Concerning MPEGS...

Factual Questions
1

OK, so why is it that some MPG files I can click the little scroll bar and jump to whatever point in the movie file I want to, whereas others are formated so that I cannot do this, and have to instead watch the whole file, even if I only want to watch a small piece at the end?

Does it have something to do with MPEG-1 vs MPEG-2? Or is it just some stupid choice an encoder made at the time of encoding? Also, is there any way to convert one to the other? So that a file that originally has to be viewed all the way through can now be viewed in segments?

2

I believe the ones that won’t let you jump around are incomplete, perhaps missing only a few seconds at the end. That’s been my experience anyway.

I’m not sure how to fix it except to run it through a program like Microsoft’s MovieMaker, which will convert it to an ASF or ASX.

3

MPEGs that don’t let you jump around are streaming video files. This means that they play as they download and you can’t jump around because that section of the video has not downloaded yet.

4

There are quite a few programs out there that can change a downloaded video file from a “streaming” to a “seekable” file in the same format. As was suggested, you could also convert the file into a different format with many of the same programs and end up with a “seekable” file.

5

OK, so I have Windows XP, which comes with Windows Movie Maker. How do I change the file format? I can load the file into the movie-maker, but I can’t save it as anything. it just shows up as a clip in the workspace.

6

A file that won’t let you seek might be missing keyframes: all the frames are there, but the only way to skip to an arbitrary point would be to decode every single frame from the beginning to that point. You can fix that with VirtualDub, by turning on rekeying in the “extended open” dialog.

Or if it’s a DivX clip (a.k.a. MPEG4), it might be missing the index, which you can fix with programs like DivFix.

7

try giving more information about the problematic file (ie: resolution and framerate). My guess is that it’s an mpg2 file that you are watching with a player that is not intended for that purpose (windows media player probably). try a software dvd player like powerdvd and see if you can seek.

8

Mr2001 is right. It’s all about keyframes .

9

Mr2001 is correct. Check your media player’s documentation to see if there is some way it can be made to generate the index/keyframes. For example, with the movie player I use (MPlayer), you simply use the -idx option.