Replace sws_scale with sws_scale_frame and enable multithreaded reformatting
#1250
| Job | Run time |
|---|---|
| 3m 2s | |
| 44s | |
| 9m 42s | |
| 9m 32s | |
| 5m 50s | |
| 9m 4s | |
| 37m 54s |