AudioGraphBuilder.spectrum() method
The RTA (spectrum analyser) tap: per window, bands log-spaced band magnitudes (dB, 20 Hz→Nyquist; default 31, max 64) as band_0..band_{N−1} readings plus a bands count. A tone reads ≈ its programme level in its band. windowMs is the FFT length.
Signature:
spectrum(input: AudioNode, opts: {
name: string;
windowMs: number;
bands?: number;
}): AudioNode;