crosspost! sorry about the noise. thanks for the inputs i will try to to this. not sure if i can. otherwise i will ask back if that’s ok! On 27 Apr 2014, at 13:03, Simon Iten <itensi...@gmail.com> wrote:
> so if i would measure at the peak of the sawtooth and would upsample inside > the pd patch, i would get higher resolution, right? > > any ideas how i can measure at the peak? (using the rpole output on both > samphold inputs does not work and delaying one of them is also not working) > > which > > i would highly recommend you try this method with your gk-3 equipped guitar > (one for each string) since you only have to cover a two octave range per > string the error is tolerable. (you can add an offset to make it fit) > On 27 Apr 2014, at 12:56, Miller Puckette <m...@ucsd.edu> wrote: > >> That is an excellent, witty way to measure pulse withs using >> only tilde obects - my hat's off to you. >> >> The methond only has limited accuracy since its measurement is in >> samples. For instance, a 1/2 cycle of a 440-hz. tone at 44.1 kHz is >> only 50 samples, so there's only 2% accuracy. That's about 1/3 of a >> half tone (30-ish cents) which would sound horribly out of tune. >> >> There's an alternative sine-to-sawtooth recipe described here: >> >> http://msp.ucsd.edu/Publications/icmc10.pdf >> >> This is the basis of my guitar processing patch, smeck, but should be more >> broadly useful. But it has its own limitations: the sawtooth you get out >> is wiggly if the input sn't a pure sinusoid. >> >> There's also the possibility of simply pitch tracking with sigmund~. Use >> a maximum frequency around 6000 and a maximum of 6 partals (default 50!) >> for best results. >> >> cheers >> M >> >> On Sun, Apr 27, 2014 at 11:27:33AM +0200, Simon Iten wrote: >>> dear list, >>> >>> i have a strange problem with my “sinetosawtooth” patch. >>> >>> it is basically a version of the pitch to voltage conversion used in the >>> old gr300 guitar synths from roland. >>> >>> i cut out all the clutter to make it easier to look at and understand. (cut >>> out the adaptive filtering at the input since i use a sine wave for this >>> example and not a guitar string) >>> >>> here is how it works (or should): >>> >>> -an input signal gets amplified by a large factor and clipped. this squares >>> the input. >>> >>> -the square wave is converted to pulses. >>> >>> -the pulses from the rising of the square wave are used to set and reset an >>> accumulating filter (rpole~) >>> >>> this results in a sawtooth wave that varies in amplitude depending on the >>> frequency of the input. >>> >>> -a sample and hold samples the peak of the sawtooth and holds it until the >>> next peak occurs. this, after a conversion gives us the input frequency. >>> yeah! >>> >>> in the example patch i used the falling edges of the square wave to >>> trigger the sample and hold. this samples the sawtooth amplitude after half >>> the rising. (this is also why i have 22050 in fexpr~ and not 44100) i >>> could not figure out how to sample the peak of the sawtooth, so suggestions >>> here are very welcome. >>> >>> now to the problem: >>> >>> the extracted frequency does not exactly correspond to the input frequency. >>> it is pretty close at low frequencies but gets worse at higher frequencies. >>> the factor is not constant. at even higher frequencies (around 5000 hertz) >>> the reported frequency gets totally out of control. >>> >>> i first thought this is because the samphold~ object is inaccurate. but i >>> then saw that the sawtooth wave from the rpole~ object has no constant >>> amplitude even with the input frequency not changing. so it seems that >>> either rpole~ or change~ is not accurate. >>> >>> or the problem is that i sample in the middle of the rising and not at the >>> top ( as described earlier) >>> >>> attached the sinetosawtooth patch. set your sound card to 44100 or change >>> the 22050 in fexpr~ to half the sampling frequency. >>> >>> i would really appreciate if somebody could have a look at this, >>> >>> thanks, simon >>> >> >> >>> _______________________________________________ >>> Pd-list@iem.at mailing list >>> UNSUBSCRIBE and account-management -> >>> http://lists.puredata.info/listinfo/pd-list >> > _______________________________________________ Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
