Tip: Trap using VOB Merge.

farss wrote on 6/27/2009, 7:01 PM
Got myself into quite a lather yesterday. Client wanted me to use footage from a NTSC DVD. Used VOB Merge and dropped the footage into Vegas and yikes it doesn't look right. Check media properties and it's 29.97p. Ah well me thinks, no wonder they had trouble playing it but how did iDVD even author this.

Once the panic attack was over it dawned on me where I'd got myself and Vegas all messed up. I'd included the menu VOBs in the merge and yes, they're progressive and Vegas simply reads the first frame or some such and assumes the whole stream is the same.

Did the VOB merge thingy again minus the menus and presto, I have 60i, phew.

Hope that makes sense. I'm posting this because I recall someone having issues with material ripped from a DVD and I'd looked at it for them and never quite understood what was going wrong. It could be related to this trap, maybe not but I think this is worth a heads up.

Bob.

Comments

darkframe wrote on 6/29/2009, 12:13 AM
Hi,

well, you certainly ran into trouble due to the menu VOBs in the first run. They're a bit different from the rest of the VOBs which are containing the main feature(s).

Menu VOBs have got their own timing. In case of e.g. a single still menu they do not contain more than a single IFrame and some timing information. Motion menus are a bit different as they are consisting of at least one movie clip. Mixed menus, i.e. menus with still menu pages and motion menu pages are a combination of both. Each menu page starts at time zero and ends either at a certain time value (which can be "infinite" for still menus) or when the motion clip ends. That means that you've got as many "timelines" within in a menu VOB as there are menu pages.

Hence, when merging menu VOBs with "normal" VOBs you'll get at least two different timelines within one "normal" MPEG output stream. Even more, the menu might consist of progressive content while the main movie could be interlaced, the menu might come with stereo audio while the movie has got Dolby 5.1, they might have different aspect ratios etc. etc. By merging them you would create a mixture of all that in one MPG (or M2V) thus getting unwanted results as you obviously found out by yourself ;)

Cheers

darkframe