Lowpass FFT filter, please help

Topics: Audio, Other, Plugin Development
Jun 16, 2012 at 6:12 PM
Edited Jun 16, 2012 at 6:19 PM

Maybe someone could help me.

I'm trying to implement lowpass FFT filter in my vst plugin but i have little problem with my filter output. Output sample chunks seems to be "swapped". But if i comment the most important part of filtering, output is OK. Please look at this image:

I'm using LomontFFT  for FFT and IFFT, very simple and efficient library.

my BUFFER_SIZE is 2048, samples contain real and imaginary doubles. Thus i have 1024 samples for signal buffer from host.

Filtering seems to work but data chunks are somehow swapped...

Maybe someone had implement filtering using FFT/IFFT? Could you give me some advice what to do? Or what is wrong with my code, because I'm going crazy trying to make this work for couple of days...

Thanx in advance,


Jun 18, 2012 at 8:18 PM
Edited Jun 18, 2012 at 8:19 PM

Hi Tomek,

Perhaps asking this question on KVRAudio will provide you with an answer?

Sorry I can't help you.

Jun 19, 2012 at 6:02 AM
Edited Jun 19, 2012 at 6:03 AM

Yes, I've posted this post here and on KVR audio and i had some answers there :)

But thank you for the answer too!

Here's the link to my post on KVRaudio if someone have also problem with FFT filtering: