[tim] >question for the reader: in order to completely prevent foldover >distortion, how much do you have to upsample for a tanh waveshaper (a >processor that introduces infinite harmonics)? To _completely_ prevent aliasing of a harmonic series extending infinitely is obviously impossible when you're limited to a finite oversampling ratio. Very slightly more practically, eventually the generated harmonics will drop below the noise floor. Where that limit lies is of course specific to your particular setup and quality demands, and strongly dependent on the amplitude of the signal to be waveshaped. As the input amplitude rises, the tanh output will approach a square wave, with harmonic amplitudes following the well-known 1/n series. Assuming this to be a desired outcome of the manipulation, a noise floor of just 72 dB results in n = 10**(72/20.) = 3981.0717055349733 and for a noise floor of 90 dB it's 10**(90/20.) = 31622.776601683792 etc. In the end, I think it's safe to assume such oversampling ratios intractable for practical purposes. Cheers, Tim _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
