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 854 or less (848 should be used for mod16 compatibility)[1] pixels for an approximate 16:9 aspect ratio (480 × 16⁄9 = 853.3). 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.[2][3] Standard definition has always been a 4:3 aspect ratio with a pixel resolution of 640 × 480 at 60Hz for NTSC regions, and 720 or 768 × 576 for PAL regions (1024 wide for widescreen displays. However, standard definition defines a 15.7Khz horizontal scanrate, which means that interlacing has to be used for those resolution modes. The lowercase letter "p" in 480p stands for progressive, so the two must not be confused.
ATSC progressive mode standards
The ATSC digital television standards define 480p with 640×480p (4:3) pixel resolutions, at p24, p30, or p60 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. When 480p30 is broadcast on air, it is frame doubled then interlaced to 480i60. The spatial resolution hasn't changed, but a 480p video stored in digital RGB format is transcoded and modulated when broadcast on the analog television network. 24p, however, needs to be processed using the 3:2 pulldown technique to be broadcast to TVs, even if the spatial resolution in the stored media is the same as the output resolution.
Resolutions
| Standard | Resolution | Aspect ratio | Notes |
|---|---|---|---|
| 480p (4:3) | 640×480p | 4:3 | The most common 480p aspect ratio, typically used for cameras and video formats. |
| 480p (3:2) | 720×480p | 3:2 | The same aspect ratio used on the iPod Touch 4 and is also used anamorphically on NTSC-region DVD video. |
| 480p (16:10) | 768x480p | 16:10 | - |
| 480p (5:3) | 800×480p | 5:3 | It is used on the Samsung Galaxy S II. |
| 480p (16:9) | 848x480p | ~16:9 | The mod16 compatible. |
| 480p (16:9) | 854x480p | ~16:9 | The resolution 854×480 is used when 480p is selected on a widescreen YouTube video. |
| 480p (1.85:1) | 888×480p | 1.85:1 | The unscaled Academy format. |
| 480p (2:1) | 960x480p | 2:1 | The double-squared 480p. |
| 480p (18:10) | 864x480p | 18:10 | - |
See also
References
- "Best Practices For Multi-Device Transcoding | Knowledge Center". knowledge.kaltura.com. Retrieved 2016-09-12.
- AfterDawn.com. "480p - AfterDawn: Glossary of technology terms & acronyms".
- CNET - Glossary - 480p Archived 2009-07-09 at the Portuguese Web Archive