When you make a “one-step DVD” on a Mac, you move your video footage directly from a video camera to the DVD. When that happens, the video gets converted into a different format for the DVD. To get the video into iMovie to edit, you have to use a different process. It’s a little complicated, because the makers of commercial DVDs don’t want to make it too easy to get video from a commercial DVD for copyright reasons.
What you need to do is convert it from the format it is in on the DVD to what’s called DV format (Digital Video), which is one of the video formats iMovie uses.
You should realize that digital information doesn’t degrade all by itself (unless the media it’s on degrades), but when converting from different formats to other formats, there is information that can’t or isn’t converted “all the way,” and that’s where the picture loss comes from. So you might see that the converted video from the DVD is lower quality than before.
And working with video can get very complicated, and what you end up doing might be different than these instructions, because of differences in versions of iMovie and other factors. But this is one way to go from DVD to iMovie.
The first thing you need to do is move the video from the DVD back to your hard drive. Use Disk Utility to do that. With the DVD in your drive, Open Disk Utility. (If a DVD player or iTunes opens when you put the DVD in, quit them.) In Disk Utility, select the DVD in the drive, and then click on “New Image.” Give the new image a name and then let the image be written; this could take a few minutes or longer, depending how much footage you have on the DVD. When it’s done, start iMovie and ten double-click on the disk image. Depending on your version of iMovie, you can import from there by selecting the video folder from the disk image.
If you can’t import from there, you’ll need to convert the video on the disk image into digital video. (DV) which is a format iMovie can work with.
The easiest way I’ve found is using a free program called MPEG Streamclip, which can be downloaded here for free.
Start Streamclip and drag and drop the disk image to the window. Save the file where you can easily find it, such as the desktop. When you start the conversion, it may take a while, depending on the speed of your Mac and the length of the video. So just let it run and do its thing.
When you use Streamclip, you may get a warning that you need the Apple MPEG-2 component for QuickTime in order to get a high quality conversion. You can get the MPEG-2 component online from this link at Apple.
Once the conversion is done, you’ll have a DV file, and with that, you can go to iMovie and use the “Import” function to bring the footage into iMovie. Once again, it may take some time, so start the process and let it run. iMovie will import the video and then make thumbnails of the footage, and then you’ll be able to edit, add titles, and anything else you want to do. Then, you can go back to a DVD when you’re done.