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An Introduction
to DVD Formats
July 2003
by Graham Sharpless
© 2001 - 2003 Disctronics
All
rights reserved. No part of this document may be reproduced or
transmitted
in any form or by any means, including photocopying
and
recording, without the written permission of the copyright holder.
The
information contained in this document is intended to provide an overview
and
is not a comprehensive description of the technology or processes involved
for
CD or DVD. Disctronics cannot be held liable for any consequence of using
this
information. For more complete information the reader is advised to see the
appropriate
CD or DVD specifications.
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Contents
1. INTRODUCTION
................................................................... 3
1.1
DVD Applications
.........................................................................................3
1.2
DVD
Features...............................................................................................3
1.3
DVD History..................................................................................................4
2. DVD SPECIFICATIONS
............................................................ 5
2.1
DVD Disc Parameters
..................................................................................5
2.2
DVD Physical Disc Formats
.........................................................................5
2.3
Burst Cutting Area
........................................................................................8
2.4
DVD Sector Structure...................................................................................8
2.5
DVD File System
..........................................................................................9
2.6
The DVD-Forum .........................................................................................10
3. DVD APPLICATION
FORMATS..................................................11
3.1
DVD-Video
.................................................................................................11
3.2
DVD-ROM ..................................................................................................11
3.3
DVD-Audio
.................................................................................................12
3.4
Copy Protection..........................................................................................12
4. DVD
PRODUCTION...............................................................13
4.1
DVD Premastering
.....................................................................................13
4.2
Manufacturing DVD Discs
..........................................................................13
5. DISCTRONICS
.....................................................................15
Figures
Figure 1 DVD Construction 5
Figure 2 DVD-5 Disc 6
Figure 3 DVD-9 Disc 6
Figure 4 DVD-10 Disc 6
Figure 5 DVD-18 Disc 6
Figure 6 Hybrid SACD 7
Figure 7 Hybrid DVD 7
Figure 8 DVD Plus 7
Figure 9 Single and Dual layer
DVD disc layouts 8
Figure 10 Burst Cutting Area 8
Figure 11 DVD Sector Structure
9
Figure 12 DVD Disc File
Structure 9
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1. Introduction
DVD, the
Digital Versatile Disc, is a high capacity CD-size disc for video,
multimedia,
games and audio applications. Capacities for the read-only disc
range
from 4.7GB to 17.1GB. The high quality of video and audio has helped
DVD-Video
to compete very effectively with VHS for pre-recorded video titles,
statistics
showing that DVD is growing faster than any other consumer
electronics
format in the
selling,
but multimedia and games applications of DVD have been slow to start.
The
advent of new games consoles using DVD is also helping to stimulate
further
sales.
1.1
DVD Applications
Despite
the success of the compact disc there has been a clear need for a
higher
capacity format to meet additional application requirements.
• DVD-Video, which was launched in 1997 in the
successful
of all the DVD formats, as it has proved to be an ideal vehicle for
distributing
video content from the movie industry. It can store a full-length
movie
in high quality video with surround sound audio on a disc the same
size
as a CD. DVD now accounts for the majority of video sales in the
and
• DVD-ROM is beginning to replace the
CD-ROM and provide a new high
capacity
disc format for the computer industry. New PCs are now provided
with
DVD drives instead of CD drives. The entertainment industry has
developed
new games consoles (eg Sony's PS2 and Microsoft's X-Box)
which
incorporate DVD-ROM drives for more sophisticated and realistic
games
applications.
• DVD-Audio, which was launched in 2000, is
slowly gathering momentum to
become
the format for very high quality, surround sound music, offering the
music
industry new revenue opportunities.
• Recordable formats such as DVD-RAM, DVD-RW and
DVD-R are
now
being
extensively used in PCs for computer backup and short runs of DVDs
and
in standalone products such as video recorders and camcorders.
DVD-Video
and DVD-ROM hardware and software have been available since
1997.
DVD-Audio was launched in 2000. DVD writers and DVD video
recorders
are now available at affordable prices.
1.2
DVD Features
DVD
started as the Digital Video Disc but now means Digital Versatile Disc or
just
DVD. It is a multi-application family of optical disc formats for readonly,
recordable
and re-writable applications. The main features of the DVD
formats
are:
• Backwards compatibility with
current CD media. All DVD hardware will play
audio
CDs and CD-ROMs and most will play CD-Rs and CD-RWs.
