Changing field order flags = losing chapter points.

[gadgetguy]

I have a DVD that I made several years ago, (before I knew better) and just discovered that the field order flags were set to TFF, but the video is BFF. I want to just change the field order flags without re-encoding and I want to be able to just reinsert the corrected VOBs into the original file structure because the menu system is rather extensive and took quite a bit of effort to create the first time using both TDA1.5 and pgcEdit (or maybe ifoEdit). The DVD is a collection of music videos with narration between the music segments to tell a story. The Main menu offers "Play" and "Song Select". The "Song Select" menu allows you to select a song and at the end of the song it returns to the menu rather than continuing on through the rest of the video. Song select skips the narration segments and only plays the songs.

The only program I could find that will change the flags without re-encoding is Restream, and it works, but it requires the elementary video stream, so I converted the VOBs to mpg using TDA 1.5, then demuxed using ProjectX. I then corrected the flags with Restream and placed the corrected video and audio into TDA 1.5 and created the VOBs without a menu. I then replaced the original VOBs with the corrected ones.

Now the problem...
The chapter points don't work correctly. When I select "Play" and then try to step forward through the chapters, it jumps to the first chapter point, but it won't go to the second. Instead it jumps back to the first chapter point (not back to the beginning of the video). The Song Select menus however, do work to take me to the correct video and return when it's completed. I always thought the Chapter point information was part of the ifo, but it would seem that isn't the case. I have tried to re-author and set the chapter points to the same frames/times as the original, but TDA won't always let me put them back in the exact same place (I also don't understand this because the files shouldn't have been re-encoded in any of this). Where I was able to set the Chapter points in the same position it seems to work, but where I had to set "nearest possible" it doesn't work.
Any suggestions on a different method or tools is welcome. TIA

[manono]

Hi-

I then replaced the original VOBs with the corrected ones.

It doesn't work like that.

I have tried to re-author and set the chapter points to the same frames/times as the original, but TDA won't always let me put them back in the exact same place (I also don't understand this because the files shouldn't have been re-encoded in any of this).

The chapter points have to be on I-Frames. By changing the field order I guess you changed the position of some of the I-Frames. That may not be fixable without reencoding, but here's how I'd do it:

Demux using PGCDemux. The chapters will be contained in the celltimes.txt you get. Don't forget to check the "demux video stream" box. Run the M2V through ReStream. Remux using Muxman, adding in the chapters in File->Import Chapters. Stick the newly fixed DVD back into the original DVD using VobBlanker. Open the original DVD in VobBlanker. Highlight the VTS containing the video in question so that it appears in the lower window. Highlight it in the lower window and hit the "Replace" button on the right. Scroll to and add in the newly reauthored DVD. Give it an output folder and process.

[gadgetguy]

Thanks. I have found where the problem lies.

Hi-

I then replaced the original VOBs with the corrected ones.

It doesn't work like that.

Except that it did.

I have tried to re-author and set the chapter points to the same frames/times as the original, but TDA won't always let me put them back in the exact same place (I also don't understand this because the files shouldn't have been re-encoded in any of this).

The chapter points have to be on I-Frames. By changing the field order I guess you changed the position of some of the I-Frames.

I know chapter points have to be on I-Frames which is why I was confused about not being able to put them back. I didn't think changing the field order flags would have any effect on the frame type, (and it didn't). What I discovered, thanks to your help, is that ProjectX altered the file when it demuxed. Using the PGCDemuxed file I was able to change the field order in Restream and set the chapter points in TDA at the original points and author without a menu then copy the resulting VOBs to the original structure and it works. Menus and chapter points both.

I did not try your complete method, because what I did worked (without downloading more tools) and I was already suspicious of ProjectX, but I suspect my method only worked because the original VOBs and the replacement VOBs were created using the same authoring tool (and version). I have noticed subtle differences in VOB sizes using different Authoring tools that would probably lead to problems using my method. I think your method would compensate for those differences if the original Authoring tool was unknown.

Anyway, thanks for steering me to PGCDemux. Great tool.