I wrote scopes for pure data via py/pyext and python, which draw waveforms and spectograms live with low cpu usage.
Drawing waveforms works well, but I'm not not shure, if the spectogram is done correctly. Have a look at the screenshots:
The default view looks ok to me, but the zoomed view shows repeating patterns.
As I'm new to analyzation with fft, I'm not shure, whether:
- it's a usual behaviour
- it's a mistake or matter of the windows function
- it's a mistake in calculating the ffts
Can someone with more experience than me help me out?
Thanks for any comments in advance,
P.S.: The code can be found here: https://github.com/XRoemer/Pure-Data-Realtime-Scopes/blob/master/pd_scopes.py
fft processing is done in lines 609 - 620
PPS: The window I used is a hanning window (numpy) Line 880