the -12db question

FiddlerMD

FiddlerMD

Well-known member
I remember reading something about broadcast being set to -12db - does that mean that maximum (clipping) on my projects that are destined for dvd and such should be at -12db? I did a project to 0db in premiere, and while it played on the dvd, it sure sounded louder than it shoudl and clipped a lot :)
 
hmmm, i always thought it was -6db, but then again, not too farmiliar with this stuff.
 
Different broadcasters will have different delivery specifications, but most of those I've worked with require that programs average around -12dB (ie. -12dB = +0VU) with maximum peeks not exceeding -6dB (-6dB = +6VU). Contact the broadcaster's you wish to target and find out exactly what their delivery specifications are, not only in terms of audio but the entire package as well (tape formats, labelling, M&E requirements, video specs, etc.)

Try using a good masterring limiter to keep your peaks under control without drawing attention to the comression.

Of course, DVD is a different beast altogether than broadcast. If you're mixing with an ear towards high-end home theaters, you may want a more dynamic film-style mix (-20dB = 0VU, max peaks at -1dB or so). Just keep in mind that home theatre subwoofers are typically callibrated much higher than those in theatrical venues.

As a point of reference, do a side-by-side comparison between your mix on DVD and other commercial DVDs. If you're DVD is significantly lower, you may want to boost your overall level a bit by running your mix through a compressor. Of course, if you find your mixed DVD sounds distorted, you'll definitely need to revise your mix. Depending on the software you're mixing in, your meters may not be that reliable. Check your overall mixed tracks using a "find peak" type of opperation that tells you how far from digital 0 the highest peak in your program is sitting. As long as that peak is -0.1dB or lower, your not overdriving the track. This opperation will also tell you how much additional gain you can apply to maximize your level.
 
The regulations make sure that the volume of "content" is well below that of commercials. :evil:
 
is it better to shoot on location with your sound boosted, so that the voice levels peak properly, while retaining the majority of the room tone and noise.

or

better to record at lower levels, and boost certain frequencies later on? All in all, better quality?
 
Strictly speaking, your production tracks should be recorded as loud as possible without introducing distortion. That way, you're dealing with the optimum sample depth (16-bit, or 24-bit depending on your equipment). If you under-mix too much, you'll wind up only using the first 8 bits and your tracks will have all the dynamic range of a good cell phone. When you boost things too much in post-production, you'll start hearing the noise and lack of definition that identifies a low bit-depth recording. Never boost when you can cut, as the saying goes.

Of course, real-world recording can be a bit unpredictable, and a bit of extra head-room is rather handy if you hit a really sibbilant line or an actor coughs.

Its also preferable to keep the levels consistent within a scene. This applies to both the dialogue and the room tone and/or background noise. If the noise floor jumps up or down across a cut, the dialogue editor and mixer will have to smooth over that jump.

As a general rule, leave dynamics compression (as well as data compression) for post production, with the exception of a good set of limiters on your production mixer. Even then, try to avoid hitting the limiters too hard, since once they kick in it is very difficult to reverse their effects later on. The same principle applies to other effects proccessing, although exerienced mixers often EQ their lav's to match their boom mics in addition to rolling off unwanted low frequencies (generally around 80Hz).

Production shoots rarely feature an ideal monitoring environment (eg. a sound truck), so you should be wary of commiting to any mix decisions that could be difficult to undo later on. To ensure that levels stay consistant during transfers, start each sound roll or camera tape with 10 to 30 seconds of line-up tone (typically 1kHz sine tone at -12dB). Be sure to provide post-production with detailed notes on the production sound, including: shot in/out points (for double-system shoots), room tone in/out points, wild take or rehearsal in/out points, EQ settings, compressor/limiter settings, line-up tone level, microphone model(s), recorder model, mixer model, bit depth, sample rate, time code settings, and production mixer contact information.

Sorry for the long meandering post. Just killin' time until heading in for the night shift.
 
SMuir said:
Contact the broadcaster's you wish to target and find out exactly what their delivery specifications are, not only in terms of audio but the entire package as well (tape formats, labelling, M&E requirements, video specs, etc.)
Click to expand...

For broadcast this is all the advice you will ever need. :)

Cheers
 
in this case i'm just burning some DVD's for friends .. so for a "regular" dvd - is there a set limit they adhere to?
 
For DVDs, keep your max peaks from exceeding -1dB. As long as you dialouge is hitting somewhere between -20dB and -1dB, your viewers shouldn't have to keep turning their speakers up in order to hear what's going on.
 
Blaine said:
The regulations make sure that the volume of "content" is well below that of commercials. :evil:
Click to expand...

Actually the regulations for commercials are the same. It's just that most commercial producers will push their levels to the maximum allowable. If a TV show was to be at the maximum allowable at all times there would be no dynamic range. Being that commercials are usually on for only 30 seconds that doesn't really matter that much. The mentallity is make it as loud as possible for that 30 seconds.
For instance if a show were to break for a commercial in the middle of a car chase or an explosion then you wouldn't notice that much of a difference in levels.
 
Compression is something those "Girls Gone Wild" commercials have mastered. God forbid you fall asleep in front of the TV anymore because you know you're gonna get awakened to that Reggae music. :(
 
Hey, Fiddler, I just ran into this problem myself. For some reason (and I'm a noob, so probably operator error) my dialog track was clipping on export, even though the levels were so low in some places that I could barely see the waveforms in Premier. The mp3s I'd imported had much larger waveforms in premier, but didn't have clipping issues...weird.

What worked for me was to turn the master volume down -9db. At that point the clipping was eliminated.
 
at this point i'm done mastering my dvd and yeah i had to go the -12db route for itto work .. that is make my peaks on all the tracks around -12db.. had to compress some speechparts cause the music would overtake them, but for my purposes right now, it worked out
 
You must log in or register to reply here.
Back
Top