cava

Turn your phone or tablet into a cool audio visualizer. Easy to use and customize. Choose from several awesome color presets or create your own.

* no ads
* no in-app purchases
* just simple free app

cava is a bar spectrum audio visualizer based on my own open source project with the same name. It takes audio from the device microphone and visualizes the amplitude of the different frequencies as bars on the screen. Each bar represents a given bandwidth of frequencies from low to high. Left most bar starts at 50Hz and rightmost bar ends at 10kHz. Although frequencies outside this spectrum are audible, they do not provide much to the general picture of the sound. You can also adjust the number of bars.

For now source is limited to microphone, currently investigating possibility of capturing audio from other apps.

The FFTW library (by Matteo Frigo and Steven G. Johnson) is used to transform the audio signal from the time domain to the frequency domain using a method called Fast Fourier transform. OpenGL is used to draw the bars on the screen.

Privacy policy:

https://stavestrand.no/karl/cava/privacy_policy.html