• Physical dimensions are identical
to the compact disc but each disc
comprises
two 0.6 mm thick substrates, bonded together.
• Single-layer/dual-layer and
single/double sided options are available.
• Up to 4.7 GB read-only capacity
per layer, 8.5 GB per side maximum.
• Designed from the outset for
video, audio and multimedia, not just audio.
• All formats use a common file
system (UDF).
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• Digital and analogue copy
protection for DVD-Video and DVD-Audio built
into
the standard.
• Recordable and re-writable
versions are part of the family.
1.3
DVD History
DVD
started in 1994 as two competing formats, Super Disc (SD) and
Multimedia
CD (MMCD). DVD now is the result of an agreement by both
camps
on a single standard to meet the requirements of all the various
industries
involved. The major milestones are listed in Table 1.
Table 1 DVD Milestones
1994
1995
Agreement on a single standard format called DVD.
1996
DVD-ROM
and DVD-Video specifications version 1.0 published
Digital
copy protection scheme (CSS) agreed
First
DVD-Video players sold in
1997
Launch
of DVD in
DVD
Consortium becomes DVD Forum, expands membership and holds
first
General DVD Forum Meeting with 120 members
1998
DVD-Video
version 1.1 and DVD-ROM version 1.01 specifications issued.
DVD
Forum adopts DVD-RW as another re-writable format
7
new members of DVD Forum Steering Committee making 17 in all
DVD
Forum publishes DVD-Audio specification version 0.9
Full
launch of DVD in
4.7
GB DVD-R and DVD-RAM version 1.9 specifications released
1999
DVD-Audio (1.0), DVD-Video Recording (0.9 & 1.0), DVD-RW (0.9)
and
DVD-RAM
(2.0) specifications published.
2000
CPPM
copy protection for DVD-Audio agreed
DVD-Audio
players launched in
First
DVD-Audio discs in
DVD-RW
Part 2 (1.0), DVD-R for Authoring (2.0), DVD-R for General (2.0)
and
DVD Stream Recording (0.9) specifications published.
2001
DVD-Audio
players & discs available in
DVD
Video Recorders launched in Europe etc
Guidelines
for IEEE 1394 transmission for DVD-Video/Audio issued.
DVD
Video Recorders launched in Europe etc
DVD-Multi
(1.0), DVD Stream Recording (1.0), DVD-Audio (1.2) and DVDVideo
Recording
(1.1) specifications published.
2002
WG-11
created to study future blue laser format
DVD-Audio
recording specification ver 0.9 issued
Hybrid
DVD-Audio format approved by DVD Forum
2003
DVD
Forum rejects hybrid DVD-Audio format
DVD
Forum selects 0.6mm HD DVD, shelves 0.1mm
DVD
Forum releases iDVD specifications
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2. DVD Specifications
The
DVD technical specifications are contained in five books A to E published
by
the DVD Forum and listed in Table 2.
Table 2 DVD Book Specifications
Book Name Part 1
Physical
Part 2
File System
Part 3
Application
Version
A DVD-ROM Read-only
ISO9660/UDF undefined 1.01
B DVD-Video Read-only
UDF MPEG-2 video 1.1
C DVD-Audio Read-only
UDF MLP & PCM audio 1.2
D DVD-R Write
once UDF not defined 2.0
E DVD-RAM/RW Rewritable
UDF not defined 2.0
Note
that SACD, DVD+R and DVD+RW, although based on the DVD format,
are
not approved by the DVD Forum.
2.1
DVD Disc Parameters
Table
3 provides a comparison between the main physical parameters of DVD
and
CD discs. Note the smaller geometries and two layers/sides.
