480p

480p is the shorthand name for a family of video display resolutions. The p stands for progressive scan, i.e. non-interlaced. The 480 denotes a vertical resolution of 480 pixels, usually with a horizontal resolution of 640 pixels and 4:3 aspect ratio (480 × 4⁄3 = 640) or a horizontal resolution of less than 854 (848 should be used for mod16 compatibility) pixels for an approximate 16:9 aspect ratio (480 × 16⁄9 = 853.33). Since a pixel count must be a whole number, in Wide VGA displays it is generally rounded up to 854 to ensure inclusion of the entire image. The frames are displayed progressively as opposed to interlaced. 480p was used for many early Plasma televisions.[1][2] Standard definition has always been a 4:3 aspect ratio with a pixel resolution of 640 × 480 pixels. Mini-DV, DVCAM, DV footage is recorded at 29.97 frames per second in this standard definition as seen on DV tapes.

480p does not qualify as high-definition television (HDTV); it is considered enhanced-definition television (EDTV).

480p24 and 480p30

The ATSC digital television standards define 480p with either 704 × 480 (BT.601 line sampling) or 640 × 480 (unscaled line sampling) pixel resolutions, at 24, 30, or 60 progressive frames per second.

Both 480p24 and 480p30 are more common in countries that use or have used the interlaced NTSC system like North America and Japan (these formats are somewhat compatible with that system, when used to broadcast progressive film content).

480p60 (480p59.94)

With doubled temporal resolution, 480p60 is considered enhanced-definition television (EDTV). It can be transported by both major digital television formats, ATSC and DVB. The frames are doubled (from either a 30 frame or 24 frame pull-down source) on broadcast (to avoid flicker) for display devices that lack any kind of frame doubling ability. Widescreen 16:9 material has only the width scaled down to fit 720 pixels instead of an unscaled 848 width.

SMPTE 344M defines a 480p59.94 standard with twice the data rate of BT.601, using 704 × 480 active pixels with 16 x 480 horizontal blanking pixels. ITU-R Rec. 601 is the specification for component digital interlaced video (480i) commonly used in standard definition television production.

Resolutions

Standard Resolution Aspect Ratio
480p 640×480 4:3
Rec. 601 720×480 3:2
Rec. 601 plus a quarter 800×480 5:3
Wide 480p 853.33×480 16:9 (unscaled)

See also

References

  1. ↑ afterdawn.com - 480p
  2. ↑ CNET - Glossary - 480p
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