1. Basic Specifications
Double Density
CD Format
Sony Establishes Double Density CD-ROM/-R/-RW Formats
----- Conventional CD technologies utilized to realize 1.3GB
capacity -----
(Tokyo, Japan, July 5, 2000) Sony Corporation today announced plans to develop
a "Double Density CD-ROM/-R/-RW (tentative name)" with 1.3GB data
capacity. The Double Density CD formats are designed to provide a natural migration
path for both consumers and manufacturers alike, as the new formats offer a
low-cost solution to high capacity discs that inherit the basic specifications
of the CD formats. This allows manufacturers to utilize their current CD technologies
and production facilities to manufacture Double Density CDs.
The recent evolution of high performance processors and high
capacity hard disk drives has empowered the PC to handle large audio, video
and still image files. That in turn has raised the need for higher capacity
CDs to store and share those files with other devices at the lowest running
cost. In light of this market demand, Sony decided to develop the Double Density
CD formats.
Double Density CD formats' high capacity is realized by a few
simple modifications to the CD formats. To increase data density, track-pitch
and minimum pit length are miniaturized to increase the data capacity from 650MB
to 1.3GB. To accommodate higher physical bit density, a parameter in the error-correction
scheme (CIRC) has been changed, and the address format (ATIP) has been expanded.
A copy control scheme will be included in the format to meet the increasing
demands for secure content protection. The remaining areas inherit the basic
specifications of the conventional CD formats to make use of the existing CD
infrastructure.
Royal Philips Electronics and Sony will license the Double Density
CD formats together. Philips will serve as the licensing contact (see website
http://www.licensing.philips.com/). The formats are being finalized for licensing
by September 2000. As for compliant media, verification services are planned
in the near future.
Basic Specifications of Double Density CD-ROM/-R/-RW formats
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Double Density CD
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Conventional CD
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Data Capacity
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1.3GB (2048B/sector)
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CD-ROM (Mode1)/-R/-RW:
650MB (2048B/sector)
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Wavelength
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780nm
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Objective Lens
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Playback: NA=0.50
Record/Playback: NA=0.55
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Playback: NA=0.45
Record/Playback: NA=0.50
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Disk Size
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Diameter: 120mm
Thickness: 1.2mm
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Track Pitch
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1.1 um
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1.6 um
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Minimum Pit Length
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0.623 um
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0.833 um
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Scanning Velocity
(multiplies according to drive speed)
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0.90 m/s
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1.2 - 1.4 m/s
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Error Correction
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CIRC7
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CIRC
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Modulation
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EFM
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2. FAQ
Double Density
CD Format - FAQ
We tried to find more info about the coming DDCD from Sony and
Philips so we did a small interview with Sony:
CDRINFO: When the new format will come out officially?
SONY: We are planning to finalize the format by the end of September. After
we finalize the format, we would like to launch the product as soon as possible,
but we can't give you the specific timing a this time.
CDRINFO: When we should expect new CDR-W drives supporting the
Double Density media?
SONY: Our plan is to introduce Double Density CD-RW drive as the first product.
Again, we can't confirm the exact timing, but we intend to introduce the product
as soon as the format is finalized.
CDRINFO comment: Other manufacturers estimate to ship DDCD drives in early 2001.
CDRINFO: Will the produced DD CDs read by existing CD-Roms drives?
SONY: DD CD Drive will be able to read the current CD-ROM/CD-R/CD-RW discs,
but the existing drives will not be able to read the discs of new format. (So,
basically backward compatibility)
CDRINFO comment: This is the most major problem that the new format will have
to face..
CDRINFO: If I understood correctly the Double Density term is
actually not for the CD but for the drive. This means that we will be able to
write existing media with 1.3GB? Or new media supporting 1.3GB will come out?
SONY: Double Density will be used for both drive and media. To have 1.3GB capacity,
you will need both new drive and new media. DDCD drive will be able to write
the existing media, but the capacity will be 650MB.
CDRINFO: Why and what this copy control scheme will be about?
As I understand it will limit the copy of pressed CDs or not? Also will the
DDCD format used in music area to replace existing 74min CDs?
SONY: The copy protection is basically for protecting AV content, but specifics
are still under discussion and we can't discuss the details at this time.
CDRINFO: What possible reading speeds of the DDCD CDR-W drives
we would see?
SONY: We can't discuss the specific product plans at this time, since we are
still working on the format.
