According to the described method, interframe similarities s(i) are calculated for the frames of the video sequence, each interframe similarity s(i) being indicative of the similarity of two consecutive frames i-1, i. As it has been found, an analysis of the interframe similarities allows to determine various parameters that are characteristic for the mean opinion score MOS, such as the downsampling rate, pausing, or a noise-dependence of the interframe similarity at the keyframes. An objective mean opinion score MOSo being a value close to the mean opinion score is derived as a value linear in the pausing parameter, a keyframe distance parameter and further quality parameters measured in the spatial domain, corrected by a second value being an exponential model in the downsampling rate.