Editing NTSC (section)

== Variants ==

=== NTSC-M ===
Unlike PAL and SECAM, with its many varied underlying [[broadcast television systems]] in use throughout the world, NTSC color encoding is almost invariably used with [[CCIR System M|broadcast system '''M''']], giving NTSC-M.

=== NTSC-N and NTSC 50 ===
NTSC-N was originally proposed in the 1960s to the [[ITU-R#CCIR|CCIR]] as a 50&nbsp;Hz broadcast method for [[CCIR System N|System N]] countries Paraguay, Uruguay and Argentina before they chose [[PAL#PALN|PAL]]. In 1978, with the introduction of [[Apple II Plus|Apple II Europlus]], it was effectively reintroduced as "NTSC 50", a pseudo-system combining 625-line video with 3.58&nbsp;MHz NTSC color. For example, an [[Atari ST]] running PAL software on their NTSC color display used this system as the monitor could not decode PAL color. Most analog NTSC television sets and monitors with a V-Hold knob can display this system after adjusting the vertical hold.<ref>{{cite web |last=VWestlife's Camcorder Tests & More |date=January 6, 2010 |title=Recording PAL and 625-line 50 Hz NTSC video on a U.S. VCR |url=https://www.youtube.com/watch?v=REsrXKGuPpg |via=YouTube}}</ref>

=== NTSC-J ===
Only [[Japan]]'s variant "[[NTSC-J]]" is slightly different: in Japan, black level and blanking level of the signal are identical (at 0&nbsp;[[IRE (unit)|IRE]]), as they are in PAL, while in American NTSC, black level is slightly higher (7.5&nbsp;[[IRE (unit)|IRE]]) than blanking level. Since the difference is quite small, a slight turn of the brightness knob is all that is required to correctly show the "other" variant of NTSC on any set as it is supposed to be; most watchers might not even notice the difference in the first place. The channel encoding on NTSC-J differs slightly from NTSC-M. In particular, the Japanese VHF band runs from channels 1–12 (located on frequencies directly above the 76–90&nbsp;MHz Japanese [[FM broadcasting|FM radio]] band) while the North American VHF TV band uses channels 2–13 (54–72&nbsp;MHz, 76–88&nbsp;MHz and 174–216&nbsp;MHz) with 88–108&nbsp;MHz allocated to FM radio broadcasting. Japan's UHF TV channels are therefore numbered from 13 up and not 14 up, but otherwise uses the same UHF broadcasting frequencies as those in [[Pan-American television frequencies|North America]].

=== NTSC 4.43 ===
NTSC 4.43 is a pseudo-system that transmits a NTSC color subcarrier of 4.43&nbsp;MHz instead of 3.58&nbsp;MHz<ref>{{cite book |last1=Poynton |first1=Charles |url=https://books.google.com/books?id=rsEwE2X3cFAC&dq=NTSC+4.43&pg=PA580 |title=Digital Video and HD: Algorithms and Interfaces |publisher=Morgan Kaufmann |year=2003 |isbn=9781558607927}}</ref> The resulting output is only viewable by TVs that support the resulting pseudo-system (such as most PAL TVs).<ref>{{cite web |title=WeetHet - Video - Overview of available formats |url=https://www.weethet.nl/english/video_formats.php |access-date=September 21, 2022 |quote=Most modern TV-sets accept the so called pseudo formats (Pseudo PAL and Pseudo NTSC)...}}</ref> Using a native NTSC TV to decode the signal yields no color, while using an incompatible PAL TV to decode the system yields erratic colors (observed to be lacking red and flickering randomly). The format was used by the [[United States Air Force|USAF]] TV based in Germany during the [[Cold War]] and [[Hong Kong Cable Television]].{{Citation needed|date=February 2024}} It was also found as an optional output on some [[LaserDisc]] players sold in markets where the PAL system is used.

The NTSC 4.43 system, while not a broadcast format, appears most often as a playback function of PAL cassette format VCRs, beginning with the Sony 3/4" U-Matic format and then following onto Betamax and VHS format machines, commonly advertised as "NTSC playback on PAL TV".

