MPEG-DASH: Why it Matters, Where it Goes From Here
[An abridged version of this article appeared in March on streamingmediaglobal.com. -- Ed.]
The need to reach multiple platforms and consumer electronics devices has long presented a technical and business headache, not to mention a cost for service providers looking to deliver online video. The holy grail of a common file format that would rule them all always seemed a quest too far.
Enter MPEG-DASH, a technology with the scope to significantly improve the way content is delivered to any device by cutting complexity and providing a common ecosystem of content and services.
The MPEG-DASH standard was ratified in December 2011 and tested in 2012, with deployments across the world now underway. Yet just as MPEG-DASH is poised to become a universal point for interoperable OTT delivery comes concern that slower-than-expected initial uptake will dampen wider adoption.
A Brief History of DASH
The early days of video streaming, reaching back to the mid-1990s, were characterised by battles between the different technologies of RealNetworks, Inc. and Microsoft, and then Adobe. By the mid-2000s, the vast majority of internet traffic was HTTP-based, and content delivery networks (CDNs) were increasingly being used to ensure delivery of popular content to large audiences.
“[The] hodgepodge of proprietary protocols -- all mostly based on the far less popular UDP -- suddenly found itself struggling to keep up with demand,” explains Alex Zambelli, formerly of Microsoft and now principal video specialist for iStreamPlanet Co., in his succinct review of the streaming media timeline for The Guardian.
That changed in 2007 when Move Networks, Inc. introduced HTTP-based adaptive streaming, adjusting the quality of a video stream according to the user’s bandwidth and CPU capacity. “Instead of relying on proprietary streaming protocols and leaving users at the mercy of the internet bandwidth gods, Move Networks used the dominant HTTP protocol to deliver media in small file chunks while utilising the player application to monitor download speeds and request chunks of varying quality (size) in response to changing network conditions,” explains Zambelli in the article. “The technology had a huge impact because it allowed streaming media to be distributed ... using CDNs (over standard HTTP) and cached for efficiency, while at the same time eliminating annoying buffering and connectivity issues for customers.”
Other HTTP-based adaptive streaming solutions followed: Microsoft launched Smooth Streaming in 2008, Apple debuted HTTP Live Streaming (HLS) for delivery to iOS devices a year later, and Adobe joined the party in 2010 with HTTP Dynamic Streaming (HDS).
HTTP-based adaptive streaming quickly became the weapon of choice for high-profile live streaming events from the Vancouver Winter Olympics 2010 to Felix Baumgartner’s record breaking 2012 Red Bull Stratos jump (watched live online by 8 million people).
These and other competing protocols created fresh market fragmentation in tandem with multiple DRM providers and encryption systems, all of which contributed to a barrier to further growth of the online video ecosystem.
In 2009, efforts began among telecommunications group 3rd Generation Partnership Project (3GPP) to establish an industry standard for adaptive streaming. More than 50 companies were involved -- Microsoft, Netflix, and Adobe included -- and the effort was coordinated at ISO level with other industry organisations such as studio-backed digital locker initiator Digital Entertainment Content Ecosystem, LLC (DECE), OIPF, and World Wide Web Consortium (W3C).
MPEG Dynamic Adaptive Streaming over HTTP (MPEG-DASH, or DASH for short) was ratified as an international standard late in 2011. It was published as ISO/IEC 23009-1 the following April and was immediately heralded as a breakthrough because of its potential to embrace and replace existing proprietary ABR technologies and its ability to run on any device.
At the time, Thierry Fautier, senior director of convergence solutions at Harmonic, Inc., said the agreement on a single protocol would decrease the cost of production, encoding, storage, and transport: “This is why everyone is craving to have DASH. It will enable content providers, operator and vendors to scale their OTT business,” he told CSI magazine in February 2012.
In the same article, Jean-Marc Racine, managing partner at Farncombe, said, “By enabling operators to encode and store content only once, [DASH] will reduce the cost of offering content on multiple devices. ... [C]ombined with common encryption, DASH opens the door for use with multiple DRMs, further optimising the cost of operating an OTT platform.”
