Is HEVC ready for prime time?
Live end-to-end delivery chain demonstration tells all
Every once in a while, innovation in compression techniques becomes incredibly useful, and one of those times appears to be imminent.
The objectives of broadcasters and operators remain the same over time: reduce content delivery costs, reach larger audiences, enhance TV offerings with additional channels and improve the TV viewing experience.
Meanwhile, viewers’ expectations have increased with regards to video quality, while the TV market is delivering new, higher-quality media formats such as UHD (Ultra High Definition).
In addition, with the increasing penetration of smartphones and tablets on the market, we are witnessing the emancipation of “TV Everywhere” usage and the rise of video quality expectations for TV on the go.
Unfortunately, limitations on both managed and unmanaged networks, combined with current digital compression levels, do not provide the best video quality for all screen sizes. These constraints prevent up to 80 percent of IPTV potential viewers from watching content in true HD, let alone Ultra HD.
Several solutions exist to address network congestion issues and bandwidth constraints. One example is the upgrade from DVB-T/S to the more efficient DVB-T2/S2 standards. But compression tool improvements should provide more significant gains faster than expected.
Ten years after the transition from MPEG-2 to H.264/MPEG-4 AVC (with up to 50 percent bandwidth savings), history is about to repeat itself with the arrival of HEVC (High Efficiency Video Coding), also known as H.265, the successor of H.264/MPEG AVC.
The standard was approved in January, and just a few months later a live end-toend HEVC content delivery chain was demonstrated for the French Tennis Open event in early June 2013, providing tangible proof that HEVC is on a path toward commercial deployment.
Building a delivery chain
In this article, we will take a closer look at how this technological demonstration came to life and answer questions about the demonstration, including: What were the required elements to build a live end-to-end HEVC delivery chain? What HEVC milestones were reached during the French Tennis Open 2013 demonstration? What challenges and complexity did this sporting event bring and how were they met? What are the benefits provided by HEVC encoding? Is HEVC the right compression technology to provide “HDTV everywhere,”
particularly on small screens? What’s next?
Bringing the chain to life
The recent demonstration, led by tierone French triple play operator Orange, France Televisions, and the 4Ever Consortium, delivered a higher level of compression efficiency, demonstrating exceptional quality production utilizing HEVC during the French Tennis Open 2013 tournament.
Audiences were presented with superior images, on both unmanaged and managed networks, for different applications including over-the-top (OTT), IPTV and digital terrestrial broadcasting.
The entire end-to-end live HEVC chain included encoders, transport and system layers, decoders, and players on different devices. The trial showed that all elements of the HEVC chain were functional and interoperable from start to finish, including these major steps:
• De-interlacing and pre-processing of the content;
• HEVC compression;
• Content stream encapsulation;
• Broadcasting on unmanaged and managed networks targeting different applications;
• Decoding and playing HEVC content on TVs, PCs and tablets.
• “HD Everywhere” and “Premium” HD content for small screens The initial objective of the project was to address both TV and OTT devices with HD content in the 720p format.
Therefore, the contribution feed delivered by France Televisions’ production truck in HD-SDI 1080i25 was de-interlaced, resized and delivered in progressive mode on a dedicated high bitrate contribution link.
Sports content, with fast and large camera motions, may result in an unsatisfying viewing experience on traditional mobile and OTT devices, as these devices generally handle only content at 25- or 30 frames per second (fps). On high motion content, a low frame rate may result in image stuttering.
Moreover, even if OTT was initially targeting low capacity devices and limited network bandwidth, devices with increased decoding capacity (typically those with multicore architectures) are about to arrive on the market with the ability to manage higher spatial resolution, frame rate and bitrate. Therefore, in order to enhance user experience, the 4Ever consortium decided to address all screens, including mobile and OTT devices with a unique feed in 720p50.
This unique feed would address both managed and unmanaged networks, enabling devices such as tablets, PC and TVs, to play “premium” HD live content at 720p50 on all screens in the delivery chain. The result - “HD Everywhere” is about to become a reality.
50% bandwidth gain
With the first objective of preparing a feed at 50 frames per second for all screens completed, the 4Ever team now needed to increase the frame rate for the OTT devices, which would lead to an increase in the required bandwidth.
A rule of thumb is that doubling the frame rate requires additional bandwidth in nearly similar proportion. The second objective was to validate that HEVC’s efficiency could make up for the additional bandwidth requirement.
During the compression process, Ateme’s Titan Live transcoder demonstrated that up to 50 percent of the bandwidth could be saved. The 720p50 feed, targeted to address OTT devices, was compressed at 3.5 Mbps for mobile devices and tablets and 4 Mbps to address big screens with IPTV and DVB-T2 applications.
