How HDTV Works | HowStuffWorks
When the first high-definition television (HDTV) sets hit the market in 1998, movie buffs, sports fans and tech aficionados got pretty excited, and for good reason. Ads for the sets hinted at a television paradise with superior resolution and digital surround sound. With HDTV, you could also play movies in their original widescreen format without the letterbox “black bars” that some people find annoying.
But for a lot of people, HDTV hasn’t delivered a ready-made source for transcendent experiences in front of the tube. Instead, people have gone shopping for a TV and found themselves surrounded by confusing abbreviations and too many choices. Some have even hooked up their new HDTV sets only to discover that the picture doesn’t look good. Fortunately, a few basic facts easily dispel all of this confusion.
In this article, we’ll look at the differences between analog, digital and high-definition, explain the acronyms and resolution levels and give you the facts on the United States transition to all-digital television. We’ll also tell you exactly what you need to know if you’re thinking about upgrading to HDTV.
- Analog, Digital and HDTV
- DTV vs. HDTV
- Buying an HDTV
- Equipment and Signal
Analog, Digital and HDTV
For years, watching TV has involved analog signals and cathode ray tube (CRT) sets. The signal is made of continually varying radio waves that the TV translates into a picture and sound. An analog signal can reach a person’s TV over the air, through a cable or via satellite. Digital signals, like the ones from DVD players, are converted to analog when played on traditional TVs. (You can read about how the TV interprets the signal in How Television Works.)
This system has worked pretty well for a long time, but it has some limitations:
- Conventional CRT sets display around 480 visible lines of pixels. Broadcasters have been sending signals that work well with this resolution for years, and they can’t fit enough resolution to fill a huge television into the analog signal.
- Analog pictures are interlaced — a CRT’s electron gun paints only half the lines for each pass down the screen. On some TVs, interlacing makes the picture flicker.
- Converting video to analog format lowers its quality.
United States broadcasting is currently changing to digital television (DTV). A digital signal transmits the information for video and sound as ones and zeros instead of as a wave. For over-the-air broadcasting, DTV will generally use the UHF portion of the radio spectrum with a 6 MHz bandwidth, just like analog TV signals do.
DTV has several advantages:
- The picture, even when displayed on a small TV, is better quality.
- A digital signal can support a higher resolution, so the picture will still look good when shown on a larger TV screen.
- The video can be progressive rather than interlaced — the screen shows the entire picture for every frame instead of every other line of pixels.
- TV stations can broadcast several signals using the same bandwidth. This is called multicasting.
- If broadcasters choose to, they can include interactive content or additional information with the DTV signal.
- It can support high-definition (HDTV) broadcasts.
DTV also has one really big disadvantage: Analog TVs can’t decode and display digital signals. When analog broadcasting ends, you’ll only be able to watch TV on your trusty old set if you have cable or satellite service transmitting analog signals or if you have a set-top digital converter.
This brings us to the first big misconception about HDTV. Some people believe that the United States is switching to HDTV — that all they’ll need for HDTV is a new TV and that they’ll automatically have HDTV when analog service ends. Unfortunately, none of this is true.
HDTV is just one part of the DTV transition. We’ll look at HDTV in more detail, including what makes it different from DTV, in the next section.
DTV vs. HDTV
The Advanced Television Standards Committee (ATSC) has set voluntary standards for digital television. These standards include how sound and video are encoded and transmitted. They also provide guidelines for different levels of quality. All of the digital standards are better in quality than analog signals. HDTV standards are the top tier of all the digital signals.
The ATSC has created 18 commonly used digital broadcast formats for video. The lowest quality digital format is about the same as the highest quality an analog TV can display. The 18 formats cover differences in:
- Aspect ratio – Standard television has a 4:3 aspect ratio — it is four units wide by three units high. HDTV has a 16:9 aspect ratio, more like a movie screen.
- Resolution – The lowest standard resolution (SDTV) will be about the same as analog TV and will go up to 704 x 480 pixels. The highest HDTV resolution is 1920 x 1080 pixels. HDTV can display about ten times as many pixels as an analog TV set.
- Frame rate – A set’s frame rate describes how many times it creates a complete picture on the screen every second. DTV frame rates usually end in “i” or “p” to denote whether they are interlaced or progressive. DTV frame rates range from 24p (24 frames per second, progressive) to 60p (60 frames per second, progressive).
