For each feature that transmits, converts or records pre-recorded synchronised time-based media that has a captions track, are the captions correctly preserved at the end of the process?

Tests

1. 4.15.1

   For each feature that transmits, converts or records pre-recorded synchronised time-based media that has a captions track, do the captions meet at the end of the process these conditions?

   Captions are present.
   Captions can be displayed.
   Captions are correctly synchronised.
   The key features of captions are preserved.