Absolute and Relative MOS-V

87.1.1 Absolute and Relative MOS-V

When comparing MOS values, it is important to consider that some types of video inherently produce a higher level of quality than others. Relying solely on absolute MOS values can be misleading when comparing dissimilar types of video service, as viewers tend to form expectations of quality based in part on the perceived capabilities of the medium.

For example, a video viewed on a handset with a small screen might receive an absolute MOS of 3.1 when little or no quality degradation is evident, while for a handset with a larger screen, the same MOS value might suggest that some noticeable impairments were present.

To facilitate quality comparisons between different video service types, VQmon provides both Absolute and Relative MOS-V:

Absolute MOS-V considers the impact of frame resolution, frame rate, codec, compression level, transmission impairments, and frame loss concealment on video quality.

Relative MOS-V considers the impact of all of the factors used to determine Absolute MOS-V except frame resolution, producing a MOS relative to the ideal for the current video format.

All VQmon MOS scores are reported as separate instantaneous, minimum, maximum, and average values, the last three spanning the current streaming session.