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7 CONCLUSION
The first set of experiments is related to the
smoothing algorithm itself. By analyzing the
smoothed video traces we can conclude that the
efficiency of the algorithm depends on the type of
the video. The
Susi und Strolch trace file have the
greatest reduction (about 65 %, based on the peak-
to-mean ratio metric), the worst performance was
observed in the Silence of the Lambs trace file (only
28 % of reduction). We think this happened because
in the
Susi und Strolch the instants of bursts are,
predominantly, punctual, while in the Silence of the
Lambs the burst is spread in time.
The smoothing algorithm proposed in this paper
is based on two other smoothing algorithms: e-
PCRTT and MCBA. We have showed that it can
bring good results in terms of peak bandwidth
reduction, keeping the simplicity of the e-PCRTT
computation associated with the ability of extend the
transmission rate runs as much as possible, which is
a characteristic present in MCBA.
The second set of experiments explores the effect
of transmitting such a smoothed video over a simple
network configuration where video competes with a
concurrent traffic (FTP). One characteristic of the
FTP traffic is that it occupies all the available
bandwidth when it is present. In this case, the
smoothing contributed to optimize the use of the
bandwidth by reducing the bursts.
The study of the client buffer occupancy is
interesting as it ensures that the buffer will never
overflow nor underflow, as this is the assumption of
the smoothing algorithm.
The end to end delay in all smoothed trace files
has almost the same value, which in turn, is higher
than in the original trace file transmission. The
delay’s variation is more sensitive in the smoothed
traces. This was expected by the principle of the
smoothing: The new transmission plan imposes
more or less delay once it changes the transmission
rate (increasing or decreasing it).
Finally, the study of packet loss is very important
in a video transmission since a single lost packet can
degrade a whole GoP. We measured this effect
through the FER and UO metrics, but since we are
not dealing with packet discard discipline, the study
is merely informative.
Some kind of intelligent packet discard discipline
at the routers leading in a better network utilization
can also be addressed.
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