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A Guide to Dolby Metadata Dialogue Level

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DP570 Multichannel Audio Tool User’s Manual 87

listeningenvironments,andisessentialinanycontentproduction,whetheritisfor

transmissioninabroadcaststreamorfordirectdistributiontoconsumers,aswithDVDs.

The Scale

ThescaleusedintheDialogueLevelsettingrangesin1dBstepsfrom–1to–31dB.

Contrarytowhatyoumightassumeatfirst,asettingof–31representsnolevelshiftinthe

consumer’sdecoder,and–1representsthemaximumlevelshift.Here’swhy:

DolbyDigitalconsumerdecoders

normalizetheaverageoutputlevel—thatis,theoutput

levelaveragedovertimeusingtheequivalentloudnessmethod,Leq(A)—

to–31dBFS(31dBbelow0dBfull‐scaledigitaloutput)byapplyingashiftinlevelbased

ontheDialogueLevelparametersetting.

Whenadecoderreceivesaninputsignalwitha

DialogueLevelsettingof–31,itappliesno

levelshifttothesignalbecausethisindicatestothedecoderthatthesignalalreadymatches

thetargetlevelandthereforerequiresnoshift.Incontrast,alouderprogramrequiresa

shifttomatchthe–31dBstandard.WhentheDialogueLevel

parametersettingis–21,the

decoderappliesa10dBlevelshifttothesignal.Whenthesettingis–11,itappliesa20dB

levelshift,andsoon.

A Simple Rule:

31+(DialogueLevelvalue)=Shiftapplied

Example:

31+(–21)=10dB

SettingtheDialogueLevelparameterisanessentialservicetothelistener.Foryour

listeners,settingthislevelproperlymeans:

•Thevolumelevelisconsistentwithotherprograms.

•TheDRCprofilesyoumakeavailabletothemworkasyouintend.

Oncedialoguelevelisset,youcan

setupDRCprofilestofurtherbenefittheconsumer.

Note:Programswithoutdialogue,suchasanall‐musicprogram,stillrequireacareful

settingoftheDialogueLevelparameter.Whensettingtheparameterforsuch

content,itisusefultocomparetheprogramtothe levelof otherprograms. Thegoal

istoallowtheconsumertoswitchtoyour

programwithouthavingtoadjustthe

volumecontrol.

Note:The–31dBFSLeq(A)shouldnotbeconfusedwiththestationreferencelevel(often

–18or–20dBFS).ItiscommontohavedifferentLeq(A)valuesforprogram

materialthathasthesamereferencelevel.Anaverageloudnesslevelof–31dBFS

Leq(A)isquitecompatiblewithfacilitiesrunningatavarietyofreferencelevels.

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