sami synchronized accessible media interchange a way to produce captions for video (microsoft...
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SAMI
Synchronized Accessible Media Interchange
A way to produce CAPTIONS for VIDEO
(Microsoft approach)
Example of SAMI file<sami> <head> style statements </head> <body>
<sync start=0000> <p class=style> A first caption
</p> <sync start=2000>
<p class=style> A second caption
</p>
</body></sami>
Based on XML. Looks like HTML
Head .. has definitions
Body ..has things to be displayed
By defaults times are stated in milliseconds
(Media Player won’t handle anything except defaults )
This example:• Displays “A first caption” from time = 0
• Then displays “A second caption” to end of video
Two ways to get caption file to synchronise with media
1. Use REDIRECTION file
2. Use <OBJECT> tag in HTML
The next slides show each method
SAMI: Method 1 - Redirection file
• Captions will appear in extended area under the video.
• Screen-reader tools (eg for blind users) can access captions and read them aloud.
http://aces.shu.ac.uk/multimedia/captions/pop-idols/pop-idols.wmx
Use HTTP to open a REDIRECTION file. (asf or wmx). This then triggers the media and the captions together
SAMI: Method 1 - Redirection file
Slight problem!
• Captions are not automatically displayed
• User has to turn them on
• How do users know to do this??
SAMI: Method 2 - Within HTML page
• Include media player as object (see earlier classes)
• Extend Object call to also call SAMI file (see next slide)
• Author of HTLP page can choose where to display caption. Can even use Javascript to let user choose size / style etc
• Example working @ SHU:pop-idol.html
See next page for code.
You can also look at the source code of the pop-idol.html example
1. <html>2. <!-- An embedded Windows Media Player object with SAMI closed captioning -->3. <body>
4. <object 5. classid="CLSID:6BF52A52-394A-11d3-B153-00C04F79FAA6" 6. width=400 height=300 >
7. <param name="URL" value="pop-idols.mpg">8. <param name="SAMIFileName" value="captions.smi">9. <param name="captioningID" value="cc">10. <param name="SAMIStyle" value="Black Print">11. <param name="AutoStart" value=true>12. <param name="AutoRewind" value=true>13. <param name="EnableContextMenu" value=false>14.</object>
15.<p 16. id=cc 17. style="margin-top:3; width:400; height:100">18.</p>19.</body>20.</html>
Redirection Files• “Redirection File” :
– doesn’t contain media file itself– Instead: contains pointers and controls to files that do contain media
• Redirection files not invented specifically for captioning … Other applications / advantages are On Demand TV
– can serve sequence of files one after another (playlist)– can insert adverts before main file, or when triggered during main film– can make playlist time-sensitive (different files after midnight!)
Load-balancing Server Farms– web server on one machine, media files on another (others)
• … But redirection is useful for captioning too
1. <asx version="3.0">2. <title> Captioning Sample</title> 3. <entry>4. <ref href="http://aces.shu.ac.uk/multimedia/captions/pop-idols/pop-
idols.mpg?5. sami=http://aces.shu.ac.uk/multimedia/captions/pop-idols/captions.smi" />6. <copyright> ….. </copyright>7. <author> ….. </author>8. <title>Captioning Sample</title>9. </entry>
10. <entry>11. <ref href="http://www.bbc.co.uk/testmatch.wmv?12. sami=http://shu.ac.uk/drone.smi" />13. </entry>
14. <entry>15. <ref href="http://whitehouse.com/reasons.wmv?16. sami=http://restOfWorld.com/truth.smi" />17. </entry>18.</asx> Spot the political sarcasm
ASX files
<entry CLIENTSKIP=“NO” >
<ref href=“mms://...?sami=http://…..?sami=http://…..smi" />
<starttime “12:00:00 />
<clipbegin “00:00:05 />
<duration “01:00.00 />
<event adbreak ref=mms://...../mp3 resume>
</entry>
This ASX example play a file at midday, starting 5 minutes into the recording, for one hour (less the 5 mins). If it receives an “adbreak” alert it plays an MP3 file, and resumes from where it left off afterwards.
The full list of ASX commands is available here
Combining HTML, ASX, SAMI
Easy! - See example @ shu
Advantages of combined approach:– Media on one server, captions on another– Web author in control of set up– Captions accessible to reader tools