#025 a Kiss FFT Example

Test drive the Kiss FFT C library with an example.

Notes

Kiss FFT is an interesting FFT implementation in C. It promises ease-of-use over absolute performance.

To build a project with Kiss FFT, it just needs the core files compiled and linked.

I found a kissfft-example which I’m building here (under MacOS).

It has the core Kiss FFT files included in the repo, and links with the real-optimised version. The Kiss FFT files it uses are:

_kiss_fft_guts.h
kiss_fft.c
kiss_fft.h
kiss_fftr.c
kiss_fftr.h

The kissfft-example comes with sample data and some python utilities for plotting the results. Data files:

Setting up the Python Environment

I’m using virtualenv, and it needs some special considerations due to restrictions of the matplotlib library using in the python code - see Working with Matplotlib in Virtual environments.

I’m setting my virtual environment path to PYTHONHOME:

$ export PYTHONHOME=$(cd ../../venv; pwd)

Then activating the environment to install requirements:

$ source $PYTHONHOME/bin/activate
(venv)$ pip install -r requirements.txt
(venv)$ deactivate
$

The virtualenv is deactivated before running the examples … they’ll find the virtualenv from the PYTHONHOME environment variable

Running the kissfft-example

There are justa few commands to clone the kissfft-example repo, compile and run the FFT, then fire up the draw-curve.py python script to visualise the results. I’ve put them in a shell script:

$ ./download_and_run

And here’s an example of the output:

Credits and References

• Kiss FFT Web Site - master on sourceforge
• Mirror on GitHub
• kissfft-example
• Working with Matplotlib in Virtual environments