When playing MP3 files, using the QMediaPlayer::setPosition does  not work as expected and can cause playing to stutter or halt.  I wrote a simple test program which starts playing an MP3 file, and clicking a button generates a random position within the file and uses setPosition to move to that location.   Occasionally, setPosition works as intended, but it will always fail after a few tries .. causing audio to stop playing without generating any discernible error.

Just wanted to bring this to your attention.  I've got several MP3 players on my system and none of them exhibit similar behavior.   On a similar note, using setPosition on video (MP4) files works better, but still can cause the audio to get screwed up on occasion.