18 Aug 2013
How DVD works
18 Aug 2013
Tags:
how
I hope you had seen and enjoyed the previous posts about ipod & LCD TV.
Today, i have come up with DVDs, While researching to creating this post i found some astonishing facts, i hope your are going to become surprise to know how a DVD stores its data and how those data are read / fetched from it.
DVD
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Today, i have come up with DVDs, While researching to creating this post i found some astonishing facts, i hope your are going to become surprise to know how a DVD stores its data and how those data are read / fetched from it.
DVD
The storage capacity of a DVD, six times that of a
traditional CD, has revolutionized the way digital
data is organized and stored in the decade since its
appearance in 1997. The DVD explosion
resounded in the world of home movies thanks to its
capability of storing entire feature films,
bonus material, and subtitles (in various languages) on only
one disc. The evolution of technology,
however, has not stopped with DVDs. Recent years have seen the
introduction of discs able to hold 12
times the data of the DVD
Reading with Light
Optical discs (CDs and DVDs) are read by a
laser beam to obtain information. This
information is transformed into a binary electric
signal that is later interpreted and converted into
sounds, images, and data.
click on the images to enlarge
click on the images to enlarge
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1.Laser emitter
generates a laser beam of
a specific wavelength.
2.Mirrors
guide the ray by working in
coordination.
3. Direction
In order to read the disc,
the laser beam must strike
the surface of the disc
perpendicularly.
4. Lens
focuses the laser beam
before it reaches the surface
of the disc.
5. Reading
The laser beam strikes the
disc's reflective surface. The
reflection varies according
to the pattern of pits on the
disc's surface.
6. Prism
changes the direction of the
laser beam that reflects from
the disc and contains the
data read from the disc.
7. Photodiodes
translate the variations in the
returning laser beam and
convert them into a digital
signal.
Blue light
Because blue light has a shorter wavelength than
red light (which is used in CDs and DVDs), a blue
laser makes it possible to read smaller pits, which
accounts for Blu-ray's greater storage capacity.
From the CD to Blu-ray
This comparison traces the evolution of the compact disc—especially its storage capacity.
This comparison traces the evolution of the compact disc—especially its storage capacity.
CD
|
DVD
|
HDDVD
|
BR-DVD
|
Maximum capacity (single layer)
|
875MB
|
4.7 GB
|
15 GB
|
27 GB
|
Maximum capacity (double layer)
|
--
|
8.5 GB
|
30 GB
|
54 GB
|
Laser wavelength
|
789 nm
|
650 nm
|
405 nm
|
405 nm
|
Transfer rate in megabits per second (Mbps)
|
6
|
11.1/10.1
|
36.55
|
36/54
|
Resistance to scratches and dirt
|
No
|
No
|
No
|
Yes
|
Maximum video resolution
|
--
|
576 pixels
|
1,080 pixels
|
1,080 pixels
|
Supported formats
|
-- VCD and
SVCD
|
DVD, VCD,
SVCD,
MPEG-2
|
MPEG-2, VC-1
(based on WMV),
H.264/MPEG-4 AVC
|
MPEG-2, VC-1,
MPEG-4 AVC
|
From the CD to Blu-ray, information storage has become
denser, and the wavelength of the reading beams has
become shorter.
1 millimeter = 1,000 micrometers (m)
1 micrometer = 1,000 nanometers (nm)
©2013 TEchnicalWisdom.blogspot.com
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