A nyquist code doesn't work.

Hello, the past several days I was trying to recreate following steganography tutorial: https://medium.com/@sumit.arora/audio-steganography-the-art-of-hiding-secrets-within-earshot-part-2-of-2-c76b1be719b3.

The exact tutorial was the “Frequency Modulation based Steganography” Tutorial. Everything worked out except the decoding.

When I used the first code to hide the secret audio inside the public audio it worked perfectly well.
But then the tutorial stated that I have to simply insert following nyquist code into the prompt and I would retrieve the hiden audio.
But nothing happened. Idk why. That’s the retriever code: https://gist.github.com/reachsumit/70bad5ab598cbd8952f8bfd07deea733#file-audio-steganography_ultrasound-receiver-ny.

That’s the hiding code: https://gist.github.com/reachsumit/9f5583a904b43407e45b49e2fd1de2df#file-audio-steganography_ultrasound-sender-ny.

I’d be really thankfull for some help.

Now you have to select the track before applying the Nyquist code, otherwise …

''Nyquist returned nil audio'' (because the track was not selected).png

Although they say that it is “frequency modulation”, Edgar rft’s code produces “amplitude modulation” (“AM” not “FM”).

For the decoder, try this:

;version 4
(mult *track* (hzosc 17500.0))