Chapters extracted with ChapterXtractor aren't right

[yukichigai]

I've done a few DVD -> KVCD and DVD -> OGM conversions, both of which allow you to import chaperts. But for some reason the chapters seem to be "lagged". Chapter 2 starts maybe a half second before it should, then Chapter 3 is a full second before hand, and so on and so forth. The later the chapters are it seems the earlier they are compared to where they should be. I've tried checking the "Closed GOP" settings for KVCDs and that doesn't help, and I ahve no clue what to try for OGMs. The only thing I can figure is that ChapterXtractor isn't pulling the chapters out correctly. I've made sure the framerate is selected correctly, but that doesn't seem to help. I have no clue what needs to be done. Is there some key bit of insight that I'm missing?

[smiller667]

In order to test if chapterXtractor is wrong ot not, try ifoedit (open the ifo, select a pgc & use tools -> save celltimes to text. Chapters will be specified as frame number.

[Emp3r0r]

Here is a screenshot of IfoEdit, ChapterXtractor, and ChapterGrabber displaying the chapter times from a IFO file.http://jvance.com/images/chaptertimes2.png

ChapterXtractor and ChapterGrabber both use vStrip.dll to obtain chapter information. Notice how vStrip obtains more precise time codes, where IfoEdit timecodes seem a little odd. Furthermore, IfoEdit frame numbers become off by one after the first eight chapters.

Anyway, in order to seek directly to where a chapter starts, there must exist a keyframe at the exact frame where the chapter starts.

There is a program that can help force keyframes called KeyframeEnforcer by zulu. Also, you could set zones to force keyframes where chapters start if you use XviD.

[wmansir]

The frames are correct, but the timecodes are off (perhaps depending on the authoring program).

You'll find they are off by 23.976/24 or the inverse I can't remember. I wrote a perl script to correct them back when I was doing SVCD (because VCDEasy took timecodes).

Here's the thread I wrote about it 2+ years ago:
http://forum.doom9.org/showthread.php?s=&threadid=25184

[sysKin]

Also, ogm splitter seeks to keyframes by default - and keyframes are not neccessarly at the location where you'd like them to be.

If you encode with xvid, you can use xvid's zones and their "force keyframe" setting to get perfect seeking. There is a program that does it automatically, use search, I don't remember the name ;)

Radek

[bond]

frame accurate seeking (meaning not only to the keyframes) is possible in .mp4

still setting chapters in mp4 is little bit hard to do, but you could use the nero mp4 dshow muxer filter for this