CALM DOWN!

Show -24 LKFS

3 -24 LKFS -21 LKFS

4 Show -24 LKFS -21 LKFS ?

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

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

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

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

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

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

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

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

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

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

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 "

SOLUTION

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

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

19 TV Station-Controlled Metadata Surround Mix Ls Lf C Rf Rs AC3 Encoder AC3 Decoder Left Right ProducersConsumers AC3 DistributionPlant TV StationsNetworks No Metadata Channel! See ATSC A/85 Chapter 7 LFE XXX Audio + Metadata

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

DISCUSSION