Apply Transition To Multiple Clips

Applying a transition to multiple clips at once

If you want to apply the same transition between multiple clips, select the clips in the timeline, then apply the transition. This adds the transition to all of the selected clips. To select multiple clips, hold down the Command key while selecting the individual clips or hold the Shift key to select a range of clips.


(That came from http://www.apple.com/ilife/tutorials/imovie/im3-6.html)

Sue

Cross Dissolve will shorten your movie by the duration of the Dissolve..!

The only transition which doesn't do this is Overlap; that freezes the last frame of the outgoing clip, and the transition then dissolves to the new clip.

If you want to keep the same overall length of the movie - to match a song, for instance - you'd have to decide how long you want each transition to be - e.g; 2 seconds - then make sure that each clip lasts two seconds longer at both the end and at the beginning (..where the transitions will be applied..), then select all the clips - as Sue says - and apply a two second transition to them all.

The last two seconds of each clip will be merged with the first two seconds of the next clip, and will thus get "eaten away" ..but the overall length of the entire movie will be preserved ..as long as you do have two seconds of spare - or "waste" - material at the end and start of every clip!

This will mean re-editing the entire movie to add two seconds - or whatever duration you choose - to the start and end of every clip!

..Sorry..!

Yes; if you've already edited it and applied your transitions, and are fading down the background track to "reveal" the original clips' sound somewhere in there, then you could just edit the 'add-on' music to match the movie's length ..unless it'll be obvious, and jarring, that you've cut out some of that background music track.

But if nobody's going to be "singing along" with the background track while they watch the movie (..and so they won't find that the background track gets "out-of-step" with the length it ought to be..) then you could, indeed, easily trim that background track to the appropriate length.

You're very welcome *nathan!

Sue