[PD] block size

J. Scott Hildebrand jshildebrand at ucdavis.edu
Wed Aug 28 00:51:15 CEST 2002


     i'm not exactly sure what you mean by the inlet is giving a block
consisting of the last half of the previous block and the first half of
the next block. the inlet takes data in and the outlet takes data out.
there is only an inlet in the block~ object and no outlet. and how would i
use this overlapping mechanism to do the overlap and add routine for
real-time convolution? thanks!

                          scott


On Tue, 27 Aug 2002 bsaylor at macalester.edu wrote:

> I'm not sure what the inlet is for, but yes, just put block~ anywhere in
> a containing window.
>
> The overlap factor is most useful for when you want to do FFT operations
> on overlapping, windowed (e.g. Hanning) blocks.  It sort of means that
> instead of just moving on to the next input block, the inlet~ will give
> a block consisting of (say the overlap factor is 2) the last half of the
> previous block and and the first half of the next block.  The outlet~
> then adds the overlapping blocks back together.  You need an overlap
> factor of at least 2 (which seems to be usually good enough) when
> working with hanning-windowed blocks.  For convolution, windowing isn't
> necessary, so depending on how your algorithm works, an overlap factor
> of 1 (e.g. no overlap) might work.  I think this is all at least
> conceptually correct; someone correct me if I'm wrong.. :)
>
> Ben
>
> On Tue, Aug 27, 2002 at 01:04:50PM -0700, J. Scott Hildebrand wrote:
> >
> >        my block size needs to be 256, but how do i know what to use as the
> > overlap factor? and also how do i use the block? it has one inlet, do i
> > just need to leave it alone and have my block anywhere in my patch?
> >
> >            thanks,
> >
> >                     scott
> >
> >
> >
> >
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