Why do I get spikes in the freqs channel of an analysis when my signal is high?

Question

I'm getting some weird output of the LiveSpectralAnalysis. When used with the sample '118 AutoBerlin NeverEngine.wav' I get spikes on the freqs channel. Scaling the sample down to 0.5 cures it. Seems like a bug?

Attached the Sound.

Answer 1

What you are seeing on the scope are the four information tracks that are at the end of every frame. Since one of them is the amplitude envelope, you see it jumping to the beat of the original input sample (and it gets smaller when you scale the amplitude of the input sample). For your analysis frequency, the frame length is 256: the first 252 of those are the amplitude/frequency pairs for each partial; the final four are envelopes for:

Voiced/Unvoiced (on/off) only utilized on Harmonic analyses

Fundamental Freq only utlized on Harmonic analyses

AmpSum (amplitude envelope)

AmpFreqSum (centroid)

Some of these are filled in on harmonic analyses only, but the amplitude and centroid are filled in for the live non-harmonic analysis as well.

If you open a spectrum file in the Spectrum Editor, you can view these envelopes by clicking the A/F button three times (first to show amplitudes only, second shows frequencies, third click shows the information envelopes).

Comments

Oh, I remember I once wondered what this signals at the end are. Thanks for the information! I think I can trash my FrameAverage and SpectralCentroid modules now ;)

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@gustav, surely you mean 'optimise' ;)
Thanks for the detailed explanation SSC

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@cristian oh, I think I made a typo there ;)