Experience with the Sliding DFT, anyone?
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From: Andor on 15 Dec 2008 16:11 On 15 Dez., 18:55, HardySpicer <gyansor...(a)gmail.com> wrote: > On Dec 16, 3:31 am, Richard Dobson <richarddob...(a)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
From: kevinjmcgee on 15 Dec 2008 21:49 On Dec 15, 4:11 pm, Andor <andor.bari...(a)gmail.com> wrote: > On 15 Dez., 18:55, HardySpicer <gyansor...(a)gmail.com> wrote: > > > > > > > On Dec 16, 3:31 am, Richard Dobson <richarddob...(a)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.pdf http://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.
From: John E. Hadstate on 16 Dec 2008 20:35
"hxtasy" <atijon58(a)gmail.com> wrote in message news:IoudnXG0AIuoztvUnZ2dnUVZ_rbinZ2d(a)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. |