Industry Experts Discuss the Future of MPEG-DASH at NAB
“More important than anything else, DASH enables interoperability,” said Iraj Sodagar, a principal multimedia architect at Microsoft and the DASH Industry Forum (DASH-IF) president. “The whole idea of DASH was gathering the best deployed streaming technologies in the market, adding more to it, and creating a standard for interoperability."
The first edition of the core standards were published in April 2012, Sodagar noted, adding, “The second edition of MPEG-DASH, which extends the functionality of the first edition, is about to published by ISO/IEC.” Sodagar is also the MPEG-DASH subgroup chair.
Sodagar made these comments during the DASH Talks, an event that took place last week at the Renaissance Hotel during the NAB conference in Las Vegas, Nevada. Will Law, an architect at Akamai, presented and hosted the talks. Setting the stage, Law reminding the audience of the limitations of the traditional player environment before the promise of DASH.
“A content owner today must build and manage 12 or more players to reach the majority of users,” Law said. “Flash Player used to provide a single player application platform. It is still dominant on desktop/laptop devices today, but the rise of mobile devices without Flash support, such as phones and tablets, has fractured that player space.”
Law noted that not only are there different player requirements, but also differing development and player environments.
“Smart televisions all have different application development environments,” Law said. “Connected devices such as Roku, Apple TV, Chromecast, have separate player environments, and game consoles such as the PS4, Xbox One, Nintendo, require separate players.”
Several speakers focused on areas where MPEG-DASH, as a relatively new standard, needed enhancements to catch up with more proprietary solutions, even for HTML5-based players.
One such area is the use of browser extensions to protect content. Lumped together, these are known as encrypted media extensions (EME) which is a W3C standard that's being integrated into the DASH standards. This proposal for EME within DASH extends the HTMLMediaElement by providing APIs to control playback of protected content.
This use of common EMEs is akin to the move to Common Encryption Scheme (CENC) which was rolled into the first edition of the DASH standards. However, EMEs offer additional benefits for media services -- such as Adobe Primetime and Microsoft Azure Media Services -- which themselves use protected SDKs (PSDKs) to protect content.
“The API supports use cases ranging from simple clear key decryption to high value video given an appropriate user agent implementation," a DASH Talks slide noted. "License/key exchange is controlled by the application, facilitating the development of robust playback applications supporting a range of content decryption and protection technologies.”
Panelists also discussed the inclusion of advertising insertion in DASH. InterDigital’s Alex Giladi touched on two types of architectures, those that are app-driven and those that are server-driven, as well as linear workflows for each.
For the app-driven model, Giladi noted that it requires translating an existing workflow into DASH, which is a robust enough set of standards to handle both types of workflows.
“The DASH client and the ad splicer are modules in the client app,” Giladi said, noting that DASH events are used to transport cue messages, including user-defined events as “timed blobs.”
“Cue events are essential,” one of Giladi’s slides stated. “A DASH client without support for a specific cue format cannot play the content.”
Giladi showed how different types of cue messages, including the ubiquitous SCTE 35 cue message, could be carried in DASH.
One hot topic in the DASH Talks and on the NAB show floor was the need for DASH-compliant players. Michael Luby of Qualcomm presented two technologies: one forthcoming and one already in place with at least one of Qualcomm’s major OEM customers. The already-implemented technology is an in-silicon DASH client designed as part of Qualcomm’s Long-Term Evolution (LTE) mobile chipsets.
“Our Multicast Service Device Client is compliant with the 3GPP Rel-9 specification, and our DASH client is integrated to MSDC,” Luby said.
The DASH client in MSDC is already on Snapdragon 800 chipsets, Luby said, adding that a key selling point for Qualcomm was the tight integration between MSDC and the Snapdragon LTE modem, including API extensions for obtaining accurate time from network, which is critical in both unicast and multicast environments such as eMBMS.
“We are expanding eMBMS support on all Snapdragon devices with LTE,” Luby said, adding that Korea Telecom launched a commercial LTE/eMBMS service in January 2014. Ongoing trials are continuing in Australia, Europe, and the United States.
View the full DASH Talks.
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