CDRINFO: What about the writing/re-write(?) speeds of the new
1.3GB media? Maybe we will see 16x write speeds (or higher)? Also will you ship
1.3GB RW media? Again what possible re-write speeds it will support?
SONY: We cant's discuss the specific product plans at this time, since we are
still working on the format.
CDRINFO:Do you believe that the RW DDCD format will become a possible
competitor for DVD+RW format which Sony backups?
Sony: For DDCD format, primary product focus will be RW product, that can be
used for CD/CD-ROM/CD-R player and CD-R/RW recorder. Although DVD recordable
products will have much higher capacity (4.7GB), CD-RW market will continue
to grow for the next one or two years and both products (CD/DVD recordable)
will coexist for the certain period. We believe that adding more capacity to
CD-RW without significant cost increase while having backward compatibility
with the current products will certainly bring benefits to the users.
3. How did they done it?
Double Density
CD - Page 3
- How did done it?
The
high capacity of the Double Density CD format is realized by a few simple modifications
to the common CD format. In order to increase data density, track-pitch and
minimum pit length are miniaturized to increase the data capacity from 650MB
to 1.3GB. This capacity is achieved
by utilising a conventional 780 nm laser and using a NA of 0.50 or 0.55, thus
reducing the track pitch (by 1.45) and the minimum pit size (by 1.33):
>
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Comparison of DDCD and CD formats
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Double Density CD
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Conventional CD
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Data Capacity
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1.3GB (2048 B/sector)
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CD-ROM (Mode1)/-R/-RW: 650MB (2048 B/Sector)
|
|
Wavelength
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780nm780nm
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Objective Lens
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Read: NA=0.50
Read/Write: NA=0.55
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Read: NA=0.45
Read/Write: NA=0.50
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Disc Size
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Diameter: 120mm, 80mm
Thickness: 1.2mm
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Track Pitch
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1.1micrometer
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1.6micrometer
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Minimum Pit Length
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0.623micrometers
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0.833micrometers
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Scanning Velocity
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0.90 m/s
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1.2 to 1.4 m/s
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Error Correction
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CIRC7
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CIRC
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|
Modulation
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EFM
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To accommodate higher physical bit density, a parameter in the
error-correction scheme (CIRC) has been changed, and the address format (ATIP)
has been expanded. Sony stated in the original press release that "...A
copy control scheme will be included in the format to meet the increasing demands
for secure content protection...".
This copy control scheme, as we can understand, means that you
can not write AudioCD format in DDCD-R/RW media! Yeap folks. Sony denied
any relation of the DDCD format with Audio CDs (and with all possible piracy
issues). Just imagine that a DDCD-R media will be able to store 148mins of music...
Someone might say that this is not a real problem since DDCD media is not playable
from current stand alone players/CD-ROMs. That is true for the present situation,
but what about the future? Sony's future CD-ROMs/CDR-W drive will probably support
the DDCD format, and then this *problem* will become a reality. Of course you
are able to write Mp3 files (as data tracks).
- Use
The product sheet of CRX200E model says that you can:
- Backup your most important files
- Store large or high quality digital photos
- Move your favorite music tracks from your HD
- Store 2 hours MPEG-1 digital motion pictures
- Store Internet homepage's multimedia contents
- Distribute and share data
Have you noticed that almost every single use contains the word "store"
and "backup"? This is where the DDCD is aimed at!
4. Media
Double
Density CD - Page 4
A
DDCD medium is an 80 mm or a 120 mm disc with a continuously recorded physical
track beginning from a radius of 24 mm and spiraling outward to a radius 37.5
mm or 58 mm. Like a conventional CD Drive/Media there are three types of DDCD
Drive/Media, Read Only (DDCD-ROM), Write Once (DDCD-R), and ReWritable (DDCD-
RW). The capacities of these media are the same. The DDCD Media Format is not
backward compatible with current CD devices.
As you can understand, due to different physical structure,
the DDCD Medium is not backwards compatible with the existing CD-ROM/DVD-ROM/CDR-W
drives. This means that the media will only be playable in the devices that
contains the "DDCD" logo.
