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Output your sound mix for Broadcast (in 2020)

Delivering the sound from your edit or mix can be a surprisingly confusing process. When delivering sound we need to think about the format it is to be played back on and ask ourselves questions: How loud should it be? How dynamic should it be (how great should the difference be between quiet and loud sounds)? How loud can the peaks be? Its it in mono, stereo or some kind of surround format? How much stereo image should it contain?

Until digital broadcasting came into use, sound engineers would mainly worry about peak levels – the level or volume your sound wasn’t allowed to go beyond before it distorts – this led to a sort of “loudness war”, with clients putting pressure on to turn up the average level of the sound to make it louder than the competitors. Can you remember when the advertising was louder on TV than the programs – and then you would have to reach for the volume or mute button every time the commercial break happened? During the loudness war Louder was Better. Television advertisers, clients and agencies wanted to have their material heard over the sounds of people boiling kettles and making dinner – the loudest commercial was the winner, the best mixer / engineer in the eyes of the clients was the one who could deliver the loudest mix without it sounding like complete mush.

When digital broadcasting arrived, in around 2014, the TV stations announced they had enough of the loudness war – viewers were complaining about having to constantly change volume levels every time the ad’s came on, so new standards came in. In the new standards, with new technology, volume would be measured and delivered in a new digital system: LUFS.

LUFS stands for Loudness Units Full Scale. Basically an algorithm is run on your audio that measures loudness as our ears percieve it and gives it a number in dB measuring down from zero ( 0dB LUFS is as loud as you can go). If you lower the LUFS number you can have greater dynamic content.

Each digital broadcast system has chosen a specific LUFS level as its standard.

Ever wondered why you usually don’t need to adjust volume when playing clips on YouTube? When you put your video on YouTube it analyses your audio and processes your sound to -14 LUFS – everything played on YouTube now sounds like it is at the same volume.

A similar process happens on Spotify, Soundcloud and iTunes.

When we deliver sound for broadcast for a TV station they don’t do the process for us – they ask us to do it ourselves.

Currently, in 2020, for a TV stereo mix in Australasia, we are asked to:

Process the sound for our entire film so that it is at -24 LUFS (you can do this in Adobe Audition)

Make sure that the difference (or range) between our loud sounds and quiet sounds is not more than -15 LUFS (so don’t make your quiet sounds and atmospheres too quiet).

Make sure that your peak sounds don’t go above -2dB (before digital broadcasting it used to be -9dB)

Make sure that a stereo mix is in phase (just in case it gets played in mono – out of phase sounds could dissppear from your mix!)

OK – if you haven’t done much audio engineering, all this might sound complicated. Don’t worry – if you just want to be an editor, you should just know that all this exists and you could pass your work onto an audio mixer to finish. But, you should still have a mixing strategy, and these would be my tips:

Create well organised mixes: Label everything, include all audio and mute the blocks you don’t need. Checkerboarding your audio can be a good strategy.

Mix to a consistent level. Set up your tone (usually at -20dB) and check your levels against a level meter now and again (but don’t keep watching them too much while mixing – it can be a mistake to “chase” the meters – trust your ears). Are the levels consistent from start to end of your project? Are your atmospheres too quiet? Does your dialouge sound smooth? (you can use a compressor to even out your volume – you can even put one on your master channel to control the dynamics of the whole mix {and make sure its not too quiet}).

Know what your ears are telling you: use good monitor speakers or headphones. Mark off a reference volume on your equipment so you know you are playing yourself the same level each time when you check your mix. Use a headphone correction plugin if you have one.

Are there any weird low bass floating around, are there any other strange unwanted frequencies in the mix. Use an EQ – especially a low cut, on your location sound. (If you don’t trust your monitoring you might want an audio engineer to look at this).

Listen to your mix in mono (a plugin can help). Has anything disappeared from your mix? Does anything sound strange?

This strategy should get you most of the way there and deliver a mix that could be finalised using loudness processing and a limiter or directly uploaded to YouTube and sound OK.

The slides for the lecture are below explaining some of the terminology: click on the images to see them bigger.

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