TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

educe the variability of the traffic and bandwidth requirement of the video stream, smoothing
technique is necessary. Smoothing makes use of a client side buffer to receive data in advance of
playback [91], [92], [93], [94], and [95].
3.2.2 Loss and Error Management
Packet loss is a problem that affects considerably the quality of the received video at the client.
It can have a very destructive effect of the reconstructed video because of frame dependency.
Packet loss may arrive at different level and under different consideration. In wired packet
networks, the congestion is the first circumstance on packet loss. Entire packet can be discarded by
routers. Whereas in wireless networks, the transmission channel may cause bit error. Thus, the
packet could be rejected by the application layer.
Before presenting the approaches for reliable video streaming, it is necessary to understand the
effect of packet loss on compressed video stream. In general, there are two basic problems induced
by video packet losses. First, the loss of bitstream synchronization or when important
synchronization marker is lost. In this case, the decoder may loss track of what bits correspond to
what parameters. Second, since the video has a particular structure composed of frames mutually
dependent, the loss of one frame may make all depending frame unusable.
To deal with the effect of losses, it is necessary to have functions to muffle the loss. There are
two types of approaches for reliable video transmission. The first approach is a sender-based
approach, in which the sender can be active or passive to recover from losses. The second
approach is a receiver-based approach in which the client conceals the loss by some techniques.
Figure 3-10 illustrates the different approaches. These approaches are discussed in subsequent
subsections.
Reliable Video Streaming
Sender-based approach
Receiver-based approach
Active
Passive
Error
Concealment
End-to-end
retransmission
Interpolation
Freeze frame
Forwarding error
correction
Interleaving
Error resilience
Media-independent
Media-specific
Application
level framing
Data partitioning
Figure 3-10: Taxonomy for reliable video transmission
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