Many of these standards have exactly the same aspect ratio and resolution — their frame rates differentiate them from one another. When you hear someone mention a “1080i” HDTV set, they’re talking about one that has a native resolution of 1920 x 1080 pixels and can display 60 frames per second, interlaced.
The 18 Primary DTV Standards
Broadcasters get to decide which of these formats they will use and whether they will broadcast in high definition — many are already using digital and high-definition signals. Electronics manufacturers get to decide which aspect ratios and resolutions their TVs will use. Consumers get to decide which resolutions are most important to them and buy their new equipment based on that.
Until the analog shutoff date, broadcasters will have two available channels to send their signal — a channel for analog, and a “virtual” channel for digital. Right now, people can watch an over-the-air digital signal only if they are tuned in to the broadcaster’s virtual digital channel. After analog broadcasting ends, the only signals people will receive over the air will be digital.
However, even though a digital signal is better quality than an analog signal, it isn’t necessarily high definition. HDTV is simply the highest of all the DTV standards. But whether you see a high-definition picture and hear the accompanying Dolby Digital® sound depends on two things. First, the station has to be broadcasting a high-definition signal. Second, you have to have the right equipment to receive and view it. We’ll look at how to get an HDTV set and signal next.
Buying an HDTV
The DTV transition is not the first change to the TV signal. In 1946, the National Television System Committee (NTSC) began setting standards for American broadcasting. In 1953, NTSC standards changed to allow color television, and in 1984, they changed to allow stereo sound.
Those changes were different from the DTV switch because they were backwards compatible — you could watch the new signal on your trusty old TV. With DTV, you’ll need some new gear, and the gear you choose will affect whether you can receive and view high-definition video. You can learn about buying a DTV set in How Digital Television Works — here, we’ll focus on HDTV.
When you start shopping, keep in mind that HDTV requires three parts:
- A source, such as a local, cable or satellite HDTV station
- A way to receive the signal, like an antenna, cable or satellite service
- An HDTV set
Most people start with the set. You can choose:
- An integrated HDTV, which has a digital tuner, also known as an ATSC tuner, built in. If a station near you is broadcasting in HDTV, you can attach an antenna to an integrated set and watch the station in high definition.
- An HDTV-ready set, also called an HDTV monitor, which does not have an HDTV tuner. HDTV-ready sets often have NTSC tuners, so you can still watch analog TV with them. This is the option for you if you want to have HDTV capabilities later on but aren’t ready for the financial commitment now. Your picture quality will still be better than on your old TV, but it won’t be high definition until you get an HDTV receiver.
Designing and building an HDTV that could display all of the ATSC formats would be virtually impossible. For this reason, HDTVs have one or two native resolutions. When the TV receives a signal, it will scale the signal to match its native resolution and de-interlace the signal if necessary. A good rule of thumb is to choose a set that has a native resolution matching the signals you plan to use most often. Film fans will generally want displays with the highest possible resolution. Sports fans will generally want displays with the highest possible progressive frame rate.
If you receive a signal that has a significantly lower resolution than your screen can display, all the extra pixels won’t help it look better. This is why some people who have bought HDTVs have been dismayed at the quality of the picture – the existing analog signal just doesn’t have enough detail to look good on a high-definition set. As broadcasters change to a digital signal, this problem will improve substantially.
In the next section, we’ll look at the options for getting a signal to your TV as well as the compatibility of your existing home entertainment equipment.
Equipment and Signal
When you’ve found an HDTV with a screen size, aspect ratio and native resolution you want, you’ll need to make sure the equipment you already own will work with it. If you already have a DVD player, a DVR, game consoles or other equipment, make sure that they can connect to the TV directly or through an audio/visual receiver. Many HDTVs have High-Definition Multimedia Interface (HDMI) connections, which can transmit audio/visual signals to the TV without compression. In some cases, you can use adapters to make your equipment compatible with your set.
Once you’ve picked up your set and installed it in your home, you’ll need to get a signal. To get a signal, you can use:
- An antenna – Depending on your location relative to the stations you want to watch, a set of rabbit ears might do, but you might need a rooftop or attic antenna. You can buy an antenna that’s specially made for digital signals, but any reliable VHF/UHF antenna will work.
