- Dolby Multichannel Audio Tool User's Manual

98 Dolby
®
DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata
Original Bitstream
ThisparameterindicateswhethertheencodedDolbyDigitalbitstreamisthemaster
versionoracopy.IthasnoeffectonDolbyDigitaldecodersanditspurposeispurelyto
provideinformation.
FigureD‐4 
DC Filter
ThisparameterdetermineswhetheraDC‐blocking3Hzhighpassfilterisappliedtothe
maininputchannelsofaDolbyDigitalencoderpriortoencoding.Thisparameterisnot
carriedtotheconsumerdecoder.ItisusedtoremoveDCoffsetsintheprogramaudioand
wouldonlybeswitched
offinexceptionalcircumstances.
Lowpass Filter
Thisparameterdetermineswhetheralowpassfilterisappliedtothemaininputchannels
ofaDolbyDigitalencoderpriortoencoding.Thisfilterremoveshigh‐frequencysignals
thatarenotencoded.Atthesuitabledatarates,thisfilteroperatesabove20kHz. Inallcases
itpreventsaliasingondecoding
andisnormallyswitchedon.Thisparameterisnotpassed
totheconsumerdecoder.
LFE Lowpass Filter
Thisparameterdetermineswhethera120Hzeighth‐orderlowpassfilterisappliedtothe
LFEchannelinputofaDolbyDigitalencoderpriortoencoding.ItisignorediftheLFE
channelisdisabled.Thisparameterisnotsenttotheconsumerdecoder.Thefilterremoves
Table D-15 Original Bitstream Settings
Original Bitstream
Yes
No
Note: TheparametersDCFilter,LowpassFilter,LFELowpassFilter,Surround3dB
Attenuation,andSurroundPhaseShiftappearaftertheExtendedBSIparameterson
DolbyEandDolbyDigitalequipmentmenus.
Table D-16 DC Filter Settings
DC Filter
Enabled
Disabled
Table D-17 Lowpass Filter Settings
Lowpass Filter
Enabled
Disabled