fft hann window not working properly

Joachim Budweiser's icon

hi there

can someone confirm this? if i build my test-patch (doing nothing except for an fft and its inverse) as recommended in the rnbo-fft-tutorial https://rnbo.cycling74.com/learn/using-the-fft, the sound gets chopped/ring-moddy as if the windowing wasn't in phase. if i export to vst3, it has the same effect. is this a known bug or a windows-issue (win10)?

thanks and best regards

joachim

Sebastián Verea's icon

I'm having the same issue.
Did you find any solution to this?

Sebastián Verea's icon

By the way, I'm on Mac.

Joachim Budweiser's icon

hey, thanks for confirming that it's not a windows issue only. well, i will try the workaround in the first picture of this tutorial https://rnbo.cycling74.com/learn/using-the-fft

ruins the whole idea of having a built in windowing into the rnbo fft~ ...

Sebastián Verea's icon

Yup, I'm trying that one too.
Still can't make it work.

Sebastián Verea's icon

I'm getting worse results with that workaround.
Will let you know If I find a solution. I need to deliver a patch by wednesday.

Joachim Budweiser's icon

yes, please let me know, if you find a solution. good luck! i'm surprised,this workaround doesnt work...

Joachim Budweiser's icon

have you tred a buffersize of 512? 256 seems odd, why should the window be smaller than the fft?

Sebastián Verea's icon

It's supposed to overlap windows.
If your fft's size is 512 and you have 4 windows, the overlapping frame is 128.

Joachim Budweiser's icon

One year later... i almost forgot about this issue and decided for myself, that fft in rnbo was buggy. Now as i was reading about the fft and windowing i came back to RNBO and voila, now the fault was clear. You only have to window on the way in, not on the way out! Now it's working without any artifacts, even tested with 4 Overlaps. Maybe this is useful information for somebody.

Sandrew's icon

Hey Joachim

Thanks so much for the update and the answer to this question! Like you, I came back to this very problem after a longer while of just giving up on it, and now found your post. Very useful information indeed.

I hope cycling74 cares to correct their faulty example in the tutorial...

Sandrew

Joachim Budweiser's icon

Hey Sandrew

Glad that info is useful and thanks for letting me know!

I wrote the cycling support about this and about changing the tutorial. They replied "Interesting and great to hear that this is working for you now!
We had some changes to the fft~ object as well so wondering if in fact this had any effect on it as well. "

The tutorial is still unchanged and i think will stay so...