- Cable – Keep in mind that digital cable is not the same as HDTV. You’ll need to check with your provider to determine which packages include HDTV stations. You’ll also either need a set-top cable box or a CableCARD™ to allow your television to receive and decode the cable signal.
- Satellite service – As with cable, check with your provider to determine which plans and stations use HDTV signals. You may need a different satellite dish and tuner to receive HDTV signals via satellite.
To learn more about TVs, HDTVs and digital broadcasting, check out the links on the next page.
Frequently Answered Questions
What does full HDTV mean?
Full HDTV means that the television has a resolution of 1080p.
Lots More Information
Related HowStuffWorks Articles
More Great Links
- U. S. FCC: DTV
- HDTV Primer
- National Association of Broadcasters Digital TV Stations
- Crutchfield Advisor HDTV Center
- Davidson, Paul. “Digital Confusion Frustrates TV Buyers.” USA Today, 12/29/05 http://www.usatoday.com/money/media/2005-12-29-hdtv-confusion_x.htm
- FCC Consumer Facts: DTV http://www.fcc.gov/cgb/consumerfacts/digitaltv.html
- Crutchfield Advisor: DTV & HDTV Glossary http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/learningcenter/home/tv_glossary.html
- Cnet: HDTV World http://www.cnet.com/4520-7874_1-5102926-1.html
- Crutchfield Advisor: Understanding HDTV http://www.crutchfieldadvisor.com/S-nQi4l0Av5xD/learningcenter/home/tv_hdtv.html
- Crutchfield Advisor: TV & HDTV FAQ http://www.crutchfieldadvisor.com/S-nQi4l0Av5xD/ learningcenter/home/tv_faq.html
- Crutchfield Advisor: Understanding CableCARD http://www.crutchfieldadvisor.com/S-wVSSW83IFo8/learningcenter/home/cablecard. html
- U.S. FCC: Buying a DTV Television http://www.dtv.gov/DTV_TipSheet.pdf
Please copy/paste the following text to properly cite this HowStuffWorks.com article:
Tracy V. Wilson
“How HDTV Works”
1 April 2000.
24 June 2023
How does HDTV work? – Explain that Stuff
by Chris Woodford. Last updated: March 20, 2022.
It’s funny to
look back on ancient home appliances and laugh at
how crude and useless they seem today. Televisions from the 1940s and
1950s, with their polished wooden cases and porthole screens, seem
absurd to us now, fit only for museums; in their time, they were
cutting-edge technology—the very finest things money could buy. In
much the same way, the televisions we’re all staring at today are
already starting to look a bit old hat, because there’s always newer
and better stuff on the horizon. Back in the 1990s, HDTV
(high-definition television) was an
example of this “newer and better stuff”; today, it’s quite
commonplace. But what makes it different from the TVs that came
before? And what will come next? Let’s take a closer look!
Photo: HD isn’t just about TVs. Most decent smartphones now boast high-definition screens, typically with Quad HD resolution (2560 × 1440 pixels) or better.
What is HDTV?
All televisions make their pictures the same way, building up one
large image from many small dots, squares, or rectangles called
pixels. The biggest single difference between HDTV and what
came before it (which is known as standard definition TV or SDTV) is
the sheer number of these pixels.
Having many more pixels in a screen of roughly the same size gives a
much more detailed, higher resolution image—just as drawing a
picture with a fine pencil makes for a more detailed image than if
you use a thick crayon. SDTV pictures are typically made
from 480 rows of pixels stacked on top of one another, with 640
columns in each row. HDTV, by comparison, typically uses either 720 or 1080
rows of pixels, so it’s up to twice the resolution of traditional
SDTV. One early HD standard, HD Ready, introduced back in 2005, required a minimum resolution
of 720 rows. Today, most HDTVs are described as Full HD (FHD): they use 1080 rows of pixels and 1920 columns,
making roughly 2 million pixels (2 megapixels) altogether, compared to about 300,000
(0.3 megapixels) in an SDTV screen, or just over six times more. (For the
sake of comparison, our eyes contain 130 million light-detecting cells called rods and
cones so our vision is effectively 130 megapixels. Put that another way and it means the
images created on our retinas are at least 50 times more detailed than the images created by HDTV
and over 400 times more detailed than SDTV.)
