EXFO EXpert IPTV Test Tools (FTB-1 / 2 Pro) - Manual (Page 62)

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For picture quality, VQmon/HD reports both Relative MOS-V and Absolute MOS-V
scores:
• Relative MOS-V is an estimated perceptual quality score that considers the effects
of codec/quantization level, the impact of IPTV impairments (e.g., packet loss) on
the GoP structure and video content, and the effectiveness of loss concealment
methods—but does not consider the image size/resolution, frame rate, or
scanning method (interlaced vs. progressive).
• Absolute MOS-V is an estimated perceptual quality score that considers all the
abovementioned factors as well as image resolution, frame rate, and the use of
progressive vs. interlaced scanning.
Some video formats offer inherently higher perceptual quality than others—for
example, in unimpaired conditions, the quality of an HD broadcast will be higher than
that of SD; 1080p better than 1080i or 720p; 60 frames per second better than 30 fps,
etc. VQmon/HD’s Absolute MOS-V score takes these factors into consideration, and
thus provides an accurate estimate of “overall” perceptual quality.
Because it is independent of image resolution/frame rate, the Relative MOS-V score
helps provide an indication of video quality relative to the ideal for a given video
format.
Example: An IPTV service provider offers 480i SD, 720p HD, and 1080p HD broadcasts.
Assuming unimpaired conditions, the services might receive the following scores
(values provided for example only):
Absolute MOS-V: 480i = 4.0 720p = 4.3 1080p = 4.7
Relative MOS-V: 480i = 4.5 720p = 4.5 1080p = 4.5
Relative MOS-V can be used to simplify alert thresholding in cases where multiple
video formats are in use.