Apple said we can use iMovie to make App Previews, but I can't export the correct size using iMovie

I'm trying to create an App Preview for an iPhone app.

I recorded a screen capture of the app in the native resolution of the phone.

Then I imported the video in iMovie and used iMovie to add transitions and text, and to arrange the clips.

According to Apple, App Previews should be 640x1136 for the iPhone 5 portrait size, but the export menu doesn't support this size or any custom sizes.

Apple said we could use iMovie, but this doesn't seem to work. How can I change the export size?

Solution 1:

Make sure you go to File->New App Preview (available on iMovie 10.0.6 on Yosemite).

Solution 2:

Add an image to the beginning of the video, e.g. one second splash screen or 0.1 second black/white screen. Make sure the image dimensions match the intended device dimensions. Video added after the image will conform to these dimensions - you will have a resizer option in the preview video to change your video size to match the initial screen dimensions.

You can also remove the beginning image after all of this and your movie will retain the new size.

Solution 3:

If like me and the OP you did all of the work to create your preview only to find that you can't 'share' it as a preview because you did not start it as a preview then here is the answer.

Start a 'New App Preview' then open your original project -> click in the timeline and select all (cmd + a) -> copy that (cmd + C) -> go to your empty app preview -> click in the timeline and -> paste (cmd + V).

All your hard work is now in the app preview video.