Dynamic Adaptive Streaming over HTTP

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Dynamic Adaptive Streaming over HTTP (DASH), also known as MPEG-DASH, is an adaptive bitrate streaming technique that enables high quality streaming of media content over the Internet delivered from conventional HTTP web servers. Similar to Apple's HTTP Live Streaming (HLS) solution, MPEG-DASH works by breaking the content into a sequence of small HTTP-based file segments, each segment containing a short interval of playback time of a content that is potentially many hours in duration, such as a movie or the live broadcast of a sports event. The content is made available at a variety of different bit rates, i.e., alternative segments encoded at different bit rates covering aligned short intervals of play back time are made available. As the content is played back by an MPEG-DASH client, the client automatically selects from the alternatives the next segment to download and play back based on current network conditions. The client selects the segment with the highest bit rate possible that can be downloaded in time for play back without causing stalls or re-buffering events in the playback. Thus, an MPEG-DASH client can seamlessly adapt to changing network conditions, and provide high quality play back with fewer stalls or re-buffering events.

MPEG-DASH is the first adaptive bit-rate HTTP-based streaming solution that is an international standard.[1] MPEG-DASH should not be confused with a protocol — the protocol that MPEG-DASH uses is HTTP, hence the "H" in the name.

MPEG-DASH uses existing HTTP web server infrastructure that is used for delivery of essentially all World Wide Web content. It allows devices such as Internet-connected televisions, TV set-top boxes, desktop computers, smartphones, tablets, etc. to consume multimedia content (video, TV, radio...) delivered via the Internet, coping with variable Internet receiving conditions. Standardizing an adaptive streaming solution is meant to provide confidence to the market that the solution can be adopted for universal deployment, compared to similar but more proprietary solutions such as Smooth Streaming by Microsoft, or HDS by Adobe.

Standardization[edit]

MPEG-DASH technology was developed under MPEG. Work on DASH started in 2010; it became a Draft International Standard in January 2011, and an International Standard in November 2011.[1][2][3] The MPEG-DASH standard was published as ISO/IEC 23009-1:2012 in April, 2012. In July 2013, the second edition of MPEG-DASH has been approved incorporating first amendment and corrigenda including support for event messages and media presentation anchors.[4]

DASH is a technology related to Adobe Systems HTTP Dynamic Streaming, Apple Inc. HTTP Live Streaming (HLS) and Microsoft Smooth Streaming.[5] DASH is based on Adaptive HTTP streaming (AHS) in 3GPP Release 9 and on HTTP Adaptive Streaming (HAS) in Open IPTV Forum Release 2.[6][7] As part of their collaboration with MPEG, 3GPP Release 10 has adopted DASH (with specific codecs and operating modes) for use over wireless networks.[6]

The DASH Industry Forum (DASH-IF)[8] further promotes and catalyze the adoption of MPEG-DASH and help transition it from a specification into a real business. It consists of the major streaming and media companies, including Microsoft, Netflix, Google, Ericsson, Samsung, Adobe, etc. and creates guidelines on the usage of DASH for different use cases in practice.

MPEG-DASH is integrated in other standards, e.g. MPEG-DASH is supported in HbbTV (> Version 1.5)[9] as well as HTML5. HTML5 offers the MPEG-DASH support via the HTML5 Media Source Extensions(MSE)[10] and supports DRM for MPEG-DASH by the HTML5 Encrypted Media Extensions.[11] Youtube as well as Netflix already support MPEG-DASH for HTML5, and different MPEG-DASH players are available.[12]

Overview[edit]

DASH is an adaptive bitrate streaming technology where a multimedia file is partitioned into one or more segments and delivered to a client using HTTP.[13] A media presentation description (MPD) describes segment information (timing, URL, media characteristics such as video resolution and bit rates).[14] Segments can contain any media data, however the specification provides specific guidance and formats for use with two types of containers: ISO base media file format (e.g. MP4 file format) or MPEG-2 Transport Stream.[5]

DASH is audio/video codec agnostic. One or more representations (i.e., versions at different resolutions or bit rates) of multimedia files are typically available, and selection can be made based on network conditions, device capabilities and user preferences, enabling adaptive bitrate streaming[15] and QoE fairness.[16] DASH is also agnostic to the underlying application layer protocol. Thus, DASH can be used with any protocol, e.g., like DASH over CCN.[17]

Implementations[edit]

Some of existing implementations of MPEG-DASH standard for clients and servers include the following solutions.

Clients and libraries[edit]

  • The DASH Industry Forum reference implemention dash.js[10] Javascript/HTML5 Player.[18][19]
  • VLC Media Player 3.0 will ship new client plugin for MP4/MPEG and Live streams. [20][21][22]
  • HTML5-based bitdash[23] MPEG-DASH player, which also has a fallback to MPEG-DASH playback in Flash.
  • The open-source library libdash[24] is platform independent and runs on mobile platforms like Android, iOS, Windows Phone.
  • HTML5 Media Source Extentions (MSE)[10]

Servers[edit]

Note that no specific support is required from server for DASH content, with the exception of Live Streaming.