Photo: More pixels: HDTV (1) gives about six times more pixels than SDTV (2). This is what six times more pixels looks like.
Another way in which HDTV differs from SDTV lies in the way the
pixels are painted on the screen. In SDTV and in earlier versions of
HDTV, odd-numbered rows were “painted” first and then
even-numbered rows were painted in between them, before the
odd-numbered rows were painted with the next frame (the next moving
picture in the sequence). This is called interlacing, and it
means you can fill the screen more quickly with an image than if you
painted every single row in turn (which is called progressive
scanning). It worked very well on old-style cathode-ray
televisions, and cruder LCD televisions that built pictures
more slowly than they do today, but it’s not really necessary anymore
now there are better LCD technologies. For this reason, the best
HDTVs use progressive scanning instead, which means they draw
fast-action pictures (for example baseball games) both in more detail
and more smoothly. So when you see an HDTV described as 1080p, it
means it has 1080 rows of pixels and the picture is made by
progressive scanning; an HDTV labeled 720i has only 720 rows and uses
interlacing; a 720p has 720 rows and uses progressive scanning. (SDTV
would be technically described as 480i using the same jargon.)
Photo: Interlacing and progressive scanning: With old-style interlaced scanning (1), the red lines are scanned one after another from the top down. Then the blue lines are scanned in between the red lines. This helps to stop flicker. With progressive scanning (2), all the lines are scanned in order from the top to the bottom. HDTV generally uses progressive
scanning, though (like SDTV), it can use interlacing at higher frame rates.
It’s a digital technology
Where SDTV was an old-style analog technology, HDTV is
fundamentally digital, which means all the advantages of digital broadcasting:
theoretically more reliable signals with less interference,
far more channels, and automatic tuning and retuning.
(If you’re not sure about the difference, check out
our introduction to analog and digital.)
It’s easy to see how old-style, cathode-ray
tube SDTV evolved from the very earliest TV technology developed by
people like John Logie-Baird, Philo T. Farnsworth, and Vladimir
Zworykin (see our main article on television
for more about that). SDTV involves electron
beams sweeping across a screen controlled by electromagnets, so it’s
absolutely an analog technology; HDTV is completely different in that
it receives a digitally transmitted signal and converts that back to
a picture you see on the screen.
How do you pack more pixels in the same space?
HDTV is about doing more with less—putting “more picture” in
roughly the same space, but how do you do that exactly? In a
cathode-ray tube TV, the size of the pixels is ultimately determined
by how precisely we can point and steer an electron beam and whether
we can draw and refresh a picture quickly enough to make it look like
a smoothly moving image. Even if you could double the number of lines
on a TV, if you couldn’t draw and refresh all those lines quickly
enough, you’d simply end up with a more detailed but more jerky
The same problem applied when cathode-ray tubes gave way to other
technologies such as LCD and
plasma, but for different reasons. In
these TVs, there’s no scanning electron beam. Instead, each pixel is
made by an individual cell on the screen switched on or off by a
transistor a (tiny electronic switch), so the size of a pixel is
essentially determined by how small you can make those cells and how
quickly you can switch them on or off. Again, making the pixels
smaller is no help if you can’t switch them fast enough to make a
smoothly moving image.
Advantages and disadvantages of HDTV
Picture quality (or resolution, if you prefer) is obviously the
biggest advantage of HDTVs, but that’s not the first thing you
notice. If you compare HDTVs with the old-style TVs that were commonplace about 20 years ago,
you can see straightaway that they’re much more rectangular. You can see
that in the numbers as well. An old-style TV with a 704 x 480 picture
has a screen about 1.5 times wider than it is tall (just divide 704
by 480). But for an HDTV with a 1920 x 1080 screen, the ratio
works out at 1.78 (or 16:9), which is much more like a movie screen.
That’s no accident: the 16:9 ratio was chosen specifically so people
could watch movies properly on their TVs. (If you try to watch a
widescreen movie on an SDTV screen, you either get part of the
picture sliced off as it’s zoomed in to fill your squarer screen or
you have to suffer a smaller picture with black bars at the top and
bottom to preserve the wider picture—like watching a movie through a
letterbox.) The relationship between the width and the depth of a TV
picture is called the aspect ratio; in short, HDTV has a bigger
aspect ratio than SDTV.
