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envelope extraction

Re: Method for generating an envelope around an audio signal:

Low pass filtering was pretty good back in the day.  A more
modern DSP method would be to connect consecutive positive
peaks in the audio signal with straight lines or connect peak
groups with bezier curves. Then perhaps apply low pass filter
at 15 - 20kHz.
The advantage of this method is that it preserves indication of
fast transients which we hear but are removed by 50-400 Hz
low pass filters. 

I suppose half wave rectification before finding consecutive
peaks will yield a slightly more accurate envelope.  It would
also make sense to use RMS rather than peak values.

I don't know of any off-the-shelf program to do this.

Dave Smith
Buy my music, I'm unemployed!

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