FFT audio data into a shader as a texture2d

With vertex shader

Uniform sampler 2D sound;
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.
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float snd = texture2D(soundt, p.xz * vec 2 (0.75, 1.0));

Although I have a description, I would like to pass FFT audio data as ofTexture.

How can we write “ofApp.cpp” to convert audio fft to texture and pass it?