Looking for an explanation of strange behaviour

[Duwgati]

A friend of mine asked me for help with a problem he is facing. I have managed to find out what is happening and how he can make a proper DVD, so that is no longer a problem.

But I am still looking for an explanation of the manifestation, because I can't figure out what could be causing the actual behaviour.
The problem is that the DVD will not playback similarly on a PC and on a DVD player.

Here are some details about the disc:
He created a DVD with the following structure:
- Main menu (only 1 choice to start the DVD)
- Sub menu (contains 2 choices: play movie and scene selection)
- 3 scenes that are intentional
- 1 more scene which is not supposed to be on the disc at all (12 min.)

Now when you play this disc in a DVD-player and in the main menu you select to start the movie, it will start playing that last (unintended) scene. ALLWAYS!!! You don't even get to see the rest of the scenes. As far as the DVD-player is concearned, the disc contains only 12 min of video.

However, when you play it in a PC, it follows the above mentioned structure as it should. And as long as you stick to the navigation menus on the DVD itself, you don't even get to see the last unintended scene. Only if you select scenes directly from the playback software, you can select that last scene.

Every diagnostic program tells me that the disc structure is OK. There are no errors on the disc. It is nicely recorded in a single session structure. So I am stumped. What the hell is happening here?

Anybody got any suggestion for me where to investigate further to tackle this problem?
Thanks for any suggestion.

[Bjs]

Use pgcedit ... rip dvd to hard drive and in pgcedit choose load, select the VIDEO_TS folder on hard drive ... then use trace mode.

Any vm commands which show up as red need to be modified.

Q: What dvd authoring application is being used ?

Q: With what are you using on the computer to verify the menu playback ? ... both vlc, nero showtime should be completely compliant and work as expected ... wouldn't trust powerdvd or windvd too much.

"diagnostic program" ... none will tell you why it won't play properly, only by using the right applications can the fault be located.

[Duwgati]

Thanks for the reply Bjs.
I never used pgcedit before, so the number of options is a bit overwhelming

Anyway, I did as you sugest, but nothing turns up red in trace mode. When I click any VMGM- or VTSM-line on the left, I sometimes get a line with a yellow or purple background in the right column, but that's it (see image):



I do get a warning though when I first load the VIDEO_TS folder, but I have no idea what that info means exactly (see image).



Regarding your questions:
1. I don't know what software he has been using. He uses an Apple, but that's about all I know for sure.
2. I tested with VLC and Windows Media Player and both give the exact same result.

I am no expert in this field but my guess is that the problem would have to be in the top menu, because the PC software willl jump correctly to the submenu whereas the DVD-player will jump to the last scene.

Any further assistance is appreciated.

[r0lZ]

Purple highlights mean that the highlighted lines cannot be executed due to GOTO commands. In your screenshot, they are NOPs (do-nothing operations), so that doesn't matter.

I guess that the menu currently selected in the screenshot is the first menu. It has 3 buttons, but apparently, all 3 buttons do the same thing: they go to PGC 16. It's strange, as usually, the different buttons should do different things. However, it is possible that PGC 16 jumps to different parts of the DVD, depending of the button that has been activated.

I can't help much more without the IFOs and the menu buttons commands. If you want so, send me a backup of the files I need: use PgcEdit's File -> Backups -> Create ZIP backup, and send me the ZIP file. I'll try to understand the problem. (You can see my email address on my home page.)

[r0lZ]

OK, I received the IFOs. As far as I can tell, the navigation is correct (although unnecessarily complex). It works (almost) correctly, but the description of the DVD structure you made in post #1 is not correct.

- Main menu (only 1 choice to start the DVD)
- Sub menu (contains 2 choices: play movie and scene selection)
- 3 scenes that are intentional
- 1 more scene which is not supposed to be on the disc at all (12 min.)

The first menu has 3 buttons, not 1, and the short title (title #4) CAN be played.

When you insert the DVD, the short Title 1 (probably a studio logo) is played, and then the first menu (PGC #7) is called. There are 3 buttons in that menu. Button 2 is selected by default. If you activate it, it jumps to title 4, the 12 min title supposed to be unavailable. Then, the nav returns to the menu, with button 2 selected again. Of course, if you accept it again, title 4 is played again. If you press Up to select the first button, then the nav jumps to the third menu (PGC 9), containing also 3 buttons. (The buttons numbers in that menu are messed up: button 2 is the topmost button, and button 1 is below it. Button 3 is the small button at the bottom.) If you select the topmost button (#2), the main movie (Title 2) is played. If you select button #1, the chapter menu is called (PGC #8 with 4 buttons - The button numbers are also wrong in the chapter menu, but it works as expected). If you select the third, small button in PGC 9, the nav returns to the first menu, as expected, and again, button 2 is selected by default. In that first menu, button 3 leads to title 3 (28 min), and returns to the first menu. This time, button 3 is selected by default.

Now when you play this disc in a DVD-player and in the main menu you select to start the movie, it will start playing that last (unintended) scene. ALLWAYS!!! You don't even get to see the rest of the scenes. As far as the DVD-player is concearned, the disc contains only 12 min of video.

If you acept the default button (#2), that's the normal behaviour.

However, when you play it in a PC, it follows the above mentioned structure as it should. And as long as you stick to the navigation menus on the DVD itself, you don't even get to see the last unintended scene. Only if you select scenes directly from the playback software, you can select that last scene.

I suppose that the difference is that on a PC, you use probably the mouse to click the button. Therefore, you select the right button to play the movie.

Conclusion: All 4 titles can be played, and the menus work well. However, the first menu button is never selected by default when the first menu is played. That's strange, as it leads to the main movie. It's a little bug, but you can select it manually anyway.

To fix the wrong button selection by default, just edit the pre-command #10 of the first menu PGC ("VTSM 1, LU 1 (en), 7"). It contains:

[71 00 00 00 00 02 00 00]  10  Set gprm(0) =(mov) 2

Simply change the value from 2 to 1:

[71 00 00 00 00 01 00 00]  10  Set gprm(0) =(mov) 1

Note that, since I don't have the VOBs, I have not seen the menus, and the highlights of the buttons. So, if you think that the first menu has only one option, maybe it's because buttons 1 and 3 are not correctly highlighted when they are selected. But even if you cannot see the highlights, there are 3 buttons, and button 1 leads to the second menu, that leads to the main movie. With the fix above, you will be able to accept the default button to jump to the movie menu directly.

[Duwgati]

Thanks for the very informative respons r0lz.
I have taken some time to figure out some of the details you describe.

My description of the structure of the disc indeed seems to be incorrect, BUT to my defense I want to say that my explanation was based on what one can see from playing the disc. And that visible part of the structure still hasn't changed.

There is only 1 item visible in the main menu and when you click either navigation button on the remote, there is no change in the highlighting. That one button stays highlighted all the time.

However, I noticed that when I press the down-arrow to navigate to the 2nd (invisible) menu button which according to you is there, that does work indeed. If I press OK, it indeed jumps to another scene on the disc immediately.

I then tried to figure out if any of the buttons would also be accessible when playing the disc with VLC, but no matter where I click with the mouse, VLC does only respond to a click on the visible button. So the other buttons are either too small or made to be invisible I guess.

But at least I now know what is causing this behaviour and I can tell my friend that he created a perfectly valid DVD but messed up the menu structure heavily

[r0lZ]

If the two other buttons are not visible, perhaps it's because they do not have highlights. You can inspect the highlights with DVDSubEdit. (It is even possible to export, edit and import the picture with the highlights, if you want to add the missing ones.

And yes, the buttons (especially the third button) are very small, so it might be difficult to click them. Use a player that can simulate a real remote with the cursors and Enter keys.

Also, if you really don't need that menu, you can remove it completely with PgcEdit's Kill PGC Playback. When you apply that function to the menu PGC, you will see the menu buttons viewer. Be sure to select the button that leads to the main movie. After that, that menu will not be played any more, and the navigation will behave as if you would have clicked the right button.

If you want to keep the menu but suppress the two other choices, you can also remove the two useless buttons with the Menu Editor, and force the selection of button 1 in all cases.

Of course, in both cases, you will not be able to play the two little titles from the menu. Consider to remove them completely.