HDTV(High Definition TV), is a generic term associated with a large family of systems to shoot and display TV images of better quality compared to what traditionally was possible to get on TV at home, referred to as the SDTV (Standard Definition TV) . Although commonly the definition of images is related to the quality of the same, technically it is not: the definition is an objective property, according to which television sets have been made for decades and television programs have been broadcast. Technically, definition is determined by the number of elementary points into which the image is decomposed, so it is a feature of the shooting process. The definition referred to the quality of an image is also measurable as number of pixels relative to the size. Resolution is rather the degree of detail with which the screen image is rendered, i.e. the number of lines and the amount of points placeable on each line, so it is a feature of the visualization process.
At first it must be said that the satellite platform is able to bear a number of channels, much higher than the terrestrial platform. The reason is purely technical, due to the inherently larger bandwidth of the satellite platform. For example, in a typical Italian region there are between 200 and 300 programs available on digital terrestrial television, whereas by pointing your dish toward a specific satellite over 1000 programs become available. Add to this technological reason, a market consideration: the spectrum allocated to digital terrestrial television services is very crowded, so it is expensive to allocate available bandwidth to transmit high-definition. Satellite bandwidth, instead, is available in larger quantities and therefore cheaper than spectrum allocated to terrestrial television. However, it can be expected that High Definition will gradually supplant standard definition on all platforms, with the uptake of compression techniques and digital signal modulation techniques more efficient in bandwidth usage.
First, you must make sure that high-definition broadcasts are available in your area, via digital terrestrial, satellite or broadband. Your TV must have a display with high-definition resolution. You must also make sure that it includes a built-in decoder capable to receive HD signals, otherwise you have to connect your TV to an external decoder capable to receive HD signals.
Let us clear the obvious case of three displays with same diagonal, placed next to each other: there is a certain distance at which you can tell whether they have different resolution images. Let us focus on the case of a single TV. To tell the difference between HD and Ultra HD, but also between SD and HD, an objective criterion is given by the minimum distance at which a viewer with normal visual acuity perceives the image on the TV without grain. This distance depends - of course - not only on the resolution, but also on the diagonal of the TV. There are some specific tables in this regard. Without having to resort to the tables right now, we can make a practical case that clarifies the idea. Imagine we have a 42inch set displaying a given image and let us put ourselves at such a distance so as to see the image without grain. Let us approach gradually: if when at a distance of about 150cm, the image begins to "shell”, we are faced with a standard definition image, otherwise it is high definition. If I get close at about 75 cm, and the image is still free from grain, we are faced with 4K image.
It is not correct to say that you have to connect the TV to the telephone wire (better said ’twisted pair’). It is correct, however, to say that the TV be connected to a device for access to the Internet. In most homes such device is an ADSL router , which accesses the Internet through the twisted pair and is able to route on it the data requested or generated by all smart devices ( computers, tablets , smartphones , TV) present at home or office, to / from the Internet. However, it could also be a coaxial cable router connected to a digitalized cable network or a router for optical fiber access connected to the Internet without the intermediation of the telephone network .
The connection between the TV and router will occur through RJ45 cable ( and then the TV must have a dedicated Ethernet port ) or WiFi ( and then the TV must feature WiFi) . Current routers have both Ethernet capabilities, as wired functionality is more efficient in terms of speed and wireless functionality is essential - among other things - for access to the Internet from tablets and smartphones. The TV has both features only for certain models of medium-high price range.
The name SmartTV is reserved, for copyright reasons, for a precise commerical line of a TV manufacturer brand. In general, we must talk about connected TV. With that device, not only can you receive programs transmitted via the Internet, but you can run widgets, which are the equivalent of the apps in a tablet or a smartphone. It also possible to browse the Internet, with a widget that opens a browser similar to that used in PCs. It should be noted, however, that while browsing is fairly easy with the arrows and direction keys of a classic remote control, data and text string entry can be boresome if made possible only with an on-screen virtual keyboard. Some connected TVs come with a touch remote control, which can present its own virtual keyboard. Indeed, the touch remote control can also be a tablet or a smartphone driven by a suitable app made available by the manufacturer of that TV.
