Hi, Dario, I, btw, ended up using blti filter from your edge of chaos library. Good collection. No noises just does the job. About precision, I use default settings by running faust2lv2 script (I guess that runs with single precision)
пт, 18 дек. 2020 г., 14:26 Dario Sanfilippo <sanfilippo.da...@gmail.com>: > Hi, Alik. > > Other people will be able to give you a more exhaustive answer but it > might be caused by quantisation of the coefficients making the filter a bit > unstable. Are you working in double precision? > > Even in single precision, the biquad filter > <https://webaudio.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html> below > seems to be more stable, although it may be computationally more expensive. > > Ciao, > Dario > > declare name "nstest"; > import("stdfaust.lib"); > fb = hslider("feedback",0,-1,1,0.001); > process(x,y) = x,y : (+ : ef.cubicnl_nodc(drive, offsetL)) ~ * (fb), (+ : > ef.cubicnl(drive, offsetR)) ~ * (fb) > //: fi.highpass(2, HPFfreq), fi.highpass(2,HPFfreq) with{ > : highpass(HPFfreq), highpass(HPFfreq) with{ > HPFfreq = hslider("HPF freq",50, 20,10000,0.01): si.smoo; > drive = hslider("drive",0,0,1,0.001); > offsetL = hslider("offsetL",0,-1,1,0.001); > offsetR = hslider("offsetR",0,-1,1,0.001); > } ; > highpass(cf, in) = biquad(a0, a1, a2, b1, b2, in) > with { > q1 = .707; > alpha = sin(w(cf)) / (2 * q1); > norm = 1 + alpha; > a0 = ((1 + cos(w(cf))) / 2) / norm; > a1 = -1 * (1 + cos(w(cf))) / norm; > a2 = ((1 + cos(w(cf))) / 2) / norm; > b1 = cos(w(cf)) * -2 / norm; > b2 = (1 - alpha) / norm; > w(f) = 2 * ma.PI * f / ma.SR; > biquad(a0, a1, a2, b1, b2, x) = fir : + > ~ iir > with { > fir = a0 * x + a1 * x' + a2 * x''; > iir(fb) = -b1 * fb - b2 * fb'; > }; > }; > > On Fri, 18 Dec 2020 at 07:14, Alik Rustamoff <alikthen...@gmail.com> > wrote: > >> Hi, >> >> when I use fi.highpass in the following example I get weird noise at the >> output if when offset parameters are not 0 and fighpass frequency is less >> than 70hz. Removing the highpass filter of raising cutoff freq removes the >> noise. Should it be like that? what is the reason? >> >> >> declare name "nstest"; >> >> import("stdfaust.lib"); >> >> >> fb = hslider("feedback",0,-1,1,0.001); >> >> >> process(x,y) = x,y : (+ : ef.cubicnl_nodc(drive, offsetL)) ~ * (fb), (+ : >> ef.cubicnl(drive, offsetR)) ~ * (fb) >> >> : fi.highpass(2, HPFfreq), fi.highpass(2,HPFfreq) with{ >> >> >> HPFfreq = hslider("HPF freq",50, 20,10000,0.01): si.smoo; >> >> drive = hslider("drive",0,0,1,0.001); >> >> offsetL = hslider("offsetL",0,-1,1,0.001); >> >> offsetR = hslider("offsetR",0,-1,1,0.001); >> >> } ; >> >> >> _______________________________________________ >> Faudiostream-users mailing list >> Faudiostream-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/faudiostream-users >> > > > -- > Dr Dario Sanfilippo > http://dariosanfilippo.com >
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