Multimedia Networking Applications

Introduction
We define a multimedia network application as any network application that employs audio or
video. Before continuing in this subject, it is important to consider the essential characteristics of
the audio and video media themselves.

Properties of Video
Perhaps the most important characteristic of video is its high bit rate. Video distributed over
the Internet typically ranges from 100 kbps for low-quality video conferencing to over 3 Mbps
for streaming high-definition movies. To get a sense of how video bandwidth demands compare
with those of other Internet applications, let s brie
y consider three different users, each using a
different Internet application. Our first user, Frank, is going quickly through photos posted on his
friend s Facebook pages. Let s assume that Frank is looking at a new photo every 10 seconds, and
that photos are on average 200 Kbytes in size. (As usual, throughout this discussion we make the
simplifying assumption that 1 Kbyte = 8,000 bits.) Our second user, Martha, is streaming music
from the Internet ("the cloud") to her smartphone. Let s assume Martha is using a service such as
Spotify to listen to many MP3 songs, one after the other, each encoded at a rate of 128 kbps. Our
third user, Victor, is watching a video that has been encoded at 2 Mbps. Finally, let s suppose
that the session length for all three users is 4,000 seconds (approximately 67 minutes). Table 1
compares the bit rates and the total bytes transferred for these three users. We see that video
streaming consumes by far the most bandwidth, having a bit rate of more than ten times greater
than that of the Facebook and music-streaming applications. Therefore, when designing networked
video applications, the first thing we must keep in mind is the high bit-rate requirements of video.