For sure, image quality improvement is not just a matter of subjective perception, but indeed the effect of more information actually available. The level of detail gets to be five times higher than with standard definition: it goes from a frame of 576 x 768 = 442k pixels to one of 1080 x 1920 = 2.1M pixels. The aspect ratio is changed from 4/3 to 16/9, more natural for the visual angle of the human eye. The scene is wider horizontally (landscape format) and contains much more detail, giving greater depth to the image. Not to be underestimated, moreover, the presence of multi-channel audio, which greatly increases the sense of immersion of the viewer in the scene. High Definition is not just a visual experience, but also auditory. The resolution of HD also lends itself to multimedia screens, presenting at once images, videos and texts, as we usually see on a PC browser or tablet.
Digital television is a technique of representation of the video and audio signal into digital form, i.e. as a sequence of binary digits. The digital video signal is inevitable for computer storage and servers, but also extremely effective for a true broadcast-quality signal. In broadcasting, terrestrial or satellite, digital technology has been gradually adopted since the late nineties and today, in many countries including Italy, has completely supplanted analog technology, with which the television had been going on for over fifty years. Numerous experiments until the early nineties had demonstrated that a high-definition signal in analogue format was impractical, though very attractive. For efficiency of storage and transmission, television services in high definition are much better delivered with digital technology. In this sense, high definition is only one of the possible formats offered by digital television, which supports a whole family of formats: SD, HD , 3D , and UHD1 UHD2 , as well as numerous other video formats available on the Internet.
Bandwidth resources needed to broadcast channels on 4K or in 8K are just not available as of today. However, the problem is not only related to non availability of bandwidth, it is mainly connected with investments and time it takes to upgrade the whole chain of production, post-production and distribution. For 4K there exist at the time, at least one experimental ‘flag’ channel broadcast from each major satellite operator. There is however also a problem of availability of content, i.e. television footage produced in 4K. It is expected that - by 2018 - some broadcast in 4K will be on-air. It would be mere futuristic exercise to predict a timeframe for availability of broadcasts in 8K.
A curved screen has a dramatic stylistic impact when furnishing an office or a home. At the Consumer Electronics Show in January 2014, curved screens were among the most quoted attractions. At present, all products are in the very high-end segment and in OLED technology. If we also consider the need to apply complex image processing circuits to compensate for distortions, we may conclude they will remain an elite product for quite some time in the near future.
Of course, these are programs and movies in digital format, otherwise they could not even get through the Internet. They can be standard definition (SD), but often also in lower definitions (especially when the terminal is a smartphone), or high-definition. Of the two main formats consolidated for high definition, normally format 720p is chosen (whereas for television broadcast, the preferred format is 1080i). It must be said, however, that for some time now programs and movies via the Internet are distributed in adaptive streaming mode: the actual definition is decided by the server, both depending on the type of user terminal and on the bandwidth actually available - and measured at subsequent time intervals - over the Internet client-server connection.
Since 2013, 4K resolution has been made available in high-end TVs but for the moment it is accessible only through satellite channels or through special media-players, with a built-in hard disk or solid-state-disk, where 4K content may be preloaded at factory time and more content can be downloaded from suitable network or cloud servers before watching. It is worth mentioning that 4K is the resolution of digital cinema (though, this comes at 24Hz frame rate) which is gradually spreading in theaters equipped with facilities for secure and DRM-protected downloading of movies, normally via satellite.
The 8K resolution is currently available in prototype displays and can be enjoyed only with content from shooting experiments. At the moment it is visible only on the occasion of demos, trade shows and events.
The UltraHD is not only a matter of spatial resolution (number of pixels) of displays, it is also about greater color depth, higher temporal resolution (number of frames per second, not more than 25 or 50Hz of the HD, but also 100Hz and over). Audio experience comes with a very high degree of viewer’s involvement, being supplied by a system of 11 or 22 channels.
Sure! A 3D TV is also capable of displaying 2D programs, i.e. SD and DVD (which are in 576p format, in Europe), as well as HD and BluRay (which are in 1080i25 or 1080p50 mode). This is precisely why a 3D TV generally has a button for switching from 3D mode to 2D mode. Naturally, an HD-only TV is not capable of displaying 3D programs. Depending on the technological choices related to the representation of a 3D signal, an HD-only TV that receives a 3D signal may display the left-eye and right-eye related images side by side (side-by-side) or one below the other (top-bottom) or fragmented and arranged in a suitable tile pattern (tiled) or may display nothing. The same would happen with a 3D TV that you have mistakenly set to 2D mode.