CONTENT
 CD Basics

 CD Audio

 CD-ROM

 DVDBasics

 DVD-Video

 DVD-ROM

 DVD-Audio

 DVD-Recordable

 Replication

 DigitalVideo

 Glossary


 
DVD physical specs title graphic

DVD Physical Specifications

Find out here how DVD discs differ from CDs and how they contain much more data for a wide range of applications. 

Please note that the descriptions below represent brief summaries of the DVD specifications which can be obtained from the DVD Forum.

The DVD technical specifications are contained in five books A to E published by the DVD Forum.
Book Name Part 1
Physical
Part 2
File System
Part 3
Appli- cation
Ver

A

DVD-ROM Read-only ISO 9660 + UDF undefined  ver 1.01

B

DVD-Video Read-only UDF MPEG-2 video ver 1.1

C

DVD-Audio
Read-only UDF high quality audio ver 1.2

D

DVD-R
Write once UDF not defined ver 2.0

E

DVD-RAM & DVD-RW
Rewritable UDF not defined ver 2.0

Physical Parameters

The table below summarises the physical parameters of DVD and compares them with those of CD and CD-ROM.

Parameter CD DVD Comments
# layers 1 single dual see Disc Formats
Thickness (mm) 1.2 0.6 2 x 0.6 mm
# sides 1 2 DVD substrates bonded
Track pitch 1.6 0.74 microns
Min pit length 0.83 0.4 0.44 microns
Scan velocity 1.3 3.49 3.84 m/sec
Wavelength (nm) 780 635/650 red laser for DVD
Numerical aperture 0.45 0.6
Modulation EFM 8 to 16 EFM is 8 to 17
Error protection CIRC RSPC Block protection for DVD
3rd layer ECC CD-ROM No Not needed for DVD
Subcode/Tracks Yes No Not needed for DVD

DVD Sector Structure

The data on a DVD disc are organised as sectors of 2048 bytes plus 12 bytes of header data (see below).  Blocks of 16 sectors are error protected using RSPC RS PC (Reed Solomon Product Code), which is block oriented and is more suitable for re-writable discs (with packet writing) than CIRC which does not use a block format. The PI and PO data are parity bytes calculated horizontally and vertically over the data bytes.

DVD sector structure

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. 

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. 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 data stored in the BCA can be from 12 bytes to 188 bytes in steps of 16 bytes. 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, tamper-proof means of identifying individual discs.

Burst cutting area
 

 

In this page:

Physical
    Parameters

DVD Sector
    Structure

Burst Cutting
    Area

 

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