# Assessment of the Quality of Video Sequences Performed by Viewers at Home and in the Laboratory
## 3 Results and Discussion
### Subjective Quality Assessment of Video Encoded Using VP9 Standard
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Bit Rate** & \multicolumn{3}{c}{**640 \(\times\) 360**} & \multicolumn{3}{c}{**858 \(\times\) 480**} & \multicolumn{3}{c}{**1280 \(\times\) 720**} & \multicolumn{3}{c}{**1920 \(\times\) 1080**} \\ \hline
**(kbps)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** \\ \hline
300 & 1.12 & 0.35 & 0.14 & 1.24 & 0.46 & 0.18 & 1.26 & 0.45 & 0.13 & 1.29 & 0.48 & 0.19 \\
400 & 1.48 & 0.51 & 0.20 & 1.52 & 0.51 & 0.20 & 1.69 & 0.56 & 0.17 & 1.62 & 0.76 & 0.29 \\
500 & 1.76 & 0.43 & 0.17 & 1.80 & 0.71 & 0.28 & 0.07 & 0.64 & 0.19 & 2.00 & 0.86 & 0.32 \\
600 & 1.92 & 0.56 & 0.22 & 1.96 & 0.71 & 0.28 & 2.41 & 0.55 & 0.17 & 2.25 & 0.75 & 0.28 \\
700 & 2.09 & 0.57 & 0.23 & 2.04 & 0.74 & 0.30 & 2.71 & 0.55 & 0.17 & 2.43 & 0.92 & 0.34 \\
800 & 2.30 & 0.62 & 0.24 & 2.29 & 0.58 & 0.23 & 2.93 & 0.71 & 0.22 & 2.64 & 0.85 & 0.32 \\
900 & 2.38 & 0.66 & 0.25 & 2.46 & 0.60 & 0.24 & 3.12 & 0.50 & 0.15 &Comparing the results of the MOS evaluation obtained in the laboratory and home conditions, it can be seen that the viewers rated the video image presented under laboratory conditions more highly; Table 9 and Figure 13 show the difference in \(\Delta\)MOS in the evaluation of video quality obtained for measurements made under laboratory and home conditions according to Formula (1). \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline
**Bit Rate** & \multicolumn{3}{c}{**640 \(\times\) 360**} & \multicolumn{3}{c}{**858 \(\times\) 480**} & \multicolumn{3}{c}{**1280 \(\times\) 720**} & \multicolumn{3}{c}{**1920 \(\times\) 1080**} \\ \hline
**(kbps)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** & **MOS** & **S** & **\(\delta\)** \\ \hline
300 & 1.32 & 0.47 & 0.14 & 1.27 & 0.45 & 0.14 & 1.26 & 0.45 & 0.13 & 1.50 & 0.55 & 0.17 \\
400 & 1.62 & 0.58 & 0.18 & 1.64 & 0.58 & 0.17 & 1.69 & 0.56 & 0.17 & 1.83 & 0.66 & 0.20 \\
500 & 2.00 & 0.44 & 0.13 & 1.98 & 0.51 & 0.15 & 2.07 & 0.64 & 0.19 & 2.17 & 0.61 & 0.20 \\
600 & 2.24 & 0.48 & 0.15 & 2.37 & 0.62 & 0.18 & 2.41 & 0.55 & 0.17 & 2.49 & 0.63 & 0.19 \\
700 & 2.50 & 0.51 & 0.15 & 2.63 & 0.49 & 0.15 & 2.71 & 0.55 & 0.17 & 2.74 & 0.76 & 0.23 \\
800 & 2.71 & 0.46 & 0.14 & 2.84 & 0.43 & 0.13 & 2.93 & 0.71 & 0.22 & 3.02 & 0.47 & 0.14 \\
900 & 2.90 & 0.30 & 0.09 & 3.02 &The statistical analysis of the results obtained using the \(t\)-test showed that at the confidence level of \(\alpha\) = 0.05, there is no basis to accept the hypothesis of the identity of the results obtained under laboratory and home conditions. The \(t\)-test values obtained with the Statistica tool for each resolution are as follows:  
* 640 \(\times\) 360; t = 11.1 \(>\) t \(\alpha\) = 2.1, at \(\alpha\) = 0.05;
* 858 \(\times\) 480; t = 11.3 \(>\) t \(\alpha\) = 2.1, at \(\alpha\) = 0.05;
* 1280 \(\times\) 720; t = 13.0 \(>\) t \(\alpha\) = 2.1, at \(\alpha\) = 0.05;
* 1920 \(\times\) 1080; t = 10.5 \(>\) t \(\alpha\) = 2.1, at \(\alpha\) = 0.05. It can be concluded that the differences between the MOS values obtained under the laboratory and home conditions are significant.