Dolby Laboratories DP570 The Scale, A Simple Rule:, Example:

A Guide to Dolby Metadata Dialogue Level
Dolby® 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.