RPI0_GPU_FFT

Experiments using the RPI Zero GPU for FFT/IFFT 1D/2D

For an input 4194304 (1D), the GPU was around 7X faster than np.fft.fft and np.fft.ifft in sequence.

For an input 1024x1024 (2D), the GPU was around 2X faster than np.fft.fft2 and np.fft.ifft2 in sequence.

The CPU is always faster for small arrays (and the min size for GPU is 256).

Instalation

Clone this repo (or simply download all files to your RPI0) and run make. It will generate a file rpi0_gpu_fft.so that you should have in the same directory as the rpi0_gpu_fft.py. That's it ;)

I'm supposing your RPI0 has the rest of the files necessary installed by default (/opt/vc/src/hello_pi/hello_fft/).

TL;DR

Totally untested and without any guarantee what-so-ever :D

You can try it by running: $ sudo -E python rpi0_gpu_fft.py.

I wrote this hack to use with my "smart" camera: https://github.com/ricardodeazambuja/Maple-Syrup-Pi-Camera

Original code / ideas from:

• http://www.aholme.co.uk/GPU_FFT/Main.htm
• http://www.peteronion.org.uk/FFT/FastFourier.html

Misc

• https://hackaday.com/2021/09/22/even-faster-fourier-transforms-on-the-raspbery-pi-zero/ (the comments may have some interesting suggestions / ideas)