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Originally Posted by
FabienTDR
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The main difference between the basic LUFS case and RMS is nothing else than a well specified freq weighting.
LUFS is a scale. Loudness Units (relative to) Full Scale. Exactly like dBFS, or Decibels (relative to) Full Scale.
LUFS has no specified frequency weighting, exactly as dBFS has no specified frequency weighting. It's a metering scale.
Fabien, would you write "The main difference between the basic dBFS case and RMS is nothing else than a well specified freq weighting"?
I would hope not, because that makes no sense.
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It consists of a high pass + a little boost at HF (so called k-weighting) before the RMS calculation.
LUFS has no K-weighting and has no RMS calculation. Again, it is merely a scale, just like dBFS. -18LUFS is the same as -18dBFS without K-weighting.
Insert a 1kHz tone aligned to -18dBFS and look at the level on a LUFS meter: -18LUFS. No K-weighting used in that measurement, no weighting filter.
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Most ppl using RMS meters also use some form of freq weighting. a, b, k, whatever.
While Sound Pressure Level meters may use A, B and C weighting, RMS metering does not have a weighting filter.
RMS only gives electrical information about a signal, and contrary to popular belief does not actually measure perceived Loudness. RMS as a measure of Loudness is about as useful as using dBFS to measure the loudness of a signal.
RMS is not the same as EBU R128.
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Another relevant difference comes into play in certain longer term EBU modes (Short Term, Integrated and Loudness Range), they use special mechanisms to ignore program pauses otherwise distorting the RMS value. For music production, this "freezing" often makes no sense and the "Momentary" mode is the main choice. This mode is a simple k weighted RMS.
No pauses are ignored in the measurement, but well a -70LUFS threshold is employed, and certain transients are ignored such as gunshots and loud crashes that may skew the measurement. The LFE is also ignored but this forms part of the frequency weighting, where if included the LFE would require +10dB of compensation. There is also channel weighting in the measurement which means 5.1 metering is weighted differently to NHK22.2 metering.
I'm surprised that you still find understanding the basic concepts of EBU R128 so difficult, while seemingly being more than capable of understanding advanced math.