The Benefits of DASH
The technical and commercial benefits outlined for MPEG-DASH on launch included the following:
- It decouples the technical issues of delivery formats and video compression from the more typically proprietary issues of a protection regime. No longer does the technology of delivery have to develop in lockstep with the release cycle of a presentation engine or security vendor.
- It is not blue sky technology -- the standard acknowledged adoption of existing commercial offerings in its profiles and was designed to represent a superset of all existing solutions.
- It represented a drive for a vendor-neutral, single-delivery protocol to reduce balkanisation of streaming support in CE devices. This would reduce technical headaches and transcoding costs. It meant content publishers could generate a single set of files for encoding and streaming that should be compatible with as many devices as possible from mobile to OTT, and also to the desktop via plug-ins or HTML5; in addition, it meant consumers would not have to worry about whether their devices would be able to play the content they want to watch.
“DASH offers the potential to open up the universe of multi-network, multi-screen and multi-operator delivery, beyond proprietary content silos,” forecast Steve Christian, VP of marketing at Verimatrix, Inc. “In combination with a robust protection mechanism, a whole new generation of premium services are likely to become available in the market.”
Perhaps the biggest plus was that unlike previous attempts to create a truly interoperable file format, without exception all the major players participated in its development. Microsoft, Adobe, and Apple -- as well as Netflix; QUALCOMM, Inc.; and Cisco -- were integral to the DASH working group.
These companies, minus Apple, formed a DASH Promoters Group (DASH-PG), which eventually boasted nearly 60 members and would be formalised as the DASH Industry Forum (DASH-IF), to develop DASH across mobile, broadcast, and internet and to enable interoperability between DASH profiles and connected devices -- exactly what was missing in the legacy adaptive streaming protocols.
The European Broadcasting Union (EBU) was the first broadcast organisation to join DASH-IF, helping recommend and adopt DASH in version 1.5 of European hybrid internet-TV platform HbbTV. Other members have since boarded, including France and Spain, which have already begun deploying DASH for connected TVs, with Germany and Italy expected to follow. In the U.S., DASH is attracting mobile operators, such as Verizon, wanting to deploy eMBMS for mobile TV broadcast over LTE.
What About HLS?
However, there remain some flies in the ointment. The format for DASH is similar to Apple’s HLS, using index files and segmented content to stream to a device where the index file indicates the order in which segments are played. But even though representatives from Apple participated in drawing up DASH, Apple is holding fast to HLS and hasn’t yet publicly expressed its support for DASH.
Neither has Google, though it has confirmed that the standard is being tested in Google Chrome. Some believe that until DASH is explicitly backed by these major players, it will struggle to gain traction in the market.
“Right now there are multiple streaming options and until Apple and Google agree on DASH, it will be a while before there is widespread adoption,” says Hiren Hindocha, president and CEO of Digital Nirvana.
Adobe has encouragingly adopted the emerging video standard across its entire range of video streaming, playback, protection, and monetisation technologies. Its backing will greatly reduce fragmentation and costs caused by having to support multiple video formats.
“We believe that if we have Microsoft, Adobe, and to some extent Google implementing MPEG-DASH, this will create a critical mass that will open the way to Apple,” says Fautier. “Timing for each of those companies is difficult to predict though.”
While Apple HLS has considerable momentum, other adaptive streaming protocols are being dropped in favor of DASH, which observers such as David Price, head of TV business development for Ericsson, and Brian Kahn, director of product management for Brightcove, Inc., reckon will mean that there will only be two mainstream protocols in use for the vast majority of streaming services.
“Since both Adobe and Microsoft have been pushing DASH as a standard, we can assume that HDS and Smooth Streaming will be replaced by DASH helping to reduce the number of formats,” wrote Kahn in a Brightcove blog post. In an email to me, Kahn wrote, “Additionally, Google Canary has a plugin for MPEG-DASH and it is rumoured that Google created the plug-in internally. In the end, we will probably end up with two main streaming formats: HLS and DASH.”
MPEG-DASH, and particularly the DASH264 spec, will help standardize and unify online video delivery, but the move to embrace has been slower going than the hype might suggest
12 Mar 2013