Video formats comparision
To understand the different common video formats and how they relate to each other we need to we can create a table of commonly used video formats. We start with RGBHV at the top and proceed down the list to composite video and RF signals used in cable TV.
Video format comparision table
|Signal Format||Coax Wires||Quality||Encoding Requirements||Decoding Requirements||Advantages||Common uses|
|R G B H V||5||Highest||None||None||Original image, highest bandwidth, very suitable for high resolution computer graphics||PC VGA, computers|
|R G B S||4||High||Combination of sync||Separation of sync||Same as above||SCART RGB, computers, DVD players in Europe|
|R GS B||3||High||Combination of sync and summing it to green video component||Stripping of sync from green channel plus separating H & V||Same bandwidth if display strips sync properly||Computers|
(Y, B-Y, R-Y) (YPbPr)
|3||Very Good||Simple matrix encoder, combine syncs and add them to Y channel||Simple matrix decoder, strip sync from Y channel||Nearly as good as RGB but requires good matrix design||Professional video editing, HDTV, DVD players in USA|
|S-video||2||Good||Matrix encoder, filtering and modulation of color signals to subcarier for S component, combination of sync signals and summing them to Y channel||Synchronous detector plus matrix decoder & sync processing||Requires only two cable connections||DVD, S-VHS, computer TV output, DV video out|
|Composite||1||Low||Matrix encoder, filtering and modulation of color signals to subcarier, combination of sync signals and summing everything together||Complete decoder with Y & C comb filtering, synchronous detector, matrix, and sync processing||Requires only one cable connection & can be used to modulate an RF transmitter||Almost every video equipment supports, very widely used|
|RF||1||Lowest||Same as for composite video plus modualtion to RF subcarrier||Demodulation and afer thas same as for composite video||Requires only one cable connection for both video and audio. Many video channels can be carried in one cable.||TV broadcasts, cable TV|
Comments on video formats
Within the RGB formats, the only issue is sync processing. However, dont be misguided by thinking that sync processing is a minor issue. There were never any significant standards established for constructing composite sync for the myriad of computer signal formats. It is possible to construct composite sync (and many computer manufacturers used it for years) for computer graphic outputs, those might cause sometimes compatibility problems. If you are using RGsB signals, removal of sync from the green channel can affect the performance of the green channel or the proper operation of the displays black level controls.
Tomi Engdahl <[email protected]>
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