[pd] 100000hz+

padawan12 padawan12 at obiwannabe.co.uk
Fri Oct 27 07:54:27 CEST 2006


This is as expected. What Chris says is no surprise. If you render the output
to a .wav file it is captured as a snapshot and the sample rate no longer 
has any effect (other than to change the overall playback rate). The problem
others were trying to explain is that the synthesis patch is not independent
of sample rate, so using the same Pd patch at different sample rates will
produce different results. If you're recording it the problem doesn't exist.

What does 100,000Hz sound like?
http://www.dsptutor.freeuk.com/aliasing/AliasFrq.htm
sr/2 is the Nyquist frequency which for a 44100Hz system is 22050Hz.
so 100,000 mod 44100 = 11800Hz which is less than 22050Hz so it doesn't
get reflected. If it was, say 30,000Hz then you would actually hear
30,000Hz - 22,050Hz = 7950Hz. Think of sampling like a hall of mirrors
where the frequencies get reflected at both ends.



On Thu, 26 Oct 2006 23:27:18 +0800
Chris McCormick <chris at mccormick.cx> wrote:

> On Thu, Oct 26, 2006 at 10:48:32PM +0900, hard off wrote:
> > this is a bummer, cos i am getting a really nice palette of sounds
> > here, and i wanted to share the patch////
> > 
> > oh well, i'll stick to normal midi notes for that i guess.
> 
> Don't be too bummed out. Given what's been said here I'm not sure exactly
> how this happened, but I made the types of sounds you're talking about
> (an [osc~] at +127 midi) and recorded them to a wav file and imported that
> wav file into a .XM file and then played that .XM file back on a gameboy
> advance, and it sounded pretty much how it did in the original instance,
> despite the fact that it was playing back at a different sampling rate and
> underwent conversions between different sample rates in the process. If
> I was you I would experiment with your sound on some different systems
> before giving up. I guess sometimes practice confounds theory.
> 
> Best,
> 
> Chris.
> 
> -------------------
> chris at mccormick.cx
> http://mccormick.cx
> 
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