[PD-dev] tooltips ideas

IOhannes m zmoelnig zmoelnig at iem.at
Fri Jun 30 09:02:19 CEST 2006


geiger wrote:
> On Wed, 28 Jun 2006, IOhannes m zmoelnig wrote:
> 
>>>why ?
>>
>>sorry: this line should really have read:
> 
> 
> ok, understood ... often I am just too paranoid. Sorry.


never mind.
i guess, when one has a reputation like me (often being a bit
harsh,sarcastic,...), then one has to take extra care that at least the
things one writes do not get obfuscated by mispelling, forgotton
letters, words, phrases, or bad english in general...

> 
> 
>>i see. this sounds like a good idea to me (generally).
>>probably not too many patches use up/downsampling anyhow.
>>the question is, whether the zero-padded upsampling is the best choice...
> 
> 
> I thought its the most general one, a resample object can use it
> to do sample+hold, linear interpolation or any other type of filtering.

i agree that it should be an as simple as possible algorithm.
zero-padding between samples is very simple, even simpler is
zero-padding at the end of the block (but otoh, the filtering gets more
complicated then)

> 
> If I remember correctly, you can do downsampling by lowpass filtering
> inside the child, and let the picking of samples up to the inlet.
> This should give you a perfectly downsampled signal (because you removed
> the frequencies above the parents nyquist frequency). The only thing that
> you need to know is the resampling factor in the child patch.
> 
>>i admit that it could have been done better (right now, if you really
>>want "cleanly" resampled signals, you need to do filtering of the signal
>>outside of the child anyhow)
> 
> 
> Really ? Isn't that too late, as you already have the aliasing in the
> signal ?

it seems like you are referring to the child as being upsampled in
relation to the parent, while i was thinking the other way round.

so if the child is downsampled (with a lower sampling- and thus
nyquist-frey), we have to do some filtering before the actual
downsampling process, in order to avoid aliasing (because when we are
downsampled it is too late).
my idea was, that the parent patch need not know anything about the
sampling frequency of the child, so if the child was downsampled, then
the downsampling algorithm itself has to take care of the pre-filtering.

this can be done with "intelligent" iolet~s (as it is now; but this is
bad since they will never be as intelligent as one would like them); it
should also be possible with an added sub-patch level between parent and
child which does the pre/post filtering as needed.

> 
> 
> well for a misunderstanding it always takes two, I really have to
> learn to read between the lines in a positive way.

after all, the sun breaks through the clouds....:-)


mfg.asdr.
IOhannes




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