Component Video Signals (CAV)

Component Video Signals (CAV)

Component Analog Video (or CAV) refers to analog video signals comprised of three separate channels, each carrying a different color component. CAV is the video type used by SDTV, HDTV, and computer graphics, and provides the highest quality transmission of analog video possible, typically used for video production and high-end viewing. There are two types of color component signal:

RGB:

• R = red, G = green, B = blue,
• The “natural” format of a color television signal where each color component corresponds to a color beam,
• Formats are RGsB (sync on green), RGBS (separate sync), and RGBHV (separate H and V sync pulses)

YPbPr (or YUV):

• Y = luminance (brightness),
• Pb or U = scaled color difference, B-Y,
• Pr or V = scaled color difference, R-Y,
• The main format is YsPbPr (sync on Y),
• Gain and timing inequalities between the components are less visible than in RGB
• The bandwidth of the color difference signals can be greatly reduced

Aspect Ratios

All CAV signals have an aspect ratio of 16:9 or 4:3, sampling from left to right, top to bottom, a luminance signal range from 0 mV (reference Black) to 700 mV (reference White), and a chrominance component (Pr, Pb) signal range of ±350 mV. In addition, HDTV signals only have an aspect ratio of only 16:9, an orthogonal pixel sampling lattice, and use a symmetrical tri-level sync of amplitude ±300 mV, with a horizontal (line) datum located at the central zero-crossing of the tri-level sync waveform.

Scanning Modes

CAV signals use three scanning modes defined as:

1. P      Progressive scan, progressive transport (also referred to as 1:1)
2. PsF   Progressive scan, segmented frame transport
3. I       Interlaced scan, interlaced transport (also referred to as 2:1)

TV Standards

There are three categories of CAV signal that define the picture resolution, frame rate, and bandwidth:

1. SDTV (Standard Definition TV)
2. EDTV (Enhanced Definition TV)
3. HDTV (High Definition TV)

The characteristics that distinguish these categories are listed in the following tables for the most common standards (or systems). Progressive systems 480p and 576p (highlighted in the tables in grey) are often grouped in with STDV standards, but in this paper are referred to more appropriately as EDTV to indicate that they lie somewhere between the SDTV and HDTV resolutions and rates.

Common Standards

The frequency in the system name refers to frame rate for progressive, or field rate for interlaced systems. There are many other official standards defined by SMPTE and ITU-R that differ in total frame size, active picture size, and frame rate.