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BuyingTips - DVD

What is a DVD?

DVD or Digital Video Disc or Digital Versatile Disc is essentially a CD, that can hold video, audio and computer data. Although it looks like a CD, it can hold between 7 to 14 times more information than its look-alike. DVD aims to encompass home entertainment, computers, and business information with a single digital format, eventually replacing audio CD, videotape, laserdisc, CD-ROM, and perhaps even video game cartridges. DVD's present spectacular pictures and sound when compared to standard TV or VHS tape as well as greater convenience and durability.

The following key features of DVD will help you decide the right one for you:

Aspect Ratio: The standard ratio of television, between the width and height of an image or display screen is 4:3 (1.33:1), which is not capable of showing most movies. Generally all of the movies are made for the wide screen of a theater, and are originally displayed at the wider ratios of 1.85:1 or 2:35:1. DVD's huge data storage capacity makes it possible to include multiple versions of a movie on a single disc as a result you get more original image. Even a DVD disc can feature a Standard (4:3) version on one side and a Widescreen version on the other.

Anamorphic: It is a type of widescreen display format optimized for playback on a TV with 16:9 aspect ratio. Usually for most of the movies (whether on disc or tape), it must be reformatted to 'Letterbox' or 'Pan and Scan' mode. A DVD played in pan-and-scan mode provides an image with full height, but shows a central "window" that is only 75% of the original widescreen width. In Letterbox mode the player using a "letterbox filter" adds horizontal black bars to the top and bottom of the picture. As a result you get a short, rectangular image.

Dolby Digital: Is a multichannel digital audio standard offering enhanced sonic realism. A Dolby Digital soundtrack can mean anything from 1 to 5.1 channels. Dolby Digital 5.1 soundtracks, will no doubt, provide the most satisfying sound quality for a home theater system. It is referred to as a 5.1-channel system because it offers five full-bandwidth channels with true stereo surrounds, and a subwoofer channel. One will need to connect player to a receiver or processor that can take the digital bitstream from the disc and convert it into 6 channels of audio, unless one's DVD has its own built-in Dolby Digital decoder.

Perceptual Coding: A data compression technique used by Dolby Digital to reduce the amount of audio and vedio data formats. Perceptual coding omits imperceptible sound and picture data which is redundant. By throwing away a lot of unnecessary information it is possible to fit multiple versions of a movie on a single disc.

Digital Output: Almost all DVD players come with at least one digital audio output for sending the Dolby Digital bitstream to a Dolby Digital decoder. Two most common types of digital output are Coaxial and Optical. Both require a cable to connect to the digital output of the Dolby Digital receiver or decoder but mostly they are not included in the set. Digital data transfer offers extremely wide bandwidth and immunity to RF interference.

Downmixed Audio: All DVD players are capabe of takeing a 5.1-channel Dolby Digital soundtrack and Downmix it to two channels, which can then be sent to a stereo receiver, or to an A/V receiver with Dolby Pro Logic decoding. Making it possibe to have excellent Stereo sound(or Pro Logic).

DTS: Or Digital Theater Systems is an established multichannel audio format in movie theaters, but a relatively new concept for home theater systems. Like Dolby Digital, DTS is a 5.1-channel format. DTS' compression technique throws away less audio data than Dolby Digital, so it should sound better.

Horizontal Resolution: These are the number of vertical lines that can be identified across the width of a TV screen. Usually a bigger number of horizontal resolution is almost always better.

MPEG2: Or Moving Picture Experts Group, is the digital video signal compression used for DVD. This adaptive, variable bit-rate process is able to allocate more bits for complex scenes involving a lot of motion, while minimizing the bits in static scenes. Some DVD players display an on-screen bit rate of data flow in the form of a bar graph.

Composite Video Signal: DVD player's standard RCA-type video jack provides a composite video signal or S-Video. It is a video signal in which the brightness and color portions of the signal are combined.

Component Video Signals: Is a video signal in which the brightness and color portions of the signal are processed separately. Component video signal splits the chrominance (the color information portion of a video signal which describes an image's color shade and vividness). As a resut one gets improved color accuracy, remarkably clear on large screens. Component video signal is far superior than S-video.

Signal To Noise ratio: Or S/N ratio basically tells how clean video signal is. Video signal to noise (as well as audio) is measured in decibels or(db). Because of the way they process signals, digital video formats like DVD and digital satellite TV are extremely clean. An example of how decibel scale works is - a VHS VCR has a S/N spec in the low 40s; and a laserdisc player has low 50s ; whereas a DVD delivers a S/N ratio of 65 db- resulting in 25 or 15 times less noise in the signal than in VCR or laserdisc player.

Multi Language Capability: All DVDs are designed to make it easier for movies to be distributed in multiple languages. A single DVD disc can contain soundtracks in upto 8 different languages! In addition to multilingual dialogue, a DVD also has space for subtitles in up to 32 languages. Ofcourse the number of soundtracks and subtitles may vary from disc to disc depending on the length of the movie and whether other special playback features are included.

Parental Lockout: A limited number of DVD movies come with variable ratings capability. According to the movie rating level you select, the player will skip over certain scenes, playing the version that you choose from those available on the disc. The parental lockout can be activated by remote control. By selecting your own personal identification number, you can prevent it from getting changed by others.

Regional Codes: All DVDs include codes which would limit playback to a specified geographical region. Since all the theater and home videos are not released at the same time, all over the world; DVD players have a builtin regional code lockout feature. As a result a DVD player will be unable to play a disc that has a different region code. It is also important to note that discs may or may not have any code, or may contain codes for more than one region- allowing to be played on any player, any where in the world.

Copy Protection: The DVD system includes both digital and analog forms of copy protection. As a result you cannot copy DVDs with your VCR.

More than 70% people, use their VCR just for playing movies, not for recording. In this senario buying a DVD player meet your needs. As DVD players have the ability to display almost twice the resolution than standard VHS playback. This means you can get clearer, more precise pictures from DVD! On the other hand, if you tape a lot of shows, then you'll certainly want to keep your VCR.

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