fftsize and framesize (fft~ in MSP and RNBO)

Jaeho Chang's icon

I have always used the same value for both fftsize and framesize arguments in the fft~ object in MSP and RNBO. But I'm wondering what happens when you set different values for fftsize and framesize?

In MSP, I actually get an error message like this:

fft~: interval must be at least one frame, setting to 512

In RNBO, no error occurs, but there doesn't seem to be any noticeable difference.

Any clue?

Thanks in advance.

Jaeho

Roman Thilenius's icon

the interval must not be smaller than the fft size, is that the problem? switching from fft 512 512 to ftt 512 1024 should work. (in the case of pfft you might need to restart DSP)

Jaeho Chang's icon

Ah, so the framesize isn't actually meant for overlap.

I've never really used fft~ in MSP, but always used pfft~.

Since RNBO doesn’t have pfft~, I was trying to use fft~ and experimenting to see if reducing the framesize might achieve overlap.

Roman Thilenius's icon

yep, you have to make the whole overlap&window stuff yourself with fft~/ifft~

Jaeho Chang's icon

I got it. Thanks a lot, Roman!