script (bottom right in the editor), select On Expression and type x in the box on the right
Now, below, you could enter something like:

decl n, aDB = {'-inf', -96,-48,-24,-12,-6,-3,0,3,6,12};
n = sizeof(aDB)-1;
Monitor.value = aDB[x*n];


You may adjust the array to your needs.

Hi All,
I found another formula option that matches closer to Live's faders : 20*(log(x*127/108))*6/3.241

Then I realised/remembered that you wanted it for NI Traktor not Live, and for the Gain (+/- 12 Trim) not the actual Fader . . .
So, a few suggestions - Try a Knob or Slider as they can be set to Bipolar which gives you the centre 0dB mark better . . .
And then try this variation on mbncp's script, and set the Precision to 1
decl n, aDB = stretch({-12,12},12);
n = sizeof(aDB)-1;
Monitor.value = aDB[x*n];

Hope that helps
Cheers
MM

20*(log(x*127/108))*6/3.241

Thanks MM for that one

No worries
Though it's not my work - I think it probably came from the MutantTalk forum originally . . .
If you are interested there is also this equation which I found in my Tech archives - though it deals with velocity I think it could be useful, though i have not worked it out yet . . .

Musically map MIDI velocity to peak amplitude within a specified dynamic range in decibels: a = (m * v + b) ^ 2, where a = amplitude, v = MIDI velocity, r = 10 ^ (R / 20), b = 127 / (126 * sqrt( r )) - 1 / 126, m = (1 - b) / 127, and R = specified dynamic range in decibels. See Roger Dannenberg, "The Interpretation of MIDI Velocity," in Georg Essl and Ichiro Fujinaga (Eds.), Proceedings of the 2006 International Computer Music Conference, November 6-11, 2006 (San Francisco: The International Computer Music Association), pp. 193-196.

The document itself is an interesting read . . .

Cheers
MM

20*(log(x*127/108))*6/3.241
This formula doesn't match with the levels indicated in Live. Sent a mail to the Ableton support to get something more precise on this subject but got no answer. Did someone impoved it ?