Standard-definition television

Short description: Digital TV with specs similar to analog broadcasts

"SDTV" redirects here. For a television broadcasting network in Shandong Province, see Shandong Television.

SDTV resolution by nation: for historical reasons, different countries use either 480i or 576i as their standard-definition picture format

Standard-definition television (SDTV; also standard definition or SD) is a digital television system that uses a resolution that is not considered to be either high or enhanced definition.[1] Standard refers to offering a similar resolution to the analog broadcast systems used when it was introduced.[1][2]

## Contents

* 1 History and characteristics
* 2 PAL and NTSC
* 3 Pixel aspect ratio
* 4 See also
* 5 References
* 6 External links

## History and characteristics

SDTV originated from the need for a standard to digitize analog TV (defined in BT.601) and is used for digital TV broadcasts and home appliances such as game consoles and DVD disc players.[3][4]

Standards that support digital SDTV broadcast include DVB, ATSC, and ISDB.[5] 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.

## PAL and NTSC

The two SDTV signal types are 576i (with 576 interlaced lines of resolution,[6] derived from the European-developed PAL and SECAM systems), and 480i (with 480 interlaced lines of resolution,[3] based on the American NTSC system). SDTV refresh rates are 25, 29.97 and 30 frames per second, again based on the analog systems mentioned.

In North America, digital SDTV is broadcast in the same 4:3 fullscreen aspect ratio as NTSC signals, with widescreen content often being center cut.[5]

## Pixel aspect ratio

Pixel aspect ratios for the scaling of various kinds of SDTV video lines  Video format  | Display aspect ratio (DAR)  | Resolution  | Pixel aspect ratio (PAR)  | After horizontal scaling

|
|
|
|

480i | 4:3  | 704×480 (horizontal blanking cropped)  | 10:11  | 640×480
720×480 (full frame)  | 655×480
480i | 16:9  | 704×480 (horizontal blanking cropped)  | 40:33  | 854×480
720×480 (full frame)  | 873×480
576i | 4:3  | 704×576 (horizontal blanking cropped)  | 12:11  | 768×576
720×576 (full frame)  | 788×576
576i | 16:9  | 704×576 (horizontal blanking cropped)  | 16:11  | 1024×576
720×576 (full frame)  | 1050×576

The pixel aspect ratio is the same for 720- and 704-pixel resolutions because the visible image (be it 4:3 or 16:9) is contained in the center 704 horizontal pixels of the digital frame. In the case of a digital video line having 720 horizontal pixels (including horizontal blanking), only the center 704 pixels contain the actual 4:3 or 16:9 image, and the 8-pixel-wide stripes on either side are called nominal analog blanking or horizontal blanking and should be discarded when displaying the image. Nominal analog blanking should not be confused with overscan, as overscan areas are part of the actual 4:3 or 16:9 image.

For SMPTE 259M-C compliance, an SDTV broadcast image is scaled to 720 pixels wide for every 480 NTSC (or 576 PAL) lines of the image,[7] with the amount of non-proportional line scaling dependent on either the display or pixel aspect ratio. Only 704 center pixels contain the actual image and 16 pixels are reserved for horizontal blanking,[8] though a number of broadcasters fill the whole 720 frames. The display ratio for broadcast widescreen is commonly 16:9 (pixel aspect ratio of 40:33 for anamorphic); the display ratio for a traditional or letterboxed broadcast is 4:3 (pixel aspect ratio of 10:11).

An SDTV image outside the constraints of the SMPTE standards requires no non-proportional scaling with 640 pixels (defined by the adopted IBM VGA standard) for every line of the image. The display and pixel aspect ratio are generally not required, with the line height defining the aspect. For widescreen 16:9, 360 lines define a widescreen image and for traditional 4:3, 480 lines define an image.

