That is strange - hbargraph seems to have some kind of a gate in it that
kicks in around -35 dB.
In this modified version, you can hear that the sound is ok:
import("stdfaust.lib");
Tg = 0.4;
zi = an.ms_envelope_rect(Tg);
gain = hslider("Gain [unit:dB]",-10,-70,0,0.1) : ba.db2linear;
sig = no.noise * gain;
process = attach(sig, (sig : zi : ba.linear2db : *(0.5) :
hbargraph("test",-70,0)));
On Wed, Jul 7, 2021 at 12:59 AM Klaus Scheuermann <[email protected]> wrote:
> Hi all,
> I did some testing and
>
> an.ms_envelope_rect()
>
> seems to show some strange behaviour (at least to me). Here is a video
> of the test:
> https://cloud.4ohm.de/s/64caEPBqxXeRMt5
>
> The audio is white noise and the testing code is:
>
> import("stdfaust.lib");
> Tg = 0.4;
> zi = an.ms_envelope_rect(Tg);
> process = _ : zi : ba.linear2db : hbargraph("test",-95,0);
>
> Could you please verify?
>
> Thanks, Klaus
>
>
>
> On 05.07.21 20:16, Julius Smith wrote:
> > Hmmm, '!' means "block the signal", but attach should save the bargraph
> > from being optimized away as a result. Maybe I misremembered the
> > argument order to attach? While it's very simple in concept, it can be
> > confusing in practice.
> >
> > I chose not to have a gate at all, but you can grab one from
> > misceffects.lib if you like. Low volume should not give -infinity,
> > that's a bug, but zero should, and zero should become MIN as I mentioned
> > so -infinity should never happen.
> >
> > Cheers,
> > Julius
> >
> >
> > On Mon, Jul 5, 2021 at 10:39 AM Klaus Scheuermann <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Cheers Julius,
> >
> >
> >
> > At least I understood the 'attach' primitive now ;) Thanks.
> >
> >
> >
> > This does not show any meter here...
> > process(x,y) = x,y <: (_,_), attach(x, (Lk2 :
> vbargraph("LUFS",-90,0)))
> > : _,_,!;
> >
> > But this does for some reason (although the output is 3-channel
> then):
> > process(x,y) = x,y <: (_,_), attach(x, (Lk2 :
> vbargraph("LUFS",-90,0)))
> > : _,_,_;
> >
> > What does the '!' do?
> >
> >
> >
> > I still don't quite get the gating topic. In my understanding, the
> meter
> > should hold the current value if the input signal drops below a
> > threshold. In your version, the meter drops to -infinity when very
> low
> > volume content is played.
> >
> > Which part of your code does the gating?
> >
> > Many thanks,
> > Klaus
> >
> >
> >
> > On 05.07.21 18:06, Julius Smith wrote:
> > > Hi Klaus,
> > >
> > > Yes, I agree the filters are close enough. I bet that the shelf is
> > > exactly correct if we determined the exact transition frequency,
> and
> > > that the Butterworth highpass is close enough to the
> > Bessel-or-whatever
> > > that is inexplicably not specified as a filter type, leaving it
> > > sample-rate dependent. I would bet large odds that the differences
> > > cannot be reliably detected in listening tests.
> > >
> > > Yes, I just looked again, and there are "gating blocks" defined,
> > each Tg
> > > = 0.4 sec long, so that only ungated blocks are averaged to form a
> > > longer term level-estimate. What I wrote gives a "sliding gating
> > > block", which can be lowpass filtered further, and/or gated, etc.
> > > Instead of a gate, I would simply replace 0 by ma.EPSILON so that
> the
> > > log always works (good for avoiding denormals as well).
> > >
> > > I believe stereo is supposed to be handled like this:
> > >
> > > Lk2 = _,0,_,0,0 : Lk5;
> > > process(x,y) = Lk2(x,y);
> > >
> > > or
> > >
> > > Lk2 = Lk(0),Lk(2) :> 10 * log10 : -(0.691);
> > >
> > > but since the center channel is processed identically to left
> > and right,
> > > your solution also works.
