Do math on Audio Analysis Band Pass Filter Frequency


Hi All,
I am trying to use the “do math” function on a knob I have set to control the frequency of a bandpass filter in the Audio Analysis plugin. The math is not calculating correctly. There seems to be some logarithmic function happening. I see that the x axis (frequency) of the Audio Analysis is showing a log scale so maybe that is the reason?

For example I am trying simple stuff like $VAL9/8 and the value it is returning would normally be the solution to $VAL4/3
There must be a simple formula I can apply across the board to negate this log craziness.
Please help!!!



JFreqs in a audio spectrum are logarithmic.
I think there is a NumFX chain that deals with logarithmic input.
Search for DDMath Parser it is what is used for the do math. You’ll have to figure out the equation yourself

Also remember that the DoMath is working math on the Val of your input ie your MIDI controller. Which is sending 0-127.

Also you formula seems wrong as you don’t have a operator after $VAL. Did you mean to do $VAL * (9/8)



Also why are you needing to do this math?
The freq reciever already seems to be doing math on a MIDI 0-127 input.



Thanks so much technomorph for chiming in!
For the formula I did mean $VAL*(9/8). I had it right in VDMX and wrong here.
I will dig deeper into the DDMath Parser.

As to your second comment, I am creating a bandpass filter for 2 or more octaves worth of each note of a just intonation musical scale. The frequency of each note of the scale can be calculated from the root note with ratios like 9/8, 5/4, 4/3, 3/2 etc. I put the root note on the midi knob so I can change it and all the other notes will stay in relationship. The plan is to have each note of the scale light up a different color. Overtones and other complex sounds will light multiple colors at once. It would be a kind of synesthesia effect. I have been thinking about this for a long time and just recently had the idea for this method - with many filters (one for each note), each triggering a color on separate layers, where the loudness of the specific frequency controls the brightness of the color.



You should really have a peak a some of the ISF tutorials. I saw one in there where he makes a color Organ.



Also this:



You can use dedicated audio restoration plugins for video and podcast creators.