Why don’t you just start everything (except the fft jammer) fft_windowsize - server_blocksize / samplerate seconds later in your NRT score?
Sam
> On Mar 18, 2021, at 7:35 PM, [email protected] wrote:
>
> Hi sc-users,
>
> I'm looking for some ideas on fixing up a little timing issue. I'm working in a Non-RealTime setting, so timing issues should be more tractable.
>
> I have a short sound file (512 samples long), let's call it fivetwelve.wav, that I want to use to impart a spectrum. My idea is to take the FFT of fivetwelve.wav (i.e. one window of FFT), take the FFT of my signal, run PV_MagMul, and then IFFT the result.
>
> This works except that it gives a timing delay because of a blank frame in the FFT (discussed in a [sc-users] thread from July 2020 called FFT first window, which for some reason I can't link to). As discussed in that thread, I've succeeded in lining up the PV_MagMul'd result signal with the original signal, by delaying the signal by (fft_windowsize - server_blocksize) / samplerate
>
> However, now both parts are delayed. I need to retain the initial timing, as there are other parts of my score that have to be aligned with this output, and this entire supercollider score must be aligned in a sequencer with other scores as well.
>
> Is there some way of deleting or skipping the initial blank frame at some point in the process, or of negative-delaying things, or some other way of making sure FFT processes are properly aligned in a non-real-time score?
>
> I'd also be curious to know if anyone has any alternative ideas of how to multiply or filter the one-window spectrum of fivetwelve.wav into the signal, but even if that bypasses the FFT timing problem, I expect to run into the FFT timing problem again sooner than later...
>
> Thanks very much!
>
> Andie
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