Dynamic Adaptive Streaming over HTTP

Dynamic Adaptive Streaming over HTTP ( DASH ), also known as MPEG- DASH, enables high-quality streaming media content over the Internet by conventional HTTP web server. Similarly, Apple's solution, the HTTP Live Streaming (HLS ), works MPEG- DASH by the content is broken down into a sequence of small HTTP - based file - segments, where each segment contains a short section of the total playing time of a media object from potentially several hours duration, such as a movie or live telecast of a sports event. The contents are kept in a selection of different bit rates, thus alternative, content matching sections that are encoded at different bit rates. If contents are reproduced from an MPEG - DASH client, it automatically chooses for the next section of the offered alternatives from the right to the current link conditions. The client selects the segment with the highest possible bit rate that can be transmitted in the time available to playback without the increased reproduction and must first be buffered again. Thus, a DASH client can seamlessly adapt to varying network conditions and ensure high-quality, smooth playback.

MPEG- Dash is the first bit rate adaptive streaming HTTP-based solution, which became an international standard.

MPEG- DASH is a widespread HTTP web server infrastructure, which is the delivery of Internet content of any kind in use. It allows devices such as TVs with internet access, TV - ons, desktop computers, smart phones, tablet computers, etc. to access delivered via the Internet multimedia content (video, TV, Radio ... ), while thanks to the adaptive streaming technology cope with varying reception conditions. Standardizing a solution for adaptive streaming to provide on the market for trust in the universal applicability, compared to similar, more provider - dependent solutions such as Apple HLS, Microsoft Smooth Streaming, or HDS from Adobe.

Standardization

DASH was developed by MPEG. Work on DASH began in 2010; in January 2011 it was adopted an official draft of an international standard and in November 2011 as the standard. The DASH standard was published in April 2012 as ISO / IEC 23009-1:2012.

DASH is technically related to Adobe Systems ' HTTP Dynamic Streaming, Apple HTTP Live Streaming (HLS ) and Microsoft Smooth Streaming. DASH is based on Adaptive HTTP streaming ( AHS ) from 3GPP Release 9 and HTTP Adaptive Streaming (HAS ) from the Open IPTV Forum Release 2 As part of its collaboration with MPEG took over 3GPP Release 10 DASH (with certain codecs and operating modes) for use over wireless networks.

Overview

DASH, a technique for adaptive streaming bit rate at which a media file is divided into one or more segments and is delivered to a client via HTTP. A media presentation description (MPD ) describes Segment information ( time, URL, media properties like video resolution and bit rates ). Segments can contain any media data, the specification of certain recommendations and formats for use with two types of container formats indicating the MPEG -4 file format or MPEG- 2 transport stream.

DASH is ( audio-video ) codec agnostic. From multimedia files, typically one or more representations are available (ie, models with different resolutions or bit rates ) and it can be a choice to be made, thereby bitrate adaptive streaming and Quality of experience fairness can be achieved based on connection situation, device capabilities and user preferences. DASH is also agnostic with respect to the underlying protocol at the application layer. This can be used with any DASH protocols, such as in DASH through CCN.

Implementations

Client implementations for desktop computers are the DASH VLC module of the Institute of Information Technology ( ITEC ) of the Alpen-Adria -Universität Klagenfurt, the open source DASH client library libdash bitmovin the Austrian company, the multimedia framework of GPAC - group of Telecom ParisTech and the client of the German company cast labs. Content creation is possible with MP4Box from GPAC or the wrapper tool " DASHEncoder " ( also from ITEC ). The first DASH server and Android ( 2.2 to 4.x) SDK -player implementation was presented by Real Networks at IBC 2012 with the Helix Universal Server and Helix SDK for Android, as a demonstration of the extradition commercially available from November 2012 - and playback formats including MPEG2 -TS (Smart TV) and ISO BMFF (MP4 smartphone / tablet ). See Helix Universal Server for more information. The open source library libdash is platform independent and therefore usable on all mobile platforms like Android, iOS, Windows Phone, etc..

Google's YouTube experimented support for MPEG - DASH with server-side. Google Chrome supports it on the client side.

From the Institute of Information Technology ( ITEC ) of the Alps -Adriatic University of Klagenfurt and the GPAC group of Télécom ParisTech several DASH records are available.

The ITEC also offers a verification service for MPEG- DASH - Media Presentation Description files ( MPD).