fft analysis woes

Jan 21, 2007 at 10:58pm

fft analysis woes

Hello,

I am working with audio analysis and am having some trouble getting
the information I need.

I want to analyse an audio signal and have an output similar to a
spectroscope (not spectrogram!) where the amplitude of the various
frequencies in a signal are displayed in a traditional x=frequency
y=amplitude and can be used as control for various other processes.

The spectroscope in max uses 30-40% of my cpu when there is a full
frequency signal going into it and I cannot seem to access the
individual frequency bands for use as control. I have read the
analysis tutorials and I can’t penetrate them. They seem to be all
aimed towards processing.

It says right at the beginning: “fft~ receives a signal in its inlet.
For each slice of time it receives (512 samples long by default) it
sends out a signal of the same length listing the amount of energy in
each frequency region.” Why can’t I access this information? I feel
like I am missing something fundamental. I don’t even need 512 bands.
10 would be okay, 64 would be better, 128 would be good.

I have a spectroscpe in my recording software only using 2% of my cpu
so I know it is possible to do I just can’t figure out how to do it in
max.

Cheers,

Carey

#29853

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