Dolby Laboratories DP570 D.7.1 Preferred Stereo Downmix Mode , D.7.2 Lt/Rt Center Downmix Level

100 Dolby® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata
ATSCdocumentA/52.Thereviseddefinitionsallowmoreinformationtobecarriedabout
theaudioprogramandalsoallowmorechoicesforstereodownmixing.Whenthe
metadataparameterscarriedinDolbyDigitalwerefirstdescribed,theyweregenerically
calledbitstreaminformation,orBSI.Werefertotheadditionalparameterdefinitionsas
extendedBSI.
Becausethereviseddefinitionsaffectmetadataparametersthatwerenotusedbythe
consumerdecoders,alldecoderswillbecompatiblewiththerevisedbitstream.Newer
decodersthatareprogrammedtodetectanddecodethenewparameterswillbeableto
implementthenewfeaturesExtendedBSIprovides.
Productsthatallowemulationoftheeffectsofmetadata,suchastheDP570,normallyhave
afeaturethatallowsemulationofanew(orcompliant)decoderoralegacydecoder.
D.7.1 Preferred Stereo Downmix Mode
ThisparameterallowstheproducertoselecteithertheLt/RtortheLo/Rodownmixina
consumerdecoderthathasstereooutputs.Consumerreceiversareabletooverridethis
selection,butthisparameterprovidestheopportunityfora5.1‐channelsoundtracktoplay
inLo/Romodewithoutuserintervention.Thisisespeciallyusefulonmusicmaterial.
D.7.2 Lt/Rt Center Downmix Level
ThisparameterindicatesthelevelshiftappliedtotheCenterchannelwhenaddingtothe
LeftandRightoutputsasaresultofdownmixingtoanLt/Rtoutput.Itsoperationissimilar
totheCenterdownmixlevelintheuniversalmetadata.
Table D-21 Preferred Stereo Downmix Mode Settings
Preferred Stereo Downmix
Mode
NotIndicated
Lt/RtPreferred
Lo/RoPreferred
Table D-22 Lt/Rt Center Downmix Level Settings
Lt/Rt Center Downmix
Level
1.414(+3.0dB)
1.189(+1.5dB)
1.000(0.0dB)
0.841(–1.5dB)
0.707(–3.0dB)
0.595(–4.5dB)
0.500(–6.0dB)
0.000(–999dB)