Monday, 12 December 2011

Components of Digital Video

Today i am talk about the components of digital video.all digital video is a collection of electronic signals recorded by a camera onto a piece of media: videotape, optical disk, hard drive, or flash memory. No matter how the signals are stored, all digital video consists of tracks, frames,  scan lines, pixels, and audio samples.

The Tracks:-
During a shoot, your video camera captures video and audio information, converts it into
electronic data, and stores it onto its recording medium. All of this data is laid down in separate
tracks (sometimes called channels or streams), typically one video track and two audio tracks.
(Some cameras and audio recorders can record four or more tracks of audio.) In addition,
most digital cameras record some form of data track that includes information such as the
time of day, timecode, camera settings, and so on.

Scan Lines
Each individual frame of video is composed of a series of horizontal lines that are scanned
across the screen starting at the top. With some types of video, these scan lines start at the top
and work their way down to the bottom, filling the screen entirely, a process called progressive
scanning .With other types of video, the scan lines start at the top but only draw the even-numbered lines until they get to the bottom; a process called interlaced scanning . Each pass across the monitor is called a field, and each frame of interlaced video consists of two fields. The order in which the fields are drawn can change, depending on how the video is recorded. If you are wondering which one is better, there’s no clear answer, but progressive scanning is definitely simpler and more intuitive, so given the choice, most filmmakers these days opt for progressive scanning. However, if your project is destined for broadcast television, the network may require that you use a form of HD with interlaced scanning.

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