What are DVI, HDMI and Component Video?

What are DVI, HDMI and Component Video?

DVI/HDMI and Component Video are all video standards which support a variety of resolutions, but which deliver the signal from the source to the display in very different ways. The principal important difference is that DVI/HDMI deliver the signal in a digital format, much the same way that a file is delivered from one computer to another along a network, while Component Video is an analog format, delivering the signal not as a bitstream, but as a set of continuously varying voltages representing (albeit indirectly, as we’ll get to in a moment) the red, green and blue components of the signal.

Both DVI/HDMI and Component Video deliver signals as discrete red, green, and blue color components, together with sync information which allows the display to determine when a new line, or a new frame, begins. The DVI/HDMI standard delivers these along three data channels in a format called T.M.D.S., which stands for “Transmission Minimized Differential Signaling.” Big words aside, the T.M.D.S. format basically involves a blue channel to which horizontal and vertical sync are added, and separate green and red channels over short and long distance it can be 0.5m to 20m ffor respactive in market serval length cable are avalible like 1m hdmi cable, 2m hdmi cable…..20m hdmi cable.

Component Video is delivered, similarly, with the color information split up three ways. However, component video uses a “color-difference” type signal, which consists of Luminance (the “Y”, or “green,” channel, representing the total brightness of the image), Red Minus Luminance (the “Pr,” or “Red,” channel), and Blue Minus Luminance (the “Pb,” or “Blue,” channel). The sync pulses for both horizontal and vertical are delivered on the Y channel. The display calculates the values of red, green and blue from the Y, Pb, and Pr signals.

Both signal types, then, are fundamentally quite similar; they break up the image in similar ways, and deliver the same type of information to the display, albeit in different forms. How they differ, as we’ll see, will depend to a great extent upon the particular characteristics of the source and display devices, and can depend upon cabling as well.