DVD

“DVD” is the abbreviation for digital versatile disc or digital video disc. It is a data storage medium, a type o optical disk technology, very similar to CD-ROM, offering higher capacity than CDs while it has the same dimensions. DVD“, as an optical disc storage was invented in 1995 by Philips, Sony and Panasonic.

What is DVD?

The Digital Video Disc (DVD) is a technology that employs optical data storage, similar to the Compact Disc (CD). Optical data storage entails using light to read the digital information stored as 1′s and 0’s. Analog information is first converted into digital information before being encoded onto the disc, starting from the inside edge and moving outwards. The disc’s recording layer is covered in pits that represent the digital data, and this encoding is done through a process known as Eight-to-Fourteen Modulation (EFM) in CDs and Eight-to-Sixteen Modulation (EFMPlus) in DVDs.

The length of the pits and the lands, which are the spaces between the pits, on a disc are varied to encode digital information. These pits are organized in a spiral pattern on the recording layer of the disc and rotate in a circular motion as the disc is played in a player. An optical head laser moves outward, maintaining its focus on the pits, and sends a beam of light that is reflected back to a detector when it encounters a land. Conversely, the laser beam is scattered away from the detector when it reaches a pit. The transition from a pit to a land signifies a binary “1” in the digital data stream.

The storage capacity of a DVD is significantly greater than that of a CD. A DVD can hold over two hours of video on one layer of the disc, whereas a CD can only store 74 minutes of data. The smaller pits on a DVD are about 0.4 microns wide, compared to the minimum width of 0.83 microns for CD pits. The closer arrangement of these pits on a DVD, with a track pitch of 0.74 microns, allows for a single-layer, single-sided DVD to hold 4.7 GB of data, compared to the 650 MB that can be stored on a single CD.

A DVD player’s laser beam must have a shorter wavelength than a CD player’s because of the smaller size of a DVD. DVD players, on the other hand, can now play both DVDs and CDs thanks to this development. CD players cannot play DVDs, and vice versa, because of this one-way compatibility.

Given the limited size of pit areas, the potential for errors in disc reading is virtually boundless. This has driven the rapid advancement of error correction storage. In CD technology, Error Correction Coding (ECC) is utilized on the disc as a means of addressing issues when they arise. The ECC algorithms are designed to detect and accurately rectify errors in the data. The same approach is also employed for error correction in DVD technology.

The higher quantity of information recorded on a DVD movie is primarily due to the smaller pit size and tighter track spacing, although compression is also a role. MPEG2 is an enhanced video compression technique developed by the Moving Picture Experts Group. This technology is based on temporal compression, which compares one video frame to the next and only stores the differences in the scene. It preserves a single frame in a delay to keep a scene’s background and save up space for storing scene updates. MPEG2 also employs the discrete cosine transform, which analyzes images to locate and compress repeating frequencies.

Video compression technology enables the storage of a range of viewing options, making DVDs a significant technological breakthrough. With full theater experience and Dolby Digital (AC-3) Surround Sound, DVD-video offers a range of options including wide-screen (16:9) or full-screen (4:3) viewing, multiple language soundtracks, and closed-captioned viewing. DVD video also allows the viewer to choose the film’s rating, such as R or PG, through preprogrammed scene cuts on the disc. In addition, the viewer can opt to watch the uncut version of the film or see outtakes from the original. All of these options are available at the beginning of the film, and the DVD will smoothly transition from one scene to the next according to the viewer’s choices.

The storage of DVD video has undergone a significant improvement with its 525-line resolution. This resolution far surpasses the resolution of laser disc media and nearly doubles that of standard VHS videotapes. The resolution can be experienced with any television monitor, regardless of its resolution capabilities. Another benefit of DVD is that the disc does not physically touch the player as it spins, thereby preventing wear and tear and maintaining its integrity over time. On the other hand, videotapes, which come in contact with the playback mechanism, eventually break down and result in a degradation of picture quality.

A Brief History of DVD

The CD Video was first introduced in 1987 and utilized analog video encoding on optical discs that were the same size as audio CDs. The Video CD (VCD) soon became a popular format for distributing digitally encoded films in 1993.

Two new optical disc storage formats were developed in 1993. The Multimedia Compact Disc (MMCD) was backed by Philips and Sony, the developers of the CD and CD-i. The Super Density (SD) disc was supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC.

By the time of the press launches for both formats in January 1995, the term MMCD was no longer used, and Philips and Sony referred to their format as Digital Video Disc (DVD).

On May 3rd, 1995, a working group consisting of five computer companies (IBM, Apple, Compaq, Hewlett-Packard, and Microsoft) announced in a press release that they would only accept a single format. The group voted to boycott both formats unless the two opposing sides reached an agreement on a unified standard. They brought in Lou Gerstner, President of IBM, to encourage the executives of the conflicting parties to reach a compromise. In a significant agreement, the MMCD and SD groups agreed to adopt proposal SD 9, which stated that both layers of the dual-layered disk would be read from the same side, instead of proposal SD 10, which would have resulted in a two-sided disk that needed to be flipped.

As a result the DVD specification allowed for a storage capacity of 4.7 GB (4.38 GiB) for a single-layered, single-sided disk and 8.5 GB (7.92 GiB) for a dual-layered, single-sided disk. The DVD specification was similar to Toshiba and Matsushita’s Super Density Disc, with the exception of the dual-layer option. The MMCD was single-sided and had the option for dual-layer while the SD consisted of two half-thickness, single-layer disks that were pressed separately and then joined to form a double-sided disk.

