DTV Formats and How That Relates to HDTV

rbinck

Here are the 18 ATSC digital TV formats:

SDTV:

480i .. ...480.......704.... ....4:3 ....Interlaced ..30

480i .. ...480.......640.... ....4:3 ....Interlaced ..60

HD Monitors
Now a display in order to be considered HD it would have to be able to display the pixels noted in one of the 6 HDTV formats. This boils down to 2 resolutions: 1280x720 and 1920x1080. Therefore for a display to be considered HD it would have to have at least enough pixels in each direction to make a 1280x720 picture. Displays can have more pixels than that minimum and still be considered HD, for example there are plasmas that have 1366x768 (Zenith P50W38) that are HD displays. They receive a signal from a set top box and scale it from 1280x720 to fit the 1366x768 screen.

HD Ready TVs
In order for the term TV to be used the unit needs to have some form of a TV tuner built in. HD ready TVs will have one or more NTSC (analog) tuners built in to qualify as a TV and will have inputs for an external HD source, such as a ATSC STB, HD cable box, HD satellite receiver, etc. These inputs maybe component video, DVI or HDMI and may allow for any or all of the HDTV formats. The display section will be capable of at least one of the 6 HDTV display formats.

HD Built-In
When the manufacturer includes an ATSC (DTV) tuner then it is tagged with the term HD built-in. Normally there will be NTSC tuner(s) built in also and the display section will be capable of at least one of the 6 HDTV display formats.

HD Capable or Compatable.
Here the manufacturers are trying to attach a display that is not really HD to the HD term in order to make the display more marketable. Many EDTV plasmas will allow a HD signal to be sent to the display where the display will convert it to the native EDTV resolution. While they are not a HD display, they can advertize the HD compatability. I have a couple of customers that bought EDTVs thinking they were getting HDTVs due to the HD compatable term.

Bottom Line
In order to view a HD picture, the screen must be able to display enough pixels to be considered HD. It does not matter what resolution you can input into the display, it matters what the resolution the display will output.

Last Note
There are a number of manufacturers that have decided to market the new 42" plasmas that have a resolution of 1024x768 as HD displays. According to the ATSC they are not HDTVs. I'm not sure why they are allowed to use the term HDTV, but they do. Be sure to use a critical eye when deciding between one of these near HD displays and a true HD 50" display.

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maximus

Very nice!

mfabien

To be HD ready, an HDTV must have an ATSC tuner, not NTSC.

HDTV compatible is a TV that can receive and display an HD signal from an HD STB. My Toshiba 57HDX82 has no ATSC tuner (it does have a NTSC tuner like most TV's) but I can assure you that I get HD of the highest quality and not ED from my SA8000HD STB/DVR.

Note that I do have an EDTV, a Sharp Aquos 13" and although it provides great image (in 480p) with basic analog cable, it's not HD.

__________________
Toshiba 57HDX82, SA8300HD, SA8300SD, Energy speakers, Yamaha RX-V540, SVS PB12-ISD, Harmony 880, HD-A1, BDP-1400, Oppo DV-970HD, Zektor HDS4.1, Ram HDMI3x1.

rbinck

Nope. From the glossary:

Quote:

HD-ready Describes a television that is capable of displaying one or both of the prescribed high-definition television formats (720p, 1080i) but is not equipped with the requisite tuner/converter to receive digital signals.

And what I was saying in order to be called a HD Ready TV as opposed to a HD Ready monitor, the set must have one or more NTSC tuners installed.

A TV with one or more ATSC tuners installed would be an integrated TV or HD built-in TV.

Any TV that will accept a HDTV signal is really HDTV compatable. This term has been used largely by manufacturers that have equipment that will receive HDTV signals but display at EDTV resolutions. Your Toshiba is a HD Ready TV. It is also HD compatable because it will accept HD video.
see product details

mfabien

Well, things have changed !

In any event I know that you know that I know...which is not of much help to people new to these things.

I will let you deal with it.

__________________
Toshiba 57HDX82, SA8300HD, SA8300SD, Energy speakers, Yamaha RX-V540, SVS PB12-ISD, Harmony 880, HD-A1, BDP-1400, Oppo DV-970HD, Zektor HDS4.1, Ram HDMI3x1.

