Ian Trow, senior director, broadcast solutions, Harmonic Inc. says High Efficiency Video Coding (HEVC) is the satellite industry’s answer to supporting Ultra-HDTV (UHDTV) video delivery over bandwidth-limited networks.
About 20 years ago, digital video compression was considered a novelty, but today it is ubiquitous as consumer demand for high-bandwidth video services like HD video-on-demand (VOD) continues to grow at an ever-increasing rate.
As broadcasters around the world complete the transition from SD to HD and create more VOD content, satellite operators must rely on advancements in video compression to cost-effectively deliver content over bandwidth constrained networks.
A new video compression standard called High Efficiency Video Coding (HEVC) sets a new benchmark in efficiency by aiming to reduce the data rate for high-quality video coding by 50% compared with the current H.264 (MPEG-4 AVC) standard. Utilising HEVC, satellite operators can dramatically increase the amount of HD content they can deliver or support innovative new services, such as 4K Ultra High-Definition (UHDTV), to greatly improve their profitability by offering an enhanced user experience.
One feature that may specifically benefit satellite operators is HEVC’s ability to more efficiently code larger block sizes, especially in regions where there is little change in the picture content
This article will provide an overview of the improvements made by the HEVC standard, as well as applications for the satellite market.
HEVC advancements
HEVC introduces a number of additional tools to exploit spatial and temporal redundancy, including enhanced motion compensated filtering, multiple coding block sizes, increased coding unit block sizes (from 8×8 to 64×64), hierarchical block coding, advanced motion vector prediction, improved context adaptive binary arithmetic coding (CABAC) processing, expanded loop filters (de-blocking, sample adaptive offset, and adaptive loop filter), and optimised intra-frame prediction.
One feature that may specifically benefit satellite operators is HEVC’s ability to more efficiently code larger block sizes, especially in regions where there is little change in the picture content. By coding larger images, HEVC will allow operators to more easily support future 4K and 8K UHDTV services, which offer television viewers a much higher resolution picture quality.
8K UHDTV (4320p) has a resolution of 7680 × 4320 (33.2 megapixels), or 16 times the number of pixels of the existing 1080p HDTV format, thereby enabling satellite operators to deliver a detail level comparable to 15/70mm IMAX to the home television screen.
Additionally, the HEVC standard optimises intra-frame prediction by combining spatial closed- and open-loop predictions to exploit redundancy within the current frame. By exploiting redundancy not only between neighbouring blocks but also within a coding block itself, the new tool — called Combined Intra-Predication — offers more prediction directions than AVC, thereby increasing the efficiencies of video compression.
HEVC also resolves contouring artifacts that are visible in H.264/MPEG-4 AVC when coding flat or smooth image backgrounds.
Via an internal increase in precision (greater bit depth), HEVC can more accurately calculate the coding necessary for complex images, eliminating banding issues. Future HEVC developments may include support for multi-view video coding or stereo 3D video combined with scalable video coding (SVC), allowing a video stream, sequence, or image to be represented in multiple ways and formats so that satellite operators can more efficiently prepare content in different resolutions, frame or bit rates, for viewing on any device, including TVs, smartphones, and tablets.
HEVC: Future and applications
The HEVC standard is currently under joint development by the ISO/IEC Moving Picture Experts Group (MPEG) and ITU-T Video Coding Experts Group (VCEG). A final version is expected in early 2013, with approval to follow shortly thereafter. Once approved, HEVC will be the ideal video compression standard for a wide range of applications, including OTT delivery, digital cinema, broadcast, videoconferencing, mobile streaming, video storage and playback, VOD, fixed point contribution (newsgathering, live events, etc.), and UHDTV.
The HEVC standard is already gaining momentum around the world based on its promise of high-quality video coding at approximately half the data rate of H.264. French media regulator CSA has publicly mandated the use of HEVC for UHDTV starting in 2016, and the first HD OTT global deployments are expected in 2014.
While 4K screens and cameras are now available, they are too cost prohibitive to enable widespread adoption of UHDTV; 4K content is limited beyond cinematic releases; and 4K set-top boxes, switchers, and encoding equipment still need to be developed
HEVC will have a significant impact on next-generation HDTV displays and content capture systems that feature progressive scanned video and display resolutions up to UHDTV; however, its success is dependent on improvements to the broadcast ecosystem. While 4K screens and cameras are now available, they are too cost prohibitive to enable widespread adoption of UHDTV; 4K content is limited beyond cinematic releases; and 4K set-top boxes, switchers, and encoding equipment still need to be developed. Finally, UHDTV lacks industry standardisation in terms of frame rate and resolution, as well as an agreement about an appropriate audio format and a business model.
Once the limitations of UHDTV are addressed, the HEVC standard has the potential to transform video delivery, enabling satellite operators and other content providers to more efficiently deliver higher quality and better resolution video using today’s already bandwidth-limited networks. UHDTV will be a game changer for TV, based on its ability to enable a shift from pan and scan to whole scene coverage of events, providing a truly immersive experience for the home viewer.
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