TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

correctly received block. The missing block can be regenerated from adjacent block. This technique
is refereed as spatial interpolation. In temporal interpolation, the missing block is replaced by the
equivalent from previous correctly received frame (freeze frame). This approach is very useful when
there is little motion. The combination of these methods (interpolation and freeze frame) can be
effective when applying a motion estimation and compensation. The problem of this approach is
how to accurately estimate the motion for the missing block. Possible approach use motion
estimation vector of neighboring motion vector. This approach is applied efficiently for one
missing block, but the problem could be more difficult when more than one block is lost. For
example, a packet loss may lead to the loss of entire frame. In this case, it is not possible to apply
interpolation or motion estimation. Generally, the lost frame is replaced by the last correctly
received frame (freeze frame).
3.2.3 Delay Management
Delay is an important performance metric of packet video applications. The delay concerns
the end-to-end transfer delay end delay variation.
3.2.3.1 End-to-End Delay Management
The end-to-end delay is viewed as the time when the packet leaves the media server until the
time it is consumed by the client. It is highly correlated to the time induced by the network element
including queuing delay and link-level retransmission. The management of the end-to-end delay is
assured by network QoS solutions which are presented in Section 3.2.4
3.2.3.2 Jitter Management
The jitter is the variation of the end-to-end delay experienced between the server and the
client. The effect of the jitter can be very disaster on the quality of the received video. It can lead to
interruption in continuous playback at the receiver. Jitter destroys the temporal relationships
between periodically transmitted media unit that constitute a real-time media stream [115]. To
overcome the effect of the jitter it is necessary to have a buffer to absorb the variation of the delay.
Buffering provides a number of advantages such as jitter reduction, error recovery through
retransmission, error resilience through interleaving and smoothing capabilities. However, the
playout buffer introduces undesired additional delay before the playback can begin. Some works
have experienced an analytic model to bound the jitter and design a model for adaptive playout
buffer such as works presented in [116], [117], [118], and [119]
3.2.4 IP QoS Network Management
Multimedia applications require stringent delay and loss requirement and a large bandwidth.
The current widely supported best-effort service model does not provide any guarantees of
bandwidth, loss and delay. Currently, there is a considerable effort by various organizations such as
IEEE, IETF, ISO, and ITU-T to design and implement a quality of service framework for various
networking technologies especially for IP. In the following subsection we give an overview of the
methods developed by the IETF, because it provides the more promising QoS framework
approaches for the Internet and we present related work that provide QoS-support for packet
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