Dolby Laboratories DP570 D.3 Dynamic Range Control

Dynamic Range Control

Dolby® DP570 Multichannel Audio Tool User’s Manual 87

DolbyDigitalconsumerdecodersnormalizetheaverageoutputlevel—thatis,theoutput

levelaveragedovertime—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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.

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

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.

D.3 Dynamic Range Control

Differenthomelisteningenvironmentspresentawiderangeofrequirementsfordynamic

range.Ratherthansimplycompressingtheaudioprogramatthetransmissionsourceto

workwellinthepoorestlisteningenvironments,DolbyDigitalencoderscalculateandsend

DRCmetadatawiththesignal.Thismetadatacanthenbeappliedtothesignalbythe

decodertoreducethesignal’sdynamicrange.

ThroughthepropersettingofDRCprofilesduringthemasteringprocess,thecontent

producercanprovidethebestpossiblepresentationofprogramcontentinvirtuallyany

listeningenvironment,regardlessofthequalityoftheequipment,numberofchannels,or

ambientnoiselevelintheconsumer’shome.

ManyDolbyDigitaldecodersoffertheconsumertheoptionofdefeatingtheDynamic

RangeControlmetadata,butsomedonot.Decoderswithsixdiscretechanneloutputs(full

5.1‐channelcapability)typicallyofferthisoption.Decoderswithstereo,mono,or

RF‐remodulatedoutputs,suchasthosefoundonDVDplayersandset‐topboxes,oftendo

not.Inthesecases,thedecoderautomaticallyappliesthemostappropriateDRCmetadata

forthedecoder’soperatingmode.

Note: The–31dBFSshouldnotbeconfusedwiththestationreferencelevel(often–18or

–20dBFS).Itiscommontohavedifferentvaluesforprogrammaterialthathasthe

samereferencelevel.Anaverageloudnesslevelof–31dBFSisquitecompatible

withfacilitiesrunningatavarietyofreferencelevels.