A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVD originally stood for Digital Versatile Disk, or Digital Video Disk. The acronym was dropped after DVD proved to have more uses than just storing video content. DVDs offer higher storage capacity than Compact Discs while having the same dimensions. Pre recorded DVDs are mass produced using molding machines that physically stamp data onto the DVD. Such discs are known as DVD-ROM, because data can only be read and not written nor erased. Blank recordable DVDs (DVD-R and DVD+R) can be recorded once using optical disc recording technologies and supported by optical disc drives and DVD recorders and then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased multiple times. DVDs are used in DVD-Video consumer digital video format and in DVD-Audio consumer digital audio format, as well as for authoring AVCHD discs. DVDs containing other types of information may be referred to as DVD data discs.
DVD Video is a consumer video format used to store digital video on DVD discs, and is currently the dominant consumer video format in Asia, North America, Europe, and Australia. Discs using the DVD video specification require a DVD drive and a MPEG-2 decoder (e.g., a DVD player, or a computer DVD drive with a software DVD player). Commercial DVD movies are encoded using a combination of MPEG-2 compressed video and audio of varying formats (often multi channel formats as described below). Typically, the data rate for DVD movies ranges from 3 Mbit/s to 9.5 Mbit/s, and the bit rate is usually adaptive. It was first available for retail around 1997.
DVD Audio is a digital format for delivering high fidelity audio content on a DVD. DVD audio is not intended to be a video delivery format and is not the same as video DVDs containing concert films or music videos. The first discs entered the marketplace in 2000. DVD-Audio was in a format war with Super Audio CD (SACD), another format for delivering high fidelity audio content. Neither format has gained a strong position in any consumer market.
A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. These devices were invented in 1994 and continue to thrive. However, with the release of high definition media, sales and popularity are expected to drop in the upcoming years. A DVD player has to complete these tasks: Read a DVD disc in ISO – UDF version 1.02 format. Optionally decrypt the data with either CSS and/or Macrovision. Read and obey the DVD’s Regional lockout codes and display a warning if the player is not authorised to play the DVD. Decode the MPEG-2 video stream with a maximum of 10 Mbit/s (peak) or 8 Mbit/s (continuous). Decode sound in MP2, PCM or AC-3 format and output on stereo connector, optical or electric digital connector. Output a video signal, either an analog one (in NTSC, PAL or SECAM format) on the composite, S-Video, SCART, or component video connectors, or a digital one on the DVI or HDMI connectors.
Additionally, most DVD players allow users to play audio CDs (CDDA, MP3, etc.) and Video CDs (VCD). A few include a home cinema decoder (i.e. Dolby Digital, Digital Theater Systems (DTS)). Some newer devices also play videos in the MPEG-4 ASP video compression format (such as DivX) popular in the Internet. Most hardware DVD players have to be connected to a television, there also exist portable devices which have an attached LCD screen and stereo speakers. Portable DVD players are often used for long road trips and other travel.
There are successors to the DVD player: the HD DVD player and the Blu-ray Disc player, utilizing two incompatible technologies that reproduce higher quality video images than standard DVD. On February 19, 2008, Toshiba, creator of the former technology announced it would cease production on all HD DVD products leaving Blu-ray as the high definition successor to DVD players. Also, upscaling and up converting DVD units are available that connect to televisions via a high definition interface and increase the overall picture quality.