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!

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