Enhanced-definition television
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Enhanced-definition television, extended-definition television, or EDTV is a CEA marketing shorthand term for certain digital television (DTV) formats.
EDTV generally refers to video with picture quality beyond what is broadcastable in NTSC or PAL, but not sharp enough to be considered HDTV. A DVD player with progressive output is considered the lower end of this class, when playing a progressively encoded disc. (The maximum EDTV frame rate of 60p is not possible from a DVD.) The common implementations of EDTV are 480 or 576-line signals in progressive scan (as opposed to 50-60 interlaced fields per second, see NTSC, or PAL and SECAM). These are commonly referred to as "480p" and "576p" respectively. In comparison, a standard definition television (SDTV) signal is broadcast with interlaced frames and is commonly referred to as "480i" or "576i".
Because EDTV signals use a progressive scan, they have about 50% more vertical resolution than interlaced SDTV pictures with the same number of lines, and do not show the spatial/temporal aliasing artifacts associated with interlaced video. As a result, EDTV material gives much better results when upconverted for display on HDTV television sets. However, because of the higher level of spatial coherence within single progressive frames as compared to single interlaced fields, EDTV does not increase the amount of data bandwidth proportionately to the greater number of pixels displayed per second.
The use of EDTV instead of HDTV allows DTV stations to broadcast multiple programs at once while still improving quality over standard broadcasts.
EDTV signals are often broadcast in a 16:9 aspect ratio, with non-square pixels. The horizontal resolution is 704 or 720 pixels regardless of aspect ratio. The image is stretched for displaying to an aspect ratio of 4:3 or 16:9.
In the United States, the ATSC official DTV formats include SDTV, and HDTV. EDTV is considered part of the HDTV standard.
Prior to the 2004–2005 television season, the Fox Network was broadcasting in EDTV in the United States. As of the 2004–2005 season, they have begun broadcasting in 720p, an HDTV format.
Nintendo is using EDTV as the format for their seventh generation console Wii, while other developers are moving to HDTV.
| Designation | Usage examples | Definition (lines) | Rate (Hz) | |
|---|---|---|---|---|
| Interlaced (fields) | Progressive (frames) | |||
| Low; MP@LL | LDTV, VCD | 240; 288 (SIF) | 24, 30; 25 | |
| Standard; MP@ML | SDTV, SVCD, DVD, DV | 480 (NTSC, PAL-M) | 60 | 24, 30 |
| 576 (PAL, SECAM) | 50 | 25 | ||
| Enhanced | EDTV | 480; 576 | 60; 50 | |
| High; MP@HL | HDTV, HD DVD, BD, HDV | 720 | 24, 30, 60; 25, 50 | |
| 1080 | 50, 60 | 24, 30; 25 | ||
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| This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen shape (aspect ratio) of these formats, which is either 4:3 or 16:9. | ||||
