Travel video using a mixture of photos, mp3 music and video clips with sound from Nikon z7 shot at 1080p. When the project is exported to a file it is perfectly in sync at any resolution - even upscaled to 4k.  When I  burn a BluRay, the A/V sync in the playback starts to drift.  By the end of a 30 minute video, it is off by several seconds.  I tried different combinations of settings, with no change. Tried to burn a dvd as a test - same sync problem.  New relatively high end desktop computer. I am not an expert.  Any ideas?