am f54da15b: am eff30e3d: Change the default time scale for audio/video track during recording and reduce rounding errors in calculating the sample duration

Merge commit 'f54da15b7c3fa55268451c485544e831832fdf15'

* commit 'f54da15b7c3fa55268451c485544e831832fdf15':
  Change the default time scale for audio/video track during recording