The DVD-ROM has largely replaced the video cassette and is much more efficient and superior in many ways. On the one hand, it stores data in digital form, while the video cassette uses less accurate analog technology. Under normal conditions, a DVD remains error-free and consistent, regardless of how often it is watched, while a videotape stretches with wear and tear and eventually needs to be replaced. It can also contain more information in a higher format, and a viewer can access certain scenes without the need to move quickly or rewind. DVDs are much more compact and easier to store, and gamers can usually play CDs. Like a CD player, a DVD player uses a laser to read scanned (binary) data encoded on the disc in the form of tiny pits that trace a spiral track between the center of the disc and its outer edge. However, since the DVD laser emits red light at shorter wavelengths than the red light of the CD laser (635 or 650 nanometers for DVD versus 780 nanometers for CD), it is able to resolve shorter pits on narrower tracks, allowing for greater storage density. In addition, DVDs are available in single and double-sided versions with one or two layers of information per page. A double-sided DVD can hold more than 16 gigabytes of data, more than 10 times the capacity of a CD-ROM, but even a single-sided, single-layer DVD can hold more than four gigabytes, more than enough capacity for a two-hour movie scanned in the highly efficient MPEG-2 compression format. In fact, shortly after the introduction of the first DVD players, one-page DVDs became the standard medium for playing movies at home, almost completely replacing videotapes.
Consumers quickly appreciated the convenience of the discs, as well as the superior quality of the video images, the interactivity of the digital controls and the presence of many additional features built into the spacious memory of the discs. Compared to a CD-ROM, a DVD-ROM has the same diameter of 5 inches and a thickness of 1.2 millimeters (mm). However, as a DVD-ROM uses a shorter-wave laser with narrower densified pits, the capacity of the disc is increased. In fact, the smallest DVD-ROM can store about 7 times more data than a CD-ROM. Consumers were also initially slow to adopt blu-ray due to the cost. [88] In 2009, 85% of stores sold Blu-ray discs. A high-definition TV and proper connection cables are also required to take advantage of Blu-ray discs. Some analysts suggest that the biggest obstacle to DVD replacement is due to the installed base. A large majority of consumers are satisfied with DVDs. [89] With two incompatible technologies on the market, consumers were reluctant to buy from next-generation players for fear that one standard would lose the other and render their purchase worthless.
In addition, film studios faced a potentially costly situation when producing films for the lost format, and computer and software companies were concerned about the type of player needed for their products. These uncertainties created pressure to commit to a format, and in 2008, the entertainment industry accepted Blu-ray as its preferred standard. Toshiba`s group has stopped developing HD DVDs. At the time, doubts were raised about how long even new Blu-Ray discs would be viable, as an increasing number of high-definition movies were available online for „streaming“ and cloud computing services offered consumers huge databases to store all kinds of digitized data. A DVD player uses a laser to read encoded data on a DVD. Since the DVD laser emits red light at shorter wavelengths than other optical discs, such as CDs, a DVD can achieve a higher storage density. The next generation beyond DVD technology is high definition or HD technology. As television systems moved to digital signage, high-definition television (HDTV) became available, which had a much higher image resolution than traditional television. Movies are particularly suitable for viewing on large flat-screen HDTV screens, and in 2002, as in 1994-95, two competing (and incompatible) technologies for storing high-definition video on a CD-ROM-sized disc were introduced: HD DVD, offered by Toshiba and NEC Corporation, and Blu-ray, offered by a group led by Sony. Both technologies used a laser that emitted light at the blue-violet end of the visible spectrum.
The extremely short wavelength of this light (405 nanometers) made it possible to follow even smaller pits on even narrower tracks than on the DVD. As a result, a one-sided side. Single-layer discs had a storage capacity of 15 gigabytes (HD DVD) or 25 gigabytes (Blu-ray). Manufacturers will continue to release standard DVD titles [Update] from 2020, and the format remains the preferred format for the release of old TV programs and movies. Shows shot and edited entirely on film, such as Star Trek: The Original Series, cannot be released in high definition without being re-digitized from the original images. [95] Shows shot between the early 1980s and early 2000s were typically shot on film, then transferred to videotape, and then edited natively in NTSC or PAL, making high-definition programming impossible because these SD standards were engraved in the final sections of the episodes. Star Trek: The Next Generation is the only show of its kind to have a Blu-ray release, as the prints were digitized and edited from scratch. [96] DVDs are used in the DVD-Video digital video format for consumers and in the DVD-Audio digital audio format for consumers, as well as to create DVD discs written in a special AVCHD format for high-resolution hardware (often in conjunction with AVCHD format CAMCORDERS).
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