## 6 Experimental Results and Discussion  
### Hurst Index Differences between Original and Temporal Recovery Data in LRD Estimation  
HFR traces are collected for different video content of 120 fps of the same duration, where the original content has been compressed according to HEVC standard. Hurst exponent is calculated for LRD estimation, where it varies depending on the coarse approach applied in the calculation. After examination, it is evidenced that in most cases it has values in the expected range, i.e., 0.5 < \(H\) < 1. This is presented for four Hurst index methods and ReadySetGo sequence in Table 2. LRD behavior is evident for the different index calculation methods applied: generalized method, DFA method, Hurst exponent calculated using periodogram and R/S statistics [68; 69; 70; 71; 72; 73; 74]. For example, the periodogram method applied in the case of crf36 is illustrated in Figure 6 for the ReadySetGo and YachtRide sequence. Lower Hurst values are obtained for TRR compared with the original, where in Figure 6, the TRR trend is presented with a solid line compared with original, which is presented with a dashed line. Still, these lower Hurst values are above 0.5, showing LRD. The dashed lines are found for data where no frame rate change is made. In the case of R/S statistics, it is also evident that the temporal resolution recovery case shows a decrease in Hurst index. This is illustrated in Figure 7. Such difference between indices may be useful for better understanding the changes found in recovered video data. The differences in Hurst evaluation using R/S statistics for UHD 120 fps compressed ReadySetGo sequence are shown in Table 3 for different crf values (\(H_{diff}\)). The method was used repeatedly for the other five original videos from Table 1. The averaged difference values \(H_{diff\text{-}range}\) for each tested crf are also shown in the table. The relative difference varies from \(-11.51\) to \(1.30\) percent. The highest absolute relative difference is obtained for crf24. Higher crfs show less variations in Hurst indices than the original sequences. This means that a higher difference in temporal recovered from nonrecovered data are expected in lower crfs, meaning higher video quality. Similar calculations are made in the case which is not common in practice for 120 fps HFR, where frame rate primarily increases and then decreases to 120 fps. In the additional case, such modifications show behavior more similar to the original data, as shown Figure 8. Nevertheless, temporal recovery data are still different from the original case. This additional case and its similarity to original traces are also illustrated in Figure 8.  
The obtained Hurst index differences between original and temporal recovery data in LRD estimation show that TRR case generally decreases index values. If the original and corresponding TRR sequences are available, such differences may be useful in recognizing the TRR change. Moreover, each content shows different behavior, where maximum absolute difference in Hurst index may vary depending on the content. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**No.** & **Hurst Method** & **crf20** & **crf24** & **crf28** & **crf32** & **crf36** & **crf40** \\ \hline
1 & Hurst (Generalized) & 0.6928 & 0.7058 & 0.7164 & 0.7138 & 0.7126 & 0.7089 \\
2 & Hurst (DFA) & 0.7527 & 0.7962 & 0.8132 & 0.8024 & 0.7975 & 0.7832 \\
3 & Periodogram & 0.7554 & 0.6036 & 0.5154 & 0.5512 & 0.5901 & 0.6113 \\
4 & R/S statistics & 0.8652 & 0.8943 & 0.8848 & 0.8721 & 0.8678 & 0.8585 \\ \hline \end{tabular}
\end{table} 
Table 2: Long-range dependency (LRD) estimation via Hurst index calculation for ultra-high-definition (UHD) 120 fps compressed ReadySetGo sequence. Figure 8: (**a**) R/S statistics method applied for ReadySetGo with crf36; (**b**) R/S statistics method applied for different crf values, where the TRR trend is presented with a solid line and the corresponding original is presented with a dashed line.