For
now there are not many manufacturers who ship DDCD-R/RW media. Only Sony and
Verbatim sell DDCD-R/RW, and we haven't heard of any other media manufacturers
going for it. Actually even Verbatim have announced DDCD media they haven't
shipped in retail market due to low demand. Our guess is that they are waiting
to see whether the new standard will be widely accepted from end users, in order
to proceed to mass production. Below is a comparison chart beetween the CD/DDCD
formats and the media that can be read/written:
As you may notice the DDCD drives can playback all CD media and
DDCD media. The normal CD-RW drives simply cannot read the DDCD-R/RW media.
Comparing the new DDCD specifications with those of the conventional
CD, some major specifications are the same, such as the size of the disc. Other
specifications indicate that some adaptations have to be made to the media production
process of the DDCD. Error correction and physical addressing require some changes
to the decoding/encoding equipment.
Note: CIRC* is different from the conventional CD. In the DDCD
system, the delay parameter “D” of CIRC is extended from 4 to 7 to
improve burst error correction ability in case of higher recording density.
The maximum burst error correction ability of CIRC* is extended to 837 symbols.
5. Recording
Double Density
CD - Page 5
- Recording methods:
The DDCD format is supposed to support: "DAO, SAO, TAO" formats.
Our tests showed that only "TAO" writing mode, Packet Writing and
Multi-Session are supported. In the case of Packet Writing we will have 2 modes:
Variable Packet Writing and Fixed Packet Writing (no futher information
is given about their main differences). There seems to be a limitation with
MultiSession of the DDCD and CD format as the following table shows:
As it is obvious, you cannot backup CDs which contain multiple
sessions in DDCD-R/RW media, and vice versa.
- Recording speeds
The DDCD format has mainly 2 different writing/re-writing speeds.
The DDCD-R media can be written at 12x and the DDCD-RW media at 8x. In other
words, you will need around 12 minutes to burn a full DDCD and around 15 minutes
for a full DDCD-RW media. We hope that newer DDCD models will support higher
recording speeds (16x) and, why not, a full 10x re-write mode.
6. Disc Structure
Double Density
CD - Page 6
Disc Structure
There are three address expressions used in the
DDCD system; the Block address contained in the sector header (Physical Sector
Number), Subcode-Q channel (Subcode frame time number), and the address referred
to the blocks of the Initiator system (LBA: Logical Block Address).
The address used by the Initiator system starts
from 0 to the end of the recorded information on the disc. LBA 0 shall correspond
with the sector header address of D300h and the Subcode-Q address of 0:12:00:16
(0 hour, 12 minutes, 00 second, 16 frame). Only the Data Area is generally addressable
by using LBA. Subcode-Q areas are addressed in time based address.
The representation for a time based address is
H:MM:SS:FF, where H = hours, MM = minutes, SS = seconds, and FF = frames. Hour
field is 1 digit. MM:SS:FF are 2 digits respectively. When the time based address
includes the hours field selection between LBA and H:MM:SS:FF is indicated by
the appropriate TIME bit. One Hour is subdivided into 60 Minutes. One Minute
is 60 Seconds. One Second is 75 frames.
Single Session Disc
A Session is a recorded sequence that includes
a Lead-in Area, Program Area, and Lead-out Area. The Lead-in / Lead-out Area
is a guard area at inner / outer part of the disc. The Lead-in Area also contains
the table of contents (TOC) for Program Area. The Program Area is also known
as the user area of the disc.
Multi-Session Disc
The multi-session allows a single disc to have
several concatenated sessions. On a recorded disc, session may appear as shown
in Figure 2. DDCD read only drives are not typically capable of reading through
unrecorded areas on the medium. The DDCD read only drive needs EFM data in order
to find and stay in the physical track. This is to ensure that a DDCD read only
drive is capable of accessing all areas of a Program Area.
In order to assure readability with DDCD read only
drives, the recording system shall always close the session before attempting
interchange. Additional information is needed in order to locate all of the
program areas. This is accomplished by using SubCode-Q Mode 5 in the Lead-in
areas.
7. Sector Structure
Double Density
CD - Page 7
Physical Sector
The physical format defined by the DDCD media standard
provides 2,352 bytes per sector. For computer data applications, 2,048 bytes
is used for user data, 12 bytes for a synchronization field, 4 bytes for a sector
address, 8 bytes for an additional information and 276 bytes – the auxiliary
field –for Layered ECC.
