Broadcast loudness meter

EBU R128, R128 s1 and ATSC A/85

Drop a master and see its integrated loudness, true peak, loudness range and short-term maximum, programme by programme, passed or failed against EBU R 128, R 128 s1 and ATSC A/85. A stereo mix, a 5.1 and an M&E in one file are measured separately, grouped by their EBU R123 or R48 track layout. Each channel also gets a quasi-peak PPM reading, on an EBU, BBC, DIN or Nordic scale. The file is measured in your browser. Nothing is uploaded.

Drop a master or a mix here

MXF (OP1a, OP-Atom, D-10), MOV, MP4, WAV and AIFF, at any size: only the audio is read. Measured in your browser; nothing is uploaded.

How the verdicts work

Each programme is judged on the rules its standard actually sets, and only those. Integrated loudness must sit within the stated tolerance of the target, and true peak at or under the ceiling. Readings are judged at 0.1 resolution, as a meter displays them.

EBU R 128 s1 (adverts, promos and other short-form content) adds a ceiling on short-term loudness, −18 LUFS, so a spot can sit on −23 integrated and still fail on a loud tag line. It also says a loudness range limit must not be set for short-form content, so LRA is shown and not judged.
EBU R 128 recommends measuring loudness range but sets no limit, so LRA is shown and not judged.

The limits come from the standards’ own documents. Delivery specs set their own targets and change; your commissioning spec is the authority. The loudness targets table lists their published figures for reference.

Multi-track masters

Channels are numbered across the whole file, as R123 and R48 number them, whether the master carries them as one multichannel track or as eight mono tracks. Pick the layout and each programme is measured on its own: stereo pairs, and 5.1 with BS.1770’s weights (LFE excluded, surrounds +1.5 dB) in the layout’s channel order. A 5.1 laid out in film order (L C R Ls Rs LFE) reads very differently if measured as broadcast order, so the order can be changed per programme. Silent channels are flagged. Dolby E and other SMPTE ST 337 data in an AES pair is detected and reported, not measured as if it were audio.

How it’s measured

ITU-R BS.1770-4 with EBU R 128 gating, loudness range per EBU Tech 3342, true peak 4× oversampled, checked against the EBU’s conformance signals (Tech 3341 and 3342) and against ffmpeg’s meter on real broadcast masters. MXF (OP1a and OP-Atom, BWF or AES3 PCM, and D-10), MOV, MP4, WAV and AIFF are read directly, and only the audio is read from them: a 90-minute XDCAM master is measured without reading its video. A truncated file is reported as truncated rather than given a figure.

The PPM reading

A quasi-peak programme meter (IEC 60268-10) reads short transients lower than they are and falls back slowly, the way the needle on a desk does. That’s different from true peak, and from loudness. The reading here is the highest each channel reaches over the whole file. There are two kinds of meter. Type II, the BBC and EBU meters, reads a 10 ms burst 2 dB low and falls back 24 dB in 2.8 seconds. Type I, the DIN and Nordic meters, is quicker: a 10 ms burst reads 1 dB low and it falls back 20 dB in 1.7 seconds. The BBC and EBU meters differ only in their scales: BBC marks 1 to 7, 4 dB apart except 6 dB between 1 and 2, with line-up tone at 4; EBU marks in dB around ‘TEST’, the line-up level. The DIN scale’s 0 is 9 dB above line-up, and the Nordic’s ‘TEST’ is line-up. Line-up tone is −18 dBFS under EBU R 68 and −20 dBFS under SMPTE RP 155; pick yours.

The meter is our own, compiled to WebAssembly. It meets EBU Tech 3205’s burst table and return time for Type II, and IEC 60268-10’s Type I table, at 44.1, 48 and 96 kHz. Both types read within 0.5 dB of Fons Adriaensen’s independent meters on speech, music and percussive material. These are readings: a ceiling such as ‘PPM 6’ is set by a delivery spec, not by the meter’s standard.