The Need For Quality Testing - OPTICOM PEVQ Manual

A D V A N C E D P E R C E P T U A L
E V A L U A T I O N O F V I D E O Q U A L I T Y
3 THE NEED FOR QUALITY
TESTING
The need for testing the perceived quality of video information after transmission and decoding is a key element to
guarantee for the customers' satisfaction, and thus the success of new video based services. The worst scenario
that could, for example, happen to service providers is that the customers are annoyed by the poor quality-of-
service in such a way that they are not likely to consider this new feature in the future at all. The second worst
effect to be expected would be if customers are going to switch to a competitive operator that provides better
service quality.
This is likely to spoil the revenue expectations for the value added by the video services on a large scale. However,
all this is not unrealistically far-fetched, in particular when we keep in mind that customers expectations are well
aligned from their daily television consume. Of course, mobile video transmission on every user's terminal
represents an innovative advantage, still comparable to the introduction of mobile phones as such. Nevertheless,
new technologies will not find acceptance if especially video information is not delivered in an acceptable quality.
A bad video connection might severely disturb the speech link, even though the voice quality as such is excellent.
These effects are known as audio-visual interaction and will be taken into account in the future design of
perceptual measurements, too.
Let us take an example. As a matter of fact lossy coding techniques and noisy transmission channels may
irreversibly destroy relevant parts of crucial information. A typical video coding technique using a simple block-
matching algorithm can already tremendously impair a video signal, as depicted in the following sequences below.
Figure 3-1 shows a single frame taken from a typical video stream – in this case, the red Ferrari of Michael
Schumacher leaves the track and rushes into the green. The video content is undistorted and it can be seen that
the Ferrari does not seem to be broken at all. Schumacher is doing ok – a vital information for every formula one
fan watching the scene on his mobile.
Figure 3-1 Schumacher and the Ferrari are ok!
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