Actually I don't know where the change~ object is from - I've nver seen t before. I would just use biquad~ 0 0 1 -1 0 (assuming that change~ simply ubtracts the previous sample from teh current one as I guessed from the patch :)
M On Sun, Apr 27, 2014 at 03:40:01PM +0200, Simon Iten wrote: > ok tried to upsample the whole thing (after the osc~) and now change~ does > nothing anymore… it just spits out the same square wave i feed in…clues? > > > On 27 Apr 2014, at 13:05, Simon Iten <itensi...@gmail.com> wrote: > > > 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
