Physical parameters Of DVD

Capacity
Parameter Units DVD CD
max payload GBytes 4.7 (12 cm SL)
8.54 (12 cm DL)
1.46 (8 cm SL)
2.66 (8 cm DL)
0.742 (mode 2)
0.650 (mode 1)


Data rates
channel rate mbit/sec 26.16 4.3218
FEC rate mbit/sec 3.00 0.4704
user rate mbit/sec 11.08 1.47
actual data rate mbit/sec 10.08 1.4112


Pits and tracks
pit width micron 0.5??? 0.5
track pitch micron 0.74 1.6
Min pit length micron 0.40 (SL)
0.44 (DL)
0.833 to 0.972
Max pit length micron 1.87 (SL)
2.13 (DL)
3.054 to 3.560
min pit length - 2T 2T
max pit length - 10T 10T


(Note: the minimum pit length for each layer of the Double layer disc is 10% greater than single layer disc. Hence the 10% less dense figure for Dual layer discs.)

Data format
sector size bytes 2048 2352 (mode 2)
2048 (mode 1)


Movement
Spiral direction clockwise clockwise
max revolutions/sec Hz 25.5 (12 cm disc) 8 (12 cm disc)
min revolutions/sec Hz 10.5 3.5
Reference scanning velocity m/s 3.49 (SL)
3.84 (DL)
1.2 to 1.4


Optics
wavelength nm 650 or 635 790
Numerical Aperture of Objective Lens - 0.60 0.45
refractive index - 1.55 1.55
Spot Size
(lambda/NA)
- 0.63 1
Focus Depth
(Focus Margin, lambda/NA^2)
- 0.47 1
Chromatic Aberration
(Title margin, lambda/NA^3)
- 0.35 1
Spherical Aberration
(Thickness Tolerance, lambda/NA^4)
- 0.26 1
Reflectivity % 70 minimum (SL)
25 to 40 (DL)
70 minimum


Mass
Thickness of substrate mm 0.6 1.2
disc thickness mm 1.2 1.2
disc mass grams 13 to 20 (12 cm)
6 to 9 ( 8 cm)
14
Thickness of spacing layer in Dual Layer micron 40 to 70 N/A


FEC
Error correction method RS product code CIRC
FEC consumption % 13 25
FEC format bytes (208,192,17)x(182,172,11) (28/32)x(24/28)
Sector constraint length - 16 (=32 Kbytes) 1
correctable burst length mm 6.0 (SL)
6.5 (DL)
2.5


Channel code
Channel modulation method 8/16 (EFM+) 8/14 + 3 merge bits
Run length bits (2,10) (3,11)


Diameters
outer mm 120 (12 cm)
80 (8 cm)
120
outer lead in mm 117 (12 cm)
78 (8 cm)
117
outer data mm 116 (12 cm)
76 (8 cm)
116
inner data mm 48 (12 cm)
48 (8 cm)
50
inner lead in mm 45 (12 cm)
45 (8 cm)
46
center hole mm 15 (12 cm)
15 (8 cm)
15
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