Something here to look at possibly ? https://x42-plugins.com/x42/x42-meters
With the source code : https://github.com/x42/meters.lv2 Stéphane > Le 13 mai 2022 à 07:58, Julius Smith <julius.sm...@gmail.com> a écrit : > > > Ok, so what I find strange is that the official specs paper does not > > specify the exact filter... > > I know! That really surprised me as well. The first stage in the spec (Rec. > ITU-R BS.1770-4 5) is clearly a shelf filter, and that could be specified > generically for any sampling rate. Instead they give us a table of filter > coefficients for 48 kHz sampling! They note: "Implementations at other > sampling rates will require different coefficient values, which should be > chosen to provide the same frequency response that the specified filter > provides at 48 kHz". Unfortunately that is not possible! (But it can be > approximated.) We thus have to GUESS the shelf parameters (or spherical > head size and air parameters, etc., if deriving it that way). The second > stage is a simple 2nd-order highpass filter, probably a Butterworth (the > zeros were surely mapped from analog infinity), but again we only get a table > of numbers to guess from. I did note that Butterworth roll-off was a bit too > fast below cutoff, so maybe it's a Bessel filter. WHY DON'T THEY JUST TELL > US? > > Zooming out, given this level of extremely simple yet poorly specified signal > processing, and the crudeness of the loudness model itself (see Zwicker, > Moore, Glasberg, Baer, et al. for way better loudness modeling), I don't take > the details as anywhere near "gospel", and I consider my > guesses/approximations so far to be more than adequate. However, I can also > see the value of matching other LUFS meters as closely as possible, and of > course there could be some other bug somewhere that's causing the > discrepancies you are seeing. We should at least determine where the > mismatches are coming from for sure, and if there are no bugs, try to tweak > them out. > > Cheers, > - Julius > > > On Thu, May 12, 2022 at 2:00 PM Klaus Scheuermann <kla...@posteo.de> wrote: > Ok, so what I find strange is that the official specs paper does not > specify the exact filter... > > I set up faustlive today with atom as an editor - pretty happy with it > for now and -double precision works :) > > Good night! > Klaus > > On Thu, 2022-05-12 at 13:12 -0700, Julius Smith wrote: > > I see that the reaper loudness meter is LGPL. Since I require MIT- > > level license freedom in the Faust world (for my consulting work), I > > won't look at that. > > It sounds like we want to tweak the filter designs to give -18 LUFS > > for the tones you shared from Reaper. > > The main unknown parameter, as I recall, is the shelf transition > > frequency, but one could also try to compensate the frequency-warping > > from the bilinear transform. > > > > I compile Faust at the command line, by the way: > > > > faust2caqt -double tlufs2.dsp > > open tlufs2.app > > > > - Julius > > > > On Thu, May 12, 2022 at 3:14 AM Stéphane Letz <l...@grame.fr> wrote: > > > > > > > double precision is not available in faustide, right? > > > > > > Yes still not. > > > > > > > I will try and > > > > install faustlive today. > > > > > > Yes. You can use « -double » in FL «Compilation / FAUST Compiler > > > Options » > > > > > > > Or would you recommend some other ide > > > > solution? (I am on arch linux.) > > > > > > > > > > Stéphane > > > > > > > > > > > > _______________________________________________ > > > Faudiostream-users mailing list > > > Faudiostream-users@lists.sourceforge.net > > > 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 _______________________________________________ Faudiostream-users mailing list Faudiostream-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/faudiostream-users
