Media Source Extensions (MSE) is aW3C specification that allowsJavaScript to sendbyte streams tomedia codecs withinweb browsers that supportHTML video andaudio.^[5] Among other possible uses, this allows the implementation of client-side prefetching andbuffering code forstreaming media entirely inJavaScript. It is compatible with, but should not be confused with, theEncrypted Media Extensions (EME) specification, and neither requires the use of the other, although many EME implementations are only capable of decrypting media data provided via MSE.^[6]

Netflix announced experimental support in June 2014 for the use of MSE playback on theSafari browser on theOS X Yosemite beta release.^[7]

YouTube started using MSE in itsHTML5 player in September 2013.

This sectionneeds expansion with: an explanation of how these affect video-blocking and autoplay blocking accessibility tools. You can help byadding to it.(May 2015)

The Media Source ExtensionsAPI is widely supported across all modernweb browsers, with the only exception being iPhone-family devices (although it is supported on iPadOS).^[8] Firefox 37 already had a subset of MSE API available for use with only YouTube in Firefox 37 on Windows Vista or later only,^[9] while Mac OS X version had in enabled starting version 38.^[10]

• Pale Moon from version 27.0, since 22 November 2016.^[19]

• NexPlayer for HTML5 MSE and EME supporting HLS and DASH
• castLabs PRESTOplay video player for HMTL5 MSE and EME supporting DASH and HLS
• Akamai Media Player as a contributor to theDash Industry Forum and DASH.js (DASH IF reference client). AMP includes Dash.js, HLS.js and advancedQUIC protocol playback from Akamai Edge Servers
• Shaka Player, an open source javascript player library for HTML5 MSE andEME video withDASH andHLS support^[20][21]
• The Video Player by Comcast Technology Solutions
• THEOplayer by OpenTelly: HLS and MPEG-DASH player for cross-platform HTML5 support without the need for Flash fallback^[22]
• Viblast Player: HLS and MPEG-DASH player for HTML5 MSE and EME, with Flash fallback^[23]
• bitmovin's bitdash MPEG-DASH player for HTML5 MSE and EME, with Flash fallback^[24]
• dash-js for HTML5 MSE^[25]
• dash.js for HTML5 MSE and EME^[26]
• rx-player for HTML5 MSE and EME (Live and On Demand)^[27]
• hls.js for HTML5 MSE^[28][29]
• hasplayer.js for HTML5 MSE and EME, supporting DASH, Smooth Streaming and HLS^[30]
• JW Player 7 and later forMPEG-DASH using HTML5 MSE and EME^[31]
• SLDP HTML5 Player supports SLDP via MSE playback^[32]
• Azure Media Player supports MSE,EME,DASH,HLS,Flash, andSilverlight. Streaming URLs are published in anism/manifest^[33]
• Unreal HTML5 player uses MSE for low latency (sub-second) live playback of streams sent via WebSockets byUnreal Media Server^[34]
• Storm Player uses MSE as one of its delivery modes for ultra-low latency streaming via WebSockets byStorm Streaming Server^[35]

• HTML video
• Dynamic Adaptive Streaming over HTTP (DASH)
• WebRTC

• HTML5
• Streaming media systems

• Articles to be expanded from May 2015
• All articles to be expanded
• Year of introduction missing