dBFS
some comments:
1) Any meter can be calibrated to read the RMS value of a steady sine
wave. i.e. Simpson 260 reads the RMS value of a steady sine wave but
is not true RMS responding.
2) True RMS meters will read the RMS value of any (within its
limitation) STEADY waveform i.e. a steady square wave or steady
triangle wave etc.
3) There is no standardized reading of RMS for a time varying waveform
like real audio, as has been mentioned the integration time and
weighting needs to be defined and I don't think there is such a
standard?
4) dBFS meters on most digital equipment are not RMS or average but
are more peak reading, that (try to) capture the peak value of even an
individual sample.
5) Most of us given a choice I suspect would choose to a dual meter
system, one that shows both the peak so that we can be assured there
is no clipping combined with another display that show the LOUDNESS.
LOUDNESS is not the same as RMS. There are some standards on metering
of loudness of audio.
Those are the two reasons we meter audio, to assure the equipment is
not overloaded even on peaks and for some gauge of the loudness.
Note: As has been discussed in another thread on intersampling peaks,
even the definition of peak is ambiguous, the peak SAMPLE value is not
always the same as the peak value of the reconstructed waveform. I
don't know, but I suspect that most peak meters calibrated in dBFS are
reading the peak SAMPLE value and not the true wavefomr peak therfore
the true audio peak can be even higher. I don't know if this is what
Randy is trying to get at or not.
Mark
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