Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread gm
thanks for your offer, I can not really read Math lab code and always have a hard time even figuring out essentials of such code My phase vocoder already works kind of satisfactorily now as a demo in Native Instruments Reaktor, I do the forward FFT offline and the iFFT "just in time", that

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread robert bristow-johnson
� i don't wanna lead you astray.� i would recommend staying with the phase vocoder as a framework for doing time-frequency manipulation.� it **can** be used real-time for pitch shift, but when i have used the phase vocoder, it was for time-scaling and then we would simply resample the

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread gm
You get me intrigued with this I actually believe that wavelets are the way to go for such things, but, besides that anything beyond a Haar wavelet is too complicated for me (and I just grasp that Haar very superficially of course), I think one problem is the problem you mentioned - don't do

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread robert bristow-johnson
what you're discussing here appears to me to be about perfect reconstruction in the context of Wavelets and Filter Banks. there is a theorem that's pretty easy to prove that if you have complementary high and low filterbanks with a common cutoff at 1/2 Nyquist, you can downsample both

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread gm
hm, my application has also WOLA ... All I find is about up- and downsampling of time sequences and spectra of the same length. Summing adjacent bins seemed to be in correspondence with lowpass filtering and decimation of time sequences even though it's not the apropriate sinc filter...

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread Ethan Duni
gm wrote: >This is brining up my previous question again, how do you decimate a spectrum >by an integer factor properly, can you just add the bins? To decimate by N, you just take every Nth bin. >the orginal spectrum represents a longer signal so I assume folding >of the waveform occurs? Yeah,

Re: [music-dsp] 2-point DFT Matrix for subbands Re: FFT for realtime synthesis?

2018-11-09 Thread gm
This is brining up my previous question again, how do you decimate a spectrum by an integer factor properly, can you just add the bins? the orginal spectrum represents a longer signal so I assume folding of the waveform occurs? but maybe this doesn't matter in practice for some applications?