remotecontrolmixers00WHAT THE BROADCAST STANDARDS SAY
The volume you set should stay set.
For decades, broadcast mixers watched peak meters, and programmes, channels and adverts could sound very different in loudness. European broadcasters switched to measuring loudness itself, so the mix engineer, not the viewer's remote control, keeps the level steady.
Check the tolerances01Principles
02THE SHORT ANSWER
Peak meters show the highest instant.
Loudness meters show how loud it sounds over time.
THE PROBLEM
The EBU says peak normalisation led to considerable loudness differences between programmes and channels, the cause of the most viewer and listener complaints.
See the numbersTHE TARGET
EBU R 128 sets a Programme Loudness target of −23.0 LUFS, and counts adverts, trailers and promos as programmes too.
Check the tolerancesTHE CEILING
During production the maximum true peak must stay at or below −1 dBTP, measured with a meter that follows ITU-R BS.1770.
The meter readings03A QUICK TOLERANCE CHECK
Pick a situation to see how much leeway the standards allow. The bar shows how tight the limit is.
From EBU R 128 (2014) and the UK BCAP Code rule 4.7.
04TWO NUMBERS WORTH KNOWING
One figure for how loud a programme should be,
one for how high its peaks may go.
−23 LUFS
Programme Loudness target level
LUFS means Loudness Units relative to Full Scale, defined in ITU-R BS.1770. The measurement covers the whole programme, without singling out voice, music or effects, and uses gating to focus on the foreground.
TARGET · EBU R 128
−1 dBTP
Maximum true peak in production
True peak is the maximum value of the audio waveform in continuous time. R 128 replaced the older peak limit in ITU-R BS.645, which it says no longer suits digital systems.
CEILING · EBU R 128
R 128 was first issued in 2010 and revised in 2011 and 2014. The ITU loudness standard it relies on, BS.1770, is now in its fifth version (BS.1770-5, 2023).
05FOUR READINGS ON A LOUDNESS METER
R 128 asks for three main measures to describe a programme, plus two short-window readings to catch moments that are too loud.
The integrated loudness over the whole programme, in LUFS. This is the number normalised to −23.
How much the loudness varies within the programme. Not recommended for items under a minute.
The highest point of the waveform, kept at or below −1 dBTP during production.
Maximum readings over short windows (short-term uses 3 seconds) show if a moment exceeds what the audience will accept.
06THE UK ADVERT RULE
BCAP Code rule 4.7 says television adverts must not be excessively noisy or strident, and their maximum subjective loudness must be consistent with programmes and junction material, so viewers need not adjust the volume in breaks.
BCAP recognises that a break can fall during a very quiet scene, making normal adverts seem loud. It says loudness measurement based on ITU recommendations is best practice.
07Questions
Loudness Units relative to Full Scale, the unit defined in the ITU-R BS.1770 standard for measuring programme loudness. LUFS is equivalent to LKFS, the name used in BS.1770 itself.
It is the Target Level set by EBU Recommendation R 128 for normalising Programme Loudness, with a tolerance of ±0.5 LU, or ±1.0 LU for live programmes.
The EBU says peak-based levelling led to considerable loudness differences between programmes and channels. Peak meters do not show how loud a signal sounds over time.
No. BCAP rule 4.7 says adverts must not be excessively noisy or strident and their maximum subjective loudness must be consistent with programmes.
The maximum value of the audio waveform in continuous time. R 128 limits it to −1 dBTP in production, measured with a BS.1770-compliant meter.
08Sources
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