Philips and Sony concluded that it was in their best interests to resolve the format war, and on September 15, 1995 they reached an agreement with companies supporting the Super Density Disc to launch a unified format incorporating technologies from both sides. Following negotiations between MMCD and SD, the computer companies, represented by TWG, ultimately triumphed and a single format was established. TWG also worked with the Optical Storage Technology Association (OSTA) to utilize their implementation of the ISO-13346 file system, known as Universal Disk Format, for the new DVDs. The specifications of the format were officially confirmed on December 8, 1995.

In November of 1995, Samsung announced its plans to begin mass producing DVDs by September 1996. The format was officially launched in Japan on November 1, 1996, featuring mostly music video releases. Four titles from Warner Home Video were among the first major releases and became available on December 20, 1996. The U.S. release of the DVD format was delayed several times, initially planned for August 1996, then October 1996, and finally November 1996, before being rolled out in early 1997.

Domestic production of players began in the winter of 1996, with the U.S. launch of the format taking place in seven test markets on March 24, 1997. On launch day, around 32 titles were available from Warner, MGM, and New Line libraries. However, the nationwide rollout was rescheduled for August 22, 1997, due to a change in distribution with retailers and studios to prevent any violations of the street date.

DTS first declared its entry into the format market toward the end of 1997. In a November 1997 online interview, the corporation disclosed its plans and announced the availability of CDs in the first quarter of 1998. But this schedule was pushed back multiple times before the business unveiled its first titles at the 1999 Consumer Electronics Show.

What are the types of DVD?

The physical properties of optical discs and the method of storing and handling data on them are defined by DVD formats. These formats vary based on their intended usage, with the most significant distinctions being whether the disc can be written to. Within each use category there are often alternative formats or implementations available.

DVDs: Non-Recordable Formats

• DVD-ROM: These are produced similarly to CDs, featuring a silver or gold reflective surface. They come in a variety of configurations, including single-sided/single-layered, single-sided/double-layered, double-sided/single-layered, or double-sided/double-layered. However, the use of double-sided discs has become increasingly rare since 2004.
• DVD-D: It is a disposable DVD format that was introduced in the year 2008. It is sold in an airtight package and has the unique feature of self-destruction through oxidation after a few hours. Similar to “EZ-D,” the “DVD-D” is designed to be used once and then disposed of.
• DVD Plus: The “DVD Plus” technology combines the features of both a DVD and a CD. It includes a CD layer as well as a DVD layer, offering the best of both worlds. It’s important to note that “DVD Plus” should not be confused with the separate “DVD+” formats.

DVDs: Recordable Formats by the DVD Forum

• DVD-R for Authoring: This is a type of DVD-R designed specifically for recording DVD masters, which can be replicated into mass-produced DVDs by duplication facilities. It requires a specific DVD-R recorder and is less commonly used today as many duplication systems are now able to accept standard DVD-R masters.
• DVD-R: This type of DVD-R is capable of recording up to 4.7 GB of data in a manner similar to a CD-R disc. Once the data has been recorded and finalized, it can be played on most DVD-ROM players.”
• DVD-RW: This type is capable of recording up to 4.7 GB in a manner similar to that of a CD-RW disc
• DVD-R DL: This type is a variant of the DVD-R that utilizes double-layer recordable discs, capable of storing up to 8.5 GB of data.
• DVD-RW DL: A derivative of DVD-RW, DVD-RW DL utilizes double-layer recordable discs to store a maximum of 8.5 GB of data.
• DVD-RAM: The DVD-RAM technology, which is currently in version 2.1, is compatible with 2.6 GB, 4.7 GB, or 9.4 GB (double-sided) discs. These discs, however, can only be used with a limited number of other-format DVD drives. Previously, DVD-RAM discs were housed in cartridges, but they are now less frequently used and can be removed from their caddy and utilized in compatible standard-tray drives. The DVD-RAM format is highly rewritable compared to other rewritable formats.
• DVD-AR: The DVD-Audio Recordable (DVD-AR) is a type of DVD that is specifically designed for recording audio.

DVDs: Recordable Formats by the DVD+RW Alliance

DVD+R: The DVD+R format has the capability of recording a maximum of 4.7 GB of data at a speed of up to 16 times faster. However, similar to DVD-R, it can only be recorded on once and cannot be overwritten.
DVD+RW: The DVD+RW format has the ability to record up to 4.7 GB of data at a speed of 16 times faster. Its defining characteristic is its rewritability, which allows for multiple recordings without the need for “pre-pits” or finalization. As a result, it can be played in a DVD player without any special requirements.
DVD+R DL: The DVD+R DL is a variation of DVD+R that utilizes dual-layer recordable discs, which can hold up to 8.5 GB of information.
DVD+RW DL: This type is a variation of the DVD+RW technology that utilizes dual-layer recordable discs to store a maximum capacity of 8.5 GB of information.

The differences between these types of DVD is as follows:

• DVD-R and DVD+R can only record data once, resulting in discs that can only be read.
• DVD-RW, DVD+RW, and DVD-RAM, on the other hand, enable multiple recordings and erasure of data.
• The DVD-ROM can only read data and does not have the capability to save information.

FAQs: Answering the Top Questions about DVD

Below you can find concise answers to the most frequently asked questions about DVDs that we received through the search bar above. We will try to update this section as often as possible as we receive other questions.