Table 3 DVD Disc Parameters
Parameter CD DVD Comments
Sides 1
1 or 2
Layers 1
1 or 2
See
2.2
Capacity (GB) 0.68
4.7 - 17 1 GB = 109 bytes (not 10243)
Track pitch (μ) 1.6
0.74
Minimum pit length (μ) 0.83
0.4 For I3 pit
Wavelength (nm) 780
650 of laser diode pickup
Numerical aperture 0.45
0.6 Defines angle of beam
Linear velocity (m/s) 1.3
3.49 Nominal 1x speed
Modulation EFM
8 to 16 EFM is 8 to 14 plus 3 padding bits
Error protection ECC
RSPC RSPC is block protection scheme
3rd layer ECC Yes
No Not needed for DVD after RSPC
Subcode Yes
No No subcode needed
Tracks Yes
No DVD uses files not tracks
2.2
DVD Physical Disc Formats
Although
identical in appearance, DVDs
and
CDs differ in a number of key
physical
parameters. To meet the
requirements
for 133 minutes of high
quality
video on one side of a single disc
requires
the use of a thinner (0.6 mm)
substrate,
two of which are bonded
together
(see Figure 1) to form a disc that
is
thick enough for general use. Figure 1 DVD Construction
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The
use of a sandwich of two substrates allows a range of formats from one
layer
to four and one or two sides, giving capacities from 4.7 GB to as much as
17.1
GB. These are listed in Table 4 and illustrated below.
Table 4 DVD Physical Disc
Formats
DVD-5 DVD-9 DVD-10 DVD-18 DVD-R
DVD-RW DVD-RAM
Capacity (GB1) 4.7 8.54
9.4 17.08 4.7 4.7 4.7 or 9.4
Layers/side 1
2 1 2 1 1 1
Sides 1
1 2 2 1 1 1 or 2
DVD-5 discs
comprise a sandwich
of
two 0.6mm substrates, one
metallised
and with data, the other
blank,
bonded together. The data is
read
from one side only so that
labels
can be printed on the top
surface
of the disc as for CDs. Figure 2 DVD-5 Disc
DVD-9 discs
comprise one semireflective
substrate
(layer 0) and one
fully
metallised substrate (layer 1)
above
it giving a capacity of 4.25 GB
per
layer. The reduced capacity is
intended
to ease the manufacturing
tolerances
for such discs. Figure
3 DVD-9 Disc
Labels
can be printed on the discs as for DVD-5 discs and CDs.
DVD-10 discs
comprise two
metallised
substrates bonded
together
and read from both sides.
The
disc label is restricted to a small
annular
area within the disc hub, on
both
sides of the disc. Figure 4 DVD-10 Disc
These
discs have been superseded by DVD-9 discs, which are read from one
side.
DVD-18 discs,
which have limited
availability,
comprise two dual-layer
substrates
bonded together and
read
from both sides. The disc label
is
restricted as for DVD-10 to small
annular
areas on both sides. Figure 5 DVD-18 Disc
These
are not yet widely used due to manufacturing difficulties and the
perceived
extra value of two DVD-9 discs instead of one DVD-18.
1 Note that for capacity purposes one GB (gigabyte)
is actually a billion bytes or 109 bytes.
This contrasts with normal
computer storage capacities whereby a GB is 1024 x 1024 x 1024
bytes. Therefore the capacity
of a DVD-5 disc is 4.337 GB using the latter definition.
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Recordable and Re-writable DVD
Formats
The
recordable and re-writable formats include two DVD-R types plus DVD-RW
and
DVD-RAM. In addition DVD+R and DVD+RW are alternative formats that
are
not supported by the DVD Forum.
• DVD-R for Authoring is
intended for professional use and requires a 635
nm
laser for writing. The lead-in area can contain information needed for
glass
mastering so that DVD-Video titles can be mastered from this type of
media
instead of DLT tape.
• DVD-R for General use is
intended for consumer applications and requires
a
650 nm laser for writing. It is not possible to write to the lead-in
area of
such
discs.
• DVD-RAM discs are re-writable discs with
a capacity of 4.7GB per side for
computer
data storage and archive applications, although this format is also
used
in some DVD video recorders.
• DVD-RW discs are re-writable discs with
a capacity of 4.7GB per side for
consumer
applications such as video recording.
• DVD+RW and DVD+R discs are not officially
part of the DVD family, but
are
similar to the corresponding DVD-RW and DVD-R for General formats.
Note
that CSS protected content cannot be written to any of these discs.
Hybrid and combination disc formats
A
number of formats that combine different formats on different layers have
been
developed.
