A DVD is a digital video disc, which has more space than a CD, which has only 4.7 GB, while a DVD has about 12.5 GB of storage. A DVD player works by using these steps. First, a drive motor will spin the disc around. Second, a laser and lens system focuses on the bumps and reads them. Lastly, a tracking mechanism moves the laser assembly so that the laser beam can follow the track.Then the tracking system has to be able to move the laser at micron resolutions. Then the movie starts up. A DVD plays when you put the DVD in, and you have to put it in properly.
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Figure 1: A picture showing all the bumps on a DVD, and a DVD player and its remote.

Blu-ray Discs
Blu-ray discs are a different kind of disc compared to a DVD. A Blu-ray player only plays certain movies(Blu-ray ones) while a DVD can play the movies that are out. A Blu-ray disc can hold up to 50 GB, while a regular DVD can only hold 4.7 GB. A Blu-ray disc can be more money than a regular DVD, but a Blu-ray disc is has better quality and is clearer than a DVD.

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Figure 2: A Blu-ray disc, which is different than a regular DVD.

Fun Facts
A DVD is very similar to a CD but it has a much larger capacity
A single layer DVD holds about 7 times more data than a CD, which means it has enough room to store a full-length, MPEG 2-encoded movie, as well as slot of other information
A DVD movie usually includes the following-
  • up to 133 min of high resolution video
  • The video compression ratio is typically 40:1, using MPEG-2 compression
  • a soundtrack presented in to eight languages, using 5.1 Dolby digital surround sound
  • Subtitles up to 32 languages

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Figure 3: This is a DVD.

DVD- digital video disc
GB- gigabyte, a type of space that is bigger than a megabyte.
Blu-ray-an optical disc storage medium designed to supersede the DVD format.
Subtitles- the little words you sometimes see at the bottom of a movie or TV screen
Video compression ratio- The size of the video signal that's not yet compressed, compared to that same signal after it's compressed.
High resolution- HRHD (high-resolution high-definition) (also HR, HRHDTV, or HR.HDTV) is an initialism referring to an image resolution derived from high-definition video, often seen as part of the filename of TV shows shared on the Internet
MPEG-Moving Picture Experts Group- The Moving Picture Experts Group (MPEG) is a working group of experts that was formed by ISO and IEC to set standards for audioand video compression and transmission

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DVD. Wikipedia. Wikipedia. September 28, 2012. Web. September 19,2012.
"DVD." Encyclopedia Britannica. Encyclopedia Britannica Online School Edition.

Encyclopedia Britannica, Inc., 2012. Web. 27 Sept. 2012.