.VOB files are not actual MPEG files. For unencrypted DVDs .VOB files can be renamed to .MPG and played, in most cases. However, there may be DVDs for which .VOB files cannot be renamed to .MPG and played properly. Depending on the MPEG-2 splitter used, the video might be jerky, with chunks missing, or it may not play at all. If the DVD is encrypted, trying to play a .VOB file directly will result in garbage output.
This problem is caused by the fact that the information required to parse the .VOB file is in the .IFO files present in the DVD directory. The correct way to play or convert a DVD using LEADTOOLS is to play or convert one of the .IFO files present in the DVD directory.