Broadcast Specs Questions

[Miggy Sanchez]

Hi there

Our small video production unit is trying to prepare itself for all aspects of TVC production. We have been informed that the following audio specs must be adhered to:

1. The digital audio scale must not exceed –7.8db.
2. Average levels not to exceed 0 VU (analog meters). Not to exceed or be sustained at +3db.

While I recently earned my first credit as a 'Sound Recordist' on a short-film, I am very much a passionate newbie learner.

I am unsure what 'digital audio scale' means. Does it perhaps mean that the audio must simply not exceed -7.8db at any one point during the TV commercial? I assume that we would need to capture audio the usual way (that is, following core principles of sound recording), and then adjust the levels in our NLE so that nothing peaks over -.7.8db. Is that somewhere in the ball park, or am I in the dugout?

As to the second specification, I assume that it does not pertain to us as we are recording digitally?

Any advice/suggestions/links etc. always APPRECIATED.

Cheers
Miggy

[Steve House]

Originally Posted by Miggy Sanchez

...
Our small video production unit is trying to prepare itself for all aspects of TVC production. We have been informed that the following audio specs must be adhered to:

1. The digital audio scale must not exceed –7.8db.
2. Average levels not to exceed 0 VU (analog meters). Not to exceed or be sustained at +3db.
...
I am unsure what 'digital audio scale' means. Does it perhaps mean that the audio must simply not exceed -7.8db at any one point during the TV commercial?...?

That's exactly whay it means ... nothing in the program can peak higher than -7.8dBFS

As to the second specification, I assume that it does not pertain to us as we are recording digitally?...

Not correct. They're referring to analog metering, not analog recording, and it still applies to digital recording. A conventional averaging VU meter is an analog meter. The normal alignment point in North America is 0VU=-20dBFS for a sinewave tone. What this spec is getting at is the "dialnorm" specs that are being legislated to reduce the wild fluctuations in volume when going from one program to another or from program to commercial and back. What they are saying is that the program levels averaged over time when measured on a conventional VU meter should be 0VU and no momentary excursion above average can exceed +3dBVU.

[John Willett]

Originally Posted by Steve House

The normal alignment point in North America is 0VU=-20dBFS for a sinewave tone.

Yes, and the EBU in Europe have 0VU = -18dBFS.

Though things are changing with the new EBU-R128 Loudness Meter spec..

The new broadcast standard is that levels should be -23LUFS (Loudness Units Full Scale)

I think the USA have now made this a legal requirement.

This means that programmes and ads do not have horrible perceived level variations between them because the ads are heavily compressed to sound "louder" - in fact, with the new method, heavily compressed stuff is likely to sound worse and hopefully we will all get back to being sensible again.

I have heard a classical recording with wide dynamic range and a heavily compressed heavy metal track both set to -23LUFS sounding correct without a nasty level change when going from one to the other - so it works.

[Rick Reineke]

"the following audio specs must be adhered to"
This pertains to program submissions, and has little or nothing to do with the acquisition recording levels.

The US 'CALM' loudness act as Steve mentioned will hopefully keep level variations less annoying. The broadcaster has the final responsibility for adhering to it.

[Miggy Sanchez]

Originally Posted by Steve House

That's exactly what it means ... nothing in the program can peak higher than -7.8dBFS

Cheers for that.

Originally Posted by Steve House

What they are saying is that the program levels averaged over time when measured on a conventional VU meter should be 0VU and no momentary excursion above average can exceed +3dBVU.

A conventional VU meter?
I'm guessing that the VU meter and the process of measurement is NOT part of my NLE?

[Steve House]

Originally Posted by Miggy Sanchez

Cheers for that.



A conventional VU meter?
I'm guessing that the VU meter and the process of measurement is NOT part of my NLE?

Depends on your NLE. Most NLEs primary meter is a peak reading meter calibrated in db below full scalle. But a number of the more professional ones also offer other metering options, including VU meters. They're also avaiable as plug-ins, for example, the Dorrough Loudness Meter plug-in from Waves which emulates the hardware loudness meters from Dorrough.