Combination disc formats,
for example combining DVD-ROM on one side
with
DVD-RAM on the other, have been approved by the DVD Forum. Such
discs
are double sided discs and are read from both sides.
Hybrid SACD is
a format developed by
Philips
and Sony and combines a SACD
(ie
physically a DVD layer) with a CD layer.
Both
layers are read from the same side,
which
means that the SACD layer must be
reflective
for the red laser but will transmit
the
infra red CD laser. Such discs can
then
be played on both a CD player (which
will
read the CD layer) and a SACD player.
Hybrid DVD is
a similar format being
studied
by the DVD Forum. The first
application
is likely to be for a DVDAudio/
CD
audio combination which is
almost
identical to the hybrid SACD
format.
DVD Plus refers
to a disc comprising a CD
bonded
to a DVD substrate. The resulting
disc
allows both DVD and CD data to be
read
from one disc, like a hybrid DVD, but
the
disc is read from both sides. Early
versions
of this format were 1.8 mm thick,
but
this has been reduced to 1.5 mm. At
the
time of writing this format is not
approved
by the DVD Forum.
Figure 6 Hybrid SACD
Figure 7 Hybrid DVD
Figure
8 DVD Plus
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Single and dual layer disc layout
Each
layer of a DVD disc contains Lead In, Data Area and Lead Out like a CD.
A
single layer disc comprises a Lead In, Data Area and Lead Out. For dual
layer
discs there are two options depending on the application (see Figure 9).
• Parallel track path, where the two layers are
independent and both start at
the
inside diameter (ID) and end at the OD with the Lead Out. Dual layer
DVD-ROM
discs use this layout for access to files on either layer.
• Opposite track path, where layer 0 starts at
the ID and layer 1 starts
where
layer 0 ends at the Middle Area. For such discs there is one Lead In
(on
layer 0), one Lead Out (on layer 1) and two Middle Areas. DVD-Video
discs
will use opposite track path so that a movie can be placed across both
layers
and played almost seamlessly from layer 0 to layer 1.
Note
that the file system data (see below) will be contained in layer 0.
Single
layer disc
Lead In ▪►
Data Area ▪►
Lead Out
Dual
layer disc – parallel track path
Lead
In ▪► Data Area (Layer 1) ▪► Lead Out
Lead
In ▪► Data Area (Layer 0) ▪► Lead Out
Dual
layer disc – opposite track path
Lead
Out ◄▪ Data
Area (Layer 1) ◄▪ Middle
Area
Lead
In ▪► Data Area (Layer 0) ▪► Middle
Area
Figure
9 Single and Dual layer DVD disc layouts
2.3
Burst Cutting Area
The
Burst Cutting Area (BCA) is an annular area within the disc hub where a
bar
code can be written for additional information such as serial numbers (see
Figure
10). The data stored in the BCA can be from 12 bytes to 188 bytes in
steps
of 16 bytes.
Figure
10 Burst Cutting Area
The
BCA can be written during mastering and will be common for all discs from
that
master or, more usually, will be written using a YAG laser to 'cut' the
barcode
into the aluminium reflective layer of the finished disc. The ill-fated
Divx
format used BCA to uniquely identify every disc. New uses of this or
similar
technologies are being developed to use the BCA as a unique, tamperproof
means
of identifying individual discs.
2.4
DVD Sector Structure
The
data on a DVD disc are organised as sectors of 2048 bytes plus 12 bytes
of
header data (see Figure 11). Blocks of 16 sectors are error protected using
RSPC
(Reed Solomon Product Code), which is block oriented and is more
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suitable
for re-writable discs (with packet writing) than CIRC, which does not
use
a block format. The PI and
and
vertically over the data bytes.
In
addition DVD uses an 8 to 16 modulation scheme giving pit lengths of 3 to
14
(minimum to maximum length) compared with CD's 3 to 11 with EFM
modulation.
This is only a small difference but does make the jitter
specification
slightly tighter.
Figure
11 DVD Sector Structure
2.5
DVD File System
All
types of DVD disc (DVD-Video, DVD-ROM and DVD-Audio) contain data in
files.
These files are accessed using a file system common to all DVD discs.
