Not getting correct frequencies from FFT #1
Description
So, an issue I'm having with the code at the moment is that I'm not actually getting sensible-looking frequencies from the FFT transform of the heart-beat signal.
Numpy has a the rfftfreq function which - in theory - tells you the frequency for each bin of an FFT, given that you know the sample rate (which is 250Hz). However, using the results of this on the face2.mp4 video give results like 22 BPM, which are clearly not correct.
Here is the line in the code where I call this.
With peak-detection I get much more reasonable looking BPMs around the 66 mark, which leads me to believe that I'm using rfftfreq wrong, or doing the FFT transform wrong, or I've made some other kind of mistake!