I'm fairly new to Pure Data, and I'm having a hard time figuring how to extract the envelope of a signal.

Now I'm simply outputting the signal to an array, but I really wanted was to extract the envelope and plot it.
Anyone can help please?

envelope.pd

Too woofing easy!.....

Should have named my example file dog.wav instead of a.wav!

I tried using that, but unfortunately what I get is not what I need.

I'm using this patch, that computes a Fourier Transform so I can analyze the frequencies of an incoming signal (the sound received on the microphone to be exact), but I want the envelope of the signal, not the signal itself.

Here goes a part of my patch, the results seem correct, I just wanted the envelope now.

Any help will be greatly appreciated, I feel I'm missing something :/
fft_hz.pd

but I want the envelope of the signal, not the signal itself.

I don't understand. What [env~] outputs is the envelope of the signal as far as I know.

Also, I found this about envelope followers (from Miller's book): http://msp.ucsd.edu/techniques/v0.11/book-html/node158.html

See if there is anything there that can help you.

Cheers,
Gilberto

What I want is something like this in the second plot (sorry for the bad drawing):

I want to plot and be able to save the envelope of the signal like this.
Maybe Im confusing envelope with something else.....

Any help is appreciated, thanks guys!

I do understand what you want, but I thought that the [env~] does exactly that. Of course it does only for the current signal arriving to it. So my idea was to save [env~]'s output to a table and then plot it, and that's what I tried with that patch I posted above.

Cheers,
Gilberto

Any idea on how to save those values to a table?
I can't seem to get the grasp on how Pure Data handles arrays and tables :/

I can't use externals because I'm going to use the patch with libpd...

Thanks again! @gsagostinho

Any idea on how to save those values to a table?

I did it by using [tabletool] but of course you can patch it yourself. The logic I use is as follows:

• when a new value is sent by [env~], use a [trigger float bang]
• the bang will first shift the table to the left (that is, value at index 2 moves to index 1, the value at index 3 moves to index 2, etc.). This is where [tabeltool] is super handy, but you can patch this yourself of course.
• then the float from will be written to the last position in the table by using [tablewrite <tablename>]. See how I dealt with the second inlet on my patch above (the last index was 100 in my case).

Cheers,
GIlberto

As I showed on the image, I want to do the envelope of a signal after I used FFT on it (now I have an array that tells me for each moment in time what are the frequencies that compose the signal).
And this is right, as I tested it already.

Now I just wanted to use those values and envelope them...

@PedroPT I thought you had written that you just wanted to visualize the envelope, not use it later. Maybe you can store the envelope in a table, and when necessary recall their values from this table and feed a [line~] into which, and multiply it by the signal. For that you have to make sure that you have amplitude between 0 and 1 ([env~] actually outputs RMS dB). But maybe there is an easier way to do what you want and I am missing it altogether...

So far this I have right, but I wanted to send the envelope instead of the FFT values...

But thanks anyway @gsagostinho, @whale-av !!