The State of MPEG-DASH Deployment
MPEG-DASH is slowly but surely becoming the main competitor to HLS, driven by adoption by major players and intrinsic strengths. Here's who's using it now, who's going to be soon, and what challenges still need to be addressed.
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Last year at the European Broadasting Union’s BroadThinking conference, the DASH Industry Forum (DASH-IF) conducted a survey of 13 major European broadcasters on MPEG-DASH adoption. At the time, about three-quarters of them projected to have DASH deployed by end of first half of 2014. Primary sources of concern for the broadcasters were the availability of DASH enabled clients and packaging tools. One year later, we haven’t seen many broadcasters deploying DASH in production, but the traction seems to have shifted to over-the-top (OTT) content distributors and operators.
So, who are the actors already in production or close to production with DASH? What are the remaining roadblocks for its adoption? How will DASH be positioned against existing Adaptive Bitrate technologies in the coming months? What is the exact status of the DASH standard and its most promising evolutions? What are the upcoming initiatives aiming at fostering DASH adoption? Let’s get a handle on where DASH is today, and where it’s headed.
DASH and OTT Services
“What's most important to us is the media file format,” says Mark Watson, director of streaming standards at Netflix. “Our media files are ISO/IEC 14496-12 MPEG-DASH compliant files—that's our strategic format. And actually those same media files are used by pretty much the vast majority of devices we support right now: TVs, set-top boxes, Blu-ray players. This format is an overall advantage that applies to all devices we might want to get onto: There's a much greater chance that the people we're working with for those devices already implemented the media format, that they understand adaptive streaming, and that the APIs we need on these platform are already present. One extremely important point for us is the Common Encryption (CENC), because we don't want to have our media files tied to a specific DRM, and it maximizes your cache efficiency to have only one version of the video library. Today there are three DRMs compatible with Common Encryption, and we are definitely using two of them with CENC.”
Netflix doesn’t, however, use the DASH standardized manifest format (MPD).
Hulu also began deploying DASH early for Chromecast devices and now uses it for all new deployments, strictly based on the ISO base media file format (BMFF) on-demand profile with demuxed essences and using CENC plus PlayReady and Widevine DRMs.
“Implementing DASH has really simplified our workflow at all levels, and we absolutely don't regret it. For VOD, MPEG-DASH is really the equivalent gold standard of MPEG-TS for the broadcast,” says Baptiste Coudurier, principal software development lead at Hulu.
When it comes to implementation effort, Coudurier also has no complaints: “DASH player development on Chromecast was relatively straightforward; we coded it from scratch, based on MSE and EME. We needed this level of control because of our heavy requirements with ad insertion. We had more problems with CDN getting CORS (cross-origin resource sharing) enabled for all players.” The results of this implementation for Chromecast devices were critical for Hulu, as its reference streaming format shifted from Smooth Streaming to DASH.
“All our new files are 100% DASH compliant; the only difference with Smooth Streaming is the manifest,” Coudurier says. “We already moved the legacy platforms to this new video format, and we now work with vendors to move to a 100% DASH solution by adding support for the new manifest format.”
YouTube is taking a somewhat more complex approach, using a mix of ISO BMFF H.264 and WebM VP9-based DASH profiles depending on the players they are targeting, also with demuxed essences.
“Our motivations to implement DASH implementation were to improve playback, enable interoperability, and reduce the total number of formats. As DASH profiles, we use ISO BMFF on demand and live, as well as WebM on demand. In terms of codecs, we are using VP8, VP9, and H.264,” explains Richard Leider, tech lead manager of YouTube Player Infrastructure.
For premium content, YouTube is also using Common Encryption with multiple DRMs. “Transactional content uses CENC. We use CENC VP8, and the Common Encrypted VP9 files are just coming down the pipe. We use Widevine or PlayReady when they are available on the device,” Leider says.
DASH fits in well with YouTube’s objectives. “YouTube's goal is always to give users the best possible video playback experience wherever they want to watch videos,” says Leider. “And so the flexibility the DASH specification gives us with profiles allows us to make the tradeoffs as performance and user experience dictate. Today we are in the process of rolling out DASH-compatible formats for all of YouTube videos. It's 98% complete right now.”
So is DASH the end of the line for YouTube? “We're always experimenting, but there is nothing experimental about our DASH deployment. YouTube playback uses DASH on TVs, game consoles, set-top boxes, Chromecast, desktop browsers, mobile web, mobile handsets,” Leider says. “Our priorities are quality, interoperability, and efficiency. DASH allows us to meet these equally.” YouTube and Google haven’t, however, made any moves to standardize its WebM approach.
