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[bug?] noise and downsampled poly~

January 12, 2012 | 12:39 pm

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

[attachment=181898,3196]

Attachments:
  1. downsamplednoise.png

January 12, 2012 | 12:53 pm

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

January 12, 2012 | 1:05 pm

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.


January 12, 2012 | 3:57 pm

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. –

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January 12, 2012 | 4:01 pm

Forgot to include…

Attachments:
  1. Screenshot20120112at11.02.18AM.png

January 12, 2012 | 4:44 pm

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


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