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CALM DOWN!

CALM DOWN!. -24 LKFS. Show. -24 LKFS. Show. -21 LKFS. ?. -24 LKFS. Show. -21 LKFS. Downmix Dilemma. ?. Ls. L. Lf. Surround Mix. C. Rf. R. Rs. Frequent Downmix. Producers Stereo Deliverables Networks Stereo Channels & Internet Distribution Stations

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CALM DOWN!

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  1. CALM DOWN!

  2. -24 LKFS Show

  3. -24 LKFS Show -21 LKFS

  4. ? -24 LKFS Show -21 LKFS

  5. Downmix Dilemma ? Ls L Lf Surround Mix C Rf R Rs

  6. Frequent Downmix • Producers • Stereo Deliverables • Networks • Stereo Channels & Internet Distribution • Stations • Stereo Infrastructure & Channels • Consumers • Stereo STBs & TVs (≥61%)

  7. Downmix Dilemma ? Ls L Lf C ? Surround Mix Rf R Rs ?

  8. Preserve Center L 0 dB Near Field C Surround Mix +6 dB R Average +3 dB

  9. Preserve Center ? Ls L Lf ∑ C Surround Mix -3 dB Rf R ∑ Rs ?

  10. Preserve Rear? Ls L Lf ∑ Can't Hear Dialog! C Surround Mix -3 dB Rf R ∑ Rs

  11. Adjust Rear Ls -3 dB L Lf ∑ C Surround Mix -3 dB Rf R ∑ Rs -3 dB

  12. Defacto Standard Downmix Ls -3 dB L Lf ∑ C Surround Mix -3 dB R Rf ∑ Rs -3 dB

  13. Defacto-Compatible Surround Mix C 70 dB SPL L ∑ C -3 dB 70 dB SPL R ∑

  14. Incompatible Surround Mix Power Sum 10*Log(3) = 4.8 dB 74.8 dB SPL Lf C Rf Voltage Sum 20*Log (1+.7) = 4.6 dB Power Sum 10*Log(2) = 3 dB 77.6 dB SPL 2.8 dB Error! L Lf ∑ C -3 dB Rf R ∑

  15. Bottom Line • If two ads are mixed in surround to measure -24 LKFS… • One can sound and measure 2.8 dB louder after downmix • Producers can "game" the system to be louder • Stations and MVPD's could be deemed non-complaint when broadcasting "compliant" content! • Not a problem when content mixed to be compatible • A real problem for some Public Television music shows • See AES e-Brief 38 for measured statistics "The Effect of Downmixing on Measured Loudness"

  16. SOLUTION

  17. Customize the Downmix Power Sum 10*Log(3) 74.8 dB SPL Lf C Rf Voltage Sum 20*Log (1+.2) = 1.8 dB Power Sum 10*Log(2) = 3 dB 74.8 dB SPL L Lf ∑ C -12 dB Rf R ∑

  18. Producer-Controlled Metadata Producer Consumer Ls Lf Left C AC3 AC3 Surround Mix AC3 Encoder AC3 Decoder Right Rf Audio + Metadata Audio + Metadata Rs LFE Manual Metadata

  19. TV Station-Controlled Metadata Producers Networks TV Stations Consumers Ls Lf Left C AC3 AC3 Decoder Surround Mix Distribution Plant AC3 Encoder Right Rf Audio + Metadata Rs LFE X X X No Metadata Channel! See ATSC A/85 Chapter 7

  20. Why No Metadata Channel? • Many producers lack interest and ability in setting metadata • For a show, requires adoption by ALL distributors • Within a network, requires adoption by EVERY station • Within a station, requires adoption in ALL equipment • Most equipment requires obscure custom settings • Some equipment cannot carry metadata • Penalty of metadata error is severe: loss of center channel! * * *I'll buy you a beer if you'll let me whine about it.

  21. Proposed Solution • Standardize downmix for systems without metadata • -3 dB for Center and Rear • Require loudness measurement of the standard downmix • Encourages producers to mix appropriate to standard downmix • Producers can use film-style mixing or shift center channel phase • Penalty of an inappropriate mix is merely a show softer in surround • Change delivery standards • Modify A/85 • Ask LKFS meter vendors to include downmix measurement

  22. DISCUSSION

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