How to keep project files small

Question

I'm a veteran Windows and Adobe Premiere user, so I come to iMovie with that frame of reference. One thing that Premiere does that it doesn't seem that iMovie does is keep the video files separate from the project file. I captured 2 hours of a 8 mm video into iMovie. It was 24 GB. I want to create a DVD out of the entire 2 hours, but to practice, I wanted to work with only about 10 minutes of it. So I put a clip on the timeline, cut it down to 10 minutes, deleted all the clips from the clip window and saved it. The file size is 24 GB.
In Premiere, all source videos are in the format they were captured in. Within a project file, you point to the source video but it doesn't get saved with the project file. Therefore you can have lots of project files (all of which are small) but only one source video file.
Is there any way to have a second iMovie project point to another project and use it as a source? Or do you always have to save the source video file with the project file?
Thanks,
Mike

Answer 1

Hi Mike, welcome to the discussion!
do you always have to save the source video file with the project file?
Your observations are spot on. iMovie HD does not "share" source files. Each project has its own files that it stores in the Media folder inside the project. As video/audio is imported to the project -- from a camera or elsewhere -- it is copied directly to the project.
(The project is not a file. It is actually a package, a special kind of folder. To look inside the package, Control-click on the project icon and choose "Show Package Contents" from the popUp menu that appears. The source files are in the Media folder.)
iMovie HD does non-destructive editing -- Media files are never modified -- so projects tend to stay large. Emptying the iMovie trash may discard clips, but not necessarily reduce the size of the project.
It helps to know how things work. Understanding the iMovie trash is important.
Media files that support the clips are never modified. In your project, you have a single 120 minute Media file. If you discard 110 minutes of your project, emptying the trash does not reduce the size of the project because of non-destructive editing. iMovie ALWAYS lets you restore that 10 minute clip back to 2 hours -- even if you Copy and Paste the clip into a different project.
The Media file itself is discarded only when the LAST clip using that Media file is discarded. If no clip uses the file when you empty the trash, it is discarded.
(In an extreme situation like yours, one option is to export the 10-minute clip to its own file, then import that file back into the project. Now you can discard the 2 hour clip.)
Note that for a project like yours, iMovie 6 has a feature that helps minimize the impact of this feature. Instead of importing the video as a single 2 hour clip, there's an iMovie 6 preference to tell iMovie to break up the video in 1 minute scenes (or whatever duration you want.) In your case, discarding 110 1-minute clips would, in fact, remove them from the project. Each clip would be the sole clip using its Media file, so discarding a clip would discard its Media file too.
This scene preference can be useful for projects like yours where scene changes aren't automatically detected as the video is imported. On modern camcorders, iMovie optionally starts a new Media file -- a new clip -- at each scene break. Later, when you discard that clip, its Media file goes out with it.
As you Copy and Paste clips from one project to another, iMovie applies the same rules as importing. Copying a clip and Pasting it into another project copies its entire Media file to the project.
That happens each time you Copy and Paste a clip. It's important, therefore, to Copy and Paste all the clips you want at the same time. Then iMovie figures out which Media files need to be copied and copies each one just one time. Otherwise, if you Copy and Paste clips separately, iMovie may copy that Media file again.
Note that the Pasted clip inherits all the non-destructive features it has in the original project.
There's pros and cons to this whole approach, of course. One important pro is that you don't have to worry about accidentally discarding a video file in a central cache that the project relies on. Non-destructive editing also helps avoid corruption problems that plagued earlier versions of iMovie as Media files were modified.
Fortunately, as FireWire drives have become cheap the problem isn't so much of a problem when you think about it.
Karl