What problem should I expect with SCR=0 ?

[MarcioAB]

I'm doing some programming to handle DVD-streams and I see that reseting SCR to zero, brings me no problem at all.

I was told SCR is a kind of reference to help DVD players stay in sync, etc, but could someone help me understand what kind of troubles should I expect reseting all SCRs to zero ?

Thank you

[Zeul]

The SCR is used as a time reference for when data enters the buffers. Do NOT mess with the SCRs. If the value is incorrect the data will enter the buffer at the wrong time producing lots of buffer overflows.

[MarcioAB]

Understood. But is ZERO also an incorrect value ?

So far, my movies are just 45 min long (with all SCRs=0) and I got no overflow yet.

By your experience, how long someone should watch a movie to see an overflow ? (like 5 minutes or something much longer ?)

Is overflow a problem with some specific DVD-player vendors ?

Thank you.

[Zeul]

There are reports that some dvd players don't use the scr values. They look at the PTS stamp (the presentation time) and use that value to determine the time that the data enters the buffers. However, this can't be assumed to be the case with all players.

Why are you resetting to 0 anyway?

[MarcioAB]

Thank you for your answer. It was exactly what I was imagining. As these videos are for my use only, maybe I can let them that way, assuming the risk to face someday a player that will not accept it.


Thank you for your interest. The reason I'm reseting the SCRs is because I'm making a lot of cut and paste from a large TitleSet. My workflow is the following:

1. Duplicate my home VHS tape in a DVD using a desk DVD-recorder. The home VHS has many small pieces of video all together (you know, turn off the camera, turn on the camera ...)

2. Using DVD-Shrink (I like it very much) I cut the DVD in pieces. DVD-Shrink will create a new VOB files for each piece (VOB1, VOB2, VOB3, VOB4 ...)

3. I want to join those VOBs in a different order (VOB2, VOB4, VOB1, VOB3 ...) but I also want a single VOB1.

4. I do not want to DEMUX/REMUX. It seems I have some "discontinuities" in audio/video inside the VOBUs (the VOB units), but the PTS seems to handle it well, so I do not want to loose the PTS as I understand I will if DEMUXING.

5. Then I rename the VOBs in the sequence I need and use VOBedit and IFOedit to join them, but the PTS and SCR are messed up. If DVD-industry allow me to let SCR=0, then part of my problem is resolved. So I just need to focus on fix the PTS issue, what I will do by the same simple programming (Visual Basic programing)

Any comments, suggestions are very welcome.
Thanks
Marcio

[Zeul]

If you demux your shrink vobids then the audio and video should synch perfectly (assuming they were originally synched ok). Then create multiple tracks/segments in an authoring app like dvdplanner or muxman. Add each track to 1 PGC of 1 TITLE. Your muxed project will contain just the 1 vob file, but each vobid will be muxed independently ensuring audio/video synch.

[MarcioAB]

I will try demux/remux again.

btw just downloaded your basic version of DVDPlanner: Very good product ! Just need to learn it better.

Thank you