Understanding Menu Structure in Video Manager (VIDEO_TS.IFO)

[sundance]

Now that I've started playing with DVDStripper & MenuModder I realized that I don't understand the structure and function principles of the DVD video manager too much. I already learned how to change the First Play Entry with IfoEdit (if I want to start my disc with the movie rather than the menu) but I have no idea how menues are working.
How can I see/change what happens, if I press the Title Menu button or Root Menu button on my player's remote? Since on my last project, where I stripped some parts of the DVD, the menu was no longer working although I left all the part of disc's menu in.

Any help/information is highly appreciated!

P.S.: Sorry for double-posting this. But since there was no answer in the IfoEdit forum, I thought I'll try here...

[Dimmer]

You can do this in IfoEdit.

Title menu: Open VIDEO_TS.IFO and look at VMG Overview that appears in the bottom part of the screen. Underneath First Play PGC, it would say Language Menu Unit 1, then a list of menus (Menu 1, Menu 2 ...), one of them marked Title-Menu. Take a note of the menu number, double-click on VMGM_PGCI_UT on the top portion of the screen, and click on the corresponding menu in the list of menu PGCs that appears. There you can look at Pre/Post commands and modify if needed. Note that some DVDs don't have Title menu at all and nothing happens when you press Title button on the remote.

Root menu: There is one for each titleset. Open VTS_01_0.IFO, in the overview panel find a menu marked Root-Menu, double-click on VTSM_PGCI_UT table, find PGC with the corresponding number and make your changes there. If you have more than titleset, you'll have VTS_02_0.IFO, VTS_03_0.IFO etc. In this case, find the largest titleset by looking at the total size of the VOB files VTS_01_1.VOB+VTS_01_2.VOB+... for titleset 1, VTS_02_1.VOB+VTS_02_2.VOB+... for titleset 2 etc. The largest titleset is most likely to contain the main movie, therefore its root menu would come up when you press Menu on the remote during the movie. I believe when you press Menu in the stop mode, root menu of the first titleset comes up.

[sundance]

dimmer,
thanks for your explanation.
I'll let you know if I was able to "disassemble" a menu structure now...

[maa]

Get yourself a copy of Marks TrayDVD Player :
http://www.mmbforums.com/modules.php?name=Forums&file=viewtopic&t=3875
it offers a lot of debug information.

[sundance]

While playing with "BASIC" (RC2) my disassemblies revealed a pre-command in title 1 (vts_01) that reads: "CallSS VMGM PGC2". The video manager video_ts.vob has vob-ids 1..5 (scanned with VobRator). Where do I find a reference, what PGC is PGC2?

edit:
I found this in IfoEdit:
Language Menu Unit 1:
Menu 1: [Title-Menu] (entry PGC) (Programs: 0) (Cells: 0)
Menu 2: [entry only] (Programs: 1) (Cells: 3) (uses VOB-IDs: 3,4,5)
Menu 3: [entry only] (Programs: 3) (Cells: 3) (uses VOB-IDs: 1,2)
Menu 4: [entry only] (Programs: 1) (Cells: 1) (uses VOB-IDs: 2)
Menu 5: [entry only] (Programs: 0) (Cells: 0)
Menu 6: [entry only] (Programs: 0) (Cells: 0)
Menu 7: [entry only] (Programs: 0) (Cells: 0)
Menu 8: [entry only] (Programs: 0) (Cells: 0)

So, does VMGM_PGC2 map to "Menu 2" then?
And, if this is true, you'll find further information like pre-/post-/cell-commands in "VMGM_PGCI_UT" in PGC-Menu_2?



@maa:
Thanks for the link; this player is a real gem!

[maa]

So, does VMGM_PGC2 map to "Menu 2" then? Yes!

[sundance]

OK, so I've been through all parts of the title menu now. And I think I have a little idea now how it works. ;-)
Then I started with the root menu of title 1 (in VTS_01_0.ifo). There are 6 PGC-Menus listed:
LU_1 (...) PGC-Menu_1 (Root Menu)
LU_1 (...) PGC-Menu_2 (Chapter Menu)
LU_1 (...) PGC-Menu_3 (Audio Menu)
LU_1 (...) PGC-Menu_4 (Subpicture Menu)
LU_1 (...) PGC-Menu_5
LU_1 (...) PGC-Menu_6

Now, is it also correct to assume that the following link commands refer to PGC-Menu_2 and PGC-Menu_3?

If GPreg<10> == (cmp-val)<2> then (LinkPGCN) Link PGC 2
If GPreg<10> == (cmp-val)<3> then (LinkPGCN) Link PGC 3
(JumpSS VMGM) Jump to VMG PGC: 4

[maa]

Yes - you're in the domain called VTSM and PGCs referenced there are in the titleset manager (VTSM)

[Dimmer]

And this command:

(JumpSS VMGM) Jump to VMG PGC: 4

refers to Menu 4 in VIDEO_TS.IFO, which corresponds to Video Manager domain (VMG).

[sundance]

Finally I managed to modify the behaviour of serveral movies to my liking now (disc starts with main movie & auto-selects streams according to player setup, "root menu" always leads to chapter selection menu and "title/top menu" now shows the main menu right when the selections are available).
Once you understand the basics it rather easy to do. And there are valuable resources beside this great forum too:

DVD-Info: http://dvd.sourceforge.net/dvdinfo/index.html
DVD-Commands: http://www.dvd-replica.com/DVD/vmcommands.php (GREAT!)
and Marks TrayDVD Player (see maa's post).

Thanks every1 who helped me here.