DB level discrepancy

[Joseph Owens]

[Kyle Haskett] “I am downloading on a set with an audio engineer who is using the Sound Devices 664 recorder. When he records his 1K on set, the mixer tells him it is recording at 0dB. When I bring the .wav files into FCP or ProTools, the 1K reads at -20dB. “

The issue is with the definition of “0” dB.

Your field recorder is most likely set to conform with “broadcast” “0” VU which is actually +4dBu, which corresponds to the “0” found on the meters on tape recorder faceplanes.

This in fact corresponds to -20 dBfs which is what you are seeing on the Final Cut timeline… which is also confusingly calibrated to reflect a “0” of -12 dBfs…

Yes, it is a mess.

jPo

“I always pass on free advice — its never of any use to me” Oscar Wilde.

[Kyle Haskett]

Okay that sounds like a promising lead. What should I ask him to set his recorder to, if not Broadcast? What will get us back on track?

Thanks for your help with this.

[Shane Ross]

Note that broadcast peak levels are -12db. And most networks want tone to be at -20db. Just to boost your levels in your timeline So they hover around -12 But not go over, and you should be fine

Shane
Little Frog Post
Read my blog, Little Frog in High Def

[Joseph Owens]

[Shane Ross] “broadcast peak levels are -12db.”

“Peak levels” being the operative term…

What I was previously referring to is the bars&tone VU level of 0=-20… just to dot the i.

You are, of course free to record at any dynamic level you want — in the field. I often get music tracks that are “full range”, which of course, have to be cranked way down to get under the -12 peak threshold. Be aware that the FCC is levying fines now under volumetric uniformity laws. All that complaining about the commercials blaring away and destroying the mood eventually held sway, I guess.

Be careful about recording too low and cranking the SPL up, though. As with all things sampled/digital, you run the risk of amplifying quantizing noise, the same way we get banding in 8-bit video.

The other gotcha is that as overall levels get cranked up and down, the overall relative mix between dialogue, music and effects will change perspective, and what, at high levels, sounds evenly distributed, will get crowded with some elements starting to overwhelm or get buried by others. Thats the beauty and mystery of sound mixing.

jPo

“I always pass on free advice — its never of any use to me” Oscar Wilde.

[Daniel E]

What would make them unusable is the actual recording is too low. The peaks should be hot enough to get a good volume on the recording. In the set up described you should see audio peaking over the -20 line consistently. If everything is below -20 then you have a lot of boosting to do. I have found this with sound men who are too worried about distortions from peaks and not worried enough about overall record level. Doubling the good tracks is not unusual as a way to boost the low recordings if the 12 db boost per track in FCP is not enough. If the audio is clean but low this is a way to deal with low signals.

Daniel Epstein
Gold Teleproductions, Inc
New York, NY
http://www.goldtele.com