## See also

* Digital Audio Broadcasting
* Moving Picture Experts Group - Alliance of working groups for multimedia coding
* Rec. 601 - Standard from the International Telecommunication Union

## References

1. ↑ 1.0 1.1 "Standard definition television (SDTV)" (in en-US). https://www.atsc.org/atsc-glossary/standard-definition-television-sdtv/.
2. ↑ "HDTV". http://www.siliconimaging.com/hdtv.htm.
3. ↑ 3.0 3.1 "What means 480i?". https://www.afterdawn.com/glossary/term.cfm/480i.
4. ↑ "BT.601: Studio encoding parameters of digital television for standard 4:3 and wide screen 16:9 aspect ratios". ITU. https://www.itu.int/rec/R-REC-BT.601/.
5. ↑ 5.0 5.1 "All-Digital Television Is Coming (And Sooner Than You Think!)". http://www.fcc.gov/cgb/consumerfacts/digitaltv.html.
6. ↑ "What means 576i?". http://www.afterdawn.com/glossary/terms/576i.cfm.
7. ↑ "RECOMMENDATION ITU-R BT.601-7 – Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios". https://www.itu.int/dms_pubrec/itu-r/rec/bt/r-rec-bt.601-7-201103-i!!pdf-e.pdf.
8. ↑ "SMPTE RECOMMENDED PRACTICE". December 6, 1995. https://pub.smpte.org/pub/rp187/rp0187-1995.PDF.

## External links

* Programmer's Guide to Video Systems

* v
* t
* e

Digital video resolutions

Designation|

| Usage examples | Definition (lines) | Rate (Hz)

|
|

Interlaced (fields) | Progressive (frames)

Low,
MP@LL|

| [[Engineering:Low-definition televisLDTV, Video CD|VCD]], HTV | 240, 288 (SIF) |  | 24, 30; 25

|
|
|

Standard,
MP@ML|

| [[Engineering:Standard-definition televisSDTV, Super Video CD|SVCD]], DVD, DV | 480 (NTSC), 576 (PAL) | 60, 50 | 24, 30; 25

|
|
|

Enhanced,
HMP@HML|

| EDTV | 480 (NTSC-HQ), 576 |  | 60, 50

|
|
|

High,
MP@HL|

| [[Engineering:High-definition televisHDTV,Blu-ray|BD]], HD DVD, HDV | 720 |  | 24, 30, 60; 25, 50

|
|
|

1080, 1440 | 25, 30 | 24, 50, 60

Ultra-high|

| UHDTV, UHD BRD | 2160, 4320, 8640 |  | 60, 120,180

|
|
|

* v
* t
* e

Broadcast video formats

Television

| Analog|

| 525 lines|

* System M
* NTSC
* NTSC-J
* PAL-M

|

625 lines|

* PAL
* System B
* System D
* System G
* System H
* System I
* System K
* PAL-N
* PALplus
* SECAM
* System B
* System D
* System G
* System K
* System L (SECAM-L)

Audio|

* BTSC (MTS)
* EIAJ
* NICAM
* SAP
* Sound-in-Syncs
* Zweikanalton (A2/IGR)

Hidden signals|

* Captioning
* CGMS-A
* EPG
* GCR
* PDC
* Teletext
* VBI
* VEIL
* VIT
* VITC
* WSS
* XDS

Historical|

* Pre-1940
* Mechanical television
* 180-line
* 405-line
* System A
* 441-line
* 819-line
* MAC
* MUSE

Digital|

| Interlaced|

* SDTV
* 480i
* 576i
* HDTV
* 1080i

|

Progressive|

* LDTV
* 1seg
* 240p
* 288p
* EDTV
* 480p
* 576p
* HDTV
* 720p
* 1080p
* UHDTV
* 2160p
* 4320p

MPEG-2 standards|

* ATSC
* DVB
* DVB 3D-TV
* ISDB
* DTMB

MPEG-4 AVC standards|

* ATSC A/72
* DMB
* DTMB
* DVB
* SBTVD
* 1seg

HEVC standards|

* ATSC 3.0
* HD DMB

Audio|

* AC-3 (5.1)
* AC-4
* DTS
* MPEG-1 Audio Layer II
* MPEG Multichannel
* PCM
* LPCM
* AAC
* HE-AAC
* MPEG-H 3D Audio

Hidden signals|

* AFD
* Broadcast flag
* Captioning
* CPCM
* EPG
* Teletext

Technical issues

* 9 compromise
* Broadcast-safe
* Digital cinema (DCI)
* Display motion blur
* Moving image formats
* MPEG transport stream
* Reverse Standards Conversion
* Standards conversion
* Television transmitter
* Test card
* Video on demand
* Video processing
* Widescreen signaling
* Templates (Analogue TV Topics)

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