How are DVDs different from CDs?
On the outside, a DVD doesn’t differ from a CD. It has the same diameter and the thickness is 1,2mm. The only difference is the capacity.
On the inside, a DVD is totally different than a CD. The pits are half the size of CD pits. (0.4µm vs. 0.83µm), and its tracks are spaced about twice as closer to each other (0.74µm vs. 1.6µm). See the image.
How the Mp3 player works
MP3 players and the new generation of portable music. It is the successor of the Discman and the walkman. A MP3 player lets you carry hours of music wherever you go.
The MP3 format
The MP3 format has completely changed the rules of music distribution. The MP3 player is getting more popular.
The MP3 format is a compression system for music. This format is reducing the number of bytes in a song, without changing the quality of the song.
The main goal of the MP3 format is to compress a CD song by a factor of 10 to 14. But without changing the quality. A 32 megabyte song can be compressed into a 3 MB song on MP3. So you can store 10 to 20 songs on an MP3 player using a relatively small amount of memory.
How MP3 files work
How a CD is built up
A CD is a piece of plastic of 1.2 mm thick. It’s made of an injection-molded piece of clear polycarbonate plastic. The CD is full of microscopic bumps which are arranged in a spiral track. One long track.
How a CD is manufactured
During the manufacturing, the piece of polycarbonate plastic is made full of microscopic bumps. These bumps are arranged in one very, very long track that goes all around the CD in a spiral. When there’s made a piece of polycarbonate plastic a thin aluminum layer is put over the bumps, this layer reflects. Then after that an acrylic layer is sprayed over the aluminum to protect it.
How the CD is read and the data is recorded on the CD
When you put the CD in a CD-player the laser of the CD-player reads it like a LP-player. The difference with and LP is that a CD can record a lot more data. The LP has bumps you can see and is read with a needle. The CD has everything high tech, with microscopic bumps and a laser to read it. The bumps are really very small. It’s approximately 0,5 microns wide, with 1,6 microns who separate one track from the next (a micron is a millionth of a meter).
Comparison
All three recorder or players have positive things.
The DVD has much more capacity and the quality is better. IT can hold more data. So I think the DVD is the best choice. But the price is one problem. To buy a DVD recorder, you’ll need a lot of money. And the DVDs are still quite expensive. But the prices will drop.
The MP3 player is also quite good, but the memory disks are expensive. But you can put more songs on the hard disk of the MP3 player than on a CD and the main advantage is that the music quality will not decrease.
The MP3 player is not really expensive, it was but now the prices have dropped. The music you have to put on the MP3 player, have to be in mp3 format, so that means it have to be downloaded songs, Or you have to change them into mp3 format. So to put a normal CD on your mp3 player you have to make a few steps.
The CD was high tech for the time when it was invented, but now we have better ways of recording data. The CD is good to use for normal use at home, because the recording of a CD is quick. CD’s are cheaper then for instance DVD’s. When you want to have very good quality a DVD is better. The advantage from a CD over an Mp3 player is that you can also put Computer data on a CD. An Mp3 player is pure for the listening of music
Tobias Nederkoorn
Fabian Berndsen
Sander van der Kuip
Ewout Meijer
