# Load Balancing Strategies for Slice-Based Parallel Versions of JEM Video Encoder
## 3 Parallel Approaches
### Asynchronous Algorithm: JEM-SP-ASync
## 5 Conclusions

Some of the most important features of the JEM video encoder in relation to intra-prediction have been briefly described here. These features focus on reducing the bitrate in order to minimize the bandwidth required for transmission. These new features cause a dramatic increase in the computational cost of encoding compared with previous video encoder standards, including HEVC. The parallel algorithms developed here make use of slices to implement domain decomposition; however, if the domain decomposition does not allow the volume of data assigned to each process to be perfectly balanced, the high computational cost causes significant cost imbalances. Moreover, a perfect balance of the data to be encoded by each process also does not ensure load balancing, unlike in the case of the HEVC encoder. In the JEM approach, it is not guaranteed that perfect domain decomposition gives rise to a perfect computational load balance. The JEM-SP-Async \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & \multicolumn{6}{c}{**PSNR (dB)**} \\ \hline Video & NoT and & Slice & & QP & QP & QP & QP \\ sequence & slices & size & & 22 & 27 & 32 & 37 \\ \hline \multirow{6}{*}{BQSQ} & \multirow{6}{*}{4} & \multirow{6}{*}{2} & Seq. & 42.7616 & 38.6735 & 34.9935 & 31.4817 \\  & & & Par. & 42.9435 & 38.8538 & 35.2465 & 31.7929 \\  & & & Diff. & 0.4\% & 0.5\% & 0.7\% & 1.0\% \\  & & & Seq. & 42.6559 & 38.5985 & 34.9282 & 31.3503 \\  & & & Par. & 42.9435 & 38.8538 & 35.2465 & 31.7929 \\  & & & Diff. & 0.7\% & 0.7\% & 0.9\% & 1.4\% \\  & & & Seq. & 42.6338 & 38.4881 & 34.7934 & 31.2209 \\  & & & Par. & 42.9312 & 38.8410 & 35.2348 & 31.7715 \\  & & & Diff. & 0.7\% & 0.9\% & 1.3\% & 1.8\% \\ \hline \multirow{6}{*}{PART} & \multirow{6}{*}{2} & \multirow{6}{*}{14} & Seq. & 42.1050 & 38.0071 & 34.2767 & 30.7610 \\  & & & Par. & 42.1459 & 38.0528 & 34.4646 & 30.9932 \\  & & & Diff. & 0.1\% & 0.1\% & 0.5\% & 0.8\% \\  & & & Seq. & 42.0037 & 37.9629 & 34.188 & 30.6701 \\  & & & Par. & 42.1434 & 38.0467 & 34.455 & 30.9788 \\  & & & Diff. & 0.3\% & 0.2\% & 0.8\% & 1.0\% \\  & & & Seq. & 41.8932 & 37.7962 & 34.1187 & 30.5650 \\  & & & Par. & 42.1409 & 38.0440 & 34.4525 & 30.9748 \\  & & & Diff. & 0.6\% & 0.7\% & 1.0\% & 1.3\% \\ \hline \multirow{6}{*}{FOUR} & \multirow{6}{*}{4} & \multirow{6}{*}{15} & Seq. & 45.1104 & 42.6808 & 39.9899 & 37.1100 \\  & & & Par. & 45.1828 & 42.7848 & 40.1469 & 37.3029 \\  & & & Diff. & 0.2\% & 0.2\% & 0.4\% & 0.5\% \\  & & & Seq. & 45.0631 & 42.6244 & 39.9007 & 36.9927 \\  & & & Par. & 45.1802 & 42.7800 & 40.1387 & 37.2943 \\  & & & Diff. & 0.3\% & 0.4\% & 0.6\% & 0.8\% \\  & & & Seq. & 45.0372 & 42.6250 & 39.8448 & 36.9191 \\  & & & Par. & 45.1785 & 42.7756 & 40.1334 & 37.2841 \\  & & & Diff. & 0.3\% & 0.4\% & 0.7\% & 1.0\% \\ \hline \multirow{6}{*}{PARK} & \multirow{6}{*}{2} & \multirow{6}{*}{68} & Seq. & 42.4621 & 39.5641 & 36.8565 & 34.2881 \\  & & & Par. & 42.5295 & 39.6277 & 36.9372 & 34.3736 \\ \cline{1-1}  & & & Diff. & 0.2\% & 0.2\% & 0.2\% & 0.2\% \\ \cline{1-1}  & & & Seq. & 42.4194 & 39.5221 & 36.8147 & 34.2439 \\ \cline{1-1}  & & & Par. & 42.5264 & 39.6253 & 36.9344 & 34.3672 \\ \cline{1-1}  & & & Diff. & 0.3\% & 0.3\% & 0.3\% & 0.4\% \\ \cline{1-1}  & & & Seq. & 42.3886 & 39.4936 & 36.7939 & 34.2173 \\ \cline{1-1}  & & & Par. & 42.5215 & 39.6188 & 36.9288 & 34.3554 \\ \cline{1-1}  & & & Diff. & 0.3\% & 0.3\% & 0.4\% & 0.4\% \\ \hline \hline \end{tabular}
\end{table} 
Table 17: Comparison of PSNR. parallel algorithm was proposed to solve these drawbacks, which, as explained above, did not arise in previous standards. The automatic computational cost balancing system included in the design of the proposed parallel algorithms was validated based on the experimental results. These results show that the average value of efficiency rose from 71.3% to 93.4% when the JEM-SP-ASync algorithm was used instead of the JEM-SP-Sync algorithm.