Dolby Laboratories DP570 D.2 Dialogue Level

86 Dolby® DP570 Multichannel Audio Tool User’s Manual

A Guide to Dolby Metadata Dialogue Level

ThereareprofessionalparametersintheDolbyEbitstreamthatarenotunderdirectuser

control,suchasTimecodeandPitchShift.

DolbyEbitstreamscarrytimecodeinformationinhours:minutes:seconds:framesformat.

ThePitchShiftparametercanbegeneratedautomaticallybyaDolbyEdecodertocontrol

theDolbyModel585TimeScalingProcessor.IftheinputtotheDolbyEdecoderisnotat

normalplayspeed(aswithvarispeedorprogramplay),thenthePitchShiftCode

parameterindicatestheamountofaudiopitchshiftingrequiredtorestoretheoriginal

programpitch.

D.2 Dialogue Level

DialogueLevel(alsoknownasdialoguenormalizationordialnorm)isperhapsthesinglemost

importantmetadataparameter.TheDialogueLevelsettingrepresentsthelong‐term

A‐weightedaveragelevelofdialoguewithinapresentation,Leq(A).Thislevelcanbe

quantifiedwiththeDolbyModelLM100BroadcastLoudnessMeter.

Whenreceivedattheconsumer’sDolbyDigitaldecoder,thisparametersettingdetermines

alevelshiftinthedecoderthatsets,ornormalizes,theaverageaudiooutputofthedecoder

toapresetlevel.Thisaidsinmatchingaudiovolumebetweenprogramsources.

Inbroadcasttransmission,thepropersettingofDialogueLevelensuresthattheconsumer

receivesastandardlisteninglevel,soswitchingchannelsorwatchingatelevisionprogram

throughthecommercialbreaksdoesn’trequireadjustingthevolume.Usingthesame

standardforallcontent,whetherconveyedbybroadcasttelevision,DVD,orothermedia,

enablestheconsumertoswitchbetweensourcesandprogramswhilemaintaininga

comfortableandconsistentlisteninglevel.

ThepropersettingoftheDialogueLevelparameteralsoenablestheDynamicRange

Controlprofileschosenbythecontentproducertoworkasintendedinless‐than‐optimal

LowpassFilter x

LFELowpassFilter x

Surround3dBAttenuation x

SurroundPhaseShift x

a.ExtendedBitstreamInformationparametersareshowninitalics.

Table D-1 Profession and Consumer Metadata Types <~Figure>(continued)