Cell types in ifo files.

[P3gasus]

I noticed that an important parameter regarding cells in ifo files is the "type". This influences whether or not the cell is interleaved, whether or not the cell is in the beginning of an angle block, whether or not there is a STC discontinuity, whether or not the playback is seamless. My question is: can I safely modify the cell types in ifo files without changing vobs or some of the above parameters needs to be changed in vobs too? If so which of the above parameters requires rewriting vob files?.
Thank you
Bye

[violao]

Originally posted by P3gasus
My question is: can I safely modify the cell types in ifo files without changing vobs ...
Try and see :), but I would expect - no. These flags are there to inform a player of cell parameters. You cannot change cell parameters by changing flags. For example if system clock is reset then the player needs to be notified, otherwise it will think that time goes backwards. Normally STC is reset at the beginning of a vob (because normally vob is made from single mpeg file that has it's timestamps start from 0).

As for seamless, you can try changing that, but it may work only for cells in a middle of a PGC. First cell in PGC is always non-seamless.

[P3gasus]

Originally posted by violao
Try and see :), but I would expect - no. These flags are there to inform a player of cell parameters. You cannot change cell parameters by changing flags. For example if system clock is reset then the player needs to be notified, otherwise it will think that time goes backwards. Normally STC is reset at the beginning of a vob (because normally vob is made from single mpeg file that has it's timestamps start from 0).

As for seamless, you can try changing that, but it may work only for cells in a middle of a PGC. First cell in PGC is always non-seamless.

Thank you violao. I asked this question just because where I am and I'll be till july, I don't have any home dvd player to test.
I was trying to strip an angle from a non seamless angle pgc. I used ifoedit but I noticed that it replaces cells of type 92 (first of non seamless angle block) with cells of type 10 (i. e. normal and seamless but with STC discontinuity). I was wondering if cells with stc discontinuity in the middle of pgc could cause stops in play. Do you have any experience on this?
Thanks
Bye

[violao]

Originally posted by P3gasus
I was wondering if cells with stc discontinuity in the middle of pgc could cause stops in play. Do you have any experience on this?
I don't think so. I would expect this dicontinuity only to change counters, and not to deal with buffers, but this definitely depends on the player. You'll see this sometimes in commercial DVDs when a PGC is composed from multiple VOB IDs. I have made a test (and a guide (http://forum.doom9.org/showthread.php?s=&threadid=72964&highlight=seamless+menu+loop+guide)) for seamless loop playback, where PGC is composed of a number of repetitions of a single cell. All repetitions start with discontinuity and all but first are marked seamless. I am even using full volume audio to make sure it plays seamless. It does in my player. I am using dvdauthor 0.6.9 for this, but other tools such as Scenarist probably may be used.

Still, if you're authoring and want to be 100% sure, you can use the trick the studios use and place the discontinuity in the scene with little or no motion and faded audio.

[P3gasus]

Originally posted by violao
I don't think so. I would expect this dicontinuity only to change counters, and not to deal with buffers, but this definitely depends on the player.

That is what I was guessing. Too bad that I've not my player here to test :(.
Thank you violao.
Bye