What Is Loudness
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The document discusses loudness in audio, contrasting the limited dynamic range of the analog era with the enhanced capabilities of today's digital sound systems. It covers various loudness measurement standards, including LKFS and recommendations for monitoring and adjusting audio levels for consistent loudness across different formats. Additionally, the document addresses the challenges posed by loud advertisements and outlines practices for managing loudness regulation and compliance.
What Is Loudness
- 2. 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
- 3. Who cares about Loudness? Specification What is LKFS? Recommended Practices How to use Loudness Regulation How will it be enforced? BS.1770-1/2 LKFS gated R128 Tech 3341/2/3 A/85 RP TR-B32
- 4. 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
- 5. 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) L ogarithmic K -weighted F ull S cale -x.yz LKFS Ungated average Higher Gated average -10dB gate
- 6. 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!
- 7. 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.
- 8. 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
- 9. 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 affidavit With meas Burn-in export CSV values report