Abstract


Ultra high definition television (UHDTV) combines 4K resolution (3840x2160), high dynamic range (HDR), high frame rate (HFR), wide colour gamut (WCG) and also delivers recommendation for the immersive 3D audio features to provide viewers with a stronger sense of “being there” [1] experience while watching television at home. With the increasing number of large screen Display from Television vendors and some native 4K content from the providers like Netflix and Amazon Prime Instant Video, Ultra High Definition is gaining popularity lately though it requires painful data rate for transmission (15Mbps for streaming 4K content in Netflix [2]). There is adequate lack of technical standardization such as format and systems 4K broadcast might adopt making it challenge for managing and carrying out 4k legacy for the broadcast industry. This paper will provide a thorough insight of the current status of UHD standards with a view to obtaining a clearer understanding of the challenges and opportunities ahead.

Introduction


Video technology had evolved from black and white to color, analog to digital, SD (Standard Definition) to HD (High Definition) and from heavy and bulky cathode ray tubes to compact and much lighter plasma, LCD or LED flat screens. Not forgetting the initiation of trans-national digital TV via satellite and the related explosion in the number of channels carried. However to provide a satisfying high quality video with full range of human visual capabilities for realistic experience requires further advances in video technology i.e. ultra-high resolution video. UHD has already been standardized as a video format with spatial resolution 4K (3840x2160) and 8K (7680x4320) corresponding to 4 and 16 times the resolution of a progressive HDTV 1920x1080 pixel picture in an ITU (International Telecommunication Union) recommendation (ITU-RBT.1769) [3]. This paper will use UHDTV for referring 4K UHDTV. The basic technologies such as high quality camera, high resolution display, large storage and wideband transmission infrastructure are essential to realize 4K video services. 4K Ultra HD is perfect resolution for full immersion and compelling experience so that the viewer can have a much wider viewing angle than with the normal HDTV and the higher resolution allows the viewer to enjoy stunning images at much closer distances to the screen. UHDTV technology is not only interesting for television broadcasting and entertainment, is also attractive in the field of scientific imaging as: astrophysics, medical imaging, art restoration, and surveillance systems. In this paper, we will discuss characteristics, functionalities and workings of 4k UHDTV. Section III describes the architecture with details of internal embodiment and its operation. The market and Business models of UHDTV is explained in section IV followed by social and legal impacts of it in section V. The future trends and conclusion is followed in section VI [4].

Background and History


UHDTV also known as Super Hi-Vision (SHV), is a video digital format proposed by Nippon Hs Kykai (NHK) or Japan Broadcasting Corporation, in a progressive scanning mode at 60 fps [4]. This resolution format is 4 times bigger than a standard high definition television (HDTV) system with 4000 scanning lines which deliver ultra-clear and realistic images. Lines are not visually noticeable even when relatively close to the screen, reflecting the high resolution of the system and conveying a stronger sense of reality because of the wider viewing angle [5].

Year Event
2001 IBM T220, IBM introduced the first UHDTV monitor
2003 NHK shows the first UHDTV public demonstration (Japan)
2005 NHK achieves the first UHDTV large link transmission, with 260 km (Japan)
2006 NHK completes the first UHDTV live broadcasting (Tokio-Osaka)
2006 BBC announces UHDTV broadcasting during London 2012 Olympic Games (UK)
2007 NHK develops a 33-million-pixel CMOS image sensor (Japan)
2008 Aptina Imaging develops new high performance CMOS commercial sensor for UHDTV (USA)
2008 NHK, BBC et al. achieve the first UHDTV international live transmission (London-Amsterdam)
2008 NHK, BBC & RAI perform the first UHDTV satellite broadcasting (Turin-London)
2009 NHK conducts the first UHDTV multi-program live transmission, with 3 channels (Japan)
2009 JVC develops a Full-Coverage, 8K-Resolution Projector (Japan)
2010 NHK announces trials of UHDTV public broadcasting in ten years (Japan)
2010 NHK presents a UHDTV 58” Plasma Display, with 0.33 Pixel Pitch (Japan)
2011 Release of first direct-view Super Hi-Vision-compatible display at 10 bits per pixel (SHARP with NHK)
2011 UHDTV allowed frame rates of 24,25,50 ,60 and 120 fps (ITU-R)
2012 NHK with Panasonic announced 145” display
2012 UHDTV was officially approved as standard by ITU
2013 NHK announced that Super Hi-Vision satellite broadcasts could begin in Japan in 2016
2013 Eutelsat announced the first dedicated 4K Ultra HD channel
2013 Broadcom announced the BCM7445 , Ultra HD decoding chip capable of decoding HEVC
2014 European Southern Observatory became the first scientific organization to deliver Ultra HD footage at regular intervals
2014 France announced DVB-T2 tests in Paris for Ultra HD HEVC broadcast
2015 Indian satellite pay TV provider Tata Sky launched UHD service and UHD Set Top Box
2016 UHD Alliance announces its UHD premium specification

