Forum

Get Index of highest value slice

vvvv beta question
#1

Hi All, its been a while since I’ve been on here, i have a last minute project which i need to get the pitch data from a fft spread and translate this to a hue value.

The idea I’ve had is to read the highest value slice from the fft spread read which index this slice is at. From here i can use the get slice from a linear to get a low to high value corresponding to which frequency is at peak within the spread. This all makes sense in my head but am struggling to find a way to get the index of a slice with the highest value in a spread. Its been a while since i looked at vvvv too.

Best

Andy
(Digipic)

#2

You could try using the Sort node in combination with the CDR. Sort arranges the spread in ascending order and also outputs the former index - the slice position of each value. CDR outputs the spread and the last element…

#3

Bounds (Spectral) finds the maximum - but sadly doesn’t return the slice it found it at. So we have to find it with Sift (Value)
This should (for more than just a few slices) be faster than sorting everything.

Try this:

maxSliceIndex.v4p (4.8 kB)

#4

hey Andy,

Sort (Spreads) has a Former Index. connect an CDR (Spreads) here.

edit: ah, late…

#5

Excellent, Thanks guys, Im stuck on a train without a PC (pain) ill try this when i get back. I have been working this out in excel, see attached pic, any thoughts, should work but may not be fast enough?

#6

https://vvvv.org/sites/default/files/imagecache/large/images/FFT CORRECT_2.png
Oops!

Hi Kalle, nice to see its still so active here :-)

#7

Hi there stranger :) There is always a Bounds (Spectral) node, to get min and max values. And it doesn’t hurt to check FFT (DShow9 4Channels), it is a module, so you can look inside how it is done. (I don’t know how to do it in Excel though ;) )

#8

Hi Guys thanks for all the help, event went well:
http://www.flickr.com/photos/fellwalker1/5252445127/in/set-72157625453316915/ this was just a small part of a temporary winter park install we did. On the route kids would shout into a lone microphone and the building would light up and change the Hue with pitch.
I had 6 Robe CitySkape Xtreme, good but still not as nice as Phillips ColorReach :-).

Merry Xmas everyone!

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