Syncing slide images and audio in iMovie

I found an MP3 recording of an old talk I gave and decided to use the slides from that talk to create a video using iMovie.

The slides were in Keynote, so I started by exporting them to individual images:

File -> Export To -> Images...

Screenshot of the Export your Presentation screen

I then imported the images into iMovie by dragging and dropping the whole pile of them from the finder.

I dragged and dropped in my MP3 recording too.

Turning off the Ken Burns effect

When you import images into iMovie it applies the Ken Burns zoom effect to them by default, which wasn't what I wanted.

To get rid of this you need to use the "Crop" tool (unintuitively). Select all of the images, click the "Crop" icon, then set the Style to "Fill".

Screenshot showing where the crop icon is

Syncing the audio

I wanted each slide to be on screen for the correct duration to match the audio.

At first I tried dragging and dropping the edges of the images, but this was way too fiddly.

Instead, I decided to manually alter the duration of each one.

I did this by selecting each image in turn, clicking the little (i) icon and manually editing the duration in seconds.

Screenshot of a iMovie edit timeline showing the form for editing the duration of an image

This was faster than I expected - I quickly got a feel for if I should jump the duration up to 8s or 10s and then tweaked those numbers by hitting the play and pause buttons.

Publishing it to YouTube

I exported the result using the File -> Share -> File... menu. Despite the 1.03GB estimate the video ended up being 259.8MB - presumably because it was mostly static images.

I used the default settings: 1080p, Quality High, Compress for Better Quality

I created a custom title slide image for it because YouTube likes those to be 1280x720px - I used Pixelmator for that.

The completed video is here:

Created 2023-06-15T21:15:44+01:00 · Edit