Table 1 : the most important UHDTV events up to now are abridged [18]

Technology Specification


While 4k UHD provides the pixel density for an immersive, big-screen TV viewing experience, following attributes helps to deliver realism on video displays of all sizes that is far beyond what has been possible today.

1. High Dynamic Range


Today’s displays presents only a small fraction of luminance range we can perceive, but HDR presents a new paradigm to displays with a greater luminance range offering greater potential to increase realism but it will require more bits to avoid artifacts-at least 10 bit/sample. To reflect better human contrast sensitivity, new electro-optic transfer functions (EOTF) and Opto-electric transfer functions (OETF) is desirable, which are complex. An EOTF specifies the non-linear mapping of illumination at the camera to digital code values. An OETF specifies the inverse non-linear mapping of digital code values to display luminance [6]. Today commercial introduction of 4K UHD sets comes with HDR combination with various iterations of LED LCD display technology, therefore greatly enhancing the viewing experience of TV. HDR cameras can capture much wider dynamic range with higher light output and reduced light leakage to be transmitted to the Display.

2. Higher Frame Rate


In addition to HDR, 4K UHD also requires higher frame rates than 25i or 30i (meaning 25fps or 30fps interlaced, equivalent to 60 or 60 fields/s) currently used in HDTV. For 4K UHDTV the maximum frame rate is specified as 60fps, that is 530Mpixels/s [1] to suffice the larger screens used for 4KTV to condense motion artifacts. HFR is related to delivering the equivalent resolution of slow-moving images on fast-moving images. Today there are HFR cameras to shoot wildlife documentaries or sports to show sharper pictures on fast moving images. Like in spatial resolution it is dependent on viewing distance to have enhanced viewing experience.

3. Viewing angles and distance


The viewing angle of a display represents how far to the left or right, and how far down or up the content on the display can be observed without loss of image integrity [7]. Human eyes has total horizontal field vision of 180 degrees but it is majorly perceived and remembered in central field of vision, 90 degrees. Larger 4K UHD display sets enable 60 degrees of the horizontal field of visions at the correct viewing distance dominating the central field of vision to provide more realistic, natural and immersive viewing experience compared to 30 degrees in conventional HD in which perception is largely outside the TV screen.

Average TV viewing distance in the UK is 2.63m and at that viewing distance it would require a 148” display to fully enjoy 4K UHD resolution [2]. Table below shows the resolution of various popular TV formats and screen size that would needed for optimal viewing at a distance of 2.63m.

Format Horizontal Resolution Screen
SD 1280 25
720p HD 1280 45
HD 1920 68
UHD 2840 148

4. Bit depth


Bit depth refers to the amount of colors a display can produce. The most common UHD display has bit depths of eight- and ten-bits per RGB channel. For instance, an eight-bit RGB display can show 256 shades of red, 256 shades of green, and 256 shades of blue per pixel. 10-bit RGB displays produce 1,024 shades of red, 1,024 shades of green, and 1,024 shades of blue per pixel. The difference in bit depths is most noticeable during color-intensive applications such as photo editing, animation, and designing. 4K UHDTV with ten-bit can produce more than one billion colors, essentially eliminating banding, artifacts, and contouring. Most viewers will have experienced unpleasant “banding” (or “contouring”) effects on screen, however, the definition of UHDTV today still allows the use of 8-bit sampling in HDTV [2].

5. Wider Colour Gamut


Current UHDTV can also see a wider color gamut (Rec. ITU-R BT.2020) than the currently used color space in HDTV (Rec. ITU-R BT.709). It produces bright saturated colors like in HDR which benefits a very wide range of contents delivering great viewing experience. 8 bit sample depth is not sufficient for this attribute to enhance its capabilities. The following are the three methods to extend the gamut:

1. Allowing out-of-range values of color components

2. Adding more primaries (RGB)

3. Changing the locations of the primaries [8]

6. Metadata


Metadata is as important as any other technical attributes because it is the property for content search in archives or controlling the production workflow. The availability of Metadata enables full user interactivity with the system, dynamic object rendering and adaptation of audio element to the loudspeaker setup making it possible for the users to interact with the content and to control audio rendering independent of the playback scenario [20].

