TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

3.1.6 Static vs. Dynamic Channels
The quality of the delivered video over networking environment is affected by the nature and
the characteristic of the communication channel such as bandwidth, delay, and loss. These
parameters may be static or dynamic. In the static channel, the bandwidth, delay, and loss are
known in advance and bounded, whereas in the dynamic channel, it is difficult to determine they
upper bound.
It is clear that delivering video over static communication environment is much easier.
Moreover, many of researches ongoing on video streaming are related to capacity varying
communication environment such as IP.
Another attribute that affect the design of multimedia streaming system is whether the
network is packet-switched or circuit-switched. Packets switched networks, such as Ethernet and
Internet are by nature shared networks in which packets may encounter losses, may arrive out of
order, and exhibit variable delay. On the other hand, circuit-switched networks such as public
switched telephone network (PSTN) or ISDN has a fixed delay and guaranteed fixed bandwidth
allocated. However, the errors still a challenge since as corrupted bit-errors or burst errors may
affect data integrity.
3.2 Requirements and Challenges for Packet Video Applications over
IP
There are a number of problems that affect packet video streaming. In this section, we discuss
the problems that influence video streaming quality over IP packet switching networks. We present
their solution found in the literature.
Video streaming over IP is a challenging task since IP is a shared environment providing best
effort service. It offers no quality of service and no guarantee of resources in term of (1)
bandwidth, (2) packet losses, (3) delay variation (jitter), and (4) transfer delay. Moreover, these
parameters are unpredictable and unbounded. Therefore, a key goal of video streaming is to design
a system that efficiently handles the video over IP and deals with the above problems. Table 3-1
summarizes issues with video delivering and their solutions.
Video Transmission Issues Solutions Section
Bandwidth Management
Codec choice
Adaptive Video Techniques
3.2.1
Packet Losses Loss and Error Management 3.2.2
Delay Variation (Jitter) Playout Buffer 3.2.3
Transfer Delay Network QoS 3.2.4
Table 3-1: Video delivering problems and solution
The bandwidth is the most important characteristic that affects directly the video quality of
service. The bandwidth between the receiver and the sender is generally known and it is time-
36