There is a "real clip" in your event file. Let's say it is 15 seconds long.
You can select and drag (say) a 5 second portion of the Event clip into your project. This is a virtual clip, because it does not physically move into your project. Your project just maintains a reference back to the real clip and the in and out points.
OK on to your question.
Lets say you take the whole real clip of 15 seconds into your project. You can select a portion of the clip and select EDIT/SPLIT CLIP. At this point, you have a 15 second real clip in the event file, and 2 or three virtual clips in the Project file. If you split the clip with a selection where either the left or right of the yellow border is on the far left or right of the real clip, you will get two clips. If neither the left or right sides of the yellow border are touching the borders of the real clip, you will get 3 virtual clips.
Join Clips reverses this operation. If it is more convenient for you to deal with the split clips as one clip, you can select them both, and EDIT/JOIN and they will be virtually back together.
Lets do this in frames.
The 15 second clip "A" in the event file has 15x30 = 450 frames.
In the project, it will say something like "Go find Clip A in Event X, and bring me frames 1 through 450."
When you split the clip, the Project will say, for example, "Go to Event X and bring me frames 1 through 200, and then bring me frames 201 through 450." These two virtual clips will play back-to-back, so on playback you can't tell they are two clips.
When you Join the clips in the project, the project will say, take these two clips from event x that go from frame 1 through 200 and frames 201 through 450, and represent them as a single clip from frames 1 through 450"
But let's say you split the clip so that it is three clips...frames 1-150, frames 151-223, and frames 224-450. Further, let's say that through your edit, you deleted the middle clip. So frames 151-223 are no longer in the project (but they still are on the real clip in the Event).
In this case, it does not make sense to "Join" clips 1 and three.
There is a "real clip" in your event file. Let's say it is 15 seconds long.
You can select and drag (say) a 5 second portion of the Event clip into your project. This is a virtual clip, because it does not physically move into your project. Your project just maintains a reference back to the real clip and the in and out points.
OK on to your question.
Lets say you take the whole real clip of 15 seconds into your project. You can select a portion of the clip and select EDIT/SPLIT CLIP. At this point, you have a 15 second real clip in the event file, and 2 or three virtual clips in the Project file. If you split the clip with a selection where either the left or right of the yellow border is on the far left or right of the real clip, you will get two clips. If neither the left or right sides of the yellow border are touching the borders of the real clip, you will get 3 virtual clips.
Join Clips reverses this operation. If it is more convenient for you to deal with the split clips as one clip, you can select them both, and EDIT/JOIN and they will be virtually back together.
Lets do this in frames.
The 15 second clip "A" in the event file has 15x30 = 450 frames.
In the project, it will say something like "Go find Clip A in Event X, and bring me frames 1 through 450."
When you split the clip, the Project will say, for example, "Go to Event X and bring me frames 1 through 200, and then bring me frames 201 through 450." These two virtual clips will play back-to-back, so on playback you can't tell they are two clips.
When you Join the clips in the project, the project will say, take these two clips from event x that go from frame 1 through 200 and frames 201 through 450, and represent them as a single clip from frames 1 through 450"
But let's say you split the clip so that it is three clips...frames 1-150, frames 151-223, and frames 224-450. Further, let's say that through your edit, you deleted the middle clip. So frames 151-223 are no longer in the project (but they still are on the real clip in the Event).
In this case, it does not make sense to "Join" clips 1 and three.
It occurred to me later that you probably are looking for a way to take three clips and join them together in a single movie. This is simple in iMovie. You just bring the clips or portions of clips up to the project area. Place them in the order you want. Add titles, transitions, color correction, audio tracks, etc. (optional).
When you are done, you need to SHARE the movie. When you have shared the movie, everything is joined into one.
You can Share to iTunes, Share to the Media Browser, Share using QuickTime (for a great deal of control, but a little more complexity), etc.
Once you have shared to the Media Browser or iTunes, you can import into iDVD through the Media Browser in iDVD.
Was searching for an answer to the exactly the same question. However, I couldn't really understand how to use the feature. It stays grayed out in the menu after I select the two clips I want to join in my project. I do understand that when I render the project, it will automatically get joined. But, I would like to join multiple clips into one after trimming so that I can move the combined clip around and place it where I want in the storyboard. Doing that with multiple clips is prone to mistakes.
I do understand that when I render the project, it will automatically get joined. But, I would like to join multiple clips into one after trimming so that I can move the combined clip around and place it where I want in the storyboard.
As Appleman point out above, the "Join" option can only be applied to clips that were previously "Split" within a project. It cannot be applied to "independent" clips or segments of clips which you add to the project.
Thanks Jon. It is clear to me now about the limitations of this feature. It is surprising that a simple feature like this, which is available in the other buggy software on Windows platform, is not available in iMovie'09.
I would like to join multiple clips into one after trimming so that I can move the combined clip around and place it where I want in the storyboard.
You could, of course, do the trimming at the "Event" level in MPEG Streamclips (QT Pro or similar application), merge them, and then use the "Save As..." option to save the "pre-editied" files for use in iMovie. Not sure if this would be a viable alternative for you or not. I admit, however, that it would sometimes be nice if iMovie '08/'09 could create "super reference objects" that contain individual "reference objects" that could all manipulated as a single "object." -- for moves, the application of effects, audio settings and/or video settings, etc.
Thanks for the great tips, Jon. You are very good at that. However, that route involves using multiple tools which I would prefer to avoid. In fact using fewer tools/steps was my goal when I upgraded to iMovie'09 as I had to use Garageband earlier to add chapter markers in iMovie'08. I just create this short stories of my home video from vacations/events and then produce them for my Apple TV. In very rare cases, I will be cutting DVDs (when I want to send them to family members).