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Dolby Laboratories DP570 Stereo System User Manual

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DP570 Multichannel Audio Tool User’s Manual

A Guide to Dolby Metadata Parameter Definitions

streamtoeitheradownstreamdecoderoranintegratedamplifierwithDolbyDigital

decoding.

Ineachofthesedevices,theanalogstereooutputisoneoftwodifferentstereodownmixes.

Onetypeisastereo‐compatibleDolbySurrounddownmix,ofthemultichannelsource

programthatissuitableforDolbySurroundPro

Logic

®

decoding.Thiskindofdownmix

isalsocalledProLogicorLefttotal/Righttotal(Lt/Rt).Theothertypeisasimplestereo

representation(calledLeftonly/Rightonly,orLo/Ro)suitableforplaybackonastereohi‐fi

oronheadphones,andfromwhichamonosignalisderivedforuse

onanRF/Antenna

output.ThedifferencebetweenthedownmixesishowtheSurroundchannelsarehandled.

TheLt/RtdownmixsumstheSurroundchannelsandaddsthem,in‐phasetotheLeft

channelandout‐of‐phasetotheRightchannel.ThisallowsaDolbySurroundProLogic

decodertoreconstructthe

L/C/R/SchannelsforaProLogichometheater.TheLo/Ro

downmixaddstheLeftandRightSurroundchannelsdiscretelytotheLeftandRight

speakerchannels,respectively.Thispreservesthestereoseparationforstereo‐only

monitoringandproducesamono‐compatiblesignal.Inalldownmixes,theLFEchannelis

not

included.

Onmosthomeequipment,theconsumercanusetheproduct’suserinterfacetochoosethe

appropriatestereooutputforhisplaybacksystem.Themonosignalfeedingthe

RF/AntennaoutputisusuallyderivedfromtheLo/R odownmix.

ThereareseparatemetadataparametersthatgoverntheLo/RoandLt/Rtdownmixes.

Certainmetadata

parametersallowtheengineertoselecthowthestereodownmixis

constructedandwhichstereoanalogsignalispreferred,butLt/Rtisthedefaultselection

inallconsumerdecoders.SeeParameterDefinitionsonpage 92forthedefinitionof

individualparameters.

Duringdownmixing,aswehaveseen,theadjustmentofDynamicRange

Control

parametersislimited.Broadlyspeaking,thestereooutputsusetheLinemodecompression

profilewhilethemonosignalusesRFmodecompression.Aswithdynamicrangecontrol,

downmixingisultimatelydependentuponeachconsumer’suniquelistening

environment.

Whiletheengineermustoptimizethemultichannelmixforreproductioninanideal

listeningenvironment,itisalsoimportanttopreviewthemixindownmixingconditions

toensurecompatibilitywithdifferentplaybacksystemswhenselectingthedownmixing

metadataparameters.ThesepreviewscanbeachievedinrealtimeusingtheDP570

MultichannelAudioTool.

D.6 Parameter Definitions

Thissectionexplainsbothprofessionalandconsumermetadataparametersingreater

detail.

Metadataparametersinclude:

•Universalparameters

•ExtendedBitstreamInformation(ExtendedBSI) parameters

ExtendedBSIparametersareactiveonlywhenboththeproducerchoosestousethemand

theconsumer’sdecoderiscapableofreadingthem.Alldecoderscansuccessfullydecodea

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