Originally posted by jbc
Are you telling me that a DVD player on a computer is called a Codec? Hmm, did not know this. This is one of the reasons why I like coming to this group I seem to learn something new everyday.
A Codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word "codec" is a portmanteau of any of the following: 'Compressor-Decompressor', 'Coder-Decoder', or 'Compression/Decompression algorithm'.
Codecs encode a stream or signal for transmission, storage or encryption and decode it for viewing or editing. Codecs are often used in videoconferencing and streaming media solutions. A video camera's ADC converts its analog signals into digital signals, which are then passed through a video compressor for digital transmission or storage. A receiving device then runs the signal through a video decompressor, then a DAC for analog display. A "codec" is a generic name for a video conferencing unit.
An audio compressor converts analog audio signals into digital signals for transmission or storage. A receiving device then converts the digital signals back to analog using an audio decompressor, for playback. Codec is the name of a special two-way radio in the popular game Metal Gear Solid.
The raw encoded form of audio and video data is often called essence, to distinguish it from the metadatainformation that together make up the information content of the stream and any "wrapper" data that is then added to aid access to or improve the robustness of the stream.
Most codecs are lossy, in order to get a reasonably small file size. There are lossless codecs as well, but for most purposes the almost imperceptible increase in quality is not worth the considerable increase in data size. The main exception is if the data will undergo more processing, especially editing, in the future, in which case the repeated lossy encoding could degrade the quality of the eventual file too much. Using more than one codec or encoding scheme throughout processing can also degrade quality but there are many situations where this cannot be avoided. There are many codecs which are designed to emphasize certain aspects of the media to be encoded. For example, a digital video (using a DV codec) of a sports events like baseball or soccer need to encode motion well but not necessarily exact colors, where a video of an art exhibit needs to perform well encoding color and surface texture. There are hundreds or even thousands of codecs ranging from free ones to ones costing hundreds of dollars or more.
Many multimedia data streams need to contain both audio and video data, and often some form of metadata that permits synchronization of the audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data stream to be useful in stored or transmitted form, they must be encapsulated together in a container format.
An endec is a similar (but not identical) concept for hardware.
While many people explain that AVI is a codec, they are incorrect. AVI (nowadays) is a container format, which many codecs might use (although not to ISO). There are other well known alternative containers such as Ogg, ASF, QuickTime, RealMedia and MP4.
A DVD player is a device for playing discs produced under the DVD Video standard. Most hardware DVD players have to be connected to a television set; there are also some small portable devices which have an LCD screen attached.
A DVD player has to complete these tasks:
Read a DVD disc in ISO - UDF version 1.2 format
optionally decrypt the data with either CSS and/or Macrovision
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 (with optional AC-3 to stereo downsampling) on stereo connector, optical or electric digital connector
output a video signal, either an analog one (in PAL, SECAM or NTSC format) on the composite, s-video, or component video connectors, or a digital one on the DVI or HDMI connectors
Most DVD players also allow users to play audio CDs (CDDA, MP3, etc.) and Video CDs (VCD) and include a home cinema decoder (i.e. Dolby Digital, Digital Theatre Systems (DTS)). Some newer devices also play videos in the MPEG-4 ASP video compression format (such as DivX) popular on the Internet.
As of 2005, retail prices for such a device, depending on its optional features (such as digital sound or video output), start between 30 and 80 USD/euros. They are usually cheaper than VCRs.
By far the largest producer of DVD players is China; in 2002 they produced 30 million players, more than 70% of the world output. These producers have to pay about US$20 per player in license fees, to the patent holders of the DVD technology (Sony, Philips, Toshiba and AOL Time Warner) as well as for MPEG-2 licenses. To avoid these fees, China has developed the EVD standard as an intended successor of DVD; as of 2004, EVD players were only being sold in China.
Software DVD players are programs that allow to view DVD videos on a computer with a DVD-ROM drive. Some examples are the VLC media player and MPlayer (both free software), as well as WinDVD, PowerDVD and DVD Player. .