FAQ
The HDTV experimental researches begun in the late 60's in Japan (NHK), followed by Europe through the Eureka project, D2/HDMAC and then in the USA with DigiCipher.
Numerous acronyms arose like ATV, ADTV, IDTV together with new Aspect Ratios (15/9, 14/9) also linked with new resolutions like 1250, 1035, 1125 Lines, etc…
The goal was to find a format that will keep some compatibility with the existing standards (SDTV, cinema).
30 years later, there is not yet a single standard, but a few are commonly used.
In the USA:
Back in 1997 the "Grand "Alliance" and the ATSC (Advanced Television Systems Committee) proposed approx. 30 standards with many combinations of Lines/Frames/Clocks/B&W-Colors/Interlaced-Progressive-Segmented Frame (without taking into account some new proposals of "2K" Super Hi-Res for the Digital Cinema).
The HDTV transition is coming up gently from NTSC to NTSC+HDTV simulcast, and eventually HDTV exclusively. This was supposed to happen by end of 2006 but there will be an approximate 2 years delay for converging into the 3 currently used resolutions (16/9):
· 1080i @60Hz: Broadcast + Post/Production + Large Events
· 720p @60Hz: Broadcast + Post/Production
· 1080sF @24Hz: Post/Production + Digital Cinema.
In EUROPE & ASIA:
Europe and Asia decided to give up the 1250i @50Hz format and to emphasize on the American standards. They translated the "Fields & frames" translated from 60 to 50Hz and 24 to 25Hz.
In JAPAN:
The followings formats are used:
· The "Hi-Vision 16/9", 1125 lines (with 1035 active lines) @60Hz/Interlaced
· And the 3 main US formats stated earlier on
To sum up, we can observe precise trends depending on the countries and can identify that 7 existing formats:
· 3 in the USA: 1080i@59.94Hz + 720p@59.94Hz and 1080sF@23.98Hz.
· One more in Japan with the 1035i@59.94Hz (in addition to these US formats)
· And 3 main US formats stated earlier on
These different standards inhibit the spread of HDTV because the user needs to invest in various equipments capable of handling and processing them all.
The above cross-conversions can be performed by some universal standards converters to solve any formats incompatibility problems.
Notes :
· I=Interlaced, p=progressive, sF= Segmented Frame
· In the television industry, we talk about the number of Lines (ex:NTSC= 525.L & PAL/SECAM= 625.L) instead of the actual visible lines (480 & 576 respectively). In the Computer and HDTV worlds it is the opposite, we talk about actual visible Lines (i.e: 1080.L instead of the total 1125.L)
The US & Japanese COLOR TV& HDTV fields frequency refresh rate is not exactly 60Hz but actually 60x1000/1001=59.94Hz. 59.94Hz is referred to as"60"Hz. It’s the same for the Film/Cinema@24Hz which in factis 24x1000/1001=23.98Hz (noted "23"Hz) giving the Film-to-HDTV transfer (color).
Aspect Ratio: a few answers to some of your questions
Aspect ratios come in many different flavors, going from square 1/1 = 9/9 to ultra large Panavision in 2.7/1 = 24/9. These multiple formats can be found in both sources (video cameras, tape recorders, DVDs, etc…) and display devices (TVs, Projectors, Plasma screens, Computer monitors, etc…).
The most popular formats are:
4/3 = 12/9 = 1.33 Standard TV, Computer
5/4 = 11/9 = 1.25 Special Computer formats (i.e.. SXGA 1280x1024)
16/9 = 1.78 HDTV, D-iLA 16/9
21/9 = Cinemascope 2.35
Particular cases of anamorphic process:
Anamorphism allows to keep the aspect ratio of an image while optimizing its signal to noise ratio and resolution (sharpness) up to 70%. These symmetrical and non-linear transformations are usually done when shooting with a camera (special lens with horizontal squeeze) and when displaying (horizontal expanding lens on the projector). It enables to obtain a final non distorted image in 2.35 Cinemascope on a narrow 35mm film support (i.e. 1.66).
You can also find « anamorphic » DVDs where the image is compressed horizontally to be compatible with the original 4/3 format of the DVDs. This image is expanded electronically or by a scaler with the anamorphic compensation in order to be displayed properly on a 16/9 video projector or plasma screen.
Analog Way Scalers
Analog Way scalers enable you to adjust the aspect ratio of your sources (set up per input) and of your output ( depending on the display used) and feature anamorphic compensation. An auto detection is also available.
Moreover, H or V size adjustments offer a fine tuning of up to 20%.
The universal inputs available on our devices can accept both Computer sources,
standard Video sources (Composite, S.Video (Y/C), Component (YUV) & RGBS)
and HDTV sources.
Input signal types are not related to a type of connector although we are accustomed
to dedicated connectors for each type of signal. For example, it is possible to
connect an S.Video source to an HD15 connector even if RCA or Mini-DIN are common
S.Video connectors. In case of universal input, using a common connector is the
only way to simplify this concept.
The universal inputs are usually provided on five-BNC connectors or on HD15
connectors to keep devices compact. The latter is the most effective to save
space.
Some inputs may have both HD15 and BNC in parallel, i.e. 2 BNCs for Composite
or S.Video and HD15 for any signal.The AW HD15-M to 5 BNC-F special 19"
long adaptor cable (ref: 10123) makes any connection very simple when using
HD15 input connectors. In this case you will make your connections as follows:
- Composite to the GREEN BNC line of the cable adaptor,
- Y/C signal to the GREEN for Y, and to the RED for C,
- Component & HDTV signals to the RED for Dr,GREEN for Y, BLUE for Db.
Analog Way also offers a HD15-M to Mini-DIN4-F 7" long adaptor cable
(ref: 10124) for simple connection of S.Video cable.
