When I copy an mpg file and move it another place it becomes a .vob file.

[DuaneBidoux]

I can't figure out why. The file is still the same size as the mpg file except the tag is .vob. If you try to play the file it (obviously) says the file has the wrong extension for playing on a player.

But, if you change the tag to .mpg it then opens and plays normally telling me that the problem is in the tagging of the file as a .vob not in the actual file being changed from an mpg to a vob.

[paparush]

1. Is this on Windows?

How, EXACTLY, are you copying and moving the original file?

[FormerDittoHead]

2. VOBs aren't Mpegs... here's the difference...

VOBs are the DVD format.

The VIDEO is encoded on DVDs in the MPEG format, but the AUDIO is *NOT* "MPEG audio".

Parting from the Mpeg standard, DVDs encode audio in AC3, which allow the embedding of surround sound. AC3 is a proprietary, licensed format, so many early video editing programs which otherwise work with mpeg files don't work with mpeg+AC3 files. DVD authoring programs will re-encode the audio of mpeg files in order to convert the audio to AC3.

So for example, my 2 DVD players (Toshiba and Phillips) will play DVDs (of course) and also Mpeg files burned to a data disc, but will NOT play vob files burned onto a data disc or play the very same file but with the extension changed to ".mpg". This is true even though these players already have AC3 capability. The way these machines think, VOBs are only for DVDs in the full blown DVD "title.ifo" structure (look at the directory of a DVD movie to see what I mean here). The point here is that players can be very picky about the difference between VOBs and MPEG.

So somewhere in there is your problem. I'm guessing the file was copied from a VOB file from a DVD? I could see this happening with those camcorders which burn directly to mini-DVD. I'm guessing this or something like this is what's going on, because the only time you'd need to do AC3 encoding would be for DVD player compatibility.

There are opensource / free programs for Windows which will convert VOBs to true Mpegs without reprocessing the video.

Was this any help?