Standard-definition television

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"SDTV" redirects here. For Arizona State University's campus channel, see Sun Devil Television.

Standard-definition television (or SDTV) refers to television systems that have 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]} YouTube refers to 640x480 for 4:3 as SD Video.^[2]

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.

Video Format (WxH)	Name	Pixel aspect ratio (W:H) (Standard 4:3)	Pixel aspect ratio (W:H) (Anamorphic 16:9)	Description
640x480		4:3		Used on YouTube
720×576	576i	5:4	64:45	Used on D1/DV PAL (ITU-R 601)
704×576	576p	12:11	16:11	Used on EDTV PAL
720×480	480i	8:9	32:27	Used on DV NTSC
720×486	480i	8:9	32:27	Used on D1 NTSC (ITU-R 601)
704×480	480p	10:11	40:33	Used on EDTV NTSC