Video

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

Video can look different depending 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 different 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 all 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 video, meaning "I see." It is the first-person present form of the verb videre, which means "to see."

History

See also: History of television

Analog video

See also: Analog television and Videotape

Video began with early systems in the 1800s. Unlike film, which uses tiny pictures you can see, video changes images into electronic signals that can be sent and recorded. At first, video was only for live broadcasts, using special cameras and screens. Later, people created machines to record video onto special tapes. These were very expensive at first but became cheaper over time, allowing ordinary people to record and watch shows at home.

Digital video

Main article: Digital video

See also: Digital television and Video coding format

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

Characteristics

Video shows moving pictures and can include sound. The speed at which pictures are shown, called frame rate, can vary. Older cameras might show only a few pictures each second, while modern ones can show over a hundred. Different TV systems use different frame rates to show smooth motion.

Videos can be shown in two main ways: progressive scan and interlaced. Progressive scan shows all picture lines in order each time, giving the clearest picture. Interlaced scan shows lines in two steps, which uses less space but can cause some flicker in movement. Most older TV systems used interlaced scan, but modern screens often 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 used for different types of TVs and digital video.

Digital video uses compression to make files smaller without losing too much quality. This lets videos be stored on devices, sent over the internet, and played back 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 to choose from.

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. Besides the way the data storage device or sender uses, the stream of ones and zeros must be in a special video coding format.

Analog video

Analog video is a video signal shown by one or more 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, like through the air using terrestrial television as either an analog or digital signal. It can also travel through coaxial cables in a closed system as an analog signal. Cameras used for broadcasting or in studios often use a single or dual coaxial cable system with serial digital interface (SDI). For details about the physical connectors and signal standards, see the List of video connectors.

Video can also move over networks and shared digital links 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 mostly shown live, with some recorded on film for important moments using Kinescope. In 1951, a new way to record videos on tape was introduced called the analog video tape recorder. Many different types of video tapes were created over the years, used by TV stations, video makers, and everyday people.

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

New ways to store video on optical discs also appeared, such as DVD and Blu-ray Disc. These provided 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 when storing videos. The smaller files might not look exactly like the original video because some details are lost during this process.

• 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)