Thanks for testing, Julius. I'll see if I can get the limiter in Zölzers book in the next few days and I'll do another PR with that if I manage.
I've also just added the stereo version of the other limiter: https://github.com/grame-cncm/faustlibraries/pull/37/commits/12763e053c7fb84371cfaa17bf89f2c9a1821418 . Dario On Sat, 23 May 2020 at 22:10, Julius Smith <[email protected]> wrote: > Since the delay for the input path is our "lookahead delay", setting it to > the attack time sounds ideal to me. > > On Sat, May 23, 2020 at 12:54 PM Julius Smith <[email protected]> > wrote: > >> I've been happy with limiter_1176_R4_mono, but I'll now compare it >> to limiter_basic_mono, by offering both with a checkbox to choose, and >> listen for the difference (see attached test program). >> My limiter needs are merely to turn hard-clipping into soft-clipping for >> voice and tonal instruments. >> >> I believe the "limiter slope" is the compression ratio to use above >> threshold (4 in the case of limiter_1176_R4_mono). >> >> >> >> On Sat, May 23, 2020 at 3:57 AM Dario Sanfilippo < >> [email protected]> wrote: >> >>> >>> Hi, Julius. I understand. >>> >>> See this: >>> https://github.com/grame-cncm/faustlibraries/pull/37/commits/8f1bd1ba78ff4919637a9bfd9ec635225cfb4ba5 >>> . >>> >>> That's a basic lookahead limiter based on this post: >>> http://iem.at/~zmoelnig/publications/limiter/. >>> >>> This algorithm is even simpler: it just calculates the amplitude profile >>> using a peak-holder and it smooths out attack and release using, >>> respectively, a one-pole lowpass and a peak envelope. Those filters are >>> based on the e^(-2pi) time constant (Chamberlin's design for 1pole >>> filters). This time constant works in this case as the input delay is set >>> by the attack of the system, so the amplitude profile to calculate the >>> scaling factor roughly reaches its maximum after the attack time. The >>> release time might be changed with some other constant, if more appropriate. >>> >>> Personally, I'm satisfied with it but I also designed it for my specific >>> case, that is, stability in self-oscillating systems. I needed a cheap >>> solution with low distortion; I'm not sure if this works well for most >>> applications. People are invited to test and comment. >>> >>> I had a look at Zölzer's limiter, pp 231 and 232, but I don't quite >>> understand what "the slope of the limiter" is. What do you think? He >>> also doesn't mention a specific delay for the input path but I'd assume >>> that it is the same as the attack time. >>> >>> Dario >>> >>> >>> On Sat, 23 May 2020 at 01:38, Julius Smith <[email protected]> >>> wrote: >>> >>>> Hi Dario, >>>> >>>> Yes the current limiter is simply a compressor, using the usual >>>> (causal) amplitude follower, that applies a ratio of 4 starting halfway up >>>> (-6 dB). Please feel free to make us a new one that is nicer! >>>> >>>> Julius >>>> >>>> On Fri, May 22, 2020 at 11:19 AM Dario Sanfilippo < >>>> [email protected]> wrote: >>>> >>>>> Hello, list. >>>>> >>>>> Am I missing something with co.limiter_1176_R4_mono? I see that there >>>>> is no lookahead mechanism inside and, if I test it with a song at +60dB, >>>>> the output of the limiter is rather consistently at about 25 dB. >>>>> >>>>> Best, >>>>> Dario >>>>> _______________________________________________ >>>>> Faudiostream-users mailing list >>>>> [email protected] >>>>> https://lists.sourceforge.net/lists/listinfo/faudiostream-users >>>>> >>>> -- >>>> "Anybody who knows all about nothing knows everything" -- Leonard >>>> Susskind >>>> >>> >> >> -- >> "Anybody who knows all about nothing knows everything" -- Leonard Susskind >> > > > -- > "Anybody who knows all about nothing knows everything" -- Leonard Susskind >
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