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Dolby

Media Meter 2 User’s Manual 5

Chapter 3

Measuring Loudness

3.1 Measuring Equivalent Loudness

Differencesinaudiolevelsbetweenprogramsandchannelsorbetweenprogramsand

commercialsareamajorannoyancetoTVviewers.Whileobvioustotheviewer,these

loudnessdifferenceshaveprovendifficulttomeasurewithconventionalmethodsand

equipment.

Foryears,theaudioindustryhasquantifiedthelevelofitsprogrammingusingpeak

programmeters(PP

M)andvolumeunit(VU)meters.Itisimportanttonotethatbothwere

developedandareusedtoread signalvoltages,andthereforemakenoattempttomeasure

subjectiveloudness.Thus,severaldifferentvoices,adjustedinlevelsothattheyalldeflect

meterstothesamemark,maysou

ndsomewhatdifferentinleveltothelistenerathome.

Thisproblemisoftencompoundedbytherapidresponseofthemeter,whichrequiresall

operatorstoperformtheirownindividualvisualintegrationoraveragingofthemeter

movementitself.

Dolby

MediaMeter2featuresDialogueIntelligence

™

technology,adoptedfromthe

award‐winningDolbyDP600ProgramOptimizer,whichautomaticallydetectsandthen

measuresloudnessonlyduringthepresenceofspeechinanaudiotrack.Enabling

DialogueIntelligenceallowsthe operatortosimplyquantifyallthesectionsofthe program

thatonlycontaineddialogueandusetheendingmeasurementva

luefor analysisand/or

normalizationpurposes.This valueisalsocommonlyusedtosetthedialogue

normalizationparameterwithinDolbybitstreams.

DolbyMediaMeter2offersthreemeasurementalgorithmchoicesinthesettingswindow,

asshowninFigure 3‐1:

•ITU‐RBS.1770‐2

•ITU‐RBS.1770‐1

•Leq(A)

Figure3‐1 

Figure 3-1 Measurement Algorithm Choices in the Settings Window

EBUR128measurements,includingintegratedloudness,short‐termloudness,and

loudnessrange,areavailablewhenITUBS.1770‐2isselected.DialogueIntelligencecanbe

usedwitheitherITU‐RBS.1770‐1orLeq(A).

Youcan measuretheloudnessofDolbyDigital,DolbyDigitalPlus,DolbyTrueHD,

Dolby E,andPCMfiles.

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Dolby Laboratories Program Optimizer DP600 Manuale Utente Pagina 9