Realizing the future of true 4K UHDTV- Ericsson
By Matthew Goldman in Future of TV , Video Compression on 21 January, 2014.
The industry is in the midst of a seismic shift to an all-digital and all-HD world. A number of 4K UHDTV landmarks emerged in 2013, including multiple test broadcasts of UHDTV and companies such as Netflix committing to screening in 4K in the near future. Commercial services are touted for 2015 and more and more people are becoming interested in what makes true UHDTV 4K so special.
However, a number of obstacles must be overcome to make this new standard a reality for all. ‘True’ 4K UHDTV imposes a unique set of requirements on the content acquisition, exchange and distribution ecosystems that are already in use by HDTV, which I will discuss below.
Bandwidth crunch problematic for true 4K UHDTV
For direct to the home (consumer) applications, the need for the lowest possible bitrate is of paramount importance. For high quality contribution feeds, however, in addition to the minimum requirements for true 4K UHDTV, the chrominance format 4:2:2 is required to maintain the color fidelity through multiple encode/decode/re-encode signals. The common consumer format (4:2:0) will lose its integrity and degradations, such as color smearing, will become noticeable.
The baseband (uncompressed) video bitrate of True 4K UHDTV equates to approximately 12 gigabits per second (Gbps). In comparison, uncompressed 720p and 1080i HDTV requires 1.5 Gbps, while “full” HDTV (1080p60/50) requires 3 Gbps. There is already, what is known as a “bandwidth crunch” with current HDTV services and so the need for four to eight times the bandwidth over HDTV to deliver uncompressed 4K UHDTV services is problematic. The highest bitrate standardized single-link professional video interface available today is 3Gbps and four of these are needed to be linked together in order to carry a single live uncompressed True 4K UHDTV signal.
While multi-link interfaces operate well, new production facilities being built to support UHDTV would prefer a single link interface for practical operational reasons. While SMPTE (The Society of Motion Picture and Television Engineers) does specify single and multi-link 10 Gbps interfaces, a single link still doesn’t support True 4K UHDTV. With higher bandwidth requirements on the horizon, many consider using multiple links of 3G-SDI (serial digital interface) to be a non-starter. There are higher bandwidth interfaces being developed within the SMPTE, but none are ready to be used as of yet.
For consumer video interfaces, the near ubiquitous HDMI only recently released a version (2.0) that will support True 4K UHDTV. TVs, DVRs, etc. will begin to come to market with the updated HDMI interface starting in 2014. Some existing products (using HDMI 1.3 or 1.4) may be upgradeable to HDMI 2.0. This is manufacturer dependent.
Advances in Satellite Transmission
One way to reduce the burden of the higher bandwidth required for UHDTV is to improve the content delivery channel. For satellite, there is a new modulation technology.
The DVB-S2 Extensions include enhancements to the worldwide used DVB-S2 standard, with the expected performance to be efficiency gains in the range of 20 to 35 percent. Better efficiency, higher bitrates, and improved service robustness are achieved by:
Increased granularity in modulation and coding (MODCODs)
Tighter roll offs
Linear and non-linear MODCODs
Higher modulation schemes, up to 64-level amplitude phase shift keying (64APSK)
Advanced filtering for improved carrier spacing
Wideband support up to 72 Mbaud
High Quality Real-Time Video over IP Networks
To aid in the delivery of high quality real-time video over IP networks there is a new family of SMPTE standards, ST 2022-x. Defining Forward Error Correction (FEC) codes to improve the underlying quality of service of the network, these standards also specify the transport format for various video compression algorithms encapsulated in the near ubiquitous MPEG-2 Transport Stream format, both constant and variable bitrate. They also define the carriage of uncompressed video streams (referred to as High Bit Rate Media Transport or BBRMT), from SD (270 Mbps) to 1080p HD (3 Gbps). In all cases, RTP/UDP/IP protocol layers are required as they provide the standard header for the data essence and FEC streams.
These new SMPTE standards aid the delivery of both compressed and uncompressed video. For the contribution and distribution of live 4K UHDTV content by on-site facilities, the highest practical picture quality is needed for mastering, archiving and post production needs. Last year, High Efficiency Video Encoding (HEVC) became an international standard for video compression and it is integral to delivering true 4K UHDTV to the home. In the near future, HEVC will be able to deliver 4K UHDTV in the same bandwidth that is used today for HDTV.
Ericsson to enable partners to begin running 4K UHDTV services in the near future
Ericsson is the only vendor in today’s market place offering satellite service providers a complete solution to enable the acquisition, exchange and distribution of True UHDTV. Intelsat and MEASAT are on the cusp of offering commercial services, while Korea Telecom Skylife is also in the process of trailing our solution. Not to mention high profile partners such as Sky Sports and Sky Italia who helped us run earlier trials last year. These services/trials are well past the experimental stage and operators are beginning to lay the groundwork towards launching commercial services in the not too distant future.
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