Additive FFT



  • I built a little flute yesterday in HISE using 10 sine generators and a noise generator and a single sample for the attack. It actually sounded pretty close to the real instrument - except there was nothing above 4000hz because I only had 10 partials.

    But this got me thinking, since HISE has FFT and Oscillator modules, would it be possible to add a module that performs an FFT on a sample and re-synthesizes it using a bank of oscillators (probably need at least 50 sines but the more the better)?


  • administrators

    Actually this is exactly what the Wavetable Synthesiser does. Think of it as a "cached" additive synthesiser that uses a lookup table (= the wavetable) instead of calculating all 50 harmonics in realtime (which is rather ineffective).

    The notorious SampleToWavetable converter creates these harmonic spectrums from a given sample set.

    I also think that using a noise generator for the air sound is not the best approach - luckily you can just "blow" into a flute without creating a tone and use these samples for the "noisy" part of the signal, which is what I did with the clarinet a few centuries ago 🙂



  • @christoph-hart Well I just recorded a trumpet and trombone and took crescendo recordings of each note to test out the wavetable thingy, I was recording in a hall though so I'm just going to hope the close mics will produce nice results.


  • administrators

    If you send me a few samples, I'll also try to extract the wavetables - it's currently rather non-deterministic which settings you have to use in order to get the best results..



  • @christoph-hart Yes definitely, I'll cut them later this week.



  • This sounds interesting.....I must try it!



  • Heres a link to my test project, I don't really understand the wavetable synth so not sure if what I've done is correct. The close mic samples are in there too for anyone who wants to play around with this.

    https://www.dropbox.com/s/x7ajq9wtg8l8d8x/CrescendoTest.7z?dl=0


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