Photo: Aspect ratio: HDTV (1) gives a more rectangular picture than SDTV (2).
What about the drawbacks? One is the existence of rival systems
and standards. Typically, HDTV can mean either 720p, 1080p, or 1080i,
and it’s not just about the television set (the receiver) itself but
about all the kit that generates the picture at the TV station and
gets it to your home, including the TV camera and the transmitter
equipment and everything else along the way. In other words, you
might have a situation where the signal is 1080i or 1080p but the TV
in your home is 720p, or the signal is 1080i but the set is 1080p, in
which case the set either doesn’t accept the signal or has to convert
it appropriately, which might degrade its quality. This problem has
largely disappeared now more people have converged on 1080p as the
standard version of HDTV, which is also known as Full HD (FHD).
However, HDTVs don’t just take their signals from incoming cable or
satellite lines; most people also feed in signals from things like
DVD players, Blu-Ray players, games consoles, or laptops. Although
decent HDTVs can easily switch between all these sorts of input, the
quality of the picture you get out is obviously only ever going to be
as good as the quality of the signal you feed in. Moreover, old
programs and movies broadcast on TV may still be in SDTV format so
they’ll simply be scaled up to fit an HDTV screen (by processes such
as interpolation), often making the picture look worse than it would
look on an older “tube” TV. It’s worth bearing this in mind when
you fork out for a new television: if you’re in the habit of watching
a lot of old, duff stuff, don’t suddenly expect it to look magically
new and terrific.
Photo: Interpolation: Programs made for SDTV look fine on SDTVs but fuzzy on HDTVs:
if bigger sets use exactly the same picture signal, the bigger you make the screen, the more area each pixel in
the signal has to cover and the fuzzier it looks. In this example, to
make a crude 704 x 480 picture (1) display on a 1920 x 1080 screen (2), we
have to scale it up by interpolation so that each pixel in the signal occupies about four pixels on the screen. Or, to put it another way, your TV is showing only a quarter of the
detail that it can.
Where next? Will televisions keep on improving, giving us ever
more pixels and ever-better pictures? Manufacturers have moved
on from basic 1080p HDTV (Full HD) to what’s called ultra-high definition (UHD), currently available in two flavors known as 4K UHD (3840 × 2160) and 8K UHD (7680 × 4320), both using progressive
scanning. (Strictly speaking, 4K and UHD are slightly different things—4K means 4000 horizontal
pixels while UHD means double the pixel dimensions of Full HD—but the terms are often used synonymously.)
Is this any more than a marketing gimmick? Are people actually going to want ever higher screen resolution?
Artwork: How many more pixels do you get for your money? This artwork compares the pixel dimensions of common SDTV and HDTV formats: SDTV (yellow, 640 × 480), Full HD/HDTV 1080p (orange, 1920 × 1080),
4K UHD (blue, 3840 × 2160), and 8K UHD (red, 7680 × 4320).
If all were the same size, you can imagine how much more detail would be packed into the higher-resolution screens.
You can see that there’s a big difference between Full HD and 4K.
Lesser versions of HD, such as 720p, come in between the orange and yellow rectangles.
Decent smartphones typically now have Quad HD (2560 × 1440) or Quad HD+ (~3000 × 1440)
The situation is much the same as it is with digital cameras.
There’s a limit to the amount of detail our eyes can process and
there are practical limits on how much resolution we really need
introduced by things like the bandwidths of Internet connections. In
the case of digital cameras, manufacturers have long liked to boast
about new models with ever more “megapixels,” largely as a
marketing trick. In practice, that doesn’t necessarily mean that the
images are better (a camera with more megapixels might still have a
smaller and poorer image sensor), that your eyes can tell the
difference, or that a super-high-resolution photo is always going to
be viewed that way (if you upload a photo to your favorite social
media site, it will end up scaled down to a few tens or hundreds of
thousands of pixels, wasting much of the detail you originally
captured—but you don’t care about that if you’re viewing the image
on a tiny cellphone.
