## 4 Results and Discussion
### Performance Evaluation
#### 4.2.2 \"Akiyo\" Video Sequence  
Table 4 presents the experimental results of the \"Akiyo\" video sequence. From the table, it can be seen that the improvement in PSNR of DIVCOM over the DIS codec is between 0.007 dB and 0.021 dB, while PDIVCOM gives an improvement in PSNR between 0.037 dB and 0.12 dB over the DIS codec. Even though the coding efficiency of DIVCOM improves by between 0.38 kbps and 1.7 kbps over DIS codec. In some cases, when the variance is less than 0.1, the coding rate of DIVCOM is worse than DIS. The coding efficiency of PDIVCOM is better than DIS by between 1.53 kbps and 10.938 kbps. On a frame-by-frame base analysis, PDIVCOM is better than DIVCOM because it has fewer occurrences of frames that have worse PSNR and coding rates than DIS. Overall, the PDIVCOM outperforms other codecs investigated for this test video sequence. Table 5 presents the results for the Wyner-Ziv (WZ) coder part for decoding WZF. For DIVCOM, the average PSNR gain per WZF over DIS ranges from 0.0137 dB to 0.413 dB, while for PDIVCOM, the gain ranges from 0.0654 dB to 0.24 dB. The average channel-decoding rate results indicate that DIVCOM achieves an average coding efficiency value between 55 bits and 243 kbits. However, in one case where a few frames had a variance of less than 0.1, additional bits were requested several times to mitigate the errors. This resulted in DIVCOM having a worse coding rate than DIS. PDIVCOM achieves an average coding rate between 219 bits and 1.28 kbits. It can also be observed that for this video sequence PDIVCOM outperforms both DIS and DIVCOM in terms of coding efficiency. The gain comparison shows that there are only slight PSNR gains acquired by both proposed codecs. This is because the estimated CNM parameter used in the decoding process is not suitable for some of the frames with a variance of around 0.1, so this results in inaccurately reconstructed frames. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Video** \\ **Sequence** \\ \end{tabular} } & \multirow{2}{*}{\(\mathbf{Q_{m}}\)} & \multicolumn{3}{c}{**Average PSNR**} & \multicolumn{3}{c}{**Coding Rate**} \\  & & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(kbps)**} \\ \cline{3-8}  & & **DIS** & **DIVCOM** & **PDIVCOM** & **DIS** & **DIVCOM** & **PDIVCOM** \\ \hline \multirow{4}{*}{Akiyo} & 1 & 36.5622 & 36.5688 & 36.5988 & 188.5562 & 187.2031 & 187.0215 \\ \cline{2-8}  & 2 & 37.9728 & 37.9896 & 38.0227 & 235.6357 & 234.3213 & 233.8198 \\ \cline{2-8}  & 3 & 38.8950 & 38.9045 & 38.9394 & 266.1543 & 264.8397 & 262.4297 \\ \cline{2-8}  & 4 & 39.7082 & 39.7128 & 39.6677 & 329.874 & 329.4976 & 322.6880 \\ \cline{2-8}  & 5 & 40.6535 & 40.6747 & 40.7688 & 387.9673 & 386.311 & 379.0576 \\ \cline{2-8}  & 6 & 40.9639 & 40.9827 & 41.0656 & 424.4033 & 439.0259 & 413.4653 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Visual quality and rate performance evaluation of different codecs for “Akiyo” video sequence at frame rate of 15 Hz. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Video** \\ **Sequence** \\ \end{tabular} } & \multirow{2}{*}{\(\mathbf{Q_{m}}\)} & \multicolumn{3}{c}{**Average Channel Decoding Rate per WZF (bits)**} & \multicolumn{3}{c}{**Average PSNR Gain per WZF Compared to DIS (dB)**} \\ \cline{3-8}  & & **DIS** & **DIVCOM** & **PDIVCOM** & **DIVCOM** & **PDIVCOM** \\ \hline \multirow{4}{*}{Akiyo} & 1 & 2733 & 2535 & 2509 & 0.0137 & 0.0654 \\ \cline{2-8}  & 2 & 3436 & 3244 & 3170 & 0.035 & 0.1034 \\ \cline{1-1} \cline{2-8}  & 3 & 4309 & 4116 & 3765 & 0.0197 & 0.0921 \\ \cline{1-1} \cline{2-8}  & 4 & 8674 & 8619 & 7623 & 0.0094 & \(-\)0.084 \\ \cline{1-1} \cline{2-8}  & 5 & 10,417 & 10,174 & 9113 & 0.044 & 0.2389 \\ \cline{1-1} \cline{2-8}  & 6 & 13,732 & 15,871 & 12,132 & 0.0413 & 0.2097 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Coding efficiency evaluation of proposed novel online CNM for “Akiyo” video sequence.