Thanks for sharing this, Orm. Is there no bibliography at all about this implementation?
Cheers, Dario On 29 October 2017 at 05:21, Orm Finnendahl < orm.finnend...@selma.hfmdk-frankfurt.de> wrote: > Hi, > > concerning avoiding aliasing in the first place, here are > abstractions for generating bandlimited versions of the most popular > analog waveforms I developed for a seminar some time ago: > > https://www.selma.hfmdk-frankfurt.de/selmafile/f/9eed9b01b9/ > > Open "bl-oscil-example.pd" to see how to use it. Note that the rect~ > oscillator has an additional pulse-width input. > > The patch uses wavetable lookup with 128 wavetables of an ideal > bandlimited sawtooth with partials 1 through 127 for each wavetable > respectively and the non-bandlimited phasor wavetable for the > 128th. In the oscillator the wavetable is determined on each phasor > wraparound based on frequency. > > At a samplerate of 44100 Hz this gives no aliasing above 173.6 Hz > which my ear considered good enough (for 173.6 Hz the aliasing happens > at about -42 dB for the first aliased partial relative to the first > partial, diminishing by 6 dB per Octave downwards). Increase the > number of wavetables for better signal/aliasing ratio. > > As this method gives ideal results and is as efficient as it can get > it's strange I haven't found it on my web research of this topic, but > maybe I've looked at the wrong places. In times when wavetable lookup > synthesis has regained popularity in commercial soft-synths I could > well imagine companies like NI or Ableton also use this or simlar > methods under the hood of the oscils for their standard analogue > waveforms. > > -- > Orm > > Am Samstag, den 28. Oktober 2017 um 19:24:00 Uhr (-0200) schrieb > Alexandre Torres Porres: > > 2017-10-28 18:30 GMT-02:00 cyrille henry <c...@chnry.net>: Its very > > different : a sawtooth have an infinite number of harmonics, but > > > not a signal distorted with tanh. And a band limited sawtooth is > > lot's > better (from sound and performance perspective) than an > > oversampled / > filtered phasor. > > > > > > > yeah, I know it's got infinite harmonics, and that a band-limited > > oscillator is better. But this is also because I'm using this to measure > > the efficiency of the anti-aliasing filter, how good it works and all > > > > cheers > > > _______________________________________________ > > Pd-list@lists.iem.at mailing list > > UNSUBSCRIBE and account-management -> https://lists.puredata.info/ > listinfo/pd-list > > > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> https://lists.puredata.info/ > listinfo/pd-list >
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