[RDP] Meters vs. dBFS(?)

Qtronix qtronix at halden.net
Sat Mar 28 13:43:40 EDT 2009

In other words, I'd be better of using a normalizing value of -3 to get
the sound to a ordinary volume level in players, and ignore the levels
constantly on the red and waveform view in meters-editor in all black?
Rivendell is the only audiopackage I've ever had this problem in.

On lør, mars 28, 2009 18:36, Dan Mills wrote:
> On Sat, 2009-03-28 at 17:58 +0100, Qtronix wrote:
>> Hi all!
>> Sorry if this is a stupid self-explainable thing, but I don't understand
>> this problem with the meters showing a whole different dB than the
>> normalize-dB function in the import dialog, and others.
>> My mp3-files on the Windows machine are imported and processed through
>> dBpowerAmp with a normalize-value of -3 dB. When I import into Rivendell
>> after that, however, the meters yell through the roof and I have to use
>> a
>> normalize value in import of -19 dBFS to get a 'peak' of -3 = (-16 - 3)
>> on
>> the meters. Why is this?
> Metering, here be a can of wyrms...
> SMPTE calls for a nominal RMS reference level of +4dbu = -20dbFS as
> being equal to 0 VU on a standard VU meter. Rivendell more or less
> follows this standard (I don't think the integration times are quite
> correct, but it is close).
> Broadcast metering is almost never done on digital peak meters (at least
> not in the studio, engineering may have some use for them), and as I say
> digital full scale is either 20db (SMPTE) or 14db (EBU) above nominal
> working level (EBU defines it as 18db above 0dbm, but almost everyone
> works around +4).
> This is done because we are working in a production as opposed to
> distribution environment and headroom is needed because we cannot know
> in advance exactly how high peaks from microphones and the like will be.
> Distribution media of course can be pushed right the way to the limit,
> so will normally need to be turned down quite a bit on import.
> The differences in required headroom probably tie into the fact that the
> type II PPM meters used in broadcast in the EU are semi peak reading,
> where a VU is something close to average reading.
> Rivendell has (almost) VU meters with the associated integration time so
> they will read zero for a steady state -20dbFS tone and general
> experience around here is that normalising a rip to around -13dbFS gives
> correct results (the normaliser is peak responding).
> With modern converters there is generally no need to get anywhere near
> 0dbFS as the noise floor is almost a complete non issue.
> Clear as mud?
> Regards, Dan.
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