> > >
> > > Bypassing is normal Faust, e.g.,
> > >
> > > process(x,y) = x,y <: (_,_), attach(x, (Lk2 :
> > vbargraph("LUFS",-90,0)))
> > > : _,_,!;
> > >
> > > Cheers,
> > > Julius
> > >
> > >
> > > On Mon, Jul 5, 2021 at 1:56 AM Klaus Scheuermann <[email protected]
> > <mailto:[email protected]>
> > > <mailto:[email protected] <mailto:[email protected]>>> wrote:
> > >
> > >
> > > > I can never resist these things! Faust makes it too
> > enjoyable :-)
> > >
> > > Glad you can't ;)
> > >
> > > I understood you approximate the filters with standard faust
> > filters.
> > > That is probably close enough for me :)
> > >
> > > I also get the part with the sliding window envelope. If I
> > wanted to
> > > make the meter follow slowlier, I would just widen the window
> > with Tg.
> > >
> > > The 'gating' part I don't understand for lack of mathematical
> > knowledge,
> > > but I suppose it is meant differently. When the input signal
> > falls below
> > > the gate threshold, the meter should stay at the current
> > value, not drop
> > > to -infinity, right? This is so 'silent' parts are not taken
> into
> > > account.
> > >
> > > If I wanted to make a stereo version it would be something like
> > > this, right?
> > >
> > > Lk2 = par(i,2, Lk(i)) :> 10 * log10 : -(0.691);
> > > process = _,_ : Lk2 : vbargraph("LUFS",-90,0);
> > >
> > > Probably very easy, but how do I attach this to a stereo
> > signal (passing
> > > through the stereo signal)?
> > >
> > > Thanks again!
> > > Klaus
> > >
> > >
> > >
> > > >
> > > > I made a pass, but there is a small scaling error. I think
> > it can be
> > > > fixed by reducing boostFreqHz until the sine_test is nailed.
> > > > The highpass is close (and not a source of the scale error),
> > but I'm
> > > > using Butterworth instead of whatever they used.
> > > > I glossed over the discussion of "gating" in the spec, and
> > may have
> > > > missed something important there, but
> > > > I simply tried to make a sliding rectangular window, instead
> > of 75%
> > > > overlap, etc.
> > > >
> > > > If useful, let me know and I'll propose it for analyzers.lib!
> > > >
> > > > Cheers,
> > > > Julius
> > > >
> > > > import("stdfaust.lib");
> > > >
> > > > // Highpass:
> > > > // At 48 kHz, this is the right highpass filter (maybe a
> > Bessel or
> > > > Thiran filter?):
> > > > A48kHz = ( /* 1.0, */ -1.99004745483398, 0.99007225036621);
> > > > B48kHz = (1.0, -2.0, 1.0);
> > > > highpass48kHz = fi.iir(B48kHz,A48kHz);
> > > > highpass = fi.highpass(2, 40); // Butterworth highpass:
> > roll-off is a
> > > > little too sharp
> > > >
> > > > // High Shelf:
> > > > boostDB = 4;
> > > > boostFreqHz = 1430; // a little too high - they should give
> > us this!
> > > > highshelf = fi.high_shelf(boostDB, boostFreqHz); // Looks
> > very close,
> > > > but 1 kHz gain has to be nailed
> > > >
> > > > kfilter = highshelf : highpass;
> > > >
> > > > // Power sum:
> > > > Tg = 0.4; // spec calls for 75% overlap of successive
> > rectangular
> > > > windows - we're overlapping MUCH more (sliding window)
> > > > zi = an.ms_envelope_rect(Tg); // mean square: average power =
> > > energy/Tg
> > > > = integral of squared signal / Tg
> > > >
> > > > // Gain vector Gv = (GL,GR,GC,GLs,GRs):
> > > > N = 5;
> > > > Gv = (1, 1, 1, 1.41, 1.41); // left GL(-30deg), right GR
> > (30), center
> > > > GC(0), left surround GLs(-110), right surr. GRs(110)
> > > > G(i) = *(ba.take(i+1,Gv));
> > > > Lk(i) = kfilter : zi : G(i); // one channel, before summing
> > and before
> > > > taking dB and offsetting
> > > > LkDB(i) = Lk(i) : 10 * log10 : -(0.691); // Use this for a
> mono
> > > input signal
> > > >
> > > > // Five-channel surround input:
> > > > Lk5 = par(i,5,Lk(i)) :> 10 * log10 : -(0.691);
> > > >
> > > > // sine_test = os.oscrs(1000); // should give –3.01 LKFS,
> with
> > > > GL=GR=GC=1 (0dB) and GLs=GRs=1.41 (~1.5 dB)
