.vob to .dv, aspect ratio problems

[Groove_Holmes]

In short:

I've been trying to convert a .vob file ripped from a dvd into a .dv file using ffmpegX, but I can do it only if I set the aspect ratio of the resulting .dv file into 4:3. If I set the video size manually, the conversion always either fails or produces a weird green bar at the bottom of the video. With all the other formats for the resulting video (.avi, .mov...) the conversion works fine.

There is, however, something which might be the key to this: When I drag the .vob file to ffmpegX it displays in the source information an aspect ratio of 720x576, even though the dvd is in 16:9 (also when I open the .vob files).

Has anyone had similar problems? Any ideas what to do?

In more detail:

I have a dvd from which I'm trying to clip a few snippets with iMovie and then use them when making my own dvd with iDVD (the material is not copyrighted, btw). All this should be done losing as little as possible of the original video quality. I ripped the dvd using MacTheRipper, but as you might know iMovie does not import .vob files. So, at first I have tried to convert the .vob files into .dv, but I've had some problems as described above.

Can anyone recommend another way to accomplish my task?


Any help is highly appreciated. Thanks.

[tomlee59]

You have a PAL DVD, apparently, then. DVD has only a small collection of legal resolutions, and 720x576 is one of them, and independent of aspect ratio. That is, just looking at the frame resolution is not enough to tell you what the aspect ratio is. An additional bit of information tells the player what the aspect ratio is. So, there's no error/inconsistency in the data you're getting from ffmpegx.

As for extracting short clips from a DVD, the easiest method is perhaps to use MPEGstreamclip. You'll need the QT MPEG2 component (but it's not expensive), but that's it. You'll be able to cut and paste directly from vob's with ease, without having to convert to an intermediate format first. Much faster, and no transcoding loss. The only limitation is that MPEG is not amenable to frame-accurate edits -- you'll have to cut/paste at keyframe boundaries, but for many purposes, that's fine-grained enough. Hopefully, that's true for you as well.

[Case]

DV (PAL) uses 720x576 frames, just like MPEG-2 for DVD, for both 16:9 and 4:3.
In ffmpegX, first set the aspect ratio in the Auto Size field, then the Video Size field (back) to 720 x 576. But the preset should have set it right in the first place, as it takes the source material aspect ratio into account.