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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 Downmixing

• FilmStandard

MaxBoost:6dB(below–43dB)

BoostRange:–43to–31dB(2:1ratio)

NullBandWidth:5dB(–31to–26dB)

EarlyCutRange:–26to–16dB(2:1ratio)

CutRange:–16to+4dB(20:1ratio)

• MusicLight

(Noearlycutrange)

MaxBoost:12dB

(below–65dB)

BoostRange:–65to–41dB(2:1ratio)

NullBandWidth:20dB(–41to–21dB)

CutRange:–21to+9dB(2:1ratio)

• MusicStandard

MaxBoost:12dB(below–55dB)

BoostRange:–55to–31dB(2:1ratio)

NullBandWidth:5dB(–31to–26dB)

EarlyCutRange:–26to–16dB(2:1ratio)

CutRange:–16to+4dB(20:1ratio)

• Speech

MaxBoost:15dB(below–50dB)

BoostRange:–50to–31dB(5:1ratio)

NullBandWidth:5dB(–31to–26dB)

EarlyCutRange:–26to–16dB(2:1ratio)

CutRange:–16

to+4dB(20:1ratio)

• None

NoDRCprofileselected. Thedialoguelevelparameter(dialnorm)isstillapplied.

ThesechoicesareavailabletothecontentproducerforbothLinemodeandRFmode.The

contentproducerchooseswhichoftheseprofilestoassigntoeachmode;whenthe

consumeror

decoderselectsaDRCmode,theprofilechosenbytheproducerisapplied.

InadditiontotheDRCprofile,metadatacanlimitsignalpeakstopreventclippingduring

downmixing.Thismetadata,knownasoverloadprotection,isinsertedbytheencoderonly

ifnecessary.Forexample,considera5.1‐channelprogramwith

signalsatdigitalfull‐scale

onallchannelsbeingplayedthroughastereo,downmixedline‐leveloutput.Withoutsome

formofattenuationorlimiting,theoutputsignalwouldobviouslyclip.Correctsettingof

theDialogueLevelandDRCprofilesnormallypreventsclippingandunnecessary

applicationofautomaticoverloadprotection.

D.5 Downmixing

DownmixingisafunctionofDolbyDigitalthatallowsamultichannelprogramtobe

reproducedoverfewerspeakerchannelsthanthenumberforwhichtheprogramis

optimallyintended.Simplyput,downmixingallowsconsumerstoenjoyaDVDordigital

televisionbroadcastwithoutrequiringafull‐blownhometheatersetup.

Note:DRCprofilesettingsaredependentonanaccuratedialoguelevelsetting.Improper

settingofthedialoguelevelparametermayresultinexcessiveandaudible

applicationofoverload‐protectionlimiting.

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