Finding the video on a DVD
Every video DVD has a VIDEO_TS folder containing three kinds of files. Only the VOB files hold video:
- VTS_01_1.VOB, VTS_01_2.VOB … — the main video, split into parts of up to 1 GB. VTS_01 is the first title set; a disc with several programmes also has VTS_02, VTS_03 and so on.
- VIDEO_TS.VOB and VTS_01_0.VOB — usually the menu or a short intro. Skip these.
- IFO and BUP files — navigation data only. They contain no video at all.
Can I convert BUP or IFO files to MP4?
No — and no converter can, because there's nothing to convert. An IFO file tells a DVD player where chapters and menus are, and a BUP file is simply a backup copy of the IFO. If you searched for a BUP to MP4 converter, the video you want is in the VOB files next to it in the same folder.
Converting a full movie
Because a DVD splits the movie into roughly 1 GB VOB files, a two-hour film is usually four or five parts. Convert each VTS_01_x.VOB in order (skipping VTS_01_0), then put the MP4s back together with Merge Videos. Converting part by part also keeps each job within what a browser can comfortably handle.
Conversion re-encodes the DVD's MPEG-2 video as H.264, which typically makes the file 50–70% smaller at the same visible quality. It runs on your computer, so a full 1 GB part can take several minutes; a recent laptop is noticeably faster than a phone.
Home DVDs vs. store-bought discs
Home videos, camcorder DVDs and discs you've burned yourself convert directly. Most commercial movie DVDs use CSS copy protection, which scrambles the VOB files; this tool can't remove that protection, and the conversion will fail or produce garbled video.