PSzalapski

Also, it seems that many TVs are marketed as HDTVs or HDTV Monitors when not capable of the full horizontal resolution. It seems that my Sanyo HT30744 is something like 800x1080/60i, not the 1920x1080/60i that I would like. However, it is definitely an HDTV, complete with logos everywhere. My understanding is that 90% of HDTVs today do not have the full horizontal res.

P-Sz

Roth

Remember that 1080i is still interlaced and can be called 800X1080 or 1920X540 given the alternating scan lines. or even 800X540 AHHHHHHHH!

Roth

or 960X540, 960X1080, its all HD

wait06

[url=http://www.bestbuy.com/site/olspage.jsp?id=1051826205151&skuId=5338208&product CategoryId=pcmcat31800050031&type=product]


using this set on BB site as an example it can't be HD ready because it has an ntsc tuner right?

Also it states 1080i display capable shouldn't say something about scan lines and pixels. Thanks

jhaustin1943

Some flat-panel computer displays are coming out called WUXGA or WQXGA, with pixel counts that would accommodate 1920x1080, but the actual ratios are not 16:9, the most common being 16:10, e.g.

1920x1200 (16:10) 2048x1536 (16:10), 3840x2400 (16:10), even 1920x1440 (4:3),

When an HD picture is displayed on such a device, it in in a "letterbox," is the pictue distorted, or are the native pixels not arranged in a square pattern, or what?

What happens to the picture quality if the actual pixel count doesn't match the ATSC scan line count, e.g, a 1280x720 broadcast on a 1920x1080 screen or 1920x1080 broadcast on a 2048x1536 screen? Even though there are more pixels, would the lack of 1:1 correspondence cause image degradation or artificats?

And BTW, do those computer displays support 30 frames per second?

rbinck

Not according to the ATSC. See http://support.gateway.com/s/CsmrEltrncs/DigitalTV/Shared/2517984faq42.shtml

If it ain't listed as a valid HD format, It's not HD. And that 1080 vs 540 dosen't make 540p HD because 540p is not in the list of ATSC formats. The progressive vs interlaced thing only really applies with computer monitors. TV is a whole different animal. That motion blur thing is way overblown. See http://highdefforum.com/showpost.php...14&postcount=5 for discussion on pixel straddling which is just as much a distortion.

Pretty much all HDTV monitors will scale the input received to add overscan. Take for example you have a 720 line fixed pixel display. You can not display all 720 lines received because the first few lines will contain video noise. The broadcasters have been using this area for years to embed data. The least amount of overscan generally acceptable is 2%, so only about 705 lines can be shown. Those 705 lines will be scaled to fit the 720 lines your display has. I used the vertical, but the horizontal is scaled in the same manner. So it really dosen't matter much as you have to have a weird resolution to get back to a 1:1 pixel mapping and generally only possible with a computer and a display that will tolerate expanded timings.

Roth

Having just an ntsc is what makes it HD "Ready" if it had a atsc it would be HD "built in". A TV is HD ready when its capable of displaying either of these resolution formats. 720p, 1080i/p and some inbetween.

Basically its tuner in or out either way its HD. just not inside the tv.

Roth

I dont think you read my post correctly i just choped 1920X1080 in half as an example of the interlaced scan lines. never said anything about proggresive vs interlaced.

ja2935

I have some questions which I imagine rbinck or some other knowledgable person can answer. I have a Toshiba 34hf84 which has a resolution option of either 540p or 1080i; linked to a Comcast Motorola HD DVR.
1. I can see no difference when switching between the two resolutions - if there is a difference expected would it only be on fast motion scenes - I have only been comparing on freeze frame?
2. Regardless of the resolution setting, non-HD material on the HD channels seems to be a much brighter and sharper picture than the analogue SD equivalent when I do an A-B comparison. Is this because the up-conversion is already done by the TV station and therefore the HD cable signal is of better quality than the 480i analogue or digital SD signal?

RSawdey

540p is obtained by putting the same data into both fields of an interlaced 1080. It's kinda fake progressive at the cost of half your res. Old video games put 240p on an SDTV. I'm pretty sure Tosh only lets you set the output format for SDTV upconverts, not for HDTV signals... that suggests you may not be connected correctly... you need DVI, HDMI, or HD Component to carry an HD signal, old style SVideo etc can only carry SDTV. You should configure the DVR for 1080i output, your native res.

The extra quality with 4:3 upconverts from a digital station is because of their digital carriage - no ghosts or static or color crosstalk.