---------- Forwarded message --------- From: Dario Sanfilippo <sanfilippo.da...@gmail.com> Date: Sun, 11 Jul 2021 at 11:43 Subject: Re: [Faudiostream-users] lufs loudness analyser To: Julius Smith <julius.sm...@gmail.com> Cc: Dario Sanfilippo <sanfilippo.da...@gmail.com>, Stéphane Letz < l...@grame.fr>, Faust users <Faudiostream-users@lists.sourceforge.net>
Hi, Julius. Sure, I now see what you mean about delay lines, but I'd guess that the required sums would make it pretty heavy even if it compiled quickly. On Sun, 11 Jul 2021 at 09:07, Julius Smith <julius.sm...@gmail.com> wrote: > On third thought, I now see how subtraction is not exact (it depends on > what shifts are needed at addition/subtraction time, which can differ). > The idea is to effectively never round, only summation and the > delayed subtraction, so that subtraction after the delay is exact, avoiding > a TIIR requirement. > It should be possible to accomplish this by converting to fixed-point, > etc. I'm back to thinking about the TIIR case... > > On Sat, Jul 10, 2021 at 12:02 PM Julius Smith <julius.sm...@gmail.com> > wrote: > >> On second thought, I don't see at the moment how anything can go wrong >> with this: >> >> sliding_mean(durSamples) = (+ ~ _) - @(int(durSamples)) : /(durSamples); >> > This appears to have two inputs, is it possible that something is missing? Just to be sure that I understand, when you say to never round, do you imply to never use an integrator? And that also implies using N_w - 1 sums for a sliding window of N_w samples? As I suggested earlier, putting the integrator after the difference would at least guarantee that the integrator shifts by only N_w * K if the input is a constant K, rather than indefinitely as in the case of the integrator being first. That's still not a final solution but it does improve things. Are embedded platforms the main reason why double-precision wouldn't be a suitable solution? Ciao, Dario >
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