Download - What Is Loudness
What is Loudness?
• Analog world of yesterday– Limited dynamic range, no meta-data volume adjustments– Setting peak effectively leveled programs
• Digital world of today– +40db more effective dynamic range, volume metadata
• Tragedy of the commons- Ads are too loud– Too much flexibility - allows “Tragedy of the commons” with ads
Who cares about Loudness?
SpecificationWhat is LKFS?
Recommended PracticesHow to use Loudness
RegulationHow will it be enforced?
BS.1770-1/2 LKFS gated
R128Tech 3341/2/3 A/85 RP TR-B32
What is Loudness?
• ITU Recommendation on Loudness Measurement
– BS.1770-1 (09/2007) & BS.1770-2 (03/2011)
• For entire audio track Mono, Stereo or 5.1
– Rear surrounds are weighted at +1.5dB
– .1 track is not incorporated
• Models human perception of loudness
– K- Weighting
What is Loudness?
• For the entire length of the content
Short form -< 2 minutes ad or promo
Long form - > 2 minutes program or promo
Overall channel - time (e.g. 6h, 1d, ..)
• Not counting quiet periods
Gating (-10dB)
Don’t silence/quiet to lower measurement
• Into one LKFS measurement (dB scale)
Logarithmic K-weighted Full Scale -x.yz LKFS
Ungatedaverage
HigherGatedaverage
-10dB gate
What is Dialnorm?
AC-3 metadata that allows programs originated with different levels to be decoded with the same perceived loudness.ATSC only
Everything sounds the same!
What really happens with Dialnorm?
It is always set to -24 (-7dB of gain)
Assets should be gain adjusted to have a -24 LKFS level
before being transmitted.
Observer Loudness Monitoring
• Loudness measurements -LKFS and LUFS -with gating
• Short (S), Medium (M) and Interval (I) measurements
• Up to 7 Short-form Interval (SI) - e.g 10s, 15s, 20s, 30s
• Up to 7 Long-form Interval (LI) - e.g. 6h, 1d, 5d
• Loudness Range (LRA) to measure audio companding
• Detailed 10Hz measurements - with Audio & Video
Loudness Monitoring Features
• Graphing of S, M and I measurements over time Multiple channel, multiple meas. Graph <=> video time navigation
• Export : Logged measurements as csv Affidavit - A/V with burned in measurements
• Short form Asset measurements • Alarming (SNMP, email, visual)
Customizable alarming profiles based on SI and LI measurements
A/V affidavitWith meas Burn-in
export
CSV values report