DASH is also used by at least one other large media company as an “under the hood“ technology to power its VOD service and cover its upcoming devices. Given this picture, there is no doubt that DASH has already conquered the VOD market segment, driven by big actors who have the budgets necessary to finance R&D and early implementations. They will not go back to older adaptive bitrate (ABR) technologies, as the benefits DASH offers in terms of workflow simplification and new platforms reach are quite significant for them.
DASH and Broadcast
Outside this VOD elite squadron, where does actually DASH extend its reach? We’ve been waiting for the Hybrid Broadcast Broadband TV (HbbTV) 1.5 TV sets for a long time, and they are finally coming to the consumer market. In the newest HbbTV specifications, DASH is the only accepted format when it comes to DRM-protected content, and deployments are starting to surface.
Gilles Boccon-Gibod, Intertrust’s senior vice president of technology and chief architect, provides some examples: “We have the most deployments in Europe,” he says. “Last November, we did our first commercial DASH deployment in France for the myTF1 VOD service on Sony 2013 TVs. We are adding more TVs if they are TNT2 compatible (HbbTV 1.5 + DRM choice), but we need to test other TVs before whitelisting them as we don't want the users to debug for us, as we have seen in our lab small difference between the DASH implementations. In the same Marlin DRM TV category, Philips TVs are compatible and will be activated soon. For PlayReady TVs, we will have models coming from Samsung, LG, and Panasonic”.
HbbTV projects are also getting off the ground in many countries in Europe, according to Dirk Griffioen, CEO of Unified Streaming. “We see a lot of broadcasters wanting to experiment with DASH, like the Norwegian broadcaster NRK doing a HbbTV POC with us, or the broadcasters from the TVRing European project with their HbbTV testbed,” he says. “As regards deployment, we have a project in southeastern Europe where broadcasters from several countries are grouped to achieve OTT delivery to set top boxes through DASH.”
In Spain, Albertis Telecom is waiting for compatible TV sets, according to Thierry Fautier, Harmonic’s vice president of solutions and strategy. The company is working with Nagra on an HbbTV 1.5 service, but compatible TV sets have been delayed by more than 18 months.
“It has been a chicken & egg problem for a long time, and it’s just starting to unlock,” Fautier says. As TVs are finally coming to the market, all the efforts deployed shall now be rewarded.
DASH is also gaining traction in other, non-HbbTV European countries. “Since December in Italy, the new Mediaset Infinity service is using DASH with Marlin DRM to power VOD delivery on ADB set top boxes and connected TVs (LG, Samsung, Sony, Philips, and others) supporting the Tivùon! technology developed by Tivù, the Italian technical consortium from Rai, RTI, and Telecom Italia Media,” says Boccon-Gibod. “Adding TNT2 and Tivù, we shall see 10 services deployed by the end of this year on our side. Our clients who started using DASH on devices are also using it when it comes to deployment on mobile.” In the UK, discussions are also engaged to use DASH as the reference format for YouView’s catchup contents and, in Australia, Freeview is deploying a HbbTV 1.5 service. These could also be major boosters for the DASH technology.
LTE Broadcast and Pay TV
The other big adoption driver for DASH is currently the LTE Broadcast market, which is booming as the mobile operators finally have the opportunity to exit the unicast bottleneck and switch to a multicast delivery mode that will multiply their per-transmitter capacity. The trick here is to let the device intelligently switch between two associated DASH manifests depending on the network/provisioning circumstances: a single bitrate DASH version for the broadcast, and a multi-bitrate version for the delivery through unicast, with the video fragments being mutualized between the two delivery channels.
Claude Seyrat, Expway’s chief marketing officer, explains the LTE Broadcast advantage. “At some point, when we detect several people watching the same stream on the same cell at the same time (usage density), the broadcast provisioning of the unicast stream is done on the fly, and when devices consuming the unicast stream detect the broadcast stream with the same channel ID, they switch transparently to the broadcast,” he says. “As regards the broadcast version of the streams, we don't use adaptive features of DASH but MPDs and ISO BMFF packaging, as the bandwidth is secured like in any managed network context.”
When asked if there was another reason than the 3GPP recommendation to use DASH, Seyrat confirms: “We could have chosen RTP/RTSP, but it's impossible to switch from unicast to broadcast in a clean way. DASH is just perfect for our use case.”
According to Seyrat, Apple is what’s slowing LTE broadcast expansion. “We have no problems implementing on Windows Phone and Android, and if we had access to modem stack of iOS we could implement our client also,” he says. When asked if it was considering changing the current iOS SDK policy to provide such an access to low-level network features, Apple had no comment.
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