[bug?] noise and downsampled poly~

Jan 12, 2012 at 12:39pm

[bug?] noise and downsampled poly~

The range of values that noise~ produces changes with downsampling.

[attachment=181898,3196]

Attachments:
  1. downsamplednoise.png
#61200
Jan 12, 2012 at 12:53pm

When trying to fix it with a pong~, it appears the problem goes deeper.
This is with max 6.0.3 on Lion.

[attachment=181899,3197]

Attachments:
  1. downsampling.png
#220581
Jan 12, 2012 at 1:05pm

isnt that because they changed how noise~ generates its ooutput with v.5?
if the new alg would somehow avoid that two or more peaks follow each other that would explain what you see.

#220582
Jan 12, 2012 at 3:57pm

This is caused by the new resampling filters. There’s some overshoot in the interpolation. When you turn it off, this goes away. (they’re on by default)

It looks like there’s some sort of sinc function at the discontinuity on the phasor. It’s pretty cool to watch. Also, check out the spectroscope for interpolation on or off. You can really see the resampling filters blocking everything above the new Nyquist rate.

If you look at the scope~ on the left you’ll see a smoothed noise function. Not a bug, just not maybe what you expected.

– Pasted Max Patch, click to expand. –

And the poly vox:

– Pasted Max Patch, click to expand. –

`

#220583
Jan 12, 2012 at 4:01pm

Forgot to include…

Attachments:
  1. Screenshot20120112at11.02.18AM.png
#220584
Jan 12, 2012 at 4:44pm

That makes perfect sense. I have seen the resampling mentioned, but forgot about it. Thanks.

#220585

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