IT is said sometimes that computers really don't make difficult things easier; they make impossible things possible. The multimedia effects generated by computer ascertain this proposition well in this modern technological era. Today multimedia elements provide best hybrid by adding sound, motion and power of communication together to give the most stunning results.
The ever-increasing demand for internet induces web developers to explore new ways of presentation so that more and more visitors attracts towards their sites. One such technology which works behind the interactive multimedia presentation on web, is known as SMIL (pronounced as smile).
What is SMIL?
SMIL stands for synchronized multimedia integrated language and it is regarded as a markup language designed for the transmission and presentation of multiple messages (sound, images, text, animations, video,etc.) at regular interval.In computer terminology, synchronous transmission is defined as, "a communication protocol in which the source and destination points operate in timed alignment to enable high speed data transfer."
The latest version of SMIL is announced by W3C on August 20 1999. It is XML-based language aimed to display animations.
Why SMIL?
• Easy download of audio and video files catch the attention of more visitors to media sites.
• Web developers can simply deal with animations; The W3C ‘s working draft has a very detailed account of animation framework. The basic animation elements are "animate", "set", "move" and "colorAnim".
• Media files are easy to manage by a web builder since multiple audio and visual files are displayed in the form of single stream.
• Experts consider that infusing SMILE instead of MP3 or Flash in your web page is much better idea, as explained by Steve Mc Cannell, "When you encode audio into the MP3 format using the standard 44.1kHz sampling rate, the general output is around 1 MB per minute of music That is a lot of bytes to download if your users have a 56kps modem connection."
• It is easy to write SMIL script if you have prior knowledge of HTML since both markups have many common factors.
• SMIL can be written using any text editor or word processor and can be saved as plain and simple text.
• Real Networks, which include Real G2 for audio and video presentation, Real Pixel for slide show and Real Text, provide full and solid support for SMIL therefore most of the media websites insist on installing Real Player to their user. There are other media networks, such as SOOJA; apple's Quick Times 4.1, etc also support SMIL.
Rules to play
SMIL have some rules, which must be followed for correct presentation. These are as follows:
1. A SMIL file must starts with "" tag and end with "" tags.
2. SMIL mark up is case sensitive. All tags and attributes are written in "lower case".
3. The ""and "" tags are optional.
4. The "" and "" tags are must.
5. All SMIL files have ". smil" or ".smi" extension.
6. Some tags do not have closing tags they need forward slash for finishing. For instance,
7. All attributes value must be quoted. As in:
8. In SMIL; comment tags do not need forward slash. They can be written as follows:
9. There is a set of coded characters, which needs to be included carefully for correct syntax. For instance, "&" for ampersand "'" for apostrophe "&qute;" for quotation mark.
10. The and tags (tags to describe outline area for video and animation) must be defined in section.
11. The hyperlink anchor tag can only included to media source tags in order to link one media clip (video, audio) with another.
Creating SMIL file
Suppose you have to create a SMIL file which has multiple number of sound files. To make it possible Real Networks provides one of the easy ways to encode sound track in real audio format we make use of ". rm" file extension. Now put this SMIL file to Real server and link it to your web page. The SMIL file will have following tags:
Since you are using Real Networks facilities to include Real Player G2 in these web page you have to give URL "rtsp" streaming protocol instead of "www". While "Realserver.company.com" is Real server address (instead of web server), which may be different for each Real server. The "/audio/" is the directory, which holds the file name.
SMIL integrate all these media files which are located on its identical server. In this case, it is a better idea to include base target to specify the URL of each file. The meta tag will be included in the head section in following way.
Media information display
Media information represents title, copyright and other relative information about audio or video files. Real Player also displays help on presentation command in its menu, along information on number of sound tracks in a SMIL file. which include name of singer, title of the song, e-mail address and copyright information. For each track an individual code is written in the following format:
This code will display information of a single track with its title on the top window and on the drop down list. The tag below indicates that each sound track pursue the next.
Putting it all together
SMIL is a best way to put audio and video on your website in the form of a single stream. The stream will run two types of files, sound and motion, as a single flow . It saves download time and increases usability of a website.
The tag in the code below indicates that two types of files are streaming side by side.
The tag in the code below indicates that two types of files are streaming side by side.
Setting time limits
Besides, above mentioned functions, the SMIL tags and attributes also help in setting following task:
1. Specify the duration of media clip: Suppose you have infused a number of sound tracks in your website, the playing length or duration for each track can be signified as follows:
The "dur" attribute runs the play back as long as mentioned above.
2. Begin and end time: In order to set begin and end time, you need to add following attributes which help you to start and end a clip at a specific time within a time line. For instance, a sound track starts on play 05 seconds after a user choose it to play for 05 seconds after a video display on a user's screen and ends in 30 seconds regardless of the fact that the duration of the song is not completed up till then.
The begin and end attributes can be used with and elements to produce group result.
3.Setting the repeat format: A playback can be repeated for several times by employing "repeat" attribute. This is useful when there are two types of media clips and one last longer then the other. Suppose that an image have a duration of 20 seconds and the playback music have 10 seconds duration. The difference between the two time limits can be overcome if the play back is repeated twice. The following code explains it.
When used with element the whole group of media clips will repeat accordingly.
SMIL is a revolutionary technology for web development. I have just mentioned a brief account of this extensive language which is ready to perform so many useful tasks to enhance your websites, such as setting language options for those who are unable to understand English.
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