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5 INTRUSIVE TESTING
Intrusive test methods insert a reference signal into the device under test
processed and therefore possibly impaired file is recorded at the far end site (receiving side).
Like in a subjective test the used video signals are
several seconds. Using natural signals for the measurement is superior to applying artificial test signals, as they
do not properly model a typical operation.
After the coding/transmission procedure the corresponding reference file and the processed (impaired) file are
compared to each other.
Figure 5-1 A typical setup for an intrusive test: The tester outputs a reference stimulus that is
inserted into a network connection at the 'near end side' (origin), while the received signal at the 'far
end side' (termination) is fed back to the tester for difference analysis.
However, due to the fact that the reference signal has to be inserted into the DUT, such measurements are called
'intrusive'
. The DUT can include a wide variety of codecs, networks, bandwidth, service types, etc.
1
The device under test can be anything, e.g. a video codec, a wired/wireless network transmission line,
2
'natural' means in this context no artificially generated test samples, but samples of video content that is or will be
most likely transmitted in such networks or coded by the appropriate codecs.
A D V A N C E D
E V A L U A T I O N
1
natural
2
video samples (audio is optional)
P E R C E P T U A L
O F
V I D E O
Q U A L I T Y
(DUT) (near end side) while the
with a length of
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