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12 Media Streaming.

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Presentation on theme: "12 Media Streaming."— Presentation transcript:

1 12 Media Streaming

2 What is Streaming Media?
The delivery of audio/video/data between a server and a client (user), as a continuous digital stream Eliminates waiting for an entire file to download Content is converted to digital files sent over the internet as data packets. Playback begins as soon as first packets arrive or as requested by the end user No impact on end-user’s computer Leading architectures: RealMedia, Windows Media, QuickTime

3 It’s a Challenge Uncompressed digital video produces data at the rate of 27 MB/sec (1.6 GB/min) A challenge to store A challenge to transport

4 Factors in Architecture Selection

5 Streaming Media Formats
Major player formats Real Networks Real Media Player – RM Microsoft Windows Media Player – WMV Apple Quicktime Player – MOV Other formats Audio downloads – MP3 Capture and editing - AVI Flash and animation - SWF CD audio playback – CDA, WAV

6 Things to Consider Identify your user audience Player compatibility
Are they using PC or Mac Offices, Dorms, Computer Labs, Homes Wireless and other mobile devices Internet Connection Low speed – 28kbps to 80kbps High speed – 80kbps to 300kbps Broadband – 300kbps to 1.0mbps Audience members Staff, Dept. Admins, Managers, Directors Anonymous users on WWW

7 Things to Consider Media delivery Network Other On-Demand
Live Webcasting CD-ROM, DVD Network User connectivity Firewalls, multicast enabled routers Other Password restrictions E-Commerce Media reports on viewer usage

8 On-Demand content and live broadcasts
Streams on demand File-based Streaming Available to users at any time, and are sent on demand. Live Streaming Live broadcast event Encoder…

9 Streaming Media Options
Encoding Choosing a format Real Media Windows Media Quicktime Determine a window size (Width x Height in pixels) 160x120 240x180 320x240 Even larger

10 Streaming Media Options
Encoding Bitrate selection Single rate - 28k, 56k, 120k, 200k, 400k One stream per bitrate One encoded file for each user’s connect speed One URL for each connect speed Multirate – (28k-56k-200k) Real - SureStream Windows - Intelligent Stream Quicktime - Alternate Movies One encoded file can reach multiple connect speeds Server finds optimum connect speed and adjusts as network bandwidth usage changes Only one url needed for all connect speeds Larger file size for archive media

11 Streaming Media Options
Authoring Include powerpoint slides sync’d to video Insert graphics, images, logos Add URL links to other sites or content Create a URL to play only parts of the media Create a playlist within one URL to stream multiple clips or media files Set player commands, end-user controls Pop-up or embedded player

12 Streaming Media Options
Indexing Assign keyframes to your content media Allows you to create smaller segments of your media and store them as clips Add keywords to clips for users to search your media from a website Convert speech, closed captioning and ppt slides to text for searching Save clips in a playlist and share them with other users

13 Streaming Media Options
Webcasting Live presentations over the internet One multicast stream to many users Include powerpoint or other rich media Hosting On demand playback of archived media Multiple streaming server platforms Unlimited streams Low storage costs No impact on your own network No hardware resources to maintain

14 Combining Media Limitations
Web browsers are not designed to fully support multimedia features Limited coordination of media elements

15 The Problem Lots of Bits Not All Bits are Equally Important
Images, audio and video are beyond Internet design specs Results in space/ time constraints at: the server the network( s) the client Not All Bits are Equally Important Time between samples often more important than bits in sample, for example lip synchronization (but not always...) Content may be Distributed Across Network Need to synchronize presentation Objectives Add synchronization to the Web Allow interoperability Use declarative format, preferably text — thus XML

16 Solution Use of a single timeline for all media
Creation of time-based multimedia delivery over the web Synchronization Coordination

17 What Is SMIL? SMIL stands for Synchronized Multimedia Integration Language SMIL is pronounced "smile" SMIL is a language for describing audiovisual presentations SMIL is easy to learn and understand SMIL is an HTML-like language SMIL is written in XML SMIL presentations can be written using a text-editor SMIL is a W3C standard SMIL 2.0 August 2001

18 What Is SMIL?

19 A Simplified SMIL Example
<body> <seq repeatCount="indefinite"> <img src="image1.jpg" dur="3s" /> <img src="image2.jpg" dur="3s" /> </seq> </body> </smil>

