[PD] problem with switch~ and downsampling in 0.38-0test7
IOhannes m zmoelnig
zmoelnig at iem.at
Mon Feb 21 17:50:44 CET 2005
Matthias Blau wrote:
> Hi all,
> Therefore I made a subpatch with [switch~ 64 1 0.5] which works most of
...
>
> Sometimes however, I get strong high frequency disturbances. I suspect a
> bug in switch, but maybe I am missing something?
>
you might have problems with aliasing.
the up/downsampling does very little (to no) pre-filtering.
upsampling: depending on the argument the iolet~s will do linear
interpolation between 2 original samples at the best(!!!); this is not
very good; the default is zero-padding which is really awful (but is
there by intent, as you will very soon notice, that "something" is going on)
downsampling: if i remember correctly, it just takes every nth sample
(even if you specify "linear" there is no smoothing or whatever)
so make sure that you filter your signal before/after down/upsampling.
mfg.asd.r
IOhannes
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