integrated loudness, true peak and the room between them — from the documents, not from hearsay
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
Targets are EBU R 128 v4 (2020) and AES TD1008.1.21-9 (2021), table 1. Loudness and peak are measured per ITU-R BS.1770-5.
An ordinary peak meter shows the largest sample rather than the crest of the wave. Between two neighbouring samples the wave rises above both, and in the worst case — a sine at a quarter of the sampling rate, shifted so that no sample lands on the crest — exactly 3.01 decibels hide there.
That is why the ceiling stands at −1 dBTP rather than at zero. BS.1770 does not measure true peak from the samples: the signal is attenuated by 12.04 dB, the sampling rate is raised fourfold, the result is filtered, its absolute value taken, and the 12.04 dB added back. A meter that skips this reads lower than the converter will put out.
The second thing that eats the room is the encoder itself. Lossy compression changes the shape of the wave, and a peak after decoding can be higher than it was before. That is why AES asks for −1 dBTP at the input of the encoder rather than at its output: after it, measuring is too late.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 7 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
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