For
compatibility with recordable and re-writable versions the
Format
has been chosen. This comprises a combination of UDF plus ISO 9660
for
compatibility with CD-ROM. The main characteristics of UDF are:
• Robust file exchange
• System & vendor independent
• Writable & read-only media
• Based on ISO 13346 (ECMA 167)
UDF
has been extended to provide the necessary features for both write-once
and
re-writable discs. The file system specifications for different writable
formats
are different in some respects.
Figure
12 DVD Disc File Structure
A
combination of UDF and ISO 9660 (known as
DVD
discs to provide compatibility with existing operating systems, including
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Windows9x
and later. Applications can access the data files using either ISO
9660
or UDF file structures, but use of UDF is recommended.
All
pre-recorded discs are DVD-ROM discs, but contain any or all of the
application
data shown in Figure 12. Only DVD-Video and DVD-Audio data
must
be contained within specific directories VIDEO_TS and AUDIO_TS.
DVD-Video
discs use only UDF (not ISO 9660) with all required data specified
by
UDF and ISO 13346 to allow playing in computer systems. The DVD-Video
files
must be no larger than 1 GB in size and be recorded as a single extent (ie
in
one continuous sequence). The first directory on the disc must be the
VIDEO_TS
directory containing all the files. All filenames are in the 8.3 format.
All
other files not included in the DVD-Video specification are ignored by DVDVideo
players.
DVD-Audio discs also only use UDF and files are contained in
the
AUDIO_TS directory.
2.6
The DVD-Forum
The
DVD specifications were originally written by the DVD Consortium, which
comprised
10 companies:
Sony,
Thomson, Time Warner, Toshiba and JVC. In late 1997 the name was
changed
to the DVD Forum and membership opened up to other companies in
the
DVD industry. The original 10 members have become the Forum's
Steering
Committee and increased its numbers to 17 with the addition of the
following
companies: IBM, Industry Technology Research Institute of
Intel,
LG Electronics, NEC, Samsung and Sharp.
The
DVD Forum has a total membership of over 220 and continues to produce
and
maintain the DVD specifications by means of nine working groups:
WG1
DVD-Video, video recording and stream recording specifications.
WG2
DVD physical specification.
WG3
File systems for pre-recorded and recordable DVD formats
WG4
DVD-Audio and audio recording specifications
WG5
DVD-RAM specifications
WG6
DVD-R and DVD-RW specifications
WG9
Copy protection review
WG10
Industrial/professional applications of DVD
WG11
New Blue laser disc formats for HDTV
In
addition, the DVD Forum has established committees for verification of DVD
discs,
players etc and promotion of the DVD Format.
DVD Format/Logo Licensing
In
2000 the DVD Format/Logo Licensing Corp (DVD FLLC) was
established
to handle issuing of the DVD specifications, granting
licenses
to manufacturers and policing the use of the DVD logos.
All
manufacturers of hardware, discs and related DVD products
must
be licensed and first products verified to ensure that all
players
will play all discs. The correct logos must be used for
licensed
DVD products in the appropriate way as shown.
The
DVD FLLC is taking firm action against companies that are
manufacturing
or selling non-licensed products or are using the
incorrect
logos.
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3. DVD Application Formats
Two
DVD application formats have been developed: DVD-Video, and DVDAudio.
DVD-ROM
is the basis of the other two and can be used for a wide
variety
of other applications.
3.1
DVD-Video
DVD-Video
discs are intended for full-length movies and offer a range of
features
including the following:
• Playing time:
a nominal 133 minutes playing time for DVD-5 or each side of
a
DVD-10 and 240 minutes for DVD-9 using opposite track path format.
• Video encoding:
MPEG-2 (for better than Laserdisc quality) or MPEG-1.
• Audio Quality and Languages:
Dolby Digital, DTS, MPEG-2 or Linear
PCM
audio for up to 5.1 channel surround sound.
• Subtitling:
Subpictures allow subtitling for up to 32 languages
•
• Interactivity: a
range of interactive features is available including seamless
transitions,
menus, camera angles and different routes or endings
Longer
movies can make use of dual layer DVDs (DVD-9) for continuous play
and
the two sides of a DVD-10 disc can be used for two different versions of a
movie.
Some video titles contain data that can be played only on a PC.
Access
to websites can be achieved in this way.
