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480i is the shorthand name for a video mode, namely the US NTSC television system or digital television systems with the same characteristics. The i, which is sometimes uppercase, stands for interlaced, the 480 for a vertical frame resolution of 480 lines containing picture information; while NTSC has a total of 525 lines, only 480 of these are used to display the image for DV-NTSC. For analog NTSC there are 486 lines, and two of those 486 being half-lines (scan line number 263 which appears as the last scan line in the first (odd) field, and scan line number 283 which is the first scan line of the second (even) field; there are 525 scan lines in a frame, and the scan line numbering starts at 1). For DV-NTSC only 480 lines are used. The digitally transmitted horizontal resolution is usually 720 samples (which includes 16 samples for the horizontal sync and horizontal blanking) or 704 visible pixels with an aspect ratio of 4:3 and therefore a display resolution of 640 × 480 (VGA); that is standard-definition television (SDTV). [1] [2] [3] [4]
The field rate (not the frame rate) is usually (60/100.1% ≈) 59.94 hertz for color TV and can be rounded up to 60 Hz. There are several conventions for written shorthands for the combination of resolution and rate: 480i60, 480i/60 (EBU) and 480/60i. 480i is usually used in countries that conventionally use NTSC (most of the Americas and Japan), because the 525 transmitted lines at 60 hertz of analogue NTSC contain 480 visible ones.
480i can be transported by all major digital television formats, ATSC, DVB and ISDB.
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More about 480i: 480p vs 480i, aastra 480i, rimage 480i,