> > > > sine_test = os.osc(1000);
> > > >
> > > > process = sine_test : LkDB(0); // should read -3.01 LKFS -
> > high-shelf
> > > > gain at 1 kHz is critical
> > > > // process = 0,sine_test,0,0,0 : Lk5; // should read -3.01
> > LKFS for
> > > > left, center, and right
> > > > // Highpass test: process = 1-1' <: highpass, highpass48kHz;
> > // fft in
> > > > Octave
> > > > // High shelf test: process = 1-1' : highshelf; // fft in
> Octave
> > > >
> > > > On Sat, Jul 3, 2021 at 1:08 AM Klaus Scheuermann
> > <[email protected] <mailto:[email protected]>
> > > <mailto:[email protected] <mailto:[email protected]>>
> > > > <mailto:[email protected] <mailto:[email protected]>
> > <mailto:[email protected] <mailto:[email protected]>>>> wrote:
> > > >
> > > > Hello everyone :)
> > > >
> > > > Would someone be up for helping me implement an LUFS
> > loudness
> > > analyser
> > > > in faust?
> > > >
> > > > Or has someone done it already?
> > > >
> > > > LUFS (aka LKFS) is becoming more and more the standard
> for
> > > loudness
> > > > measurement in the audio industry. Youtube, Spotify and
> > broadcast
> > > > stations use the concept to normalize loudness. A very
> > > positive side
> > > > effect is, that loudness-wars are basically over.
> > > >
> > > > I looked into it, but my programming skills clearly
> > don't match
> > > > the level for implementing this.
> > > >
> > > > Here is some resource about the topic:
> > > >
> > > > https://en.wikipedia.org/wiki/LKFS
> > <https://en.wikipedia.org/wiki/LKFS>
> > > <https://en.wikipedia.org/wiki/LKFS
> > <https://en.wikipedia.org/wiki/LKFS>>
> > > <https://en.wikipedia.org/wiki/LKFS
> > <https://en.wikipedia.org/wiki/LKFS>
> > > <https://en.wikipedia.org/wiki/LKFS
> > <https://en.wikipedia.org/wiki/LKFS>>>
> > > >
> > > > Specifications (in Annex 1):
> > > >
> > >
> >
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> >
> > >
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> >>
> > > >
> > >
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> >
> > >
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> > <
> https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-3-201208-S!!PDF-E.pdf
> >>>
> > > >
> > > > An implementation by 'klangfreund' in JUCE / C:
> > > > https://github.com/klangfreund/LUFSMeter
> > <https://github.com/klangfreund/LUFSMeter>
> > > <https://github.com/klangfreund/LUFSMeter
> > <https://github.com/klangfreund/LUFSMeter>>
> > > > <https://github.com/klangfreund/LUFSMeter
> > <https://github.com/klangfreund/LUFSMeter>
> > > <https://github.com/klangfreund/LUFSMeter
> > <https://github.com/klangfreund/LUFSMeter>>>
> > > >
> > > > There is also a free LUFS Meter in JS / Reaper by
> > Geraint Luff.
> > > > (The code can be seen in reaper, but I don't know if I
> > should
> > > paste it
> > > > here.)
> > > >
> > > > Please let me know if you are up for it!
> > > >
> > > > Take care,
> > > > Klaus
> > > >
> > > >
> > > > _______________________________________________
> > > > Faudiostream-users mailing list
> > > > [email protected]
> > <mailto:[email protected]>
> > > <mailto:[email protected]
> > <mailto:[email protected]>>
> > > > <mailto:[email protected]
> > <mailto:[email protected]>
> > > <mailto:[email protected]
> > <mailto:[email protected]>>>
> > > >
> > >
> > https://lists.sourceforge.net/lists/listinfo/faudiostream-users
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users>
> > >
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users>>
> > > >
> > >
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users>
> > >
> > <https://lists.sourceforge.net/lists/listinfo/faudiostream-users
> > <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
>
--
"Anybody who knows all about nothing knows everything" -- Leonard Susskind
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