What is MPEG – DASH ?

DASH is the name used to refer to the MPEG Dynamic Adaptive Streaming over HTTP specification – sometimes snappily referred to as ISO/IEC 23009-1. It is an adaptive bitrate system, which can be used for both live streaming and on-demand content.

The media is encoded a number of times at different bitrates. Each encoding is called a Representation. These are split into a number of Media Segments. The client plays a programme by requesting segments, in order, from a representation over HTTP. Representations can be grouped into Adaptation Sets of representations containing equivalent content. If the client wishes to change bitrate it can pick an alternative from the current adaption set and start requesting segments from that representation. Content is encoded in such a way to make this switching easy for the client to do. In addition to a number of media segments, a representation generally also has an Initialisation Segment. This can be thought of as a header, containing information about the encoding, frame sizes, etc. A client needs to obtain this for a given representation before consuming media segments from that representation.

Finally, there is also a Media Presentation Description (MPD), commonly referred to as the manifest. This documents the Adaptation Sets and Representations, together with durations and URLs.


Subscribe with Valid Email Id to receive updates in Inbox. ( Secured by Google FeedBurner )

   


For Playing mpeg dash streams refer our another post Online MPEG Dash player / Test mpd audio, video streams

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 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 playback time. While the content is being played back by an MPEG-DASH client, the client uses a bit rate adaptation (ABR) algorithm [1] to automatically select the segment with the highest bit rate possible that can be downloaded in time for playback without causing stalls or re-buffering events in the playback[2]. The current MPEG-DASH reference client dash.js offers both buffer-based (BOLA[3]) and hybrid (DYNAMIC[2]) bit rate adaptation algorithms. Thus, an MPEG-DASH client can seamlessly adapt to changing network conditions and provide high quality playback with fewer stalls or re-buffering events.

lynxbee_ezoic

Leave a Comment

Android Android Build system Android Commands Android Java Applications Application Libraries Application Stack / User Interface Bash / Shell Scripts Bluetooth driver Cloud Technologies Commands and Packages Compilation Content Management System Core Kernel C Programs Development & Build Development, Debugging and Performance Tools Development Environment Setup Django & REST Api Errors & Failures Git Hardware Platforms HTML JAVA Programs Linux, OS Concepts and Networking Linux Device Drivers Linux Host, Ubuntu, SysAdmin Linux Kernel Linux Networking Middleware Libraries, HAL Multimedia Audio, Video, Images NDK / Middleware / HAL OS Concepts PHP Programming Languages Scripting and Automation Search Engine Optimisation ( SEO ) Social Media Source Code Management ( SCM ) System Administration, Security Testing and Debugging Uncategorized Web design and development Website Hosting Wordpress Yocto / Bitbake / Openembedded