As part of the transition to 64-bit technology in macOS, you may see an alert in iMovie about media files that won't be compatible with macOS Catalina or later.
Before you upgrade to macOS Catalina or later, you can use iMovie to detect and convert all incompatible media files so they'll be compatible with future versions of macOS. After you upgrade, the option to convert the incompatible files will no longer be available.
In macOS Catalina or later, you might see an incompatible media message in the viewer when trying to play incompatible media if you haven't converted it before upgrading.
Detect and convert incompatible media files in iMovie on macOS Mojave
When you import media or open a library in iMovie 10.1.11 or later on a Mac with macOS Mojave, a window appears that lists incompatible media files in your library.
To convert incompatible media files immediately, click Convert in the window. iMovie creates copies of the media files in the H.264 format. The original files are moved to an iMovie Incompatible Media folder, located in the same folder as the library. Your original media is not modified.
If you want to convert them later, you can use iMovie to scan the library and convert the incompatible files:
- In iMovie choose File > Check Media for Compatibility.
- In the window listing incompatible media files, click Convert.
Learn more about how iMovie detects and converts incompatible media files.
Formats compatible with macOS Catalina or later
These video, audio, still-image, and container formats are compatible with iMovie on Mac computers with macOS Catalina or later:
- Apple Animation Codec
- Apple Intermediate Codec
- Apple ProRes
- AVCHD (including AVCCAM, AVCHD Lite, and NXCAM)
- DV (including DVCAM, DVCPRO, and DVCPRO50)
- Motion JPEG (OpenDML only)
- MPEG-4 SP
- Photo JPEG
- MOV (QuickTime)
Media formats affected by the transition to 64-bit technology
Examples of media that will be affected by the transition to 64-bit technology include video files from early Flip Video cameras that use the 3ivx codec, early web videos encoded with the Sorenson codec, and media converted from DVD to the DivX format.
Third-party developers may continue to offer compatibility with some formats by building support directly into their apps. Contact developers of third-party apps for more information about media formats supported in their apps.
Here are some examples of media formats affected by this transition:
- 3ivx MPEG-4
- AV1 / VP9
- AVC0 Media AVA0 Media
- BitJazz SheerVideo
- Flash Video
- Indeo video 5.1
- Intel Video 4:3
- JPEG 2000
- Microsoft Video 1
- Motion JPEG A
- Motion JPEG B
- On2 VP3, VP5, VP6, VP6-E, VP6-S, VP7, VP8, VP9
- Perian collection of codecs (Microsoft MPEG-4, DivX, 3ivx, VP6, VP3, and others)
- Planar RGB
- QuickTime files encoded using still image formats (SGI, TGA, PNG, and others)
- Sorenson 3
- Sorenson Sparc
- Sorenson Video / Video 3 / YUV9
- Streambox ACT-L2
- Windows Media Video 7, 8, 9
- Xiph.org’s Theora Video
Convert incompatible media not contained in an iMovie library
To convert an incompatible media file, open it with QuickTime Player (version 10.0 and later) in macOS Mojave or earlier, then save a copy with a new name. This method isn't supported in macOS Catalina.
You can also use Compressor to transcode one or more media files into a format such as H.264, HEVC, or Apple ProRes. These formats will be supported in versions of macOS after macOS Mojave. H.264 and HEVC preserve image quality with the smallest file size. ProRes preserves the best image quality and provides better performance when editing in iMovie, but creates much larger files that use more storage space than H.264 and HEVC files use.