With UHD it is possible to add customized additional information either through a second screen or through an overlay, so now watching video is no longer passive. This enables a rich set of metadata to compliment entertainment. Searching and selecting programs has become more than just textual grid today. It’s more contextual with social media connections, intelligent recommendations and feeds [4].

System Architecture


1. 4K System


In UHDTV to detect and conceal corrupted video, the BcP (Block-concealed Processor) extracts the side information from video decoder. The new BsP (Bandwidth-suppressed Processor) classifies the image content and corrects the algorithm parameters for optimizing the compression performance. To realize 4K and 60fps, that is 530Mpixels/s, the architecture operates blocks of pixel row decoding in different cores. It decreases processing cycles and lowers frequency by 65 %. The 10 bit compact scheme efficiently stores 10 bit pixel into 8-bit pixel in DRAM space. To meet the multi-standard video format requirements, it integrates 14 standards into a single chip including MPEG-2/4, WMV-7/8/9, VC1, RM 8/9/10, AVS, VP 6/8, H.264 and HEVC/H.265. It improves the area efficiency and reduces the integration cost by 28%.

Fig: Block diagram of 4K TV [21]

2. H.265/HEVC-Video Codec


The High Efficiency Video Coding standard (HEVC) is the current state-of-art of MPEG-H standard for video coding mostly used for UHDTV. UHDTV signal is associated with large volume of data which is eight times more than HDTV, so it requires an efficient video compression technology. Therefore, ITU Video Coding Experts Group (VCEG) and ISO Moving Picture Experts Group (MPEG) joined efforts in a partnership called Joint Collaborative Team on Video Coding (JCT-VC) to develop the High Efficiency Video Coding (HEVC) standard [9]. HEVC will outperform its predecessor Advanced Video Coding (AVC) with 50% or higher reduction in bitrate for same quality, provides Main, Main 10 and Main Still Picture profiles for a wide range of applications. The improved compression efficiency comes at the expense of 4 times more complexity [11], especially at encoder side. Three novel HEVC optimization techniques to achieve higher compression efficiency at the cost of higher computational complexity over H.264 are Multiple Early Termination (MET) for motion estimation, Adaptive Reference Frame Selection (ARFS) and Adaptive Partition Selection (APS) for motion compensation [10]. It works by comparing different parts of frame of video to find the redundancy within a single frame as well as subsequent frames. These redundant areas are then replaced with short description instead of original pixels. HEVC also includes expansion of pattern in pattern comparison and difference-coding areas up to 64x64, upgraded variable block-size segmentation, improved intra prediction within the same picture, precise motion vector prediction and merging, higher motion compensation filtering and additional filtering step called sample-adaptive offset filtering (to reduce artifacts at the block edges) [13].

Fig : Block diagram of H.265/HEVC encoder

The video input is transformed and quantized; the quantized data is coded by entropy coding producing stream output. To decode picture, the quantized data is processed by inverse quantization, inverse transform and in-loop filter. For spatial and temporal redundancy, the decoded picture utilizes intra- and inter-prediction. To improve coding efficiencies, adaptive block size, many prediction modes, sample adaptive offset and in-loop filtering is adopted in this technology [11].

4. AC-4 /MPEG-H : Audio codec


The mostly used audio codec in UHDTV today, is advanced audio codec AC-4 which is based on MPEG-H Unified Speech and Audio Coding (USAC). TV audio system, based on the MPEG-H Audio standard, is being developed jointly by Fraunhofer, Qualcomm and Technicolor, who formed the MPEG-H Audio Alliance [14]. It serves as basic audio coding formats for video codec HEVC/H.265. AC4 is backward compatible with the systems and the practices currently used in AC-3 or HE-ACC with improved compression efficiency for broadcast by about 50% reduction in bitrate. The standard feature supports dialogue enhancement, intelligent loudness and advanced dynamic range control as well as multiple languages and descriptive services. It also gives more personalized (adaptation to viewers preferences), interactive (allowing end-users to customize the different levels of audio elements), immersive (compelling sound experience coming from all directions produced in different formats) and rich 3D (to create more realistic audio experience to enhance today’s surround sound) audio experience for the viewers at home [16].

