Understanding Clip Collisions in Final Cut Pro

Posted on by Larry

[ This article was first published in the February, 2011, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]


Derrick Charleston asks on my Facebook page:

How come when you try and ripple a video on V1 on top of voiceovers on A1.A2 it will say “clip collision”? What’s colliding? The video & audio are not locked so the video has no relationship to the audio it’s so fiercely trying to stay locked to which was brought in separately via the patch panel.

Larry replies: Derrick, this is a great question.

Before answering your question, though, let me clear up something. The Patch Panel is only used to route clips from the Viewer to the Timeline. Once a clip is on the Timeline, the Patch Panel has no further affect on the clip.

So, regarding clip collisions, it doesn’t make any difference if you brought in a clip via the Patch Panel or by dragging. Once it is on the Timeline, the method you used to get it there no longer matters.

A clip collision generally occurs when you are trimming. Specifically, when you are ripple trimming (i.e. adjusting one side of a clip). That’s because the process of ripple trimming moves both the clip you are trimming AND all downstream clips affected by the trim.

The reason a clip collision occurs is that, during the trim, Final Cut reaches a point where it is moving a clip and needs to make one of four incompatible decisions about what to do when two, or more, clips touch.

For example, here, in this ripple trim to the video clip on V3, the only other clip that will move during the trim is the second clip on V1 (the one with the marker in it).

As I move the Out of the V3 clip to the left, the entire last clip (with the marker) also moves left. (The other clips are not affected by the ripple, nor is the audio on A3, A4, A5, or A6.

Note what happens when the clip collision message appears (I’ve hidden it here so you can see why it showed up).

The second clip (with the marker) has moved left with the ripple trim of the V3 clip. (Again, all the audio is independent, so it hasn’t moved, except for the linked audio of the marked clip.)

With the trim, the two clips on V1 are touching. If I continue to drag the Out of V3 to the left, Final Cut has four potential trims that it COULD do to the V1 clips:

1. The In of the second clip could overwrite the Out of the first clip.

2. The Out of the first clip could overwrite the In of the second clip.

3. The second clip could push the entire first clip earlier in the Timeline

4. The first clip could force the second clip not to move and not to change.

Clearly, only one of these four options can be true. But which one? Since Final Cut doesn’t know, it displays the clip collision message and forces you to stop the trim until you figure out how you want the conflicting clips to interact.

Clip Collisions are simply Final Cut’s way of asking for help in deciding what to do when two clips need to occupy the same spot during a trim.

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2 Responses to Understanding Clip Collisions in Final Cut Pro

  1. Brian says:

    I get all of the above – and yet it allows me to move the clip by grabbing and dragging?

    • Larry says:


      This article was written for Final Cut Pro 7. Final Cut Pro X handles clip collisions differently.

      In both applications, you are always able to move clips – the question is simply what happens when the edges of two clips overlap.


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