The DASH-IF collected an initial set of Frequently Asked Questions (FAQs) and answers related DASH-IF, MPEG-DASH and related issues. Please find below. If you have issues with the questions, or if you have additional questions, please feel free to post this through the DASH-IF FAQ bug tracker.
MPEG-DASH simplifies and converges the delivery of IP video, to provide a rich and enjoyable user experience, to help drive down costs and ultimately to enable a better content catalogue to be offered to consumers, because more revenues can be re-invested in content, rather than paying for operating overheads. It will help streamline and simplify workflows and enable operators and content providers to build sustainable business models to continue to deliver the services that consumers demand.
MPEG-DASH builds on the already excellent adaptive streaming technologies deployed today. The MP4 File Format (based on the ISO Base Media File Format) enables common encryption to allow delivery of content to a wide range of devices with various DRM schemes. MPEG-DASH also allows multiple language versions of the same content to be delivered thus enlarging target audiences. Whether consuming traffic from a service provider’s own content offering, or using a new over-the-top service, video consumption to IP-enabled devices is driving up traffic on operators’ networks. Building out new capacity to cope with today’s demands and the predicted growth over the coming years is prohibitively expensive, yet consumers continue to expect higher quality IP video without a corresponding hike in broadband access charges.
MPEG-DASH will help to overcome some of the challenges of other adaptive streaming formats and provides service providers with the confidence coming from embracing a truly global standard.
What MPEG-DASH aims to do is simplify the delivery landscape and help realize the promise of adaptive streaming.
MPEG-DASH (ISO/IEC 23009-1:2012) was published as an ISO in March 2012. A second edition was published in May 2014 as ISO/IEC 23009-1:2014.
DASHAVC-264 was developed by the DASH Industry Forum interoperability subgroup to provide recommended guidelines for deployment of MPEG-DASH. DASHAVC-264 recommends a specific subset of MPEG-DASH. This is important, since MPEG-DASH is a wide-ranging specification, and implementation and deployment of everything in MPEG-DASH would likely be too large of a task for more companies. DASHAVC-264 also recommends specific video and audio codecs and profiles (something which MPEG-DASH doesn’t cover), to ensure interoperability at this level. DASHAVC-264 is based on contributions of test vectors provided by DASH Industry Forum members, and thus all of the recommended guidelines within DASH264-AVC have been tested for interoperability within the DASH Industry Forum.
MPEG-DASH enables the delivery of content to all devices. One of the major challenges facing content and service providers is the fragmentation of devices. It is no longer enough to create a single version of a video asset for presentation on the household TV. Multiple viewing devices with differing screen sizes receive content over networks with capacities that vary over time; a Smartphone on a 3G mobile network requires a completely different asset than the 50” HDTV in the living room. MPEG-DASH reduces cost at every step of the chain from content preparation, hosting, caching to final delivery. MPEG-DASH, as an http adaptive streaming technology, promises to reduce complexity by allowing the receiving device to select which resolution and bitrate stream to view, and the ability to change the choice over time as network conditions demand. This will allow content providers to concentrate on generating a fixed number of choices for each asset, greatly simplifying their workflow. It will also allow business models to expand to cater for content even further down the “tail”. It will also allow delivery of content to homes that were previously out of reach commercially.
The DASH Promoters Group (DASH-PG) has been formed by several companies and organizations, who are working together to promote the adoption of MEG-DASH standard in the market –The goal of this group is to accelerate the deployment of MPEG-DASH across all applications: mobile, broadcast, Internet and of course enable interoperability between all MPEG-DASH content and connected devices to the highest extent possible. This is exactly what was missing in the legacy adaptive streaming protocols.
Several consortia and organizations adopted or are considering adopting MPEG-DASH in their specifications. EBU is the first broadcast organization to join the DASH Promoters Group.
While 2012 was the early adopters deployment development year, with real demonstrations of end to end systems, 2013 will be the year of broader commercial deployments with a broader range of devices, especially in the latter half of the year. Broad interoperable adoption of the MPEG DASH adaptive streaming protocols are likely to follow publication of based on publication of the first implementation guidelines, DASHAVC-264, now available at http://xxx.yyyy.zzz for public review before final release on March 31, 2013. With this movepublication, DASH will effectively grow beyond 2012’s early adopters and into more mainstream OTT and hybrid services. 2014 will be the mass deployment year of MPEG-DASH technology.
DASH’s common encryption will allow for multiservice and multidevice support along with efficiency of manifest management as well as the sizable advantages of a global standard. DASH, as a single new standard, will allow content producers to encode once then securely distribute their content to players universally, from mobile to OTT, as well as desktop via HTML5 or plug-ins. Today a content operator might publish content to three separate devices using three separate adaptive bit rate formats, Apple HLS, Smooth Streaming and Adobe HDS. This operator incurs the packaging, storage and delivery costs three times over. DASH, as a universal standard, allows the content operator to package, store and deliver content a single time, significantly reducing costs.
In regards to data format, Microsoft Smooth Streaming and Adobe HDS content are similar to the DASH ISOBMFF Live Profile while Apple HLS content is similar to the DASH M2TS main profile. For more quantitative studies on the subject, see:
S. Akhshabi, A.C. Begen, and C. Dovrolis, “An Experimental Evaluation of Rate-Adaptation Algorithms in Adaptive Streaming over HTTP,” Proc. ACM Multimedia Systems Conf., ACM Press, 2011 (http://www.cc.gatech.edu/~dovrolis/Papers/final-saamer-mmsys11.pdf)
Christopher Müller, Stefan Lederer and Christian Timmerer, “An Evaluation of Dynamic Adaptive Streaming over HTTP in Vehicular Environments”, In Proceedings of the ACM Multimedia Systems Conference 2012 and the 4th ACM Workshop on Mobile Video, Chapel Hill, North Carolina, February 24, 2012 (http://www-itec.uni-klu.ac.at/bib/files/p37-mueller.pdf)
And, for a more practical comparison:
DASH: A Universal Standard for Streaming Video Content to Multiple Devices (http://www.harmonicinc.com/sites/default/files/20120830_DASH_Article_0.pdf)
Most of an operator’s existing content and production equipment will be compatible with DASH. To use the DASH protocol, an operator will have to upgrade existing servers with DASH streaming capability. A software upgrade of the packaging will be required of other existing technologies such as encoders. Client side upgrades would also be needed, where browsers such as Chrome and IE must be modified to support DASH. Basically, the transition to MPEG DASH is a software upgrade of currently deployed adaptive streaming technologies.
More to come on this soon.
More to come on this soon.
The DASH-IF’s Interoperability Working Group is focused on the development and production of DASHAVC-264, an application profile that will outline the specifics, such as the codex, test vectors, software tools and syntaxes for transmitting over HTTP needed for interoperability.
Several companies have already announced support for DASH in encoders and on servers, while several other notable companies, such as Microsoft, have announced plans to support DASH in the near future. 2013 should see broader adoption of MPEG DASH.