Hi folks, I was experimenting with convolution, using the the overlap-add ideas with FFT. I was using an impulse of fading white noise to test the algorithm for smoothness, and I noticed to made an almost perfect diffusion sound. My question; is it possible to feed the FFT with white noise and a mixture of the previous noise or something to create a nice diffusion fall-off without using a huge noise table? Basically having a nice long diffusion tail without the massive impulse. I have tried diminishing the noise then adding a new random set on top with each frame, but I only got very repetitive buzzing, could this or something similar actually work? Thanks, Dave Hoskins
Diffusion using convolution
Started by ●March 12, 2007
Reply by ●March 13, 20072007-03-13
Oh, nevermind. Be all that ends all. : ) If you know anyone that says the words "Paradigm shift," then your with the wrong company. : ) ...... ..... .... ... .. . "Zot" <bob@yahoo.com> wrote in message news:J2cJh.132269$HO5.95382@fe1.news.blueyonder.co.uk...> Hi folks, I was experimenting with convolution, using the the overlap-add > ideas with FFT. I was using an impulse of fading white noise to test the > algorithm for smoothness, and I noticed to made an almost perfect > diffusion sound. > > My question; is it possible to feed the FFT with white noise and a mixture > of the previous noise or something to create a nice diffusion fall-off > without using a huge noise table? Basically having a nice long diffusion > tail without the massive impulse. I have tried diminishing the noise then > adding a new random set on top with each frame, but I only got very > repetitive buzzing, could this or something similar actually work? > > Thanks, > Dave Hoskins > > >
Reply by ●March 14, 20072007-03-14
What is a "diffusion sound" ? On 13 Mrz., 05:19, "Zot" <b...@yahoo.com> wrote:> Oh, nevermind. Be all that ends all. : ) If you know anyone that says the > words "Paradigm shift," then your with the wrong company. : ) ...... ..... > .... ... .. . > > "Zot" <b...@yahoo.com> wrote in message > > news:J2cJh.132269$HO5.95382@fe1.news.blueyonder.co.uk... > > > > > Hi folks, I was experimenting with convolution, using the the overlap-add > > ideas with FFT. I was using an impulse of fading white noise to test the > > algorithm for smoothness, and I noticed to made an almost perfect > > diffusion sound. > > > My question; is it possible to feed the FFT with white noise and a mixture > > of the previous noise or something to create a nice diffusion fall-off > > without using a huge noise table? Basically having a nice long diffusion > > tail without the massive impulse. I have tried diminishing the noise then > > adding a new random set on top with each frame, but I only got very > > repetitive buzzing, could this or something similar actually work? > > > Thanks, > > Dave Hoskins- Zitierten Text ausblenden - > > - Zitierten Text anzeigen -
Reply by ●March 14, 20072007-03-14
In diffusion, I meant something similar to the long drawn out tail of a reverb unit. Normally done with a bank of different length delay lines in parallel to blur the sound. The trouble with this method is that you have to apply a lot of delays and add modulation and countless listening tests and tweaking to make it acceptable and non-metallic - Which is fine, but I noticed that convolving a white noise signal with it did a fine job also. So I was wondering if it was a valid solution, and also if the impulse could be adjusted each frame instead of having a giant fading white noise impulse for long tails. I hope that makes sense! Dave "Andor" <andor.bariska@gmail.com> wrote in message news:1173888952.923873.302240@n76g2000hsh.googlegroups.com...> What is a "diffusion sound" ? > > On 13 Mrz., 05:19, "Zot" <b...@yahoo.com> wrote: >> Oh, nevermind. Be all that ends all. >> >> "Zot" <b...@yahoo.com> wrote in message >> >> news:J2cJh.132269$HO5.95382@fe1.news.blueyonder.co.uk... >> >> >> >> > Hi folks, I was experimenting with convolution, using the the >> > overlap-add >> > ideas with FFT. I was using an impulse of fading white noise to test >> > the >> > algorithm for smoothness, and I noticed to made an almost perfect >> > diffusion sound. >> >> > My question; is it possible to feed the FFT with white noise and a >> > mixture >> > of the previous noise or something to create a nice diffusion fall-off >> > without using a huge noise table? Basically having a nice long >> > diffusion >> > tail without the massive impulse. I have tried diminishing the noise >> > then >> > adding a new random set on top with each frame, but I only got very >> > repetitive buzzing, could this or something similar actually work? >> >> > Thanks, >> > Dave Hoskins- Zitierten Text ausblenden - >> >> - Zitierten Text anzeigen - > >
