You can set Pages to optimize the format and quality of movies and images in your documents for viewing on iOS devices.
Note: These settings apply only to movies you add from now on and not to any existing movies in your documents.
Choose Pages > Preferences (from the Pages menu at the top of your screen), then click General at the top of the preferences window.
To convert incompatible movies and images for iOS, select the “Optimize movies and images for iOS” checkbox.
When this preference is selected, incompatible movies and images you add to documents are converted to an iOS-compatible format. By default, movies are converted to H.264 format, which plays on most iOS devices and Mac computers.
Click the Movie Settings button below Adding Media, then choose any of these preferences:
Movie Format: If you’re using macOS 10.13 or later, you can choose either H.264 or HEVC format. Movies in HEVC format have the best quality at the smallest file size, but they can be played only on devices with iOS 11 or later and Mac computers with macOS 10.13 or later.
Movie Quality: Choose a maximum resolution for movies. Movies with a resolution smaller than the maximum aren’t scaled up when you add them to documents.
Note: H.264 and HEVC don’t support alpha channels, so transparency is converted to a black background.