DVD Players and Titles
All
DVD-Video players should be capable of playing all types of DVD-Video
discs
(within the region specified), CD audio discs and Video CDs, but most will
play
additional formats as well. DVD-Video players will output video to both
wide-screen
and conventional TVs. The user can choose between widescreen,
letterbox
and pan & scan outputs where available. Players in the
will
generally only play NTSC video, whilst those in
as
well as PAL, but only if the monitor/TV is capable of both systems.
DVD-Video
titles can also be played on PCs with DVD-ROM drives and MPEG-
2
hardware or software decoders.
Region coding
Many
DVD-Video discs are region coded to restrict playing to specific regions
as
shown below.
Region
1:
Region
2: Europe,
Region
3:
Region
4: Central & S
Region
5:
Region
6:
DVD
titles do not have to be region coded, but players generally are coded for
only
one region. Non-region coded discs will play on any player.
3.2
DVD-ROM
DVD-ROM
is essentially the pre-recorded DVD physical and logical format
used
for DVD-Video, DVD-Audio and a range of other applications, particularly
general
computer and multimedia applications, for which it can provide at least
7
times the capacity of a CD-ROM. Applications can include MPEG-2 video, as
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used
on DVD-Video discs, to give added realism to games and richer content
for
multimedia applications.
DVD-ROM
drives will also play CD-ROM and CD audio discs and are forecast
to
replace CD-ROM drives within the next few years. They are already
available
as add-on drives and built into new PCs. Early drives were 2x speed,
but
much faster drives are now available.
3.3
DVD-Audio
The
DVD-Audio specification was released in 1999, copy protection methods
agreed
in 2000 and players and discs are now available. DVD-Audio discs use
scalable
multi-channel linear PCM coding with optional lossless compression.
Additional
content can comprise video, text and still pictures. DVD-Video like
navigation
is also included in the specification.
DVD-Audio
discs will require DVD-Audio players or universal DVD-Video/DVDAudio
players.
DVD-Audio discs can optionally include DVD-Video content for
compatibility
with DVD-Video players. Most discs released so far include DVDVideo
content
so that they will play on DVD-Video players, although the audio
quality
is not as good as DVD-Audio can provide.
Philips
and Sony have developed Super Audio CD (SACD), an alternative to
DVD-Audio,
which uses DSD (direct stream digital) encoding and offers a
hybrid
disc version containing CD and DVD audio on different layers so that the
one
disc will play on both SACD and CD audio players (although with a
difference
in quality). Future DVD-Audio discs may also offer a hybrid option.
3.4
Copy Protection
Copy
protection for DVD is only for video and audio content and comprises
both
digital and analogue methods for preventing users from making perfect
copies
of the source material.
Digital
copy protection involves scrambling the raw data using certain
keys,
which
are stored on the disc in encrypted form. In the decoder, the original keys
are
obtained by inverting the encryption process and the data is then descrambled
using
the decrypted keys.
• DVD-Video titles can use CSS
(Content Scrambling System)
• DVD-Audio titles can use CPPM
(Content Protection for Pre-recorded
Media)
• Recordable discs can use CPRM
(Content Protection for Recordable
Media).
For
DVD-ROM there is no copy protection, but techniques currently used for
CD-ROM
are being extended to DVD.
Analogue
copy protection (APS) makes use of a technique developed by
Macrovision,
which distorts the analogue output waveform so that the picture
quality
is unaffected but it cannot be successfully played back from VHS tape.
Watermarking
systems have been developed for both audio and video content
and
are undergoing tests. These systems allow the source and ownership of
the
audio or video to be verified.
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4. DVD Production
DVD
discs are produced by first premastering and then manufacturing.
4.1
DVD Premastering
Premastering
of DVD applications is relatively straightforward for DVD-ROM
but
can be very complex for DVD-Video and DVD-Audio.
DVD-Video premastering
DVD-Video
premastering comprises the following processes.
• Video encoding to MPEG-2 using
variable or constant bit rate encoding
• Audio encoding to
Dolby Digital, MPEG or PCM
• Subtitles created
as subpictures
• Authoring to
add interactivity and create menus and navigation data
• Emulation/title testing
DVD-Audio premastering
DVD-Audio
premastering is similar to DVD-Video and can include:
• Audio encoding and
lossless packing
• Still image encoding for
slideshows (optional)
• Text preparation for
audio related text
• Authoring for
optional interactivity, menus and navigation data.
