Sony HDR-AS50 Manual page 57

Hint
Use the "Settings" menu in advance to change the movie length, BGM
* This setting is only available in some countries and regions.
After creating the highlight movie, you can "Copy" it to your smartphone.
5
Hint
Use the movie player application of a smartphone to play the copied highlight movie.
Note
Update PlayMemories Mobile to the latest firmware version in advance.
The created highlight movie's format is MP4.
*
and the audio mix.