For comparative purposes, compressing the same HD content in H.264/ MPEG-4 AVC would have required 40 percent to 50 percent additional bandwidth, i.e., 7 Mbps at equivalent subjective and objective video quality (PSNR-based). For mobile and tablets, HEVC’s compression benefits made up for the need for additional bandwidth when increasing frame rates compared to 720p25, while improving the overall video quality.
As trials progress and opportunities to utilize the new codec present themselves, HEVC benefits are expected to continue to increase.
Quality vs. cost reduction
HEVC benefits operators and broadcasters by providing the flexibility to decide where to put the cursor between video quality improvement offers on the one hand and costs reduction (bandwidth, content delivery networks) on the other.
The question is, will they choose to improve the viewing experience of their current customer base, or increase their customer base while providing the same viewing experience? Is it a matter of strategy and service offering, or positioning? Operators and broadcasters will appreciate the reduction of bandwidth requirements, and should see their content delivery network (CDN) costs significantly reduced. Content storage costs will also drastically decrease; alternatively videoon- demand (VOD) catalogs for end users could have the potential to double.
For instance, if video consumption is still low in Europe, compared to North America usage, expanding VOD catalogs and increasing video quality may be a good opportunity to trigger consumption.
Also, the bandwidth bottleneck currently generated by pick-usage of VOD, catch-up and start-over services will be decongested.
Once bandwidth congestion is cleared up, operators, broadcasters and TV channel providers are able to foster relationships that address additional users and also allow them to increase video catalog offerings. Market trends will demonstrate soon that operators and content providers will use “saved space” to add new video and new channels.
Democratization of HD
In what cases can HEVC improve end user satisfaction and the viewing-quality experience? It is observed that only 20 percent of TV over DSL users have access to true HD, while 80 percent still remain non-eligible.
HEVC will reverse this ratio and by bringing “HD Everywhere”, HEVC will democratize HD content resulting in market expectations to provide HD content to up to 80 percent of overall TV over DSL users.
The OTT market also calls for broadcast quality. The primary beneficiaries of improved quality through HEVC, will be mobile users; as mobiles are, among all OTT devices, the ones that experience low playback capacities and unreliable connection speeds (OTT devices can use broadband or high-bitrate network.) Mobile users will watch sporting events on small screens at a very satisfying video quality. Furthermore, of all markets, OTT shall be the first market to see a finalized end-to-end HEVC chain.
HEVC will also be an enabler of the higher resolution market like UHD. As an example, it has been demonstrated that the broadcast quality of UHD could be offered by HEVC at around 13 Mbps, very close to of the data rate of MPEG-2 HDTV broadcasts today.
With the entire HEVC delivery chain ready, UHD offers will likely take off sooner rather than later as UHD screens are already available at affordable market prices.
HEVC compression benefits arrived only a few months after the definition of the standard in January. As the standard was being defined, system and transport layers were prepared to accommodate it. The French Tennis Open demonstration validated that the preparation was a success and that the necessary network infrastructures and delivery systems were ready for prime time. Finally, the workflow in which the system needed to operate was seamless.
TS, MP4 and MPEG-DASH formats have now been modified and enable the interoperability of HEVC within current network delivery systems. To address the different applications, and in preparation of the demonstration at the French Tennis Open, content was packaged in MPEG-DASH for the OTT devices and provided in MPEG-2 TS for IPTV and DVB-T2 for big screens.
This “world premiere” was a testament that live HEVC content can be played seamlessly today for an OTT, IPTV or DVB-T2 application and that network infrastructures and delivery systems are in place.
Both marketable products, and open source decoders and players, have been recently implemented. The GPAC (open source) and VisualOn (commercial) implementations are readily available today.
The recent end-to-end demonstration accelerated the development of interoperability between encoders and decoders, making the playback of HEVC content from all types of screens, (tablets, monitors, TVs) a reality.
Four different HEVC players and decoders were used during the French Tennis Open trial including: Sony mobile and VisualOn, while Orange Labs players/ decoders were used for the OTT application; Ateme’s Kyrion DR8400decoder enabled the IPTV HEVC content to play on an SDI monitor and an Open HEVC decoder and GPAC player running on PC were used to feed HDTVs for both IPTV and DVT-T2 applications.
It has now been demonstrated that a live end-to-end HEVC delivery chain was successful. OTT operators, broadcasters, and channel provider’s expectations will be fulfilled in the very near future:
• Increase HD eligibility and “HD Everywhere”
• Bandwidth and CDNs cost reduction
• Increase in market coverage, larger audience
• Potentially enhanced service offerings with more channels and premium services
• Increased end user satisfaction, decreased churn rate. ■