Clearcast — UK Television Advertising Clearance

Clearcast clears advertising for the UK commercial broadcasters. An advert does not reach UK television without passing through it, so its technical specification functions as a delivery requirement regardless of what any loudness recommendation says.

On loudness it defers to the European standard: integrated loudness is stated as EBU R128, −23 LUFS. What makes the document worth reading is the requirement that has no equivalent anywhere else.

Loudness measurement is indifferent to phase. A stereo mix with a polarity-inverted element, an over-wide stereo plug-in on a bus, or a mono element duplicated and delayed can integrate to exactly −23 LUFS, sit under every true-peak ceiling, and still fail this check.

The consequence is not academic. A mix with poor phase coherence partially cancels when summed to mono — which is what happens on a phone speaker, a television with a single driver, and a large part of broadcast distribution. The gate exists because the audience frequently hears the mono sum, and a number caught it more reliably than an engineer listening in stereo would.

The practical answer is to check the mono sum before delivery rather than after rejection, and to treat aggressive stereo widening on a full mix bus as something to justify rather than default to.

The received wisdom is that a UK television advert must be delivered at −23 LUFS because EBU R 128 requires it. That is wrong about the regulation, and the body that writes the rule says so in its own guidance.

The binding rule is BCAP Code rule 4.7, and it is a RELATIVE test, not an absolute one. It says advertisements must not be excessively noisy or strident and that their maximum subjective loudness must be consistent and in line with the maximum subjective loudness of the programmes and junction material around them — with the aim that the audience need not adjust the volume during the break. Nowhere does it name a number.

R 128 arrives as the CONTRACTUAL route to compliance rather than the regulatory one: the DPP specification mandates it, and Clearcast enforces its own QC gate on top. So a spot still has to hit −23.0 LUFS in practice — but because of the delivery contract and the clearance gate, not because the advertising code says so. The distinction matters the moment a broadcaster or a creative asks for an exception, because the code explicitly contemplates one.