20 What Can SMIL Do? SMIL can be used to create Internet or Intranet presentations SMIL can be used to create slide show presentations SMIL has been described as the Internet answer to PowerPoint SMIL presentations can display multiple file types (text, video, audio...) SMIL presentations can display multiple files at the same time SMIL presentations can display files from multiple web servers SMIL presentations can contain links to other SMIL presentations SMIL presentations can contain control buttons (stop, start, next, ...) SMIL has functions for defining sequences and duration of elements SMIL has functions for defining position and visibility of elements

21 SMIL Files A SMIL file contains all the information necessary to describe a multimedia presentation SMIL files are stored with the extension *.smil A SMIL file contains the following: The layout of the presentation The timeline of the presentation The source of all multimedia elements

22 How to Play a SMIL File? You will need a SMIL player. Different SMIL players can be found RealOne Platform by RealNetworks has full support for SMIL 2.0 SMIL Player by InterObject supports the SMIL 2.0 Basic Profile With Internet Explorer 5.5 or later, SMIL elements can be inserted into HTML files This way any SMIL presentation can run over the Internet as standard HTML files

23 SMIL in HTML Adding References
Adding a "time" namespace definition to the <html> tag Adding an <?import> element to import the "time" namespace Adding a <style> element to define the class "time" <html xmlns:time="urn:schemas-microsoft-com:time"> <head> <?import namespace="time" implementation="#default#time2"> <style>.time {behavior: url(#default#time2)}</style> </head> <body> <time:seq repeatCount="indefinite"> <img class="time" src="image1.jpg" dur="3s" /> <img class="time" src="image2.jpg" dur="3s" /> </time:seq> </body> </html>

24 SMIL Timing time formats: Duration When To Start? hh:mm:ss.f
number [h|min|s|ms] wallclock (YYY-MM-DDThh:mm:ss+zone) Duration The duration (dur="5s") attribute When To Start? The begin (begin="2s") attribute

25 SMIL Sequence <seq> - the most common SMIL element - defines a sequence The <seq> element can have a number of attributes: begin, dur, repeatCount <html xmlns:t="urn:schemas-microsoft-com:time"> <head> <?import namespace="t" implementation="#default#time2"> <style>.t {behavior: url(#default#time2)}</style> </head> <body> <t:seq repeatCount="indefinite"> <h2 class="t" dur="1s"> I will display for one second</h2> <h2 class="t" dur="2s"> I will display for two seconds</h2> <h2 class="t" dur="3s"> I will display for three seconds</h2> </t:seq> </body> </html>

26 SMIL in Parallel Objects inside the <par> element will be played at the same time Attributes: begin, dur, endsync= "first"|"last"|id(clip), repeatCount <html xmlns:t="urn:schemas-microsoft-com:time"> <head> <?import namespace="t" implementation="#default#time2"> <style>.t {behavior: url(#default#time2)}</style> </head> <body> <par> <t:audio src="liar.wav" repeatCount="indefinite" type="wav" /> <t:seq repeatCount="indefinite"> <h2 class="t" dur="1s"> I will display for one second</h2> <h2 class="t" dur="2s"> I will display for two seconds</h2> </t:seq> </par> </body> </html>

27 SMIL Transitions IE 6 supports transitions based on the SMIL 2.0. Transitions are implemented with the element <transitionfilter> Attributes: type, begin, mode, from, to Transition Filters fade, barnDoorWipe, barWipe, clockWipe, ellipseWipe, fanWipe, irisWipe, pushWipe, slideWipe, snakeWipe, spiralWipe, starWipe <t:transitionfilter targetelement="keyb" type="clockWipe" begin="keyb.begin" dur="2s" /> <img id="keyb" class="t" src="pic_keyb.jpg" dur="4s" width="128" height="107" />

28 SMIL Media Elements <animation> <audio> <brush> <img> <param> <ref> <text> <textstream> <video> Attributes: erase src type <html xmlns:t="urn:schemas-microsoft-com:time"> <head> <?import namespace="t" implementation="#default#time2"> </head> <body> <t:video src="http://www.ananova.com/about/vap_windows_check.wmv" repeatCount="indefinite" type="wmv" /> </body> </html>


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