Reply by ●March 14, 20072007-03-14
Andor wrote: ...>> - Zitierten Text anzeigen -Zitierten Text anzeigen? Verwenden Sie Google? Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●March 15, 20072007-03-15
On 14 Mrz., 23:10, Jerry Avins <j...@ieee.org> wrote:> Andor wrote: > > ... > > >> - Zitierten Text anzeigen - > > Zitierten Text anzeigen? > > Verwenden Sie Google?Aber klar doch! Gruss, Andor
Reply by ●March 15, 20072007-03-15
I guess I'm either barking up the wrong tree or exactly the right one! Nizza, wenn jemand mir einen Tip gab. "Andor" <andor.bariska@gmail.com> wrote in message news:1173946784.480496.321400@y66g2000hsf.googlegroups.com...> On 14 Mrz., 23:10, Jerry Avins <j...@ieee.org> wrote: >> Andor wrote: >> >> ... >> >> >> - Zitierten Text anzeigen - >> >> Zitierten Text anzeigen? >> >> Verwenden Sie Google? > > Aber klar doch! > > Gruss, > Andor >
Reply by ●March 16, 20072007-03-16
Zot wrote:> I guess I'm either barking up the wrong tree or exactly the right one!I still don't know exactly what your question is. You want to use white noise as reverb, and somehow compress the white noise to reduce the "table size" (what table?)? You know that you can't compress white noise (by definition). Can you elaborate on your goal / problem a bit?
Reply by ●March 16, 20072007-03-16
O.K. thanks. If I convolve a sample of say a drum with a long fading out white noise impulse, I get a really nice gradual fading drum sound, that's all and mixed up and blurred out through time, which is what I termed diffusion. If I'm doing a 1024 point FFT to convolve through this white noise, do I really need the large white noise impulse, because large convolutions take longer to calc? Is there a way to populate the 1024 FFT every block using some kind of residue of the old FFT and new random numbers? The more I (try to) explain this, the more it sounds unlikely, as each sample has to be multiplied by the whole of the existing noise sample.. hmmm... head hurting, must stop! Cheers, Dave "Andor" <andor.bariska@gmail.com> wrote in message news:1174069061.703709.286660@n59g2000hsh.googlegroups.com...> > > Zot wrote: >> I guess I'm either barking up the wrong tree or exactly the right one! > > I still don't know exactly what your question is. You want to use > white noise as reverb, and somehow compress the white noise to reduce > the "table size" (what table?)? You know that you can't compress white > noise (by definition). Can you elaborate on your goal / problem a bit? >
Reply by ●March 18, 20072007-03-18
I think what you are looking for is how to approximate a given impulse response (FIR system) through a system with rational transfer function. You can start searching using "model order reduction" and "system identification". Zot wrote:> O.K. thanks. > If I convolve a sample of say a drum with a long fading out white noise > impulse, I get a really nice gradual fading drum sound, that's all and mixed > up and blurred out through time, which is what I termed diffusion. > If I'm doing a 1024 point FFT to convolve through this white noise, do I > really need the large white noise impulse, because large convolutions take > longer to calc? Is there a way to populate the 1024 FFT every block using > some kind of residue of the old FFT and new random numbers? The more I > (try to) explain this, the more it sounds unlikely, as each sample has to be > multiplied by the whole of the existing noise sample.. hmmm... head hurting, > must stop! > > Cheers, > > Dave > > "Andor" <andor.bari...@gmail.com> wrote in message > > news:1174069061.703709.286660@n59g2000hsh.googlegroups.com... > > > > > > > Zot wrote: > >> I guess I'm either barking up the wrong tree or exactly the right one! > > > I still don't know exactly what your question is. You want to use > > white noise as reverb, and somehow compress the white noise to reduce > > the "table size" (what table?)? You know that you can't compress white > > noise (by definition). Can you elaborate on your goal / problem a bit?- Zitierten Text ausblenden - > > - Zitierten Text anzeigen -
