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Standard-definition television (or SDTV) is a television system that has a resolution that meets standards but not considered either Enhanced-definition television (EDTV) or High-definition television (HDTV). The term is usually used in reference to digital television, in particular when broadcasting at the same (or similar) resolution as analog systems. In the USA, SDTV refers to digital television broadcast in 4:3 aspect ratio, the same aspect ratio as NTSC signals.^[1] When a television set is labeled "SDTV", this means that the set includes an ATSC tuner, but scans its picture in the same 480i pattern used in NTSC.^{[citation needed]}

Standards that support digital SDTV broadcast include DVB, ATSC Standards and ISDB. The last two were originally developed for HDTV, but they have proved to be more often used for their ability to deliver multiple SD video and audio streams via multiplexing, than to use the entire bitstream for one HD channel.^{[clarification needed]}

In ATSC Standards, SDTV can be broadcast in 704 pixels × 480 lines with 16:9 aspect ratio (40:33 rectangular pixel), 704 pixels × 480 lines with 4:3 aspect ratio (10:11 rectangular pixel) or 640 pixels × 480 lines with 4:3 ratio. The refresh rate can be any of 24, 30 or 60 frames per second.

Digital SDTV in 4:3 aspect ratio has the same appearance as the regular analog TV (NTSC, PAL, SECAM) minus the ghosting, snowy images and white noise. However, if the reception is poor, one may encounter various other artifacts such as blockiness and stuttering.

When resolution is considered, both the resolution of the transmitted signal and the (native) display resolution of a TV set are taken into account. Digital NTSC, and PAL/SECAM-like signals (480i60 and 576i50 respectively), are transmitted at a horizontal resolution of 720 or 704 format.

[edit] See also

Television portal

• Digital television
• digital audio broadcasting
• DVB
• ATSC Standards
• ISDB
• SBTVD
• Enhanced-definition television
• High-definition television
• MPEG

[edit] References

[edit] External links

• Programmer's Guide to Video Systems

v • d • e Digital Video Resolutions 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, Blu-ray Disc, HDV 720   24, 30, 60; 25, 50 1080 50, 60 24, 30; 25 This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen or pixel shape (aspect ratio) of these formats, which is either 4:3, or 16:9.

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