user manual

86 Dolby
®
DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata Dialogue Level
Special Parameters
ThereareprofessionalparametersintheDolbyEbitstreamthatarenotunderdirectuser
control,suchasTimecodeandPitchShift.
Timecode
DolbyEbitstreamscarrytimecodeinformationinhours:minutes:seconds:framesformat.
Pitch Shift
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)
Metadata Parameter Professional Consumer