The Internet does not currently offer any resource reservation or quality of service management facilities. How do the existing Internet-based audio and video streaming applications achieve acceptable quality? What limitations do the solutions they adopt place on multimedia applications?

Question

What will be an ideal response?

Answer 1

There are two types of Internet-based applications:

a) Media delivery systems such as music streaming, Internet radio and TV applications.

b) Interactive applications such as Internet phone and video conferencing (NetMeeting, CuSeemMe).

For type (a), the main technique used is traffic shaping, and more specifically, buffering at the destination.Typically, the data is played out some 5–10 seconds after its delivery at the destination. This masks the uneven latency and delivery rate (jitter) of Internet protocols and masks the delays incurred in the network and transport layers of the Internet due to store-and-forward transmission and TCP’s reliability mechanisms.
For type (b), the round trip delay must be kept below 100 ms so the above technique is ruled out. Instead, stream adaptation is used. Specifically, video is transmitted with high levels of compression and reduced frame rates. Audio requires less adaptation. UDP is generally used.
Overall, type (a) systems work reasonably well for audio and low-resolution video only. For type (b) the results are usually unsatisfactory unless the network routes and operating system priorities are explicitly managed.