Photo: An LG Ultra-HD (UHD) TV.
Photo by courtesy of Kārlis Dambrāns
published on Flickr
under a Creative Commons (CC BY 2. 0) Licence.
Similar considerations apply to TVs. Just because you have an
HDTV, it doesn’t follow that you will always be viewing
high-definition material on it. Maybe you’ll be sitting too far away
from it to appreciate the extra level of detail? Or perhaps the
screen itself isn’t big enough to let you appreciate the difference
between 4K and 1080p? Or maybe you do quite a lot of your viewing
using IPTV or streaming videos from YouTube, so the quality of your
Internet connection—how much data you can download per second—is
also going to play a factor in the quality of what you see on your
screen. Maybe you’re streaming on a mobile network and trying to stay inside a limited data allowance?
For example, I rent and stream a lot of movies online,
but, although I have an HD screen, I generally opt for the standard
resolution (SD) versions, because I don’t really notice the difference and
it’s a lot cheaper (I can rent four SD movies for the price of three HD ones).
It’s also worth noting that some online streaming services that claim to offer “HDTV” actually
deliver just 720p in practice, even if you’re watching on a much higher resolution (4K)
screen. And if you’ve got a slow Internet connection, you might well be reduced to watching in lower-resolution
SD, automatically, whether you like it or not.
In short, just because bigger, better, faster, and neater is available, it
doesn’t follow that people either want, need, or are automatically
going to use it. Having said that,
shipment statistics show a clear peak in sales of Full HD sets in 2013/2014, with a
decline of about 25 percent since then as 4K sets have become increasingly popular;
worldwide 4K sales have increased by over 10 times between 2014 and 2019, to the current figure of around 110 million units a year. The shift to 4K and 8K has begun! Another key trend is the rapid switch to “smart TVs” that incorporate
Internet connections for easier streaming; most new TVs now fall into this category and annual
sales are predicted to reach 266 million by 2025. For some viewers, if not all, the “smartness” of a TV may
be a more important factor than the definition of its picture, although you can, of course, have both.
HDTV Resolutions and Standards on TVs
Modern TVs are capable of working with various signal sources:
– Terrestrial or cable analog and digital television.
– Satellite television.
– DVD players and camcorders.
– Computers, laptops, Flash drives, Internet.
– Decoders and receivers offered by ISPs or cable TV providers
To implement a high-quality image, taking into account the need to transmit and store video information, various systems and standards for forming a video signal were developed at different times.
SECAM and PAL color television systems popular in our country, widely used in on-air and cable broadcasting,
transmit 625 lines and 50 fields per second in an interlaced manner. Alternate odd and even lines.
As a result, the visible image is formed from 25 full frames per second.
Interlaced display of a frame on the screen allows you to use half the bandwidth of the video signal,
which is especially important for HF modulation in terrestrial analog television,
therefore, this method is widely popular in terrestrial and satellite systems for broadcasting television programs.
Due to the existence of a reverse beam during the formation of frames and lines in televisions with a cathode ray tube,
some of the lines are not involved in image transmission, but are used to transmit technical information – color synchronization and data transmission in teletext mode.
In LCD or plasma TVs, the use of such a video signal in popular PAL or SECAM systems, when scaling with a graphics controller, the decomposition standard 9 is implemented0019 526i , which uses 526 lines (out of 625 existing) to form the visible image.
Index i indicates that the scan is interlaced.
The NTSC video signal transmits 525 lines and 30 frames in 60 fields. Implemented in graphic format by the decomposition standard 480i .
With the growing popularity of computers and LCD TVs, it became necessary to form an image
with a higher resolution, which contributed to the spread of the progressive (progressive) method of framing on TVs.
This is how video signal decomposition standards for higher HDTV resolutions were born.
The standard entry usually indicates the number of visible lines and the method of framing.
Index p – progressive corresponds to progressive scanning with progressive frame display, or i – interlaced indicates interlaced scanning.
For example, the decomposition standard 720p specifies,
that the video signal consists of 720 visible lines and is formed line by line for progressive scanning.
Progressive scan has certain advantages in image quality, but requires a wider bandwidth for RF modulation, so it is rarely used for transmitting an analog signal over the air.
When a computer generated a VGA or SVGA video signal, only progressive scan was always used to display it on the monitor.
