Black photos when exporting slideshow with iPhoto

Question

I used to make slideshows with iPhoto and export as video. Today I'm trying to make another one but some photos appear totally black when exporting in 1080p...

I tried to export at lower resolutions, and everything works ok.

So it's only when exporting at 1080p...

Answer 1

The problem was that the images were all too big. I suppose iPhoto can't handle this amount of very high res photos, all around 5616*3744px in my case.

I resized all the images to a little higher than 1080p, and it worked well.