back to home

GLASSHEADS, pt. 5 Challenge #1 - Fidget Spinner

The Setup

Can you find the flag in this transmission? Don't listen to it on high volume (... you don't even need to listen to it at all).

We are given an audio file, signal.mp3.

The Signal

There is nothing hidden in the metadata, nothing useful in strings, and nothing obvious when listening to the audio itself.

That leaves the frequency domain: the flag is drawn in the spectrogram. Feeding the file into a spectrum analyzer, such as academo.org/demos/spectrum-analyzer, reveals the flag written across the frequencies. Really cool!