How to convert 'vob' file to 'mpeg'

I want to convert my dvd files(VOB) into mpeg. Please, tell me. What to do for it?

VOB files ARE MPEG files.
MPEG-2, so you may need proper decoders to read them on your PC. For example http://sourceforge.net/projects/gplmpgdec
And they may have stuff you don’t need, like multiple subtitle tracks or multiple languages. You can demultiplex those (look for TMPGEnc free edition).
If you just copied the file from a commercial DVD, then it’s encrypted and you definitely won’t be able to read it. You have to 'rip' it, that is decrypt the VOB from the DVD to an unencrypted VOB on your hard drive. Google for smartipper for the task.
If you want to convert the VOB (which is MPEG-2) to MPEG-1, use TMPGEnc free edition.

Or you can use DVDShrink to copy it, you’ll be able to read it if you use that.

ulrichburke