Multi-standard video monitors were already in use in Europe to accommodate broadcast sources in PAL, SECAM, and NTSC video formats. The [[Heterodyne#Heterodyning in analog videotape recording|heterodyne]] color-under process of U-Matic, Betamax & VHS lent itself to minor modification of VCR players to accommodate NTSC format cassettes. The color-under format of VHS uses a 629&nbsp;kHz subcarrier while U-Matic & Betamax use a 688&nbsp;kHz subcarrier to carry an ''amplitude modulated'' chroma signal for both NTSC and PAL formats. Since the VCR was ready to play the color portion of the NTSC recording using PAL color mode, the PAL scanner and capstan speeds had to be adjusted from PAL's 50&nbsp;Hz field rate to NTSC's 59.94&nbsp;Hz field rate, and faster linear tape speed.

The changes to the PAL VCR are minor thanks to the existing VCR recording formats. The output of the VCR when playing an NTSC cassette in NTSC 4.43 mode is 525 lines/29.97 frames per second with PAL compatible heterodyned color. The multi-standard receiver is already set to support the NTSC H & V frequencies; it just needs to do so while receiving PAL color.

The existence of those multi-standard receivers was probably part of the drive for region coding of DVDs. As the color signals are component on disc for all display formats, almost no changes would be required for PAL DVD players to play NTSC (525/29.97) discs as long as the display was frame-rate compatible.

=== OSKM (USSR-NTSC) ===
In January 1960, (7 years prior to adoption of the modified SECAM version) the experimental TV studio in Moscow started broadcasting using the OSKM system. OSKM was the version of NTSC adapted to European D/K 625/50 standard. The OSKM abbreviation means "Simultaneous system with quadrature modulation" (In Russian: Одновременная Система с Квадратурной Модуляцией). It used the color coding scheme that was later used in PAL (U and V instead of I and Q).

The color subcarrier frequency was 4.4296875&nbsp;MHz and the bandwidth of U and V signals was near 1.5&nbsp;MHz.<ref>{{cite book |last1=Sokolov |first1=Georgii |url=http://ca.cryptocom.ru/tmpfiles/mrb_0469.djvu |title=Amateur Colour TV Receiver TSVET-2 |last2=Sudravskii |first2=Dmitrii |year=1963 |access-date=September 5, 2022 |archive-url=https://web.archive.org/web/20220905221709/http://ca.cryptocom.ru/tmpfiles/mrb_0469.djvu |archive-date=September 5, 2022 |url-status=dead}}</ref> Only circa 4000 TV sets of 4 models (Raduga,<ref>{{cite web |date=September 6, 2022 |title=Raduga OSKM Color TV (1962) |url=http://rw6ase.narod.ru/00/twc/raduga_tw62.html |url-status=dead |archive-url=https://web.archive.org/web/20220906041751/http://rw6ase.narod.ru/00/twc/raduga_tw62.html |archive-date=September 6, 2022 |access-date=September 6, 2022}}</ref> Temp-22, Izumrud-201 and Izumrud-203<ref>{{cite web |date=September 6, 2022 |title=Izumrud-203 OSKM Color TV (1959) |url=http://rw6ase.narod.ru/00/twc/izumrud203.html |url-status=dead |archive-url=https://web.archive.org/web/20220116162957/http://rw6ase.narod.ru/00/twc/izumrud203.html |archive-date=January 16, 2022 |access-date=September 6, 2022}}</ref>) were produced for studying the real quality of TV reception. These TV's were not commercially available, despite being included in the goods catalog for trade network of the USSR.

The broadcasting with this system lasted about 3 years and was ceased well before SECAM transmissions started in the USSR. None of the current multi-standard TV receivers can support this TV system.

=== NTSC-film ===
{{Main|24p}}
{{Expand section|date=June 2008}}

Film content commonly shot at 24&nbsp;frames/s can be converted to 30&nbsp;frames/s through the [[telecine]] process to duplicate frames as needed.
:<math> \frac{23.976}{29.97} = \frac{4}{5}</math>

Mathematically for NTSC this is relatively simple as it is only needed to duplicate every fourth frame. Various techniques are employed. NTSC with an actual frame rate of {{frac|24|1.001}} (approximately 23.976)&nbsp;frames/s is often defined as NTSC-film. A process known as pullup, also known as pulldown, generates the duplicated frames upon playback. This method is common for [[H.262/MPEG-2 Part 2]] digital video so the original content is preserved and played back on equipment that can display it or can be converted for equipment that cannot.