[PD] Filters...

Derek Holzer derek at umatic.nl
Mon Apr 12 22:21:00 CEST 2010

The frequency components introduced by aliasing cannot be removed (at 
least not by low-pass filtering) once introduced, and this happens at 
the level of signal generation, not at the interface to the dac. Since 
it is the phasor which is actually aliasing, it needs to be antialiased 
with a low pass filter before it continues on the a lower sampling rate. 
So the signal source and the filter need to be in the same upsampled 


On 4/12/10 5:49 PM, Pierre Massat wrote:
> Hi all,
> recently there was a discussion about the different ways of avoiding
> aliasing. One of these is oversampling, but as far as i know there is
> only one example of it in Pd help patches, and it has a phasor in the
> subpatch. I m assuming that i could use the Butterworth filter in the
> subpatch without the phasor, am i right? In this case would it make
> sense to use it everytime i need i low-pass filter?
> This is probably a very silly question...

::: derek holzer ::: http://macumbista.net :::
---Oblique Strategy # 45:
"Disciplined self-indulgence"

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