The 720p decomposition standard can be implemented in TVs with screen resolutions of 1280×720 or 1366×768 for a 16:9 aspect ratioand at a resolution of 1024×768 for a 4:3 aspect ratio.
The remaining 48 lines are not involved in imaging and can be used to convey technical information or
blanking during the reverse motion in televisions with a kinescope.
For a 1920×1080 resolution of a 16:9 frame format, there are decomposition standards 1080i and 1080p ,
respectively for interlaced (i) and progressive (p) scanning.
1080i decomposition is currently used in many satellite channels broadcasting as HDTV,
where the modulation bandwidth is relevant.
1080p decomposition standard can be implemented in video signal generation and transmission by computers,
camcorders or Blue-Ray DVD players.
It should be recalled that there are EDTV (Enhanced Definition) standards,
which became a transitional stage from standard SDTV television to high-definition television HDTV.
In the US, EDTV has been adopted by the Electronic Consumers Association (CEA).
to designate digital decomposition standards 576p (PAL) and 480p (NTSC) using progressive scan.
In EDTV standards, the frame rate is 25 Hz for 576p and 30 Hz for 480p .
In Russia, EDTV is known under the term “High Definition Television”. According to GOST R 53536-2009,
implies the transmission of signals with progressive frame decomposition and the number of visible lines in the frame is 720. Complies with the decomposition standard 720p .
On-air digital DVB-T, DVB-T2 or cable DVB-C does not use frequency modulation, and frames are transmitted according to MPEG standards, so concepts such as bandwidth and video signal decomposition are no longer relevant.
Full HD or HD ready?
Often on TVs you can see the logos Full HD or HD ready , also
these inscriptions may be present in the technical specifications and on the price tags of TVs. What do they mean?
Many controversial and dubious arguments about this can be found on the Internet.
HD ready is a European standard that prescribes certain technical possibilities for implementing HDTV on a TV.
HD ready – Provides support for 720p and 1080i resolution standards.
This means that this TV is able to accurately (pixel-for-pixel) display the signal with a resolution of
1280×720 at 50 or 60 Hz progressive scan, as well as
with a resolution of 1920×1080 at 50 or 60 Hz, but only interlaced.
The 1080p (progressive) format will be interpolated and therefore displayed on screen with some quality loss.
HD ready 1080p – indicates the ability of the TV to support, in addition to the modes described above for HD ready,
also progressive scan at a resolution of 1920×1080. For this option, the term Full HD was introduced, that is, a complete set of all HD modes.
Full HD – an advertising inscription or logo that declares support for all HDTV modes.
In some cases, Full HD logos may indicate the maximum HDTV capabilities, for example:
Full HD 1080p – Advertises the TV’s ability to support all HD standards, namely: 720p .
1080i and 1080p for all possible TV resolutions and frame rates.
For more details on the modes supported by the TV, it is better to check its technical characteristics.
In August 2012, two more sets of 4K UHD TV 9 digital television standards were adopted.0019 2160p and 8K UHDTV 4320p .
Televisions of the 2160p decomposition standard with a resolution of 3840×2160 have already appeared on sale.
To implement the 4320p standard, only demonstration samples exist so far, for example, presented by the Japanese company NHK,
developed the Super Hi-Vision broadcast format with support for 8K UHDTV resolutions.
One hour of uncompressed video in this format takes about 25 terabytes.
The page was created in addition to the article with recommendations on how to choose a TV when buying
to clarify some questions about HDTV resolutions and standards in televisions and televisions.
HDTV TVs, basic resolutions
The development of high-definition television has led to the emergence of new methods for processing and transmitting television signals, and today this standard is referred to as HDTV (High-Definition Television). With such television broadcasting, modern methods of image decomposition are used, which in terms of resolution far exceeds the signal of standard definition television. For this, only digital methods of video and audio signal processing are used.
HDTV signals are transmitted using digital satellite, cable and terrestrial television. For transfer between devices, HDMI and DVI-D interfaces are used. HD DVD and Blu-Ray media are used to distribute high-definition video; the capacity of these media reaches tens of gigabytes and reaches 100 GB.
