Standard-definition television

SDTVstandard definitionSDstandard-definitionstandardSD DigitalSD videoStandard Definition Television(SDTV)625-line
Standard-definition television (SDTV or SD) is a television system which uses a resolution that is not considered to be either high or enhanced definition.wikipedia
9,627 Related Articles

High-definition television

HDTVhigh definitionHD
Standard-definition television (SDTV or SD) is a television system which uses a resolution that is not considered to be either high or enhanced definition. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions.
High-definition television (HDTV) is a television system providing an image resolution that is of substantially higher resolution than that of standard-definition television (SDTV).

Enhanced-definition television

enhanced definitionEDTVED
Standard-definition television (SDTV or SD) is a television system which uses a resolution that is not considered to be either high or enhanced definition.
Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).

576i

625-line720x576analogue
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.
576i is a standard-definition video mode originally used for terrestrial television in most countries of the world where the utility frequency for electric power distribution is 50 Hz.

Digital television

digitaldigital TVDTV
SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions.
Digital television was previously not practically feasible due to the impractically high bandwidth requirements of uncompressed digital video, requiring around 200Mbps bit-rate for a standard-definition television (SDTV) signal, and over 1Gbps for high-definition television (HDTV).

480i

480i60525 line525 lines
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.
480i is a shorthand name for the video mode used for standard-definition analog or digital television in Caribbean, Myanmar, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay and Uruguay).

NTSC

analogNTSC-M30p
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.
Digital broadcasting allows higher-resolution television, but digital standard definition television continues to use the frame rate and number of lines of resolution established by the analog NTSC standard.

ATSC standards

ATSCdigitalATSC standard
Standards that support digital SDTV broadcast include DVB, ATSC, and ISDB.
It also includes standard-definition formats, although initially only HDTV services were launched in the digital format.

Pan and scan

fullscreenpan-and-scanPan & Scan
In North America, digital SDTV is broadcast in the same 4:3 aspect ratio as NTSC signals, with widescreen content being center cut.
Pan and scan is a method of adjusting widescreen film images so that they can be shown in fullscreen proportions of a standard definition 4:3 aspect ratio television screen, often cropping off the sides of the original widescreen image to focus on the composition's most important aspects.

ISDB

ISDB-TIntegrated Services Digital BroadcastingISDB-S
Standards that support digital SDTV broadcast include DVB, ATSC, and ISDB.
(s0 is generally used for 1seg, s1-s12 are used for one HDTV or three SDTVs)

Interlaced video

interlacedinterlaceinterlacing
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.

Pixel aspect ratio

square pixelaspect ratiosquare pixels
The table below summarizes pixel aspect ratios for the scaling of various kinds of SDTV video lines.
However, some imaging systems, especially those that must be compatible with standard-definition television motion pictures, display an image as a grid of rectangular pixels, in which the pixel width and height are different.

Aspect ratio

4:3aspect ratiosaspect-ratio
In North America, digital SDTV is broadcast in the same 4:3 aspect ratio as NTSC signals, with widescreen content being center cut.

Nominal analogue blanking

In case of digital video line having 720 horizontal pixels, only the center 704 pixels contain actual 4:3 or 16:9 image, and the 8-pixel-wide stripes from either side are called nominal analogue blanking for horizontal blanking and should be discarded before displaying the image.
Nominal analog blanking or nominal analogue blanking is the outermost part of the overscan of a standard definition digital television image.

Multiplexing

multiplexedmultiplexmultiplexes
The last two were originally developed for HDTV, but are also used for their ability to deliver multiple SD video and audio streams via multiplexing.
This may involve several standard definition television (SDTV) programmes (particularly on DVB-T, DVB-S2, ISDB and ATSC-C), or one HDTV, possibly with a single SDTV companion channel over one 6 to 8 MHz-wide TV channel.

Overscan

underscancrop the edges of the pictureoverscan/underscan
Nominal analogue blanking should not be confused with overscan, as overscan areas are part of the actual 4:3 or 16:9 image.
Digital foundations to most storage and transmission systems since the early 1990s have meant that analogue NTSC has only been expected to have 480 lines of picture – see SDTV, EDTV, and DVD-Video.

PAL

colour television25pPAL-N
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.

SECAM

SÉCAMCIS-SECAMSECAM L
The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems, and 480i based on the American NTSC system.

Refresh rate

refreshvertical scan rate120Hz
Common SDTV refresh rates are 25, 29.97 and 30 frames per second.

Frame rate

frames per secondfpsframe/s
Common SDTV refresh rates are 25, 29.97 and 30 frames per second.

Digital Video Broadcasting

DVBDigital Video BroadcastDVB Project
Standards that support digital SDTV broadcast include DVB, ATSC, and ISDB.

16:9 aspect ratio

16:91.78:1widescreen
However, in other parts of the world that used the PAL or SECAM color systems, digital standard-definition television is now usually shown with a 16:9 aspect ratio, with the transition occurring between the mid-1990s and mid-2000s depending on region.

Ghosting (television)

ghostingghostghost images
Digital SDTV eliminates the ghosting and noisy images associated with analog systems.

Noise (video)

staticnoisevideo noise
Digital SDTV eliminates the ghosting and noisy images associated with analog systems.

Intra-frame coding

I-frameintra-frameintraframe
However, if the reception has interference or is poor, where the error correction cannot compensate one will encounter various other artifacts such as image freezing, stuttering or dropouts from missing intra-frames or blockiness from missing macroblocks.