LUMIÈRE
What LUFS measures
Volume meters in older mixers showed the peak level: the highest point of the signal. Peaks say little about how loud something feels. Loudness measurement tries to describe what a listener perceives, over time.
The unit is LUFS, Loudness Units relative to Full Scale. It is measured with the method in ITU-R BS.1770, which weights the signal the way hearing does. The same measurement is called LKFS in some documents. One LU (loudness unit) is the same size as one dB, so a change of 1 LU is a change of 1 dB.
The three numbers in R128
- Integrated loudness. One figure for the whole programme, from start to end. R128 asks for -23 LUFS, with a small tolerance around it. This is the number most delivery specs check first.
- True peak. The highest level the audio reaches, measured so that it also catches peaks between samples that appear when audio is converted or compressed. R128 sets a maximum true peak of -1 dBTP.
- Loudness range (LRA). How much the loudness moves between the quiet and the loud parts, in LU. It describes dynamics. It is a figure to read, not a pass or fail target. EBU Tech 3342 describes how it is measured.
The EBU's Tech 3341 describes the loudness meter, and Tech 3343 gives practical guidelines for producing programmes to R128.
Why platforms differ
R128 was written for broadcast, so television and radio in Europe follow it. Streaming and social platforms publish their own loudness targets, and these are not the same as -23 LUFS. Some regions use other standards, such as ATSC A/85 in the United States. A platform may also turn playback up or down on its own.
So there is no single number for "the internet". Check the current delivery spec of the place you publish, and compare your measured values with it. A measurement against R128 is a useful baseline either way, because it tells you where your mix stands.
How Lumière measures your file
Lumière's loudness check measures the file you upload. It runs as part of a compliance job, so you upload the master exactly as you plan to deliver it. The job reports integrated loudness in LUFS, true peak in dBTP and loudness range in LU, and the report as PDF or DOCX prints the figures with a pass or fail.
Pass or fail is decided on two values: integrated loudness against -23 LUFS (Lumière allows ±1 LU) and true peak against a maximum of -1 dBTP. Loudness range is reported for information.
This is a measurement, not a correction. Lumière does not normalise the loudness of a master. If a file fails, fix the mix in your audio or editing software, then scan the new version. A scan costs 1 ✦ per started minute, with a minimum of 1 ✦. The Trial's 15 ✦ is enough to check a 15-minute video.