Audio standards

[WarrickF]

Hi All,

I'm reading some specs for TV and was hoping someone could help me understand \ check that my footage is within these bounds.

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1. For digital:
Tone average level must be -20 dBFS.
Content average levels must be -20 dBFS.
Content peak must not exceed -10 dBFS.
2. For analog:
Tone must be 0 dB @ +4 Ref.
Average levels must be between -4 dB and 0 dB @ +4 Ref.
Peak must not exceed +3 dB.
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I'm using Vegas Movie Studio Platinum and Sony Sound Forge 8 and would like to check that I'm within these limits.

Almost all my tools report sound as dB. Why is digital measured in dBFS and how can I check these values?

[Erik Bien]

I'm out (http://en.wikipedia.org/wiki/DBFS). Anybody?

[fstopopen]

okay, I'm sure I am going to sound retarted here, but this is what I have always done in the past. (and without sending my resume, let it be said that I have A LOT of experiance in television production AND audio production) When you view a meter with both paradigms, the analog numbers and the digital numbers, -20db on the digital scale is EXACTLY the same as 0db on the analog scale. For some reason most NLE's use the analog numbering system. So I try to PEG "0" but not even a little bit above. That will translate to the -20 you are looking for on the digital side. I'm sure there are some technical reasons or explinations, but in practical terms, just punch it to zero.

drake

[joachim]

correct me if i'm wrong.

0dB analog is a standard, analog equipment leaves some room to go over this point, without crucial damage to the sound. sometimes going over the 0 is done on purpose to have some natural analoge compression.

a digital signal doesn't allow a signal to go over the digital 0 level, without totaly damage the sound (clicks, ...).

so the analoge 0 (db) is set according a digital -20 (dBfs) to leave a safe headroom while recording.

for film, with all the recording sound under control, a -15 dBfs is offtened used, where in recording of ENG/EFP for tv, with the use of limiters, you can use -18 dBfs.

all these values are set using a 1000 Hz reference tone.