5.1 surround sound offers a very good listening experience compared to stereo, but it lacks the height element of convince realism to viewer. While the 7.1 speaker configuration offers improved spatial accuracy behind the viewer and the sound from above that was missing in 5.1. Each mono dialogue element can be encoded in MPEG-H Audio with a bitrate typically between 20 and 40 kbit/s. Thus, the immersive sound system is termed 3D [17]. NHK broadcaster in japan proposed an audio system using 22.2 channels which provides excellent realism at a bit rate of 1200 kb/s transmitted in transparent network (all the network elements are optical) [15].

Fig: Top level block diagram of AC4 audio decoder

The figure above shows the top level diagram of MPEG-H audio decoder. The main components are a so-called USAC-3D core decoder, a set of renderers for the different signal classes and mixer to convert compressed data representation. The different signal classes (waveforms for channel signals and object signals or HOA coefficient signals) are then fed to their associated renderers that map those signals to loudspeaker feeds for the particular reproduction setup that is available at the receiver side. As soon as all rendered signals are available in the reproduction format, they are combined in a mixing stage to form a loudspeaker feed. In case a binaural representation is requested, the reproduction setup is determined by the Binaural Room Impulse Response database of a binaural renderer and the signal is converted to a virtual 3D scene for headphone reproduction. It is possible to transmit any combination of the different signal types in a single MPEG-H stream with objects [14].

Content and Services


There is scarcity of native 4K resolution content today but its accelerating as well with the creation of new shows, movies and other Live Broadcasts. The best sources of 4K content is from streaming media on internet like Netflix, new 4K UHD Blu-ray disc movies expanding quickly and via Video On Demand from the services like DirecTV. To access to the streaming source like Netflix and Amazon Prime, 4K TV set needs to be compatible with HEVC (H.265) video compression encoding, should be HDCP 2.2 compliant and ideally should also be compatible with Google’s VP9 video compression. Finally, it requires an internet connection with robust speed of at least 20 to 25 Mbps. Following are one of few popular content providers:

1. Netflix


To watch 4K on Netflix, users has to be subscribed to its highest-price plan and costs $11.99 /month. The movie selection is very feeble but everything is free to subscribers.

2. Amazon Instant Video


To get the most out of Amazon’s 4K selection, users requires a Prime subscription although few titles are available to non-Prime members also. The Prime subscription is priced $99/year (includes many other benefits) or can buy some titles for $19.99 and up. Prime users get the original series and few movies without having to pay but newest films are pay-only even for the Prime members.

3. Ultraflix


The UltraFlix app is available on Samsung and Vizio TVs (with others such as Sony coming soon) offering an array of 48 hours of rentals but there is no option to buy or subscribe to the service yet, although both are coming soon. Some clips and videos are free and others are up to $9.99 to rent

4. Youtube


YouTube has lot of 4K mini-documentaries, demos and travelogues. Many UHDTV Display from 2015 and up support YouTube’s VP9 hardware decoding where you can watch 4k content directly from Display without having to connect a PC to TV.

5. DirecTV


DirecTV subscription and Genie HD DVR costs $3.99 to $15.99 for 48 hour rental. For DirecTV customers with a Genie HD DVR and a Samsung TV, a selection of 20 movies can be downloaded to the DVR on a rental basis. DirecTV's 4K satellite, launched in 2015, should add more content options soon.

6. Comcast


Billed as a "UHD Sampler," the Comcast app for Samsung TVs offers three shows from Comcast subsidiary NBC Universal. At least they're free. Comcast promises to "add on-demand programming across multiple networks and studios in the future. It will also launch a 4K set-top box, model X1, later this year.

Conclusion


The transition from SD to HD took almost 10 years, so it is important to be realistic about the 4K adoption timeline. Although the popularity of 4K UHDTV adoption will be driven by content availability, the entire industry is involved in the development of the ecosystem. . 4KTV and all the aforementioned technologies and attributes have potential for new opportunities for profitable business in TV industry if there is balancing between costs and perceived benefits to consumers.

ACKNOWLEDGEMENT


The authors would like to thank Professor Fernando Manuel Bernardo Perreira, for his expertise guidance and suggestions throughout the project.

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