Sector Structure
A Sector, called Mode2 Sector, shall consist of
2,352 bytes arranged with 12 Sync bytes, 4 Header bytes, 8 SubHeader bytes,
2,048 User Data bytes, and 4 Error Detection Code (EDC) bytes, 172 P-Parity
bytes, 104 Q-Parity bytes. The User Data bytes are identified from 24th to 2071st.
The Header shall consist of 3 bytes of Sector Address and 1 Mode byte. The Mode
byte shall be 02h to indicate Mode 2 Disc Type.
The physical format of DDCD media uses smaller
unit of synchronization than the other magnetic or optical recording systems.
The basic unit of the data stream synchronization is a small frame. This is
different from large frame (sector) as referred to in the HMSF unit. Each small
frame consists of 588 bits. A sector on DDCD media consists of 98 small frames.
A DDCD small frame consists of:
1. 1 synchronization pattern (24+3 bits)
2. 1 byte of sub-channel data (14+3 bits)
3. 24 bytes of data (24 x (14+3) bits)
4. 8 bytes of CIRC code (8 x (14+3) bits) Total:588 bits.
Data, sub-channel and CIRC bytes are encoded to
14-bit codes according to the EFM table; then three merging bits are added.
The merging bits are chosen to minimize DSV (Digital Sum Value) and provide
DC free characteristics. The data bytes of 98 small frames comprise the physical
unit of data referred to as a sector. 98 small frames times 24 bytes per small
frame equals 2,352 bytes of data per sector.
Sub-Channel
Information Formats
The sub-channel 1 byte of each frame is assigned
one bit for each of the 8 sub-channels, designated P, Q, R, S, T, U, V, W. Sub-channel
P and R to W are all reserved and set to zero. All the sub-channel Q bits of
a sector define the sub-channel Q information block. The sub-channel Q block
consists of 98 bits, one bit from each small frame in a sector.
The format provides the information of the location
and is defined as follows:
1. 2-bits sub-channel synchronization field
2. 4-bits ADR field (defines the format)
3. 4-bits control field (defines the type of information in this sector)
4. 8-bits Track number
5. 8-bits index number
6. 28-bits reserved
7. 28-bits Absolute HMSF address ( 4-bits Hour, 8-bits Minutes, 8-bits Seconds,
8-bits Frames)
8. 16-bits CRC error detection code
TNO = 01 to 99 is the track number in BCD
INDEX = 00.
AHOUR, AMIN, ASEC, AFRAME
= the absolute time address expressed in 7 BCD digits.
8. Recordable Structure
Double Density
CD - Page 8
DDCD Recordable and DDCD
ReWritable Structure
An unrecorded DDCD-R or DDCD-RW disc does not have an EFM to find the physical
track in the traditional way of DDCD read only drives. A blank DDCD-R or DDCD-RW
has pre-groove and it has the built in wobble for the purpose of defining and
finding the physical track. The wobble is a 22.05KHz signal modulated with digital
information. The position within the pre-groove is contained in each pre-groove
frame of 42 bits. This is known as an Absolute Time In Pre-groove (ATIP). The
ATIP frame shall consist of 42 bits.
In the area that is expected to be the disc’s Lead-in Area,
the additional information is interleaved between positional ATIP frames.
The additional information provided is:
- First possible start address for disc Lead-in (TOC)
- Last possible start address for disc Lead-out
- Special information about recording permissions
- Power and speed requirements for recording the medium
- DDCD-R vs. DDCD-RW medium
DDCD-R/RW discs have two additional areas prior to the first Lead-in;
the Power Calibration Area (PCA), and the Program Memory Area (PMA). The Power
Calibration Area (PCA) is present only in DDCD-R and DDCD-RW media for the purpose
of write power calibration.
The PCA is divided into two areas: the test area and the count area. The test
area is divided into 1000 calibration partitions. The count area is a counting
area for use of the test recording. The Program Memory Area (PMA) is present
only for DDCD-R and DDCD-RW media for the purpose of counting for the use of
user data area on the medium. This information is contained only within the
Subcode-Q channel of the PMA frames.
9. Packet Layout
Double Density
CD - Page 9
Packet Layout for DDCD
The layout of a Packet on DDCD media is shown in Figure 5. Each
packet starts with Link block followed by three Run-in blocks. The User data
blocks are placed directly after the Run-in blocks. Finally, three Run-out blocks
are located following the User data blocks. In the case of Fixed packet writing,
the size of each Packet in a Track is constant in length.
Example of Packet written Track layout out:
