Reply by John E. Hadstate●December 16, 20082008-12-16
"hxtasy" <atijon58@gmail.com> wrote in message
news:IoudnXG0AIuoztvUnZ2dnUVZ_rbinZ2d@giganews.com...
> Hello I would like to know if anyone has experience with the
> sliding DFT
> algorithm. It is somewhat similar to the Goertzel algorithm.
>
> All I would like to know is what application this algorithm
> would be
> useful in?
>
>
> I cannot find that much information on the internet and have
> not had time
> to look into any books about the sliding DFT. So if anyone
> could mention
> the mathematics behind it the help would be appreciated.
>
>
Try Rick Lyons' book, Understanding Digital Signal Processing.
In the 2nd edition (Nineth [sic] printing) it on pages 532 to
540, a very lucid treatment.
Reply by ●December 15, 20082008-12-15
On Dec 15, 4:11�pm, Andor <andor.bari...@gmail.com> wrote:
> On 15 Dez., 18:55, HardySpicer <gyansor...@gmail.com> wrote:
>
>
>
>
>
> > On Dec 16, 3:31�am, Richard Dobson <richarddob...@blueyonder.co.uk>
> > wrote:
>
> > > hxtasy wrote:
> > > > Hello I would like to know if anyone has experience with the sliding DFT
> > > > algorithm. It is somewhat similar to the Goertzel algorithm.
>
> > > > All I would like to know is what application this algorithm would be
> > > > useful in?
>
> > > Probably the most unorthodox and extravagant of all possible
> > > applications, but I have been using it for musical (audio) applications,
> > > mainly in its use as part of a full (but very slow!) "sliding phase
> > > vocoder" (SPV):
>
> > >http://dream.cs.bath.ac.uk/SDFT/index.html
>
> > > Now fully incorporated in Csound.
>
> > > Our initial paper on the SDFT was for ICMC2005, which can be found via here:
>
> > >http://dream.cs.bath.ac.uk/DigitalLibrary/index.php
>
> > > (use the ICMC link; see also the Dafx08 link for some initial
> > > explorations of a ConstQ form)
>
> > > We have yet to put our 2007 ICMC paper online, but the first link above
> > > gives access to the slides we used with some sound examples (though it
> > > is far more about the SPV than the SDFT itself).
>
> > > I am not the one to ask about the maths though - not my area!
>
> > > Richard Dobson
>
> > Do you have a ref for the original sliding DFT paper?
>
> It is just the standard recursive algorithm to compute a running sum
> (store the sum in a state variable, subtract the oldest input and add
> the newest input) with an additional twiddle factor multiplication.
> You'll find tons on the web.
>
> Regards,
> Andor- Hide quoted text -
>
> - Show quoted text -
It's a very old technique. You can find it in many textbooks from the
1970's (e.g.: Rabiner and Gold, p. 382-3). Googling "sliding dft'"
found >1600 hits; among them:
http://www.comm.utoronto.ca/~dimitris/ece431/slidingdft.pdfhttp://www.ingelec.uns.edu.ar/pds2803/Materiales/Articulos/SlidingDFT_BW.pdf
The second link is the 'dsp tricks and tips' paper from IEEE Signal
Processing Magazine.
It's often used when you don't want all N frequency points that you
would get from a regular DFT or FFT. And, just as with the
conventional DFT, you can compute it for fractional frequencies, and
your data can be any length N.
Reply by Andor●December 15, 20082008-12-15
On 15 Dez., 18:55, HardySpicer <gyansor...@gmail.com> wrote:
> On Dec 16, 3:31�am, Richard Dobson <richarddob...@blueyonder.co.uk>
> wrote:
>
>
>
>
>
> > hxtasy wrote:
> > > Hello I would like to know if anyone has experience with the sliding DFT
> > > algorithm. It is somewhat similar to the Goertzel algorithm.
>
> > > All I would like to know is what application this algorithm would be
> > > useful in?
>
> > Probably the most unorthodox and extravagant of all possible
> > applications, but I have been using it for musical (audio) applications,
> > mainly in its use as part of a full (but very slow!) "sliding phase
> > vocoder" (SPV):
>
> >http://dream.cs.bath.ac.uk/SDFT/index.html
>
> > Now fully incorporated in Csound.
>
> > Our initial paper on the SDFT was for ICMC2005, which can be found via here:
>
> >http://dream.cs.bath.ac.uk/DigitalLibrary/index.php
>
> > (use the ICMC link; see also the Dafx08 link for some initial
> > explorations of a ConstQ form)
>
> > We have yet to put our 2007 ICMC paper online, but the first link above
> > gives access to the slides we used with some sound examples (though it
> > is far more about the SPV than the SDFT itself).
>
> > I am not the one to ask about the maths though - not my area!
>
> > Richard Dobson
>
> Do you have a ref for the original sliding DFT paper?
It is just the standard recursive algorithm to compute a running sum
(store the sum in a state variable, subtract the oldest input and add
the newest input) with an additional twiddle factor multiplication.
You'll find tons on the web.
Regards,
Andor
Reply by Richard Dobson●December 15, 20082008-12-15
>
> Do you have a ref for the original sliding DFT paper?
>
Not sure what you mean - ~our~ original paper is via the link above. If
you mean some particular original (older) publication, I have no idea.
Not sure there is one, as such. The basic principle (a complex rotation
applied to an input DFT buffer, for each sample) is the sort of thing
that might have been regarded as too trivial to write a whole paper on -
it is probably documented in the classic DSP reference texts from the
70's (none of which I own, sadly). I found a few papers dating from the
late 80's to early 90's (e.g. "Generalized Sliding FFT..." by B.
Farhang-Bouroujeny, IEEE somewhere, 1994), but doubt if they can be
called "the original".
Richard Dobson
Reply by HardySpicer●December 15, 20082008-12-15
On Dec 16, 3:31�am, Richard Dobson <richarddob...@blueyonder.co.uk>
wrote:
> hxtasy wrote:
> > Hello I would like to know if anyone has experience with the sliding DFT
> > algorithm. It is somewhat similar to the Goertzel algorithm.
>
> > All I would like to know is what application this algorithm would be
> > useful in?
>
> Probably the most unorthodox and extravagant of all possible
> applications, but I have been using it for musical (audio) applications,
> mainly in its use as part of a full (but very slow!) "sliding phase
> vocoder" (SPV):
>
> http://dream.cs.bath.ac.uk/SDFT/index.html
>
> Now fully incorporated in Csound.
>
> Our initial paper on the SDFT was for ICMC2005, which can be found via here:
>
> http://dream.cs.bath.ac.uk/DigitalLibrary/index.php
>
> (use the ICMC link; see also the Dafx08 link for some initial
> explorations of a ConstQ form)
>
> We have yet to put our 2007 ICMC paper online, but the first link above
> gives access to the slides we used with some sound examples (though it
> is far more about the SPV than the SDFT itself).
>
> I am not the one to ask about the maths though - not my area!
>
> Richard Dobson
Do you have a ref for the original sliding DFT paper?
H
Reply by Richard Dobson●December 15, 20082008-12-15
hxtasy wrote:
> Hello I would like to know if anyone has experience with the sliding DFT
> algorithm. It is somewhat similar to the Goertzel algorithm.
>
> All I would like to know is what application this algorithm would be
> useful in?
>
Probably the most unorthodox and extravagant of all possible
applications, but I have been using it for musical (audio) applications,
mainly in its use as part of a full (but very slow!) "sliding phase
vocoder" (SPV):
http://dream.cs.bath.ac.uk/SDFT/index.html
Now fully incorporated in Csound.
Our initial paper on the SDFT was for ICMC2005, which can be found via here:
http://dream.cs.bath.ac.uk/DigitalLibrary/index.php
(use the ICMC link; see also the Dafx08 link for some initial
explorations of a ConstQ form)
We have yet to put our 2007 ICMC paper online, but the first link above
gives access to the slides we used with some sound examples (though it
is far more about the SPV than the SDFT itself).
I am not the one to ask about the maths though - not my area!
Richard Dobson
Reply by Greg Berchin●December 15, 20082008-12-15
On Mon, 15 Dec 2008 06:53:09 -0600, "hxtasy" <atijon58@gmail.com>
wrote:
>Hello I would like to know if anyone has experience with the sliding DFT
>algorithm.
Hello I would like to know if anyone has experience with the sliding DFT
algorithm. It is somewhat similar to the Goertzel algorithm.
All I would like to know is what application this algorithm would be
useful in?
I cannot find that much information on the internet and have not had time
to look into any books about the sliding DFT. So if anyone could mention
the mathematics behind it the help would be appreciated.