DVDs may appear to made entirely of plastic, but inside the plastic coating is a layer of aluminum. This is necessary so that the laser inside the machine can shine light through the plastic and have it reflected back to a lens on the other side. This laser is very thin and precise, not like one you would use in a typical science class. The computer inside the DVD player, using a device called an MPEG-2 decoder, translates the data from the lens into audio and digital signals, which it then parlays to your television through the audio and video connection cables.
If the disc simply sat stationary in the DVD player, the laser would not be able to read it properly. Instead, the machine's motor rotates it, and the player deciphers the data for the entire film by moving in a spiral from the inside to the outside of the disc. The speed at which it moves depends on the disc you're playing.
If you're playing a "dual-layer" DVD, once the laser reaches the outside, it reads additional tracks by heading back to the middle of the disc.
Connecting a DVD player to your stereo receiver or television, if you don't have a receiver involves making two basic connections: audio and video.
The first connection to make is for the audio portion of the signal. There will be several options depending on the receiver you have. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close.
Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. By: Gayle A. DVD Drive The DVD drive consists of three fundamental components: A drive motor to spin the disc - The drive motor is precisely controlled to rotate between and rpm, depending on which track is being read.
A laser and a lens system to focus in on the bumps and read them - The light from this laser has a smaller wavelength nanometers than the light from the laser in a CD player nanometers , which allows the DVD laser to focus on the smaller DVD pits. A tracking mechanism that can move the laser assembly so the laser beam can follow the spiral track - The tracking system has to be able to move the laser at micron resolutions.
Video CDs Some players can handle this format, which is used mostly for music videos and some movies from foreign countries. CD-Rs Some players can play content that you create on your own computer. Audio DVDs A few players can handle this format for high-quality audio. This feature is not necessary if you have a Dolby Digital receiver, which has a digital input that carries all of the audio information. Again, this feature is not necessary if you have a receiver with a DTS decoder. They pass the digital audio information on to the receiver, which then decodes it.
Simulated surround If you are going to hook the DVD player up to a TV or a stereo system with only two speakers, a DVD player with simulated surround processing will give you some sense of surround sound without the extra speakers. Disc capacity Some DVD players can hold three, five or even several hundred discs. Since most DVD players can also play audio CDs, if you buy a player with a high disc capacity you could store your whole CD collection in the machine. A dedicated remote , which only runs the DVD player A multibrand remote , which can control other components, like VCRs and TVs made by other manufacturers Usually, they only support the more common brands.
A learning remote , which can learn the signals from other remotes and assign them to a button This feature is useful if you have uncommon brands of components to control. DVD Extras. Because DVDs are so durable, film aficionados can watch a favorite movie repeatedly without the disc losing its quality. This is also good for parents whose children like to watch the same movies over and over again.
DVD players allow you to find scenes, play them in slow motion or freeze a scene, and the video quality will remain the same.
An entire encyclopedia can fit onto one DVD, whereas other formats would require multiple discs. Digital video recorders write recorded video to an internal hard drive.
The amount of video the DVR can store depends on the size of this hard drive. Some models, however, connect to a home network to allow transfer to a computer. Users can play any of these discs in a compatible DVD player or computer. DVRs connect through the television signal and provide an onscreen guide for watching and recording TV. These guides can automatically find shows to record by name or time.
0コメント