PGCEdit: What Do Those Numbers Mean?

[jamewoong]

http://i16.tinypic.com/6bwrdbq.png
This is for all the non-dummy PGC.

Is there any DANGER if I put the number (0,0) back?

[r0lZ]

The previous PGCN link is the PGC that is called when you press the previous chapter button of the remote when the first program of the current PGC is playing. When this number is equal to the current PGC number (as it is in your example), the pre-commands of the current PGC are executed again. Usually, that means that the current PGC is restarted from the beginning, but in some cases, another thing can happen.
If you replace the link by 0, the previous chapter button will be disabled.

Similarly, the Next PGC link can be used to jump to another PGC when the last program of the current PGC is playing, or to jump to the post commands of the current PGC if the link points to itself.

[blutach]

It is perfectly OK as is.

Regards

[bigotti5]

It is perfectly OK as is.

Since this PGC is in menu domain this is not correct.
From the spec PrevPGCN link has to be "0" in system space (and NextPGCN link has either to be "0" or can only point to itself in system space).
• The Previous_PGC_number should be '0' when found in a PGC in the System space.
• The GoUp_PGCN should be '0' when found in a PGC in the FP_DOM space.
• The PG_Playback_mode should be '0' when found in a PGC in the Menu space.

[blutach]

Aaah, you got me there bigotti5. :)

Experience says this is not a practical limitation, AFAIK.

Regards

[bigotti5]

Experience says this is not a practical limitation, AFAIK.

Agreed :)

[Video Dude]

I reauthor my backups as movie only and always keep the (previous, next) as (0,0).

When playing back the first chapter on all of my standalone players and pressing the previous chapter button on the remote, the movie always skips back to the beginning.

But in WinDVD and PowerDVD pressing the previous button during chapter 1 does nothing, which I expected since it is (0,0).

Does anyone know if most standalones skip back to the beginning during chapter 1 even if Previous PGCN link is set to 0? I tested multiple Panasonic and Toshiba models that I own and they all go back.

[blutach]

Without having access to "most standalones", it does seem to be the way things work. Certainly using Prev PGCN = 1 also helps. You can also try the authoring enhancements in the DVD Shrink plugin to PgcEdit.

Regards

[r0lZ]

There are two different methods implemented by the players to go to the previous chapter with the Prev button.

On good (and usually expensive) players, pressing the Prev button should jump to the beginning of the current chapter, except if the chapter is just playing the very beginning of the cell, in which case it should jump to the previous chapter. That means that it is usually necessary to press the Prev button two times to jump to the previous chapter.

Since that method is relatively difficult to implement, most cheap players go directly to the previous chapter, regardless of the position in the current chapter.

The method used determines if it is possible to go back to the beginning of the first chapter during its playback. The good players should be able to do it, at least if you wait a few seconds after the beginning of the playback of the title, as they come back to the beginning of the current chapter any way.

In the case of the cheap method, since there is no previous chapter, the player will usually simply ignore the command. However, some players are smart enough to verify if the current chapter is the first one, and jump to the beginning of the title if it's the case.

I have 3 cheap players unable to go back to the beginning of chapter 1 (unless the PrevPGCN link points to itself) and one very old and expensive player that can do it.

Last precision: the Prev and Next Chapter buttons go to the previous or next PG (program), not PTT (chapter). But since in most Titles, there is one chapter per program, you will not notice the difference. In menus however, there are no chapter, but the buttons can be used to jump from PG to PG.

[Video Dude]

Thanks for the detailed explanation.