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© Oxford University Press 2007. All rights reserved. 1
Data Synchronization in Mobile Computing Systems
Lesson 12Synchronized Multimedia Markup
Language (SMIL)
© Oxford University Press 2007. All rights reserved. 2
Language required to specify the multi-modal multimedia communication
• Mobile devices not only have to synchronize data but also multimedia (music, video clips, images, and slide shows)
• The transmitted text shown onto the display of the video clip
• The text also rendered with the voice• The displayed text, images, and audio
needs to be synchronized
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Language required to specify the multi-modal multimedia communication
• To specify the synchronization messages in order to enable appropriate synchronization and for integration of multi-modal multimedia communication
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Multi-modal
• Usage of different modes—text, image, video, or audio
• Multi-modal communication integrates and synchronizes multimedia.
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SMIL
• Used for text, speech, or multimedia integration for multi-modal communication
• Like SyncML, the SMIL based on XML• SMIL version 2.1 enables coding of
messages for interactive audio–visual presentations
• The coding of SMIL messages needs a simple text editor
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SMIL
• SMIL specifies the standard ways and tags which integrate text, images, and streaming audio and video
• SMIL─ a W3C council (World Wide Web Consortium)
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Coding for a text-to-speech synthesis (TTS) engine
• TTS deployed in automobiles and many other applications
• If the driver of an automobile attempts to read a text message, his attention may get diverted
• TTS engine converts text messages to voice messages
• SMIL can be used for coding the TTS engine
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SMIL features
• Just as SyncML refers to objects by URIs, SMIL refers to multimedia objects by URLs ( (universal resource locators)
• SMIL provides the commands for Multimedia objects sharing between presentations and may be required to be stored on different servers for load balancing the actions
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SMIL features
• SMIL provides commands for Different media objects required to be transmitted at different bandwidths
• SMIL document has two components(i) a header between start and end tags, <header> and </header> and (ii) a body between start and end tags, <body> and </body>
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SMIL Features
• Due to multimedia synchronization, the <body> section also provides the timing information
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Sample Code 9.4
<smil><SyncHdr>
…</SyncHdr><SyncBody>…
</SyncBody></smil>
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SMIL Tags within the <SyncBody>
1. <layout> within the header element to specify layout of SMIL document
2. <seq> for sequential operations within the body element. The specified operations should be performed in sequence
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SMIL Tags within the <SyncBody>
3. <par> for parallel operations within the body element. The specified operations should be carried out in parallel.
4. <switch> for a different set within the body element for presenting multimedia contents
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Sample Code
1. <SyncBody><seq> <!- - Source of WBXML text file is my.wml, maximum period 10 s, duration is 1 s,
repetition is 5 times- - ><text src = “my.wml” max= “10s” dur = “1s” repeatCount =”5”/>
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Sample Code
<!- - Source of video file is my.mpg, identifier is my_vid and end duration = 10s. - - > <video src = “my.mpg” id = “my_vid” end = 10s/>
</seq></SyncBody>
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Sample Code
2. <SyncBody><!- - Assume that all operations image and
audio begin in parallel and begin at 2s” -- >
<par begin = “2s”> <!- - Source of image file is myimage.jpg,
end is 2s and freeze on display for 2s - ->
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Sample Code
<img src = “myimage.jpg” begin = “2s” end myimage.end – 2s” fill = “freeze”/>
<!- - Source of audio file is myaudio.wav, id is “my_id”, begin at t = 0s for 10s duration. - - >
<audio id = “my_id” src = “myaudio.wav” begin = “0s” dur = “10s” /></par>
</SyncBody>
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Multimedia messaging service (MMS)
• MMS is the video and picture equivalent of SMS, is a subset of SMIL
• It can be implemented on handheld computers and mobile devices
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SMIL messages
• Can be structured as in a document object model (DOM) tree
• DOM tree specifies a tree-like structure of the tags
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SMIL messages
• Tree-like structuring of objects as in URI specifications
• In a DOM tree, a manager is the root and SMIL messages are the branches and leaves
• SMIL messages scheduled using SMIL scheduler software
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SMIL Parsing
• Just as an XML document or SyncML message, SMIL message needs to be parsed
• A DOM interface specifies the parsing and layout
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Summary
• Funambol provides Java-based synchronization using SyncML messages
• SMIL enables coding of messages for interactive audio–visual presentations
• SMIL specifies the standard ways and tags which integrate text, images, and streaming audio and video
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End of Lesson 12Synchronized Multimedia Markup
Language (SMIL)