  • Helix Universal Server has support for DASH in various modes.
  • Nginx-rtmp-module supports generating MPEG-DASH live streams since version 1.0.8.[25] They can be played with a modified version of dash.js[26] and with bitdash.[23]
  • Nimble Streamer supports MPEG-DASH live streams and VOD.[27]
  • Path1 PiXiE Encoder supports generating DASH live streams.[28]
  • Wowza Streaming Engine has full support for MPEG-DASH.[29]
  • bitcodin.com Transcoding Cloud Service supports MPEG-DASH for live streams and VOD.[30]
  • Akamai CDN supports DASH.

[31]

[32]

Content Generators[edit]

  • ITEC's DASHEncoder.[20][34]
  • MP4Box and its multimedia framework from GPAC at Telecom ParisTech[35]

Other[edit]

  • ITEC offers a validation service for MPEG-DASH Media Presentation Description (MPD) files.[20]
  • Multiple DASH datasets are offered by the Institute of Information Technology (ITEC) at Alpen-Adria University Klagenfurt,[34][36] the GPAC group at Telecom ParisTech[35] and Digital TV Labs.[37]
  • BBC has DASH test streams, including DASH over HTTP/2[1]

References[edit]

  1. ^ a b "MPEG ratifies its draft standard for DASH". MPEG. 2011-12-02. Retrieved 2012-08-26. 
  2. ^ HTTP streaming of MPEG media – blog entry
  3. ^ ISO/IEC DIS 23009-1.2 Dynamic adaptive streaming over HTTP (DASH)
  4. ^ - MPEG-DASH 2nd edition - blog entry
  5. ^ a b Updates on DASH – blog entry
  6. ^ a b ETSI 3GPP 3GPP TS 26.247; Transparent end-to-end packet-switched streaming service (PSS); Progressive Download and Dynamic Adaptive Streaming over HTTP (3GP-DASH)
  7. ^ Open IPTV Forum Solution Specification Volume 2a – HTTP Adaptive Streaming V2.1
  8. ^ DASH Industry Forum
  9. ^ HbbTV Specification 1.5
  10. ^ a b c HTML5 Media Source Extentions
  11. ^ HTML5 Encrypted Media Extentions
  12. ^ The Status of MPEG-DASH today, and why Youtube & Netflix use it in HTML5
  13. ^ Overview of Dynamic Adaptive Streaming over HTTP (DASH)
  14. ^ DASH Overview by C. Timmerer and C. Mueller
  15. ^ 3GPP Dynamic Adaptive Streaming over HTTP – Standards and Design Principles by T. Stockhammer
  16. ^ http://scholar.google.com/citations?view_op=view_citation&citation_for_view=ZDbuOE4AAAAJ:hqOjcs7Dif8C
  17. ^ Y. Liu, J. Geurts, J.-P. Point, S. Lederer, B. Rainer, C. Mueller, C. Timmerer and H. Hellwagner, “Dynamic Adaptive Streaming over CCN: A Caching and Overhead Analysis”, In Proceedings of the IEEE International Conference on Communication (ICC) 2013 – Next-Generation Networking Symposium, Budapest, Hungary, June, 2013
  18. ^ "Dash-Industry-Forum/dash.js". 
  19. ^ "DashIf reference client". 
  20. ^ a b c DASH at ITEC, VLC Plugin, DASHEncoder and Dataset by C. Mueller, S. Lederer, C. Timmerer
  21. ^ C. Müller and C. Timmerer, “A VLC Media Player Plugin enabling Dynamic Adaptive Streaming over HTTP”, In Proceedings of the ACM Multimedia 2011 , Scottsdale, Arizona, November 28, 2011.
  22. ^ "VLC 3.0 features". 
  23. ^ a b bitdash MPEG-DASH player for HTML5 and Flash
  24. ^ libdash: Open-source DASH client library by bitmovin Gmbh
  25. ^ MPEG-DASH in nginx-rtmp-module 1.0.8
  26. ^ MPEG-DASH live streaming in nginx-rtmp-module
  27. ^ MPEG-DASH in Nimble Streamer
  28. ^ http://path1.com/products/pixie-encoder
  29. ^ MPEG-DASH Support in Wowza Streaming Engine
  30. ^ bitcodin.com Transcoding Service for MPEG-DASH, HLS, etc.
  31. ^ http://www.akamai.com/html/about/press/releases/2014/press-040814.html
  32. ^ http://www.arkena.com/arkena-intertrust-announce-partnership-deliver-secure-premium-ott-services/
  33. ^ http://msdn.microsoft.com/en-us/library/ie/dn551370(v=vs.85).aspx
  34. ^ a b S. Lederer, C. Mueller and C. Timmerer, “Dynamic Adaptive Streaming over HTTP Dataset”, In Proceedings of the ACM Multimedia Systems Conference 2012, Chapel Hill, North Carolina, February 22-24, 2012.
  35. ^ a b GPAC Telecom ParisTech
  36. ^ S. Lederer, C. Mueller, C. Timmerer, C. Concolato, J. Le Feuvre and K. Fliegel, Distributed DASH Dataset, In Proceedings of the ACM Conference on Multimedia Systems (ACM MMSys) 2013, Oslo, Norway, 2013.
  37. ^ MPEG DASH Test Suite

External links[edit]