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Feature uhdtv


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Feature uhdtv

  1. 1. 162 163TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 09-10/2013 — — 09-10/2013 — TELE-audiovision International — 全球发行量最大的数字电视杂志 FEATURE Ultra High Definition Television • peut mieux afficher les couleurs, principalement des tons rouge et vert • adapté pour la 3D grâce à sa vitesse supérieure • nécessite une bande passante énorme • les utilisateurs auront besoin d'un équipement flambant neuf que UHDTV n'est pas compatible
  2. 2. ■ 164 TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 09-10/2013 — FEATURE Ultra High Definition Television We all are familair with High Defini- tion Television. HDTV uses picture reso- lutions of either 720p, 1080i or 1080p. The first two are used for broadcasting TV via satellites while the last one is mostly used with Blu-ray discs. A HDTV video signal has either 50 or 60 picture frames per second. If a complete picture is sent in every frame, the letter “p” is added after the resolution figure (720p or 1080p). If only half the horizontal lines are sent in one frame (only odd number lines, then only even number lines and so on), the letter “i” depicts such interlaced video. Most of the contemporary satellite TV receivers upscale any 720p or 1080i video signals to 1080p and then output the video to your living room TV. Now, if we focus on the best version of HDTV – 1080p – it has a picture resolution of 1920 x 1080. The new 4K UHDTV stand- ard has doubled the resolution in both axes to 3840 × 2160 while the 8K UHDTV has even quadrupled it: 7680 × 4320. The best way to realize how big an im- provement UHDTV introduces is to look at our simple picture showing TV screens for different standards but the same pix- el size (see picture). Imagine this: 4K is like arranging 4 HD TV-sets in a 2x2 ar- ray, while for 8K UHDTV one would need 8 HD TVs arranged in a 4x4 array! Though resolution is the most obvi- ous improvement over classical HDTV it is by no means the only parameter that has been changed. The other two related to video are: color space and frame rate. UHDTV has a wider color space than HDTV. In particular, UHDTV picture is able to reproduce more deeply red and more deeply green colors which can not be shown by our existing HDTV equipment. In this way, UHDTV is able to reproduce more natural colors. The standard extends the allowable frame rates up to 120 frames per second. In this way 3D video can be reproduced with up to 60 fps for each eye. 60 fps are typical for North American TV whilst 50 Is it even a standard?Jacek Pawlowski What‘s behind the new standard? Comparison of the TV screens for different resolution standards. fps is used in most other areas including Europe. Therefore European 3D TV will use 100 fps rather than 120 fps. Adding to these enormous improve- ments in video performance, UHDTV also expanded the audio quality. With the new UHDTV standard an astounding 22 audio channels plus 2 low frequency effects channels are possible. The 22 channels are divided into three groups: an upper layer of nine channels, a middle layer of ten channels and a lower layer of three channels. Such complex audio setups can be found at movie theatres and thus with UHDTV this also becomes available to the average viewer. Of course, the first thing in order to enjoy that big resolution is a UHDTV compliant TV monitor. The best TV manufacturers already offer 4K UHDTV TV-sets with large screen (70” or more). Monitors capable of showing 8K can be seen at the professional broadcasting exhibitions but sofar we know of no such monitor available at regular stores. Now, what about the sources of ul- tra HD video? Presently, the choice is extremely small. One model of UHDTV video player has been announced with a few pre-stored movies in 4K format on the internal HDD. Blu-ray Disc As- sociation have just started their work on extending Blu-Ray Disc specification to include 4K Ultra HD video. Similarly, Sony announced that their PlayStation 4 will support 4K resolution but only for photos and videos – not for the games themselves. And what is going on in the satel- lite industry? In Europe EUTELSAT has started 4K UHD test transmissions cod- ed with the MPEG-4 codec on EUTELSAT 10A. Quite recently, SES has done one step further and started a 4K channel coded with the newest HEVC (H.265) co- dec that helped reducing the necessary bitrate down to 20 Mbit/sec. You do not have to be an expert to realize that 4K UHDTV requires 4 times more bits than HDTV and 8K UHDTVre- quires 16 times more bits. This is really a problem because the communication networks have finite throughput rates. HEVC, known also as H.265, can help here as its efficiency is roughly 2 times better than MPEG 4. But even using the best available codec you still need about 20 Mbit/sec for 4K UHDTV and as much as 80 Mbits/sec to broadcast a single channel. And all this for 50/60 fps. If you liked to double the frame rate to 100/120 to transmit 3D UHDTV you would need twice the bandwidth. It is funny to think that if in the future 8K is introduced to satellite broadcast, one transponder will be carrying a maxi- mum one channel – like in the old days of analog TV. The list of devices and standards that still have to be developed or extended is long: UHDTV cameras and other studio equipment, HDMI interface, audio equip- ment, and, of course, all kinds of digital TV receivers: satellite, cable, IPTV and (maybe) terrestrial. New equipment will require new chip-sets and perhaps even new hardware architecture to do the job efficiently. UHDTV is not backward compatible with HDTV. In other words, your pre- sent HDTV receiver will not process a UHDTV channel. Naturally, in the begin- ning, there will be a scarcity of ultra high resolution programs and many UHDTV channels will be created by up-scaling regular HDTV. We can still remember the first years of HDTV or more recently 3D HDTV – the same will happen with UHDTV. However, despite all the technology, communication and media problems linked with UHDTV, we strongly believe that the race has started for good and sooner or later we will all enjoy the won- derful ultra high definition pictures in our houses.