067 – Audio Streaming Levels - LUFS
If you’re new to livestreaming audio, start by making sure you have a solid understanding of LUFS.
Written by Scott Adamson
Short for “loudness units full scale,” LUFS is a standardized system of loudness measurement used in a variety of broadcast situations.
You probably know that peak values reflect a signal’s highest levels and RMS (root mean squared) values reflect a signal’s average levels. However, RMS values don’t always reflect how we actually hear things. For instance, a 30 Hz tone will sound a lot quieter than a 1kHz tone metering at the same level. LUFS was developed to give us a more accurate and holistic indication of the overall loudness of an audio signal, taking human perception into account.
With that in mind, check out this video to hear veteran engineer and corporate audio specialist Brian Maddox break down a few ways to achieve optimal audio levels for your livestream.
In a nutshell, the audio signal is sent from the point of origin — perhaps the console at your venue or studio — and embedded into a video. That embedded signal is then sent to an encoder which converts it to a digital format before sending it out to the livestream.
If you’re directly overseeing all parts of the signal chain and you know your signal won’t be amplified elsewhere along the way, you have more freedom to send a hotter signal. If not, it’s safest to leave some headroom for what may occur between you and the final output.
Streaming platforms like YouTube and Facebook each have their own LUFS standards. Figure out what this number is ahead of time — a quick Google search should do the trick — and take this knowledge into consideration!
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If you deliver a signal too far above or below the LUFS standard, your signal will likely be adjusted to meet the platform’s desired loudness curves. If they’ll ultimately send it out at -18 LUFS regardless of what level you send from the console, it doesn’t make sense to push a hot -9 LUFS mix. This could lead to major overcompression. Conversely, sending a really quiet mix that needs to be boosted could lead to a higher noise floor.
To keep track of this, you’ll want to monitor both sides of the audio — what’s being sent to the stream and what’s coming out of it. There are an abundance of loudness meter plugins that can help you keep levels in check. By placing one meter on the audio signal leaving the console and one meter (with the same settings) on the livestream itself, you’ll have an easy reference point for what’s happening along the way and can adjust accordingly.
The Youlean Loudness meter that Brian mentioned in this video is the one I use the most!
