WRITTEN BY IAN HOWARD
RE-RECORDING MIXER, BOOM BOX POST

Do you remember watching TV or listening to the radio and it driving you crazy that the audio levels were extremely different whenever something new came on or if you changed the channel? These dark ages of audio were commonly referred to as the Loudness Wars and thanks to channel broadcast specifications, we no longer have these issues (or at least they aren't as extreme).

Every network has specific audio mix specifications. They are designed to keep all the shows uniform so there's no need to be turning up or down the volume of your TV, laptop, phone, or other device.

Until streaming services came about, the standard specification for audio on network television dialogue was between -23 & -25. Now, streaming services are allowed to have different specifications of their own. Some of the plugin presets that have come about from these standards are specifically designed to center the metering around dialogue, referred to as “dialogue weighted.” These plugins give a representation of how loud the dialogue is compared to the sound effects and music.

Common Mix Specification terms

  • LKFS - Loudness K- weighted relative to Full Scale

  • True Peak - Instantaneous level of audio

  • ITU-R - International Telecommunication Union for radio communication. Basically what we all use for broadcast

So let's say for example your network specifications are:

  1. Meet a -27 LKFS (+/- 2 LU) ITU-R BS.1770-1 measured over the entire program.

  2. Maintain +18db (-2 dBFS) maximum level (true-peak) over reference of -20 dBFS, achieved by peak limiting and not lowering the mix level.

Looks confusing right? It's actually quite simple once you break it down.

Number 1 is telling us the overall program audio level, which in this case is -27 (+/-2). The +/- 2 allows for wiggle room so your final reading overall needs to be within -25 and -29. The second part of number one (ITU-R BS.1770-1) is referring to the algorithm to use on your metering plugin to achieve that specification. Most metering plugins (at BBP we use Nugen VisLM) have handy built in presets so all you have to do is select this setting and you’re good to go!

Nugen VisLM2

Avid Pro Limiter

Number 2 is referring to your true peak level or your loudest moment of what you are metering. These levels are set using a limiter in your session with the threshold and ceiling set based on the spec; in this case -2 dBfs. Since plugins are not foolproof, you may want to set it slightly lower than spec, just to be safe. Lastly, be sure to set the limiter at the very bottom of your signal chain on all master busses. Once this is in place, you should be good to go! Be aware though that if you do have a heavy hand mixing and you really crank up a sound that goes to that limit, there is the potential for the limiter to unflatteringly color your sound.

Remember that every network has different mix specifications so before you get too far, always check and adjust your plugins accordingly.

It may sound intimidating trying to hit your specification mark, but in reality, if you follow Jacob’s advice on mixing around the dialogue and not getting too carried away in the loud sections, you should have no problem hitting your target metering specification.

If you enjoyed this blog, check out these:
STEP-BY-STEP AUDIO POST-PRODUCTION WORKFLOW
LUNCH AND LEARN: OBJECTIVE-BASED MIXING
LUNCH AND LEARN: RECREATING A MUSICAL TUNE AS A SOUND EFFECT

Comment