Today, the production of HD DVD by the founder of this format, Toshiba, has been discontinued. Therefore, only one Blu-Ray disc format remained on the market. And only the use of such discs and players for them will allow you to create an HDTV system at home if you purchase a Full HD TV. Today many TV channels practice broadcasting their programs on the air in high-definition format, although it is not always possible to watch them for free. As for cable operators, each of them has its own rules and you need to find out about the availability of high-definition channels from them.
Today, when buying a TV, you can see several logos that determine the resolution of the TV. What do they mean? The ability of a television receiver to display HDTV signals is determined by the screen resolution. But this is not the only condition that will allow you to wear the HDTV logo. Let’s see what logos are used and what they mean.
These logos represent internationally recognized associations and are marks of quality for a device capable of processing and displaying TV signals in the desired format. Each logo indicates that the machine meets the minimum requirements that a device that supports that format must meet. These requirements are described in the terms and conditions adopted by the EICTA association.
This logo indicates that the TV can display a high definition TV signal. In order to receive this sign, the TV must meet the following conditions:
- minimum screen resolution of 720 lines in 16×9 format;
- there are interfaces for data transfer: analog YPbPr, digital DVI or HDMI. Digital formats must support HDCP content protection;
- format support: 720p (1280×720 progressive scan, 50 or 60 Hz), 1080i (1920×1080, interlaced, 50 or 60 Hz).
These are mandatory requirements and if the TV does not meet at least one condition, then it will not receive the HD Ready logo. Note that in the mandatory conditions there is no 1080p format common today. For example, a computer can play HD video, but it can’t get the HD Ready logo if it doesn’t have the correct connector.
This standard is based on the requirement for HD Ready, but the addition of the line “1080p” indicates that a TV bearing this logo can display video at 19p resolution. 20 x 1080 progressive scan. It is this parameter (1080p) that also corresponds to the designation Full HD. The designation Full HD is not a standard and only means that you can connect this TV to an HD video source, and it will process and display this high definition video without distortion. Full HD indicates only the presence of a resolution of 1920×1080 pixels and does not affect other parameters.
And the HD Ready 1080p standard itself includes all the requirements for the HD Ready standard, plus a few more points:
- minimum resolution 1920×1080;
- all supported video formats should be played without distortion;
- 1080p and 1080i display without overscan;
- display video at a given frequency or more;
- 1080p support.
Let’s look at these differences between the two formats.
1) Some HD Ready TVs do not display video at full resolution or at the same frame rate as they receive from the source. This leads to some signal distortion.
2) The lack of pixel count in HD Ready devices means that they cannot accurately display the high resolution 1920×1080 pixel by pixel. This also leads to some distortion of the picture.
HD Ready 1080p devices do not have these disadvantages.
HD compatible devices, this is another class of devices that have a resolution lower than the HD Ready standard, but they support the HDMI interface.
HDTV 1080p. This logo indicates that the device is equipped with a digital tuner. The characteristics of the requirements remain the same as above.
The most common logos today are HD Ready and HD Ready 1080p (Full HD). When buying, you need to remember their main difference. This is the difference in the minimum permission requirement. HD Ready devices come with a resolution of 1280×720 (720p). HD Ready 1080p (Full HD) devices come with a resolution of 1920×1080 (1080p).
Since 2016, 4K Ultra HD resolution (3840×2160 pixels) has become the main resolution for TVs. Here the number of pixels is 8 times more than Full HD. For both technology and video, this resolution is designated 2160p. It does not have a separate HD logo. Most TV models from all manufacturers in 2016 have 4K resolution. Learn more about Ultra HD here.
Your TV will best display a video signal that matches the resolution of your screen. Therefore, not all high-definition televisions can display a standard broadcast television signal, which has only 576 lines, well. Over-the-air channels on CRTs may be better than some high-definition flat-panel televisions. Also, terrestrial channels are often transmitted in 4:3 format, and all HD TVs are produced in 16:9 format. Format matching can be done in different ways:
- – there will be black bars on the sides on a 16:9 screen;
- – the frame is stretched to the full width, to reduce distortion, the extreme parts of the frame are stretched more;
- – the frame is enlarged to full screen, and the top and bottom are cut off;
- – a combination of the last two methods, that is, the frame is stretched in width and slightly cropped from above and below.