[PD] raw resampling

IOhannes m zmoelnig zmoelnig at iem.at
Mon Jun 30 17:44:49 CEST 2008


Atte André Jensen wrote:
> Hi
> 
> I'm trying to do a simple resampling (downsampling) of an audio signal. 
> I thought a simple snapshot, triggered by a metro 1 would do, but 
> apparently not. Attached is a patch that does this, but the resampled 
> signal sounds nothing like a rising (20hz-15kh<) sine.
> 
> Am I totally off track here, or how do I resample an audio signal to, 
> say, 4410 khz?
> 
> NB: I'm still quite new to pd, so any comments on the patch, with 
> regards to how to do certain things easier/better/cleaner is highly 
> appreciated.


i haven't looked at your patch but in text view, but here are some remarks:

- [metro 0.1] won't work at all; currently [metro] has a well known 
"bug" that prohibits it from emitting bangs at an interval lower than 
1ms. workarounds have been posted on this list using [delay]

- [snapshot~] will quantize the triggers to signal-block boundaries 
(1.45ms). you have to use [vsnapshot~] for this (afaik, there is no 
helppatch for [vsnapshot~]; i assume it works the same as [snapshot~] 
but is sample accurate)

- you could also use Pd's builtin resampling (using [block~ 64 1 0.125] 
or whatever)

fgmad
IOhannes




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