Audio levels for broadcast projects.

Jessariah67 wrote on 10/31/2002, 9:14 PM
Okay, there's the "let it breathe" school of audio engineering where you keep the signal bouncing and allow the dynamics to shine through. Then there's the digital rock-n-roll crowd that isn't happy unless the VU is in the red 99% of the time.

When it comes to handing someone a VHS (or miniDV to load into a Cable system), what is a good place to be when it comes to peaks. Lately, I've been doing some TV work, and I tend to let the singal be a bit "quieter" than I would have if it were an audio-only project. I find "local" stuff usually has very quiet audio. I don't want that, but I don't want to blow people out of their chairs either. Obviously, you can balance different sections of a standalone project -- the viewer hits the volume once and doesn't have to mess with it anymore -- but an actual commercial that will be mixed in with a cable network is a different story.

Anyone have some insight on this?

Thanks

Comments

Tyler.Durden wrote on 11/1/2002, 7:11 AM
Hi Jessariah,

You might mix & master you project to a peak level of -12db, using that as the reference, as you would use 0Vu in analog.

Set tone at -12db, and the station tape-ops should optimize playback accordingly, in the same fashion as they would analog tone at 0Vu.

A brief chat with the friendly station engineers might be helpful too.

HTH, MPH
MixNut wrote on 11/1/2002, 2:00 PM
The industry standard [thanks to Sony] is -20dBfs = 0Vu [which is at 48kHz, 20bit]. If you're going to layback your project DIGITALLY, then this should be your *average* level with *peaks* no hgher than -10dBfs. If you are going to layback from Vegas in the ANALOG domain, then you'll need to determine the reference level of your D/A converters first and adjust your digital levels to that reference level. In that case, -12dBfs is a common reference level.

Jessariah67 wrote on 11/1/2002, 3:08 PM
So, in Vegas, the peaks shouldn't go above -12dB on the master fader? That seems a bit quiet, unless I'm misunderstanding.
Former user wrote on 11/1/2002, 3:16 PM
I don't really have any technical insight, but the point of a commercial is to catch attention. You don't want your audio to be quieter than program. You want your commercial to jump out from the noise. Use of compression can increase perceived volume level without actually pegging meters.

My wife always complains that the commercials are louder than the programming, but I have to remind her that is how I make my living. :)

Dave T2
MixNut wrote on 11/1/2002, 3:55 PM
The *peaks* should not go beyond -12 to -10 dBfs on the meters, assuming a peak ballistic meter and an average level of -20dBfs...It's only too quiet if you haven't adequately compressed [dynamically] the content. I'm not sure how you'd classify the meter ballistics in VV3...

This is really difficult to explain or to do without a meter that shows both average [slow response] and peak over average [fast response] at the same time. THIS METERING OPTION WOULD BE AN EXCEPTIONALLY USEFUL FEATURE IN VV4!!!

I use Mytek DDD-603 peak/average metering, which is an external, rather expensive piece. Penguin Audio makes some decent PC-based metering that will show the same info. There's a free, limited demo on the web.

In the meantime, I'd rely on the metering on your layback deck to show you where you are in relation to 0Vu.

Clear as mud?

If you can't make it happen, then CLEARLY document your reference level on the dub master and set test tone at what you intend your 0Vu reference to be so that the station can adjust that tone reference to match their house reference level.
Jessariah67 wrote on 11/1/2002, 6:44 PM
So as long as I set my test tone level the same "volume" as the soundtrack, it can be adjusted accordingly?

Thanks
MixNut wrote on 11/2/2002, 1:11 PM
yes, assuming you get an astute and caring person at the local TV/Cable company dubbing it into their spot server. If they don't care, then you're spot will be *crushed* by an equal loudness limiter in the broadcast chain.

Best get it as close to -20dBfs average as possible...

Jessariah67 wrote on 11/2/2002, 3:22 PM
dBfs - is that different than dB?
MixNut wrote on 11/4/2002, 10:49 AM
dBfs = dB Full Scale

This refers to a measurement made on a digital full scale meter with a legend that *ends* at 0dBfs or clip.

Finster wrote on 11/5/2002, 11:31 AM
It seems to me that on the Vegas' meters, 0db means just what it says, and if you set peaks at -12, then you are running, well, about 12db low. This is different than when you are printing out to a digital deck where 0db becomes -20db, like the Panasonic DVCPro decks at the TV station where I work. There having peaks that just touch -12 would be just about right. I think you have to pay extra attention these days to how the program, mixer or recorder meters are calibrated.

Below is a link to a good article that says audio in Vegas should be "mixed to a level not exceeding 0dB, and not less than -6dB at peaks."

http://www.creativecow.net/articles/spottedeagle_douglas/audio_mastering/index.html

MixNut wrote on 11/5/2002, 12:46 PM
This is why the question of whether he intends to layback his mix in the analog or digital domain becomes imperative. The answer to his question of proper levels cannot be given without knowledge of potential differences in 0 reference outside of Vegas.

If his mix is to pass *digitally*, at unity gain, from Vegas to another professional VTR that follows the industry standard -20dBfs reference level = 0Vu, the he'd best have his average reference at -20dBfs as well.

If his mix is to pass in the *analog* domain, at unity gain, from Vegas to a professional ANALOG VTR, then the answer to the question of levels depends on the 0Vu reference of the D/A converters he uses to perform the layback.

FuTz wrote on 11/5/2002, 1:40 PM
Maybe it can help...

http://www.locationsound.com/pdf/soundcatalog/29testequipmenttools.pdf
(note: go to p. 146)

and...

http://www.locationsound.com/pdf/soundcatalog/21portablemixerspreamps.pdf
(note: go to p. 104)
SeanC wrote on 11/5/2002, 6:41 PM
you'll find that levels have come up quite a bit over the last 5 years when delivered on digital media. I've at times delivered with peaks at -3 or -6 and found good results on some local tv affiliates. By purchasing either waves or tc electronics bundles, there are some great limiters you can patch in, and get any amount of dynamics processing you want, as well as control your absolute top.

There's one station where if you deliver at -12, you're dead. quiet. Smart stations will control levels on the way in. Many seem to set it so no peaks can make it into their storage system, so if someone is at -6, and you're at -12, you're 4 times quieter. Even their on air processing won't make that even.

Most network commercials have VERY limited dynamics (tons of compression / limiting applied prior to delivery). If you're trying to compete in that arena, be prepared to understand how to squash it without it sounding like crap and how to deliver it hot.

Sean

www.seancaldwell.com