Angshu Kumar Das lays threadbare the technology behind 4K/UHDTV and explains how it can herald new opportunities for manufacturers, broadcasters and content owners
ver the years the global television industry has seen several technology changes. Initially, there came black & white TVs invented by John Logie Braid in 1936, followed by the introduction of colour TV in 1953. The analogue composite colour system has stood the test of time and is still around. Digital signal processing started in the late 70s and digital transmission in form of DTH started in early 2000.
However, the limitation of Standard Definition TV (SDTV) was soon felt as its resolution was not high enough for larger screen sizes. With the introduction of digital signal processing, compression techniques, now transmitted through high throughput bandwidth, can be reduced considerably. This made the transmission of High Definition (HD) TV viable.
It also led to a six-fold increase of pixels (the smallest picture element) in HDTV as pictures became sharper. Two standards emerged; namely the 720p and 1080i/p. The 720p is 1280×720 pixels and the 1080i/p is 1920×1080 pixels. The aspect ratio for HDTV is 16:9 where as it is 4:3 for SDTV. The 16:9 aspect ratio increased the horizontal vista, which enhanced viewing pleasure.
WHY 4K MADE AN IMPACT
While HDTV made a big impact in TV viewing, consumers wanted near cinema experience in their living room. To achieve this more pixels had to be transmitted, which led to the development of 4K. Often, Ultra high Definition TV (UHD TV) and 4K is used synonymously , but there is a slight difference between the two. UHD TV has 3840 horizontal pixels, which is exactly twice that of 1920 pixels of HDTV, and 2160 vertical pixels, which is twice of 1080. The aspect ratio is maintained at 16:9. On the other hand, the aspect ratio in 4K is 17:9 and it has 4096 horizontal and 2160 vertical pixels, which is ideal for digital cinema.
Another redeeming feature of 4K/UHD TV is that it occupies almost 76% of what the human eye can perceive as compared to HDTV, which is restricted to only 36 percent. This makes its colours more vibrant and realistic.
The colour resolution or the bit depth of 4K/UHDTV is also higher than HDTV. Where the latter employs 8 bit resulting in 256 levels of colour, 4K/UHDTV can use 10 to 12 bits of colour depth, resulting in 1024 to 4096 colour layers.
4K/UHDTV can also be transmitted at a much higher frame rate giving extremely smooth slow motion even in very fast moving sports action. The frame rates range from 23.976p to 120p.
EFFECT ON MANUFACTURERS and BROADCASTERS
Due to the increased bandwidth of 4K/UHDTV, the design of the 4K plant also needs special consideration. Presently, the baseband infrastructure is Quad Full HD compliant meaning the signal is routed and distributed through 4x1080P infrastructure. For routers and distributors this is rather straight forward as four parallel channels pass through the four quadrants of the 4K signal. But switchers and other processing equipment pose lot of challenges. Wipes and DVEs in switchers require extra resources thus limiting the overall specification
of the switcher.
4K creates very high quantity of data, which needs to be captured, stored, edited, archived, repurposed and delivered to the consumer. A 3840×2160 pixel data of 50fps streaming at approximately 12Gb/s requires 5,600GB storage per hour. These fast bit rates and huge storage requirement require interfaces that can handle this bandwidth and storage devices that can handle this high read/write speed.
Thankfully due to the advancement of codec technology, bit rates can be brought down to below 5Gb/s. For UHDTV/4K HEVC/H.265 codec is used for delivery that has a bit rate almost half that of H.264 which is used for HDTV. Currently, storage devices like eSATA drives, SSD or RAID arrays or USB 3 and Thunderbolt 2 interfaces make working with 4K rather straight forward.
During the transition period from HD to 4K, 4K capture with HD delivery can have various cost saving opportunities for
broadcasters. A single 4K camera can capture an entire scene and selective HD images can be cut out to give a multicamera effect. Tight close up or zoom is very difficult when shooting fast moving sports action. With digital zoom on a 4K image tight HD images can be generated from a single 4K camera. Similarly, when it comes to archiving and repurposing to multiple screen in different formats, it makes a lot more sense when the original content is captured in 4K.
Since 4K is progressive there is no temporal aberration encountered with de-interlacing. Progressive scanned images can be easily interlaced. Displays are progressive, web and mobile is also progressive. Only scaling is required, no complex conversion is required.
OUTCOME FOR VIEWERS
UHDTV/4K brings an immersive viewing experience to the audience. The image size is big, the pictures are sharper, the colours are vibrant and the best impact of these enhanced programming can be witnessed while watching wildlife, nature or sports programs. It is no wonder, therefore, then that it is gaining a lot of traction amongst viewers.
While the hardware is in place in the form of 4K/UHD TVs, the biggest dilemma amongst Indian consumers face is about availability of content. With so little content offered presently is it justifiable for them to invest in an expensive UHD TV?
Currently, there are few DTH operators providing 4K service for special events. The World Cup cricket in Australia broadcast some of its matches in 4K. Popular streaming sites are also gearing up to provide content in 4K. The Rio Olympics were showcased in 4K, albeit with some time lag in telecast. These are some cinks that need to be ironed out soon if 4K/UHDTV’s acceptance has to go up.
4K/UHDTV brings new opportunities to manufacturers, broadcasters and content owners. As hardware prices come down and more content becomes available to consumers, it will be a win-win situation for all the players in the ecosystem.