-12db reference from FCP and the rest of the broadcast world -20db

[Bouncing Account needs new email address]

Notice how everyone jumped right in to answer this? 🙂

There may be a “standard” somewhere, but its never the same one for everybody.

If you’re talking TONE, its easy to decide where to set it, it doesn’t MOVE.

So if you decide -12 is your reference to “Zero” on a VU meter. Where do you let your audio PEAKS go to?

So if you decide -20 is your reference to “Zero” on a VU meter. Where do you let your audio PEAKS go to?

Digital peak-reading meters are very hard to read as to AVERAGE level.
Analog average-reading VU meters are very hard to read as to PEAK level.

I “cheat” by leaving FCP connected to a deck with VU meters on it and read THEM as I edit. They will better show real audio levels by ignoring the instantaneous peaks that the FCP meters register.

Then, I set my FCP tone to the “Zero” point on the VU meters and dub out.

It really doesn’t matter if you use -12, -20, -14, (etc.) in FCP as long as you adhere to that as the “reference” and set your tone to that point.

The operators of the “final” playback can set their gear to YOUR reference so it will match THEIR reference.

Now, I’m sure there are others who can shoot this full of holes… but I’ve had no complaints about my levels from the dozens of places I send my dubs to.

[Chris Poisson]

Paul,

I’m not a techie by any means, but my understanding is that if you output digitally, say to Digibeta, you use -20 and if you output analog like a Beta SP you use -12. I’m not sure why this is so, but I’ve been outputting to beta SP at -12 for 4 years and have never had a dub rejected by any station.

[Mark Maness]

You guys hit the nail on the head and both of you are exactly correct. BUT we do live in a world where people are generally lazy and don’t want to have to do anything. Therefore, everybody has adopted their own “standards” and expect all of us to adhere to those. I tend to edit like Matte and I haven’t gotten many complaints either but there are those who don’t want to check your levels and complain that your levels are too low or too high. So basically, it comes down to do what is right for the industry and make the broadcaster adjust to their levels. That’s why we have these neat little things called level adjustment knobs.

_______________________________

Wayne Carey
Schazam Productions

[John Calhoun]

It has always been my understanding that where you set your reference actually depends upon what your dynamic range is; i.e. if you’re doing a motion picture with loud explosions, you would probably use -20db because it gives you greater headroom so you won’t go above 0 digitally because it would clip. (You could go lower if you have a greater dynamic range). If you’re doing an average corporate video the -12db is fine. It merely lets the broadcaster know where the reference is; hence, I don’t think there is a wrong answer. That’s why FCP allows flexiblity for setting reference all the way down to -60db.

pxlmvr

John A. Calhoun
Zone Communication Group
Cincinnati, Ohio

[Mark Maness]

You got it! Now, if we could just convince all of the master control operators and programming managers of this, our lives would be just peachy.

_______________________________

Wayne Carey
Schazam Productions

[C. Park seward]

It’s all about headroom. As you know, 0 DBfs is as loud as you can be: anything above is distortion. In the analog world, you didn’t have a hard ceiling, just increasing distortion. You wanted to get your level high enough so it didn’t sound noisy but low enough so it didn’t contain too much distortion. Many analog audio recorders set peak levels at 3% distortion which gave them around 60 db noise floor. They set their “0” to a certain magnetic signal strength (like 186 nanowebers per meter) to fit audio between distortion and noise.

Since a Digital Betacam VTR samples 20 bits in audio, your S/N ratio is very high. Subtracting 20 db won’t hurt at all.

While many broadcasters will accept tapes with incorrect reference levels, you should use the proper reference level of the machine you are dubbing to. It is a mark of professionalism to set proper audio and video reference levels. -20 db can be used for all broadcast formats.

[John Calhoun]

“-20 db can be used for all broadcast formats.”

————————————————

-20db won’t work for analog. Analog reference remains 0db. If you are mastering to a digital format, then -20 will work in most instances, but is not a hard and fast rule.

-20db is a good broadcast level because you will likely not need more headroom. Again, for movies you may need additional headroom. Keep in mind some broadcasters are quite specific about reference levels; example, MTV requires -18db on a digibeta master. If in doubt contact the broadcaster for technical specifications.

In any event, reference level should be noted on the tape label.

pxlmvr

[C. Park seward]

Take a +4 dbm audio tone. It will read “0” on a Digi Beta AND an analog Beta. The Digi Beta is -20 DBfs. That is an exact match for 0 VU on the analog Beta.

It does work for analog.

[C. Park seward]

Take a +4 dbm audio tone. It will read “0” on a Digi Beta AND an analog Beta. The Digi Beta is -20 DBfs. That is an exact match for 0 VU on the analog Beta.

It does work for analog. To be clear, we should use the notation “DBfs” (full scale) when referring to digital levels.

[Bryce Whiteside]

Broadcast Engineering Managing Audio Levels is an article worth reading.

By the way Park, welcome to the the Cow.

I’m Bryce, Peter’s brother–now there are some cobwebs–from B.R. Peter is at Electric Arts the largest game software company on the planet. I’m am teaching Advanced Editing with Final Cut Pro at the Academy of Art University in San Francisco and freelance edit with FCP. We are both in the San Francisco Bay Area now. Never thought I would run into you here.

Enjoy FCP,
Bryce

Don’t worry Mr. B. I have a cunning plan…

PowerBook 1.67 Ghz ATI 9700 128 MB 2 GB
Final Cut Pro HD
DVD Studio Pro 3
Motion