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TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

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In RBF,<br />

2<br />

D = X − is the distance between X and U . ϕj(x) measures similarity, i.e. the<br />

k<br />

U k<br />

mapping function. λjk in the Figure is a set of scalar weights that connect each of the receptive<br />

fields to the class outputs of the network. The general equation of an output of the neuron j is<br />

given by:<br />

n<br />

∑<br />

F ( X ) = λ ϕ ( X )<br />

k<br />

j = 1<br />

jk<br />

j<br />

R<br />

j<br />

The classifier maps the vector X (an Audio Visual Object) to the class with the largest output:<br />

n<br />

{ x ∈ R / F ( x)<br />

≥ F ( x ∀k}<br />

≡ )<br />

j<br />

k<br />

{ (x)}<br />

F j<br />

A neural network takes in it input the feature vector X, produces computing class outputs<br />

, and then, classification decisions are made based on the largest output. The classification<br />

cannot be accomplished without knowing the characteristic of the underlying transport<br />

mechanisms.<br />

4.1.3 Performance Evaluation<br />

This section presents our experiment testbed, and some results got by using our MPEG-4<br />

platform. During experiments, two scenarios are investigated, the first on the standard MPEG-4<br />

framework (without any mechanism of QoS) and the second with the new MPEG-4 framework<br />

(with Classification Layer and prioritization mechanisms).<br />

We loaded the network by background traffic to generate congestion. Measurements are done<br />

to evaluate packet losses and end-to-end one-way delay from the server to the client.<br />

4.1.3.1 System and Network Models<br />

In our experiments, we have used an MPEG-4 video composed of three <strong>Video</strong> Objects. Each<br />

object is carried through an elementary stream. These objects are (see Figure 4-4 for more details):<br />

(1) Object 1: The logo at the top left of the MPEG-4 <strong>Video</strong>,<br />

(2) Object 2: The background of the MPEG-4 <strong>Video</strong>,<br />

(3) Object 3: The person.<br />

Scene<br />

logo<br />

Background<br />

Speaker<br />

MPEG-4 Scene<br />

Figure 4-4: MPEG-4 scene used for experiment<br />

69

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