Need help with DL DVD authoring in DVDSP: incompatible GOPs?!

[Mike Barber]

I have cut a project that is an instructional (bellydance) video that contains three video stream: a front view, side view, and rear view.

On my first attempt at compressing (via Compressor) and importing to DVDSP, I found I had incompatible GOPs with my "alternate angles" (the side and rear views). I believe this was due to both: 1) not having identical chapter markers (or any, in my case) in the alternate angles, and 2) not having checked the "Include Chapter Markers only" option in the Extras tab in Compressor.

So, I went back and meticulously made sure I had identical chapter marker positions and made sure I checked the "Include Chapter Markers only" option and went at it again. For most of my alternate angle stream, I had success. On three of them I have incompatible GOP structures again.

I've made sure my in/out points and lengths are identical, I made sure the chapter markers are identical, and I made sure that the "Include Chapter Markers only" option was checked -- so what could I be missing?

[Robert Lane]

Alt Angles are very, very tricky to work properly and there are several "gotchas" to be aware of - one you've already figured out.

Although not documented anywhere that I could find in either the online manual or the Apple Training books, there seems to be a limit as to how many angles you can have per chapter/sequence. I've found that more than 2 or 3 angles per sequence and DVDSP4 doesn't like it and you'll need to break up the sequence into another physically separate chapter.

The best method I've found for dealing with alt angles is that if I have a chapter that I want angles for, rather than break them up into several angles per chapter I'll simply make all those angles available for the entire track (or as much of it as the GOP structure will allow). This avoids this problem of more than 2 angle sections per chapter.

The other gotcha is that if you have an alt-angle occurring where your layer break is, forget about it, the image won't build properly at all.

This may or may not work for your project but should help troubleshoot the issue.

One tool that can help make sure your build is correct is "DVDAfterEdit"; it's a highly advanced authoring tool that literally checks every bit for proper ISO code setup - do a google search.

[Mike Barber]

Originally Posted by Robert Lane

The best method I've found for dealing with alt angles is that if I have a chapter that I want angles for, rather than break them up into several angles per chapter I'll simply make all those angles available for the entire track (or as much of it as the GOP structure will allow). This avoids this problem of more than 2 angle sections per chapter.

That's basically my approach as well. For example, the "Preparation" sequence has three versions: front, side, back. So it is three streams of equal length, just taken from a different side. This way, at any time, the user can decide to look at it from the front, side or back.

Originally Posted by Robert Lane

The other gotcha is that if you have an alt-angle occurring where your layer break is, forget about it, the image won't build properly at all.

Ah, didn't know about that! Thanks for the heads up. I could have really lost time trying to figure that one out.