Video

Video is an electronic way to record, copy, play back, send, and show moving pictures, sometimes with sound. It began as a way to send images live and later grew to save images on special tapes. Today, most video is digital, making it easier to store, edit, and share on TV, computers, and the internet.

Video can look different based on how clear the pictures are, how wide the screen is, how often the pictures change, and how well the colors look. Video can travel on many kinds of materials, like radio waves, special tapes, shiny discs, computer files, and internet connections. This flexibility has changed how we make and share movies, shows, news, and lessons around the world.

Film and Footage tell us more about making video content, and you can learn about other meanings of the word "video" here. Be sure not to mix it up with Vidio.

display resolution, aspect ratio, refresh rate, color reproduction, radio, magnetic tape, optical discs, computer files, network streaming

Etymology

The word video comes from the Latin word video, which means "I see." It is the present form of the verb videre, meaning "to see."

History

See also: History of television

Analog video

See also: Analog television and Videotape

Video started in the 1800s. Unlike film, which uses tiny pictures, video turns images into electronic signals. At first, video was only for live broadcasts with special cameras and screens. Later, machines were made to record video on special tapes. These machines were very expensive at first but got cheaper, so ordinary people could record and watch shows at home.

Digital video

Main article: Digital video

See also: Digital television and Video coding format

Digital video made video better and cheaper. After DVDs and Blu-ray discs became popular, old tape machines were used less. Today, even simple computers and phones can easily record and play video. High-quality digital cameras are now used more than film cameras in movies.

Characteristics

Video shows moving pictures and can have sound. The speed of the pictures, called frame rate, can change. Older cameras showed just a few pictures each second, but modern ones can show more than a hundred.

Videos can be shown in two main ways: progressive scan and interlaced. Progressive scan shows all lines of the picture in order, giving a clear image. Interlaced scan shows lines in two steps, which can cause some flicker. Most older TVs used interlaced scan, but modern screens use progressive scan for better quality.

Videos also have different aspect ratios, which describe how wide the picture is compared to its height. Older TVs usually had a 4:3 ratio, while modern widescreen TVs use a 16:9 ratio. The way colors are shown in videos also varies, with different systems for different types of TVs and digital video.

Digital video uses compression to make files smaller while keeping good quality. This lets videos be stored on devices, sent over the internet, and played smoothly. There are also ways to create 3D videos that give a depth effect, using special glasses or screens.

Formats

Different ways of sending and saving video each have their own formats.

For sending video, there is a special connector and set of rules (see List of video connectors). A certain connection can show video with specific refresh rates, display resolution, and color space.

Many ways to record video exist, both analog and digital, and digital video clips can be saved on a computer file system in different formats. The way the data storage device or sender uses affects how the video is saved in a special video coding format.

Analog video

Analog video is a video signal shown by changing electric signals. Analog color video signals have luminance (Y) and chrominance (C). When mixed into one channel, like with NTSC, PAL, and SECAM, it is called composite video. Analog video can also use separate channels, like two-channel S-Video (YC) and multi-channel component video formats.

Analog video is used in both everyday and professional television production ways.

Digital video

Formats for digital video signals include serial digital interface (SDI), Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI) and DisplayPort Interface.

Serial digital interface (SDI)

Digital Visual Interface (DVI)

HDMI

DisplayPort

Transport medium

Video can be sent in many ways. It can travel through the air using terrestrial television. It can also move through wires in a closed system. Cameras often use special wires with serial digital interface (SDI). For details about connectors and signal standards, see the List of video connectors.

Video can also travel over networks using formats such as MPEG transport stream, SMPTE 2022, and SMPTE 2110.

Display standards

Further information: Display technology, List of common resolutions, and Broadcast television systems

Digital television uses special formats to send moving pictures. It is used in many places, like the United States, Canada, Europe, Japan, and Brazil.

Analog television was an older way to send pictures on TV. Many different systems were used around the world, such as NTSC in the United States and Canada, and PAL in Europe and Asia.

Computer display standards decide how pictures look on screens, including size and clarity. A list of common resolutions is available.

Recording

Early television shows were often shown live. Some important moments were recorded on film using Kinescope. In 1951, a new way to record videos on tape was created, called the analog video tape recorder. Over the years, many types of video tapes were made and used by TV stations, video makers, and everyday people.

Some early formats were VERA from the BBC, 2" Quadruplex videotape by Ampex, and U-matic by Sony. Later, formats like VHS and Betamax became popular in homes. As technology got better, digital video recorders offered improved quality.

New ways to store video on optical discs also appeared, like DVD and Blu-ray Disc. These gave people an alternative to large tape formats, especially for home use.

Digital encoding formats

See also: Video codec and List of codecs

A video codec is software or hardware that makes video files smaller and then brings them back to their normal size. This helps save space. The smaller files might look a little different because some details are lost.

• CCIR 601 (ITU-T)
• H.261 (ITU-T)
• H.263 (ITU-T)
• H.264/MPEG-4 AVC (ITU-T + ISO)
• H.265
• M-JPEG (ISO)
• MPEG-1 (ISO)
• MPEG-2 (ITU-T + ISO)
• MPEG-4 (ISO)
• Ogg-Theora
• VP8-WebM
• VC-1 (SMPTE)