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25-02-2009, 02:25 PM
Nearly every movie produced today is available on DVD, and many older movies are being moved to the DVD format. Often, a movie comes out on DVD before it comes out on videotape, because the manufacturing and distribution costs for DVDs are so much lower! By bringing outstanding picture and sound to our favorite films, the DVD format is doing for movies exactly what CDs did for music. A DVD is very similar to a CD, but it has a much larger data capacity. A standard DVD holds about seven times more data than a CD does. This huge capacity means that a DVD has enough room to store a full-length, mpeg-2-encoded movie, as well as a lot of other information.Here are the typical contents of a DVD movie:
1). Up to 133 minutes of high-resolution video, in letterbox or pan-and-scan format, with 720 dots of horizontal resolution (The video compression ratio is typically 40:1 using MPEG-2 compression.)
2). Soundtrack presented in up to eight languages using 5.1 channel Dolby digital surround sound
3). Subtitles in up to 32 languages
DVD can also be used to store almost eight hours of CD-quality music per side.DVD picture quality is better, and many of DVDs have Dolby Digital or DTS sound, which is much closer to the sound you experience in a movie theater.
2). Many DVD movies have an on-screen index, where the creator of the DVD has labeled many of the significant parts of the movie, sometimes with a picture. With your remote, if you select the part of the movie you want to view, the DVD player will take you right to that part, with no need to rewind or fast-forward.
3). DVD players are compatible with audio CDs.
4). Some DVD movies have both the letterbox format, which fits wide-screen TVs, and the standard TV size format, so you can choose which way you want to watch the movie.
5). DVD movies may have several soundtracks on them, and they may provide subtitles in different languages. Foreign movies may give you the choice between the versions dubbed into your language, or the original soundtrack with subtitles in your language.
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24-03-2011, 03:12 PM
DVD Technology.doc (Size: 305.5 KB / Downloads: 59)
DVD TECHNOLOGY AND APPLICATIONS
Digital Versatile Disc, or DVD is a collection of new optical disc technologies that have the potential to significantly improve the quality of a number of consumer electronics and personal computer products. These discs are capable of holding up to 17 gigabytes (GB) of data storage, with current research offering a potential for 15 times more storage. This technology is made available through advances in laser technology and advances in manufacturing processes for optical discs. A Digital Versatile Disc is basically a double density, double sided, compact disc. In addition, the laser used to read a DVD utilizes a shorter wavelength, allowing the storage surface of each of these layers to be more compact.
The purpose of this report is to present the format, creation, current applications, and economic forecasts for DVD technology. To emphasize the advances afforded using this technology, a side by side comparison with current Compact Disc technology will be used. Motorola’s Research and Development is currently investigating the possibilities for implementation of a DVD Group to interact with current research and product groups. This report will give the introduction and background necessary to determine the feasibility of DVD integration into current marketing and research products. This report will provide a simplified explanation of the construction methods required for DVD replication, solely for the purpose of presenting the difference in construction needed to manufacture a DVD.
The four parts of this report will discuss (1) a technological overview of DVD, utilizing a comparison of CD vs. DVD technologies, (2) the construction of a DVD, (3) current applications utilizing DVD, and (4) project and implimentationed sales and revenues of DVD devices. The technological overview section will use a comparison of current CD specifications vs. DVD specifications to convey the advances made possible using DVD. The construction section explains the manufacture of a DVD to show the physical advantages of DVD for data storage and retrieval. The section covering current applications examines the five current formats for DVD specifications and how they are currently being used today. Finally, the sales and revenues section includes forecasts of DVD sales and distribution, based upon current sales and technology release.
II. DVD TECHNOLOGY OVERVIEW
Digital Versatile Disc (DVD) technology was pioneered in 1993 by the Toshiba Corporation to fulfill two primary technical goals, provide both higher throughput and higher capacity than current CD-ROM technology. While DVD optical discs are quite similar to CD-ROM optical discs, there are a number of key physical differences, as well as philosophical differences. CD-ROM technology was originally designed to accommodate high quality audio data, and a large quantity of textual data. While the use of CD-ROM has been extended to include video data, the format falls short of providing broadcast television quality video and cannot store full-length feature films. The DVD format was specifically designed to address each of these limitations.
Beyond the inception of DVD technology, advances have been developed by a group of ten consumer electronics companies, called the DVD Forum, who have agreed on the set technical specifications for each DVD format. Until recently, there were two competing groups of companies: one led by Sony, and the other by Toshiba, that were both trying to develop proprietary high-density optical disc formats. Fortunately, these two groups joined forces and agreed to form the DVD Forum. The DVD Forum has also actively encouraged participation from members of the entertainment and computer industries so that the DVD format will have a broad base of support in both the consumer and computer electronics areas.
As mentioned before, two of the primary goals of DVD are to provide both higher capacity and higher throughput than current CD-ROM technology offers. To demonstrate the advances afforded using DVD, this section will reference the specifications of CD-ROM vs. DVD technology.
CD-ROM vs. DVD Comparison
The table on the following page shows some of the key similarities and differences between the CD-ROM and DVD formats.
The key features, which comprise the difference between CD and DVD technologies, are the physical characteristics, data structure characteristics, and operating characteristics.
The physical characteristics of the optical discs including thickness, diameter and structure are nearly identical, with the only exception being the DVD possessing a double substrate with half the thickness of a conventional CD. This allows multiple layers of data to be stored within the same thickness of a conventional CD single layer, as seen in Figure 1.
Data Structure Characteristics
The data structure characteristics of the optical discs include laser wavelength, track pitch, and pit length. All of these characteristics differ from CD to DVD and allow for the significant improvements in data capacity and throughput seen in the DVD operating characteristics. Using a red laser for DVD devices vs. a standard infrared laser used for current CD devices, provides a much smaller wavelength, allowing better selectivity and smaller data structures, as seen in Figure 2. Data can be stored in half the length previously necessary using conventional CD technology.
The advances provided by the shorter wavelength laser and multi-layer structure, exponentially increase the throughput of DVD devices vs. CD devices. All DVD formats and playback devices will support a minimum throughput rate that is eight times faster than conventional CD-ROM, and many DVD playback devices will support even higher transfer rates. In addition, by doubling both the number of layers and the number of sides utilized, capacity of DVD has been increased to a maximum of 17.0 GB of memory, compared to 650 (megabytes) MB of storage on a standard CD-ROM, an increase of more than 26 times the capacity.
III. CONSTRUCTION OF A DVD
DVD construction is similar to traditional CD-ROM construction with a few added steps, and a much higher degree of manufacturing tolerance required. Each of the following major manufacturing steps will be presented using an explanation followed with a diagram to show the actual progression of the disc construction: