Calculate Amplitude for Frequencies node could be off

Steps causing the bug to occur

Hi I hope this is useful. I’m unsure whether this is a bug or a known limitation of the node. But here goes…

The “calculate amplitude for frequencies” sends data that doesn’t match well the information received by other software frequency analysers. In particular the lowest bins appear much too loud. I’ve tried using exponential, logarhythmic scales etc etc on the x-axis but the best I can acheive is still well off what I see on other software.

Have you found a workaround?

A workaround is to apply subsquent maths nodes to compensate.

Other notes

  • Vuo version: 2.3.0
  • macOS version: macOS 10.14
  • How severely does this bug affect you? It’s annoying but I can work around it.

Please see the pictures below.
The first is a fairly basic plotting of the data from the calculate frequencies node. The Frequency Bin Averaging is set to none and the X-axis is exponential. This is about as good as I can make it look.
The second picture is a free software analyser VST from voxengo. Both analysers are receiving the same pink noise audio.

Screen Shot 2021-04-20 at 16.45.22.png

Screen Shot 2021-04-20 at 16.45.45.png


Vuo’s Calculate Amplitude for Frequencies node currently uses linear amplitude scaling. Feeding the output of Calculate Amplitude for Frequencies to Calculate List with the expression log(X) (like in the attached noises-log-log.vuo composition), might more closely match the output you are looking for.

If this is something you would like to see simplified in Vuo, you could create a feature request that allows choosing between linear and logarithmic amplitude scaling for the Calculate Amplitude for Frequencies node. In the meantime, we’ll review our node documentation. (1.75 MB)

Thanks for this, it didn’t even occur to me that the amplitude would be logarithmic or require some maths! I tried it out the attached composition and I’ll probably use this approach in future. I’m constantly amazed by the super useful support I get from you guys. :-)

We’re going to clarify the type of amplitude scaling in the documentation.

Clarified the documentation and added a “Compare Scaled Audio Frequencies” example composition in Vuo 2.4.0.