Add Photos and Transitions without Killing Audio

Chuck writes:

I want to insert a photo into my video clip and maintain the original audio. Everything works fine until I add transitions at either end of the photo which results in the loss of synchronization between the audio and video. Is this possible to achieve in iMovie HD or am I barking up the wrong tree?

iMovie’s Paste Over at Playhead will accomplish this, but just for the photo; when you add transitions, the audio of the underlying clip gets knocked out of sync because iMovie transitions steal frames from the surrounding video (see the sidebar “iMovie’s Habit of Stealing Time” on page 139 of iMovie HD & iDVD 5: Visual QuickStart Guide for the explanation of why this happens).

However, you can work around the problem by using a bit of math. Depending on which transition you use, extend your photo’s duration by the total time of the transitions you add. Let’s say we want to add a 3-second photo into the middle of a video with audio, with a pair of Cross Dissolve transitions around it. Here’s how it works:

  1. Extract the audio from the video clip in the Timeline (select the clip and press Command-J).
  2. Position the playhead at the point where you want to add the photo and choose Split Clip at Playhead (or press Command-T).
  3. Position the playhead 3-seconds further down the timeline and split the clip again. This gives us a nice 3-second chunk that can be pulled out.

  4. Drag that chunk to the Shelf to get it out of the way.
  5. Insert your 3-second photo into the space where the extracted chunk was. It’s a good idea to play back the section to make sure the audio is still synchronized after the photo.

  6. Decide the duration of the transitions; let’s say we want brief 10-frame dissolves.
  7. Now, increase the photo’s duration by the total amount of time that the transitions will occupy – in this case, that means we need to add 20 frames (0:20) to the photo: double-click the photo clip and change the duration field to read 0:03:20. Click Set to continue.

  8. Add the transitions by setting their duration in the Trans pane and dragging them to either side of the photo clip.

When you play back the clip, the audio should be correctly in sync. (You may have to manually change the volume levels of the transition clips.) Click below to view the clip in action (1.3 MB QuickTime Movie).

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: