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U977
31st October 2003, 09:53
Hello,

I hope I post my question at the right place. It's more about DVD structure in general, but my question is based on my understanding of what IFOEDIT displays.

I recently started to invest some time in learning more about the structure of DVDs.

I'd like to understand thet information that ifoedit displays.
And there is a gap that I did not manage to fill yet. I know what the files on the DVD are for, their content, what is a cell (well, I just know it's the smallest unit on a DVD), and so on.

Having read the Big3 backup method, for example, I saw examples of seamless branching, or layer breaks (demux by Vob-ID or not).

But I don't fully understand the link between VOB-IDs, cells and PGCs.

I take an example from the guide, a capture from IFOEDIT:
PGC_1 (program chain): [Title(TTN): 1] [00:25:59.21 / 30 fps] (Programs: 8) (Cells: 8) (uses VOB-IDs: 1,6)
[Ch 01] [Pg 01] [Cell 01] [V/C Id: 1/ 2] : time: 00:02:51.00 / 30 fps [Pos: 00:02:51.00] [Frames: 5130]

A PGC defines what cells should be displayed; in what order, that's right?
I see that cells seems to be first numbered according to the PGC they belong to (hence [Cell 01]), but cells are actually grouped in VOB content identified by the VOB-ID ([V/C Id: 1/ 2] means that Cell 1 from PGC_1 is actually the second cell of VOB-ID 1. Is that correct?

Cells are part of VOB content identified by a VOB-ID, and just displayed according to the PGC?

Thanks a lot for your help!

*** EDIT ***
I started to read some 2COOL guides. I began to understand that I'm... only at the beginning of understanding what can be found in IFOEDIT, and how to understand an IFO file, aw :-)

U977
31st October 2003, 16:41
Fine, I finally realized what I was asking for, and what else I wanted/needed too.

I found a link answering this question, on the web site of Lord of the Disks, in the advanced authoring forum.

Thanks.

Dimad
31st October 2003, 16:44
Material in vob files is grouped into blocks (actual structure is more complicated, but it is not important to get an idea) which are identified by 2 numbers: vobID and cellID.

Program Chain (PGC) lists all cells (blocks identified by vobID cellID) used in the PGC.

Sequence in which they are played depends on the pgc playback mode, selected angle and cell commands (if any).

U977
3rd November 2003, 12:54
Thanks, Dimad!

I've much more to learn about DVDs than I thought... :-)