Dynamic Adaptive Streaming over HTTP

Dynamic Adaptive Streaming over HTTP (DASH) is a multimedia streaming technology currently being developed under MPEG. Work on DASH started in 2010; it became a Draft International Standard in January 2011, and it is expected to become an International Standard in November 2011.^{[1] [2]}

Overview

DASH is a multimedia streaming technology where a multimedia file is partitioned into one or more segments and delivered to a client using HTTP. ^[3] A media presentation description (MPD) describes segment information (timing, URL, media characteristics such as video resolution and bit rates). ^[4] Segments can contain any media data, however the specification provides specific guidance and formats for use with two types of containers: MPEG-4 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. ^[6]

DASH is a technology related to Adobe Systems's HTTP Dynamic Streaming, Apple Inc.'s HTTP Live Streaming (HLS) and Microsoft's 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. ^{[7] [8]} As part of their collaboration with MPEG, 3GPP Release 10 has adopted DASH (with specific codecs and operating modes) for use over wireless networks. ^[7]

The first DASH player implementations are the DASH VLC plugin of the Institute of Information Technology (ITEC) at Alpen-Adria University Klagenfurt ^[9] and the multimedia framework of the GPAC group at Telecom ParisTech^[10]. Content generation is possible using MP4Box from GPAC ^[11] or the wrapper tool DASHEncoder (also of ITEC) ^[12].

References

1. ^ HTTP streaming of MPEG media - blog entry
2. ^ ISO/IEC DIS 23009-1.2 Dynamic adaptive streaming over HTTP (DASH)
3. ^ Overview of Dynamic Adaptive Streaming over HTTP (DASH)
4. ^ DASH Overview by C. Timmerer and C. Muller
5. ^ ^{a b} Updates on DASH - blog entry
6. ^ 3GPP Dynamic Adaptive Streaming over HTTP - Standards and Design Principles by T. Stockhammer
7. ^ ^{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)
8. ^ Open IPTV Forum Solution Specification Volume 2a - HTTP Adaptive Streaming V2.1
9. ^ DASH at ITEC, VLC Plugin & Dataset
10. ^ GPAC Telekom ParisTech
11. ^ GPAC Telekom ParisTech
12. ^ DASHEncoder Repository at Github.com

External links

• DASH mailing list