Basics of Analog Video Signal Video Signal l

Basics of Analog Video Signal

Video Signal l The quality of a video signal has a direct correlation to the type of connection linking it to video equipment. l In general, an analog video signal is comprised of luma (brightness) and chroma (color) components. l How those signals are combined together or kept separate affect the video quality and specifically the fidelity or resolution of the color information.

Connection Quality: Connector quality from best to worst l 1. Component l 2. Y/C (S-Video) l 3. Composite Although a video recording may be of a very high quality, if the connection from one device to another does not reflect that quality, the final video signal quality will be less than the original recorded quality.

Composite: l Composite provides a video signal whereby the luma and chroma elements are combined together into a single signal. l It is used in both NTSC and PAL formats and labeled as Composite Video l It is the most common signal connection on analog consumer equipment, like TV's, VCR's and consumer video cameras. It is the lowest quality color resolution in use today.

l It is NOT acceptable for post production needs like chroma keying, because the combined luma and chroma signals cannot be accurately or precisely decoded. l Display on television is also less than ideal as the signal must be decoded/converted back into red, green and blue intensities for display.

l Composite signal may be connected by a coax cable with a BNC connector or with a yellow RCA connector on consumer equipment.

Y/C (S-Video) l Stands for luma (Y) and chroma (C). It is also referred to as S-Video (this is the most common connection type that's used, although it may be found in studio environments with a BNC connection). l S-Video is the next step up in quality from composite. Y/C transmits the video signal with the luma and chroma components kept separate.

l Color is initially separated into 2 color difference components but with Y/C video, the color components are combined together. l Although the color components are combined, they are still kept separate from the luma component thus leading to better color fidelity than composite.

Component: l Component provides the best quality for analog video. This signal type maintains luma and both color difference components all separately. l Three cables connect component video, one for luma and one for each of the color difference components.

l Although the cables and the interfaces are often color coded red, green and blue, they are usually connecting luma, and two color difference components, NOT direct red, green and blue signals. l The connections on decks and other video equipment are labeled as Y, R-Y, B-Y or Y Pb Pr.

l Component connections maintain the highest quality for recording, monitoring, and post production applications like chroma-keying. l Although it is not common, some studio environments convey the component video by three cables transmitting separate red, green and blues signals (not luma and color difference channels).

l There are some inherent pitfalls in Analog Video signal - all analog video is transmitted by electrical signals which are prone to interference, distortion and quality loss when transmitted. l Copying an analog source results in "generation loss" which is a noticeable deterioration of quality. l Transmitting digital video does not incur this kind of generation loss.

Thank u