Backport of "qtmux: do not base default timescale on centiframes" into 1.20
requested to merge tpm/gstreamer:backport-mr-3049-into-1.20-qtmux-no-timescale-precision-loss into 1.20
Backport of !3049 (merged) "qtmux: do not base default timescale on centiframes".
Commits:
- 194dcd91 qtmux: For video with N/1001 framerates use N as timescale instead of centiframes