What is dual layer DVD? What is double layer DVD? How does dual-layer record? What are its orientations? What are the capacities of dual-layer DVDs?

1. Title: Double/Dual Layer DVD: Definition/Recording/Orientation/Capacity
Keywords: dual layerdvd,dvdrdual layer,whatisa dual layerdvd, double layerdvd, whatisdual
layerdvd, whatis double layerdvd
Description: What is dual layer DVD? What is double layer DVD? How does dual-layer record?
What are its orientations? What are the capacities of dual-layer DVDs?
URL: https://www.minitool.com/lib/dual-layer-dvd.html
Summary: This library created by MiniTool introduces an advanced technology of DVD called dual-
layer or double-layer DVD. It covers its meaning, working policy, orientations, as well as capacities.
Read the below content and learn the details.
What Is a Dual Layer DVD?
To learnthe meaningof a dual-layer(DL) DVD,let’slookatthe definitionof the DVD+RDL and DVD-
R DL.
Dual Layer DVD±R
DVD+R DL (DVD recordable dual layer),alsoknownasDVD+R9, isa derivative of the DVD+Rformat
developedbythe DVD+RWAlliance. While DVD-RDL(DVDrewritable dual layer),alsocalledDVD-
R9, is a derivative of the DVD-Rformatstandard.
DVD±R dual-layerdiscsadopt2recordable dye layerswitheachcapable of savingabout4.7 GB of
data of a single-layer(SL) disc,almostdoublingthe total disccapacityto8.5 GB. They can be read on
manyDVD deviceswithlesscompatibility witholderones.
What is double layerDVD? In October2003, itwas demonstratedthatdouble-layertechnology
couldbe usedwith a DVD+R disc,which beganto be seeninthe marketin the middle of 2004 with
pricescomparable tothose existingsingle-layerdrives. In2005, the dual-layerversionsof DVD-R
appearedonthe market.
However,asof March 2011, DL drives are up to twice as expensive assingle-layermedia.The latest
DL driveswrite double layerDVDdiscsat a slowerspeed(upto12x) thancurrent single-layerdiscs
(upto 24x).
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Dual Layer DVD±RW
In 2005 a specificationfordual layerDVD-RWdiscswithacapacityof 8.5 GB was approvedbythe
DVD Forumand JVCannouncedtheirdevelopmentof the firstmediainthatformat.In March 2006,
a double-layerDVD+RWspecificationwasapprovedwithacapacityof 8.5 GB. Yet,manufacturing
supportfor those rewritabledual-layerdiscsdidn’tmaterialize tocostsandexpectedcompetition
fromnewerandhigher-capacityformatssuchas HD DVDand Blu-ray.
Dual Layer Recording
Dual-layerrecordingenablesDVD+RandDVD-Rto save significantlymore data,upto 8.5GB per disc,
comparedwith4.7 gigabytesforsingle-layerdiscs.Double-layerDVD-RwasdesignedbyPioneer
Corporationforthe DVD Forum,whereasdual-layerDVD+RwascreatedbyPhilipsandMitsubishi
KagakuMedia (MKM) for the DVD+RW Alliance.
Also read: Best DVDBurning Software - Burn Image/Audio/Video to DVD

2. Dual layerDVD discsare differentfromtheircommonDVDcounterpart byemployingasecond
physical layerwithinthe driveitself.The drive of double layer reachesthe secondlayerbyshining
the laserthroughthe firstsemi-transparentlayer.
There isa noticeable pause(uptoseveral seconds)whenthe layerchange happensinsome DVD
players,whichmakesmany usersthinkthattheirdual layerDVDsare damaged.Thus,studiosbegan
listingastandardmessage explainingthe double-layerpausingeffectonall dual-layerdisc
packaging.
DVD recordable (DVD-R) discssupportingthistechnologyare backward-compatible withsome
existingDVDplayersand DVD-ROMdrives. A lotof currentDVD recorderssupportthe techof dual
layerand the price of dual-layermediaisnow comparable tothatof single layerdiscs,thoughthe
blankmediaremainmore expensive.Yet,the datatransferratesof DL discsfor bothreadingand
recordingare still muchslowerthanthat of SL drives.
The stacked,shine-througharrangementof layersdoescome withasmall increase inerrorrate due
to reduce the reflectivityof the writtenlayers,andasimilarsmall riskof crosstalkinterference.One
of the techsadoptedto compensate forthose reliabilitydrawbacksisa10% increase inminimum
mark (digital 1or 0) lengthonthe drive withacorresponding10% increase inrotationspeedand a
10% reductioningrossrecordable capacity.
That is accountedforthe lowercapacityof a single-sideddual-layerDVDat8.5 billionbytes,versusa
double-sizedsingle-layerDVDat 9.4 billion(for12 cm discs). Detail differencesinformattingandfile
structure meanthe “usable”data area capacitydoesnot change byexactlythismuch,but for all
intents, aDVD-RDL haseffectively20/11thsthe capacity of a DVD-R SL,and the same holdsfor+R,
commerciallypressed,and8cm discs.
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Dual Layer DVD Orientations
There are 2 kindsof dual-layerorientation,opposite trackpath(OTP) andparallel trackpath (PTP).
PTP isappliedtoDVD-ROMwhose bothlayersstartrecordingat the inside diameter(ID) withthe
lead-inandendatthe outside diameter(OD) withthe lead-out.Sectorsare sequencedfromthe
beginningof the firstlayertothe endof the firstlayer,thenthe beginningof the secondlayertothe
endof the secondlayer.While inthe OTPmode,the secondlayerisreadfromthe outside of the
disk.
Whereas,OTPisusedin DVD-Video.Yet,the videodataisreadfromthe beginningof the firstlayer
towardsthe endof the firstlayer.When the readingof the firstlayerfinishes(notnecessarilyatthe
endof the track),the readingistransferredtothe secondlayer.The secondlayerreadingstartsfrom
the beginningof the secondlayer,the same physical locationasthe endof the firstlayer,andends
at the endof the secondlayer.
That is to say,the beginningof the secondlayermaynothave anyrecordedmaterial presentfor
minimizingthe time the videoplayerspendsonlocatingandfocusingonthe secondlayer.So,this
offersthe shortestpossible pause inthe contentasthe layerchanges.
Easily,nota fewpeople willmistakethe conceptionsof OTPandPTP. Theymaythinkthat for the
OTP pattern,the discwill firstspininone directionandthenanother.Thatisincorrect!All DVD-
Writerswill spinadiscin the clockwise direction.

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Recordable DVD Capacities
The followingisatable showingthe storage capacitiesof the 4most commonDVD recordable
media,excludingDVD-RAM.
Disc type Numberof sectorsfor
data (2,048 B each)
Capacityinbytes Nominal capacityin
GB
DVD+R DL 4,173,824 8,547,991,552 8.5
DVD-RDL 4,171,712 8,543,666,176 8.5
DVD+R SL 2,295,104 4,700,372,992 4.7
DVD-RSL 2,298,496 4,707,319,808 4.7