Video & Multimedia on the Web

CSCI E-12 April 3, 2007

Larry Bouthillier CSCI E12 - April 3, 2007

Larry Bouthillier • 1st career in audio/multimedia production • Harvard Extension School C.A.S in Software Engineering, 1996 • Director of Software Development/Director of Educational Technologies, Harvard Business School, 2000-2006 • Multimedia Technology Architect, Harvard University, 2006• Author, Speaker, Consultant, Instructor – streamingmedia.com – http://www.learningapi.com/blog Larry Bouthillier CSCI E12 - April 3, 2007

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Outline • Why is video different from other media on the Web? • Formats and codecs and platforms • Tools for content creation and encoding • Delivery options

Larry Bouthillier CSCI E12 - April 3, 2007

Then & Now • RealVideo - RealPlayer 5.0, 28.8kbps • http://www.educause.edu/ir/library/html/cem/cem97/cem9744.html

• Flash VP6 - Broadband • http://www.brightcove.com/title.jsp?title=627011240&channel=1842533 09

• What’s different? – – – –

Better codecs Faster CPUs More bandwidth Standards

Larry Bouthillier CSCI E12 - April 3, 2007

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Linking an image • • Image downloads to browser • Images can be cached • Browser natively supports file formats

Larry Bouthillier CSCI E12 - April 3, 2007

What makes video different? • Large volume of data • Plugin player renders video • Time-sensitive realtime delivery

Larry Bouthillier CSCI E12 - April 3, 2007

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Delivery - Downloading vs. Streaming • Http download – Also called progressive download or progressive streaming – Can be done with a standard Web server

• Streaming – Requires specialized streaming server

Larry Bouthillier CSCI E12 - April 3, 2007

HTTP downloading • • • •

Web server accepts request for file Web server dumps data onto network Whole file sent as fast as the network can carry it User can usually begin to watch video as soon as enough of it has downloaded

Larry Bouthillier CSCI E12 - April 3, 2007

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What happens when you stream • Realtime streaming protocols – rtsp:// rtmp:// mms://

• Two-way conversation between server and player • Measured delivery of bits at the precise rate required by the bitstream • Dropped packets are discarded (no resend requests) – (has codec implications)

• Server can request content from the middle of a file - seeking ahead in long content, or begin play from the middle of a video Larry Bouthillier CSCI E12 - April 3, 2007

Streaming vs. http download HTTP • Short clips • Constant quality, variable time • Can deliver high-quality content for low-bandwidth users, if they are willing to wait

Streaming • Longer-form content • Constant time, variable quality • Scales bitrate to available bandwidth in realtime • Random access into content • Managed bandwidth (benefits infrastructure and costs) • Viewing statistics • Live video

Larry Bouthillier CSCI E12 - April 3, 2007

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Streaming metafiles • Small files linked on your Web page and served by your Web server • Contain a set of instructions that tell the streaming media player how to connect to the streaming server to play the requested file • Disentangles the URL/mimetype of the media file from the type and protocol that loads the media player

Larry Bouthillier CSCI E12 - April 3, 2007

What happens when you stream metafiles

(.asx, .ram, .qtl, .smi)l

Larry Bouthillier CSCI E12 - April 3, 2007

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Metafiles • Playlists • Alternate media sources – .asx (WindowsMedia) – .ram (Real) – .qtl (Quicktime)

• Synchronized media • Bitrate and language detection – .smil (Quicktime & Real)

Larry Bouthillier CSCI E12 - April 3, 2007

Metafiles - asx (basic) • Microsoft Windows Media format

Larry Bouthillier CSCI E12 - April 3, 2007

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Metafiles - asx (time offsets) • Microsoft Windows Media format My Video Title

Larry Bouthillier CSCI E12 - April 3, 2007

Metafiles - asx (playlist) Backyard outtakes Outtakes of a lazy backyard day Click here to see this asx source code Swingin' on a hammock Watching the wildlife float by Ducks and geese Goin' for a swim Click on this grayscale banner to see the source code Larry Bouthillier CSCI E12 - April 3, 2007



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Metafiles - ram Basic: rtsp://myserver.com/myvideofile.rm

Time offsets: rtsp://myserver.com/myvideofile.rm?start=00:05:00&end=00:08:00&title =My video title&screensize=double

Larry Bouthillier CSCI E12 - April 3, 2007

Metafiles - smil • Synchronized Multimedia Integration Language – Offers full multimedia authoring

• Full support in RealPlayer • Partial support in Quicktime • Many mobile devices

Larry Bouthillier CSCI E12 - April 3, 2007

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Metafiles - smil



Larry Bouthillier CSCI E12 - April 3, 2007 Source: Cognitive

Development Laboratory; http://www.psych.uiuc.edu/~kmiller/smil/download.html

Metafiles - smil (time offsets)