chrislos

I searched through multiple threads but I suppose my question seems not to be that trivial than I thought.

So I have a given audio input and I'd like to breake down the signal via fft (let's assume 100 bands) and convert the spectrum into a list of (100) floats.

An additional topping of the cake would be add some spectral smoothing via vectral~ or sth. similar to filter the behaviour a bit. But my most recent problem is to translate 100 fft band-powers into a floating list.

Maybe it's because it is already evening time in my head. But I didn't find a solution how create such a list.

So I have a given audio input and I'd like to breake down the signal via fft (let's assume 100 bands) and convert the spectrum into a list of (100) floats. 

An additional topping of the cake would be add some spectral smoothing via vectral~ or sth. similar to filter the  behaviour a bit. But my most recent problem is to translate 100 fft band-powers into a floating list. 

Hello everyone,
I searched through multiple threads but I suppose my question seems not to be that trivial than I thought.
So I have a given

fft-spectrum-to-float-list

whatever you do, dont attempt to do it in realtime using snapshot. it should be fine to record it into a buffer, write it to disk, and when you open it again you can later read it out using peek.

if you go into the plot~ helpfile and check out the 'spectral' tab there, it can show you the math and setup for something similar to what you're asking for (you can also use the 'capture~' object to view signal-outputs in a list of floats... to do this with fft~, you'd need to sample-and-hold(sah~) at the exact bin-number you'd want, though...)... there's also more about analyzing signals in the MSP "Analysis" tutorials:

https://docs.cycling74.com/max8/tutorials/14_analysischapter01

see all four of them listed in the "Analysis" section here:

https://docs.cycling74.com/max8/tutorials/00_mspindex

'convert the spectrum' is a general phrase, though, i'm not sure i understand what you're asking for... there's math you implement on your own to translate FFT analysis into various forms of data which can describe the frequency 'spectrum' of a signal in different ways, then beyond that, allow you to transform it effectively the way you'd like by vectral~, etc.(this is math you'd implement on your own as it's beyond just technical knowledge of Max/MSP and takes too much time to explain here).... so in case it helps further, here are my favorite tutorials on the subject in general:

https://cycling74.com/tutorials/the-phase-vocoder-%E2%80%93-part-i

https://cycling74.com/tutorials/the-phase-vocoder-part-ii

https://cycling74.com/tutorials/advanced-max-ffts-part-1

if you go into the plot~ helpfile and check out the 'spectral' tab there, it can show you the math and setup for something similar to what you're asking for (you can also use the 'capture~' object to view signal-outputs in a list of floats... to do this with fft~, you'd need to sample-and-hold(sah~) at the exact bin-number you'd want, though...)... there's also more about analyzing signals in the MSP "Analysis" tutorials:
https://docs.cycling74.com/max8/tutorials/14_analysischapter01 
see all four of them listed in the "Analysis" section here:
https://docs.cycling74.com/max8/tutorials/00_mspindex

'convert the spectrum' is a general phrase, though, i'm not sure i understand what you're asking for... there's math you implement on your own to translate FFT analysis into various forms of data which can describe the frequency 'spectrum' of a signal in different ways, then beyond that, allow you to transform it effectively the way you'd like by vectral~, etc.(this is math you'd implement on your own as it's beyond just technical knowledge of Max/MSP and takes too much time to explain here).... so in case it helps further, here are my favorite tutorials on the subject in general:
https://cycling74.com/tutorials/the-phase-vocoder-%E2%80%93-part-i 
https://cycling74.com/tutorials/the-phase-vocoder-part-ii 
https://cycling74.com/tutorials/advanced-max-ffts-part-1 

👽R∆J∆ The Resident ∆lien👽 also answered my request but it seems it' hasn't been published in the thread here. (I don't know why).

But bottom line is, that it isn't that trivial at all and it seems that it'll take quite a lot of math to do it.

It's quite weird. A friend of mine realised that in vvvv with just one node. 

sound -> fft in -> list of spectrum values out. Too baad I have to work on osx on that particular project.

Thanks in advance to everyone, who might add a hint.

👽R∆J∆ The Resident ∆lien👽 also answered my request but it seems it' hasn't been published in the thread here. (I don't know why).

He recommended a few tutorials:
 https://docs.cycling74.com/max8/tutorials/14_analysischapter01 
https://cycling74.com/tutorials/the-phase-vocoder-%E2%80%93-part-i

But bottom line is, that it isn't that trivial at all and it seems that it'll take quite a lot of math to do it.

It's quite weird. A friend of mine realised that in vvvv with just one node. 
sound -> fft in -> list of spectrum values out. Too baad I have to work on osx on that particular project.

haha, i trashed my response after i saw Roman's because i liked his better.. short and sweet 👍

(also was saying take a look at the helpfile for plot~ under the 'spectral' tab, you can hook up a 'capture~' object to fft~, and sample-and-hold(sah~) into capture~ according to the bin/index number you want for a list... but it might not be that helpful to view it that way... i dunno.. depends on what data regarding the spectrum you specifically need and how you'll use it eventually)

haha, i trashed my response after i saw Roman's because i liked his better.. short and sweet 👍
(also was saying take a look at the helpfile for plot~ under the 'spectral' tab, you can hook up a 'capture~' object to fft~, and sample-and-hold(sah~) into capture~ according to the bin/index number you want for a list... but it might not be that helpful to view it that way... i dunno.. depends on what data regarding the spectrum you specifically need and how you'll use it eventually)

in theory it IS that easy (vvv example), what is difficult is to transfer a signal into numbers in realtime.

what speaks against implementing things all-signal in your case?


in theory it IS that easy (vvv example), what is difficult is to transfer a signal into numbers in realtime.

what speaks against implementing things all-signal in your case?


the only honest reason why I didn't solve it on the msp layer is my lack of dsp knowledge and a deadline to solve. The list has to be sent via osc so it doesn't need to be as fast as msp.

this morning I came to the conclusion to skip fft for now and use multiple band passes (fffb~).

Here's my sloppy version with way too much wires...

Emmanuel Jourdan's interpolation algorithm works quite ontop of the raw lists.

I guess the patch isn't perfomative at all. But yeah. At least I have a list of numbers to work with...

the only honest reason why I didn't solve it on the msp layer is my lack of dsp knowledge and a deadline to solve.  The list has to be sent via osc so it doesn't need to be as fast as msp.

Here's my sloppy version with way too much wires...
Emmanuel Jourdan's interpolation algorithm works quite ontop of the raw lists.
I guess the patch isn't perfomative at all. But yeah. At least I have a list of numbers to work with...


there is that bin/sample counter object for pfft, that could be of help to perform calculations on them (unless you have to do sorting) - what was its name again? (you can also use index~)

I do something similar for bark analysis. Look at the gen~.bark example for how to store values from a pfft~ into a buffer. Then use the 'output' message to jit.buffer~ into jit.spill and you've got the list.

fft Spectrum to float list