• Emulation/title testing
DVD-ROM premastering
DVD-ROMs
can be premastered in a similar way to CD-ROM. Premastering
tools
must format the data according to the DVD specifications including the
UDF
file system. For Windows 95, the ISO 9660 file system with
extensions
must be included as well. A single disc can comprise any or all of
DVD-Video,
DVD-Audio and DVD-ROM content each complying with the
appropriate
specifications. Combination discs are likely to play differently on a
DVD-Video
player, DVD-Audio player and DVD PC.
4.2
Manufacturing DVD Discs
Manufacturing
CD and DVD discs both require similar processes. The data are
stored
as minute pits (which are much smaller for DVD) in the surface of the
plastic
disc. A stamper is created by a glass mastering process and used to
mould
the DVD pits in the surface of the polycarbonate disc substrate. An
additional
stage, bonding, is required only for DVD discs to bond two thin
substrates
together to produce the finished disc.
Glass mastering
Both
CD and DVD discs glass mastering is needed to create stampers used to
mould
pits in the surface of the disc. The differences between DVD and CD
means
that much of the mastering process for DVD needs new equipment
including
improved glass master preparation, laser beam recording and
developing.
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Replication
Replication
comprises injection moulding, using the stamper created during
mastering,
of two disc substrates, metallisation of one or both substrates and
bonding.
Disc Finishing
Printing
of single sided DVD discs can be the same as CDs, eg using screenprinting
of
up to six colours. Double-sided discs can only be printed within the
hub
area but on both sides.
New
Packaging has been developed for DVD to differentiate it from CDs and,
in
most cases, to allow the disc to be removed from the packaging while
protecting
them from any force that might delaminate the substrates.
Quality Assurance
DVD
discs must meet certain stringent quality parameters, the most important
of
which are disc flatness, low jitter and signals within specifications.
Mastering
and
replication equipment must be set up to ensure these specifications are
met
and measurement equipment is needed to check the actual parameters.
In
addition, mastering and replication is the only way to ensure that a DVD title
has
been pre-mastered correctly. Therefore it is important to verify the
replicated
discs using DVD players to ensure correct functionality.
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5. Disctronics
Disctronics
is the largest independent CD and DVD disc manufacturer in
seven
days a week. The company has replication plants in the
pre-mastering,
mastering, copy protection, on-line order tracking, replication,
fulfilment,
CD cards, custom CDs and e-commerce services for the music,
software
and home video industries. Disctronics is ISO 9001 registered,
accredited
by IRMA, ELSPA and FACT and is a founder member of IODRA.
Disctronics
thrives on offering the best service to our customers. In addition to
our
disc replication and fulfilment services, we also provide information and
advice
to our customers where and when they need it. This is particularly
important
for new technologies such as DVD and copy protection.
For
more information on CD, CD-ROM and DVD replication email
sales@disctronics.com
or visit our website www.disctronics.com.
Disctronics
Manufacturing (
Tel:
+44 (1403) 739600 Fax:+44 (1403) 733786 FreePhone: 0800 626698
Email:
sales@disctronics.com
Disctronics
Blackburn Ltd
Tel:
+44 1254 505300 Fax: +44 1254 263673 Email:
blackburnsales@disctronics.com
Disctronics
Fulfilment Services
Focal
Point,
Tel:
+44 1293 590400 Fax: +44 1293 590471 Email: dfs@disctronics.com
Disctronics
24,
rue Evariste Galois, BP 35, F-81 001 ALBI Cedex, France
Tel:
+33 5 63 78 22 50 Fax: +33 5 63 78 22 55 Email:
jgiraud@disctronics.com
5-7,
rue de l'Admiral Courbet, F-94 160 SAINT MANDE, France
Tel:
+33 1.53.66.15.40 Fax: +33 1.53.66.15.50 Email:
cmadsen@disctronics.com
Disctronics
Italia SpA
Via
Rossini, 4 - 20067 Tribiano,
Tel: +39 02 90621.1 Fax: +39 02 90630564 Email: aricci@disctronics.com__