Image ratio
The Relive videos are rendered in 16:9.
If you take your photos in 4:3 format it will be displayed with black bars on the sides of the picture in your Relive video. To avoid the black bars in your Relive video, it is recommended to take photos in 16:9 format.
When taking vertical photos you will always see the black bars. To avoid the black bars on the side, it is recommended that you take photos horizontally.