Version 2 ECE IIT, Kharagpur
At the end of this lesson, the students should be able to:
1. Define multimedia signal.
2. Name at least five different sources of multimedia signal.
3. State the motivation behind the growth of multimedia technology.
4. State the elements of multimedia communication system.
5. State at least five challenges involved with multimedia signal processing
In the era of information technology, we are dealing with free flow of information
with no barriers of distance. Take the case of internet as one of the simplest
examples. You can view and download information across the globe within a
reasonable time, if you have a good speed of connection.
Let us spend a bit of time to think in which form we access the information. The
simplest and the most common of these is the printed text. In every web page,
some text materials are always present, although the volume of textual contents
may vary from page to page. The text materials are supported with graphics, still
pictures, animations, video clippings, audio commentaries and so on.
All or at
more than one of these media, which we can collectively call as
“multimedia”, are inevitably present to convey the information which the web site
developers want to do, for the benefit of the world community at large. All these
media are therefore utilized to present the information in a meaningful way, in an
Internet is not the only kind of information dissemination involving multiple media.
Let us have a look at some other examples as well. In television, we have
involvement of two media – audio and video, which should be presented together
in a synchronized manner. If we present the audio ahead of video or video ahead
of audio in time, the results are far from being pleasant. Loss of lip
synchronization is noticeable, even if the audio and the video presentations differ
by just 150 milliseconds or more. If the time lead or the lag is in order of seconds,
one may totally lose the purpose of the presentation. Say, in some distance
learning program, the teacher is explaining something which is written down on a
blackboard. If the audio and the video differ in time significantly, a student will not
be able to follow the lecture at all.
So, television is also a multimedia and now, we understand one more
requirement of multimedia signals. The multimedia signals must be synchronized
and if it is not possible to make them absolutely synchronized, they should at