Using VOB and MPEG files without reencoding
MPEG files will automatically be passed through if they are DVD compliant:
Video 720x576 (PAL) or 720x480 (NTSC)
Audio MP2 or AC3, 48000Hz
and the same format is chosen in DVD settings dialog.
You can check the audio/video encoding option in the title properties dialog: it must be set to Copy to skip reencoding (since DVDStyler 1.7.0).
VOB files will normally neither be reencoded nor be remultiplexed -- see the option "Do not remultiplex/transcode" in the title properties dialog (since DVDStyler 1.7.0).
But Note: DVDStyler does not support split VOB files yet. If the VOB size is greater than 1 GB, it will automatically be split into multiple VOB files before burning the DVD. If you have such files (e.g. vts_01_1.vob ... vts_01_4.vob), you need to join them together as one single VOB file using the command line
copy /B vts_01_1.vob + vts_01_2.vob + vts_01_3.vob + vts_01_4.vob vts_01.vob
or other tools such as VOBMerge.