The Link Between Motion Layers and Media Files
Before learning how to add media to your Motion project, it’s important to understand
the correspondence between layers and source media. Every time you add a file to your
project, you create a link between the layer you see in the Layers list and Canvas and its
corresponding media file on your hard disk.
Motion is a nondestructive application. This means that changes you make to media
objects in a Motion project aren’t applied to the source media files on the hard disk.
Because of this link, when you add a file to a project, the file must remain available on
your hard disk for as long as you work on that project. If you move, delete, or rename
media files that correspond to layers in a Motion project, those layers go “offline.”
If this happens, it’s easy to reconnect the offline layers in your project with new copies
of the media you lost, assuming those files are still available. For more information, see
Online Versus Offline Media