Supported file types for import
For most document types, you can import images and media in the following formats into the Library:
Other file types
To use a local asset in another format, add the file to the
assets subfolder for the project in your computer's file system. The asset won't appear in the library, but you can reference the file in the Source or Sources property of the appropriate element.
Supported codecs for media assets in video documents
For video ads, video and media assets should be encoded using the following codecs:
VP8 (Windows only)
VP9 (Windows only)
Some file types that may use the above codecs include .mp3, .mp4, .m4a, and .mov. If your media file uses a different codec, Google Web Designer will display an error when you try to import the file into a video document.