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Transforming audio from time-domain to frequency-domain and back is not trivial, because it involves:
The SuperpoweredFrequencyDomain feature solves all with a very simple API call: time-domain audio goes in, magnitudes and phases come out. Or vice-versa. No need to dig deep into FFT if that’s not your bailiwick.
The Superpowered Frequency Domain is a singular audio DSP feature, and also the fastest solution with the highest performance on mobile devices. It is, at minimum, 2.5 times faster than an Apple vDSP implementation.
The Superpowered Audio SDK has a simple frequency domain example project for both iOS and Android. You can work with magnitudes and phases within minutes, and implement your own linear phase EQ for example!
SuperpoweredFrequencyDomain has an interesting twist too: you can define the value of Pi. You can leave it at 3.14xxx, but some algorithms that work with phases greatly benefit if Pi is translated to something else, such as 1.0 or 0.5.