Well First off:
The video is 1940X1080 I hope you meant 1920.
If you play a Self Contained HD file 48m in length off the desktop,…you could have sync issues just from a threw-put drive speed issue.
Export Current Settings. Make sure there are no in/out markers on the sequence.
Drop that file into compressor.
Create the DVD mpeg and ac3 file.
Bring them into DVDSP.
They should match.
Chris Tompkins
Video Atlanta LLC