MPEG DASH: The File Format of the Future?
Posted on November 9, 2011
"If HLS were perfect, DASH would not exist," said Thierry Fautier, Harmonic's senior director of telco solutions, referring to Apple's proprietary HTTP Live Streaming (HLS) protocol and the newer MPEG-backed Dynamic Adaptive Streaming over HTTP (MPEG DASH) standard specification.
"What Apple has introduced to IETF (Internet Engineering Task Force) is merely an informational draft," added another panelist on the five-person panel. "We don't see that they're necessarily planning to push HLS as a true internet standard."
The MPEG DASH panel, led by Microsoft's Iraj Sodagar, who has chaired the MPEG subcommittee on DASH for the past year, was a hot ticket at the 2011Streaming Media West show, held this week at the Hyatt Regency Century Plaza in Los Angeles. A standing-room only crowd listened to representatives from a number of companies that are on the MPEG-DASH promoters' group.
"The growth of video over mobile networks is exponential, from a Qualcomm perspective," said Mike Luby, Qualcomm's vice president of technology. "As such we see getting standardization around video as very important and we participated heavily in the standards committee to make sure there was an adaptive-optimized common format that can be delivered via standard web servers, using common encryption."
The common file format (CFF) that Luby refers to is based on the UltraViolet CFF that the Digital Entertainment Content Ecosystem (DECE) published along with a Common Encryption (CENC) scheme that uses five distinct digital rights management (DRM) schemes in an interoperable manner.
"We also see a value in unmuxed audio and video," added Luby, using an example of non-multiplexed elementary audio streams in a variety of languages for an "online DVD" equivalent as an example. "Above all, we welcome the chance to use a modern file format all delivered in an open standard."
Will Law, Akamai's principal architect for media engineering, offered his perspective from a content delivery network (CDN) perspective.
"We're pushing 8.5 terabits today," said Law, referring to a recent peak record that Akamai set for simultaneous CDN content delivery.
"We've spent the past five years delivering a variety of adaptive video formats—SmoothHD, HDNI, HLS and HDS—all of which are 80 percent the same but 100 percent incompatible," said Law.
"We need to use HTTP to keep up with the demand curve for video on the web, but we can't do it with proprietary servers, since that means splitting our resources into three parts and trying to deliver equally to all three parts," he added. "What we really need to do is use all our edge cache servers for one standard, so that we and our users can focus on content and marketing rather than replicating the same thing three times for three separate streaming server solutions."
A representative from Netflix, senior engineer Mark Watson, said that MPEG-DASH was a natural extension of what his company is already doing to deliver fragmented MPEG-4 video via HTTP to a large number of streaming customers.
"We're already using these file formats, and we see huge cache efficiencies of a single file format," said Watson. "We feel we can lower CDN costs by using a standard web but we also see the DRM agnosticism of MPEG-DASH across multiple consumer electronics devices using Common Encryption (CENC) will benefit premium content owners whose content we deliver.
Watson also alluded to the online DVD equivalent, thanks in part to the use of elementary streams (those not multiplexed together like Apple's proprietary HLS protocol).
"We see unmuxed audio and video elementary streams as a way to effortlessly allow multi-language experiences," said Watson, "mimicking the offline multi-audio DVD experience. In doing so, we see a huge benefit to having an open standard that's a collaboration of a number of companies in the streaming space."
Ericsson's David Price, vice president of business development for the company's compression business, said consumer behavior and a move to mobile devices is driving the need for a common standard.
"Changes in consumer behavior that are driving the need for MPEG-DASH, at least according to our consumer surveys where we interview people from 40 countries," said Price. "We saw a need for a common delivery solution when we started into 3GPP unicast years ago, and those learnings form much of the basis of MPEG-DASH, along with technology contributions from other companies on this panel."
"We also see a need to make money in the ecosystem," added Price. "Ericsson sees there's a need for content management systems, third-party billing and back-office solutions. We all agree on the efficacy of the standard for delivery and to create a robust ecosystem."
Panelists were asked about the expected timeframe for DASH-compliant players, and Price stressed interoperability is key.
"Even though we don't know where the tipping point will be for DASH, as HLS is widespread," said Price, "we think that the time spent on the commonality of MPEG-DASH will be time well spent. Everyone at this table wants to promote interoperability.
Harmonic's Fautier said it's about the need to move to television-sized audiences.
"We've been successful with our ProMedia transcoding products," said Fautier, "but we feel that there's a need for a standard to be able to scale adaptive streaming to a TV-sized audience. To that end, all our ProMedia solutions are software upgradable to MPEG-DASH using a special software license."
Fautier also said that, in connected TV space in Europe, there's a move to go to MPEG-DASH.
"We expect to see a common file format with common encryption beginning in 2012," said Fautier, "perhaps using Marlin, one of the five DRM schemes, as a standard. France and Spain will be implementing first."
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