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Separate Video,〔(S-Video – Definition ) About.com〕 commonly termed S-Video, Super-Video and Y/C, is a signaling standard for standard definition video, typically 480i or 576i. By separating the black-and-white and coloring signals, it achieves better image quality than composite video, but has lower color resolution than component video. == Signal == The S-video cable carries video using two synchronized signal and ground pairs, termed Y and C. Y is the ''luma'' signal, which carries the ''luminance'' - or black-and-white - of the picture, including synchronization pulses. C is the ''chroma'' signal, which carries the ''chrominance'' - or coloring-in - of the picture. This signal contains both the saturation and the hue of the video. The luminance signal carries horizontal and vertical sync pulses in the same way as a composite video signal. Luma is a signal carrying luminance after gamma correction, and is therefore termed "Y" because of the similarity to the lower-case Greek letter gamma. In composite video, the signals co-exist on different frequencies. To achieve this, the luminance signal must be low-pass filtered, dulling the image. As S-Video maintains the two as separate signals, such detrimental low-pass filtering for luminance is unnecessary, although the chrominance signal still has limited bandwidth relative to component video. Compared with component video, which carries the identical luminance signal but separates the color-difference signals into Cb/Pb and Cr/Pr, the color resolution of S-Video is limited by the modulation on a subcarrier frequency of 3.57 to 4.43 Megahertz, depending on the standard. It is worth noting that this difference is meaningless on consumer videotape systems, as the chrominance is already severely constrained by both VHS and Betamax. Carrying the color information as one signal means that the color has to be encoded in some way, typically in accord with NTSC, PAL, or SECAM, depending on the applicable local standard. Also, S-Video suffers from low color resolution. NTSC S-Video color resolution is typically 120 lines horizontal (approximately 160 pixels edge-to-edge), versus 250 lines horizontal for the Rec. 601-encoded signal of a DVD, or 30 lines horizontal for standard VCRs. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「S-Video」の詳細全文を読む スポンサード リンク
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