BTC640/Video
Lecture
Textbook chapter: 6
Since TV took off video has been one of the best ways to deliver information to consumers. Like other presentation technologies it's better for some kinds of information than others, and also like other presentation technologies there is lots to learn about it.
Because the technology is quite complex we will only get an overview of video in this course, without going into too much detail, but you need to know some basics at least.
Channels and Interfaces
There are two big categories here: analog and digital. With video the differences between the two are similar to the differences between analog and digital audio, though unlike analog audio - analog video is lossy.
Video is rarely used without audio, but the two are separate technologies that are combined into one by placing them into the same container and synchronising their playback. The transmission channels are usually separate though.
Here are the most popular channels and interfaces for video:
Analog channels
- Component video: three cables with an RCA jack each. If audio is required - a fourth cable (usually also RCA or double-RCA for stereo) is used.
- VGA cable/connector: the most common video-out connector in a computer. This is also component video. Though it usually comes out of a computer - it does not carry a digital signal.
- S-Video: one cable with a DIN connector. Only two channels instead of 3 as with component thus lower quality. The cable does not carry audio, usually the separate audio cable has TRS connectors.
- Composite: a single cable with an RCA jack. All the information goes over this single channel, which makes it the lowest quality of the three. If audio is required - a fourth cable (usually also RCA or double-RCA for stereo) is used.
Digital channels
- DVI: a specification for digital transmission of video, and also the common name for a connector. No audio. Interestingly a DVI cable also carries an analog signal for the same video.
- HDMI: an interface that includes digital video, digital audio, CEC, and even ethernet. Mini HDMI and micro HDMI are also becoming popular, used on smaller devices such as smartphones.
channel conversion cable cable
