As part of the upcoming transition to 64-bit technology in macOS, you may see an alert in iMovie about legacy media files that won't be compatible with future versions of macOS, released after macOS Mojave.
These media files were typically created using formats or codecs that rely on QuickTime 7—an older version of QuickTime that is included in macOS Mojave for compatibility purposes. However, versions of macOS after macOS Mojave will no longer include the QuickTime 7 framework. To continue to use those files in iMovie on versions of macOS after macOS Mojave, an updated version of iMovie—available in the first half of 2019— will include a feature to help you identify and convert legacy media files.
Legacy media formats affected by the transition to 64-bit technology
Support for many legacy formats was provided by third-party software from camera manufacturers, or from installing applications that could generate or edit video files. This support often came in the form of plug-ins to the Quicktime 7 framework, which won't be available in versions of macOS after macOS Mojave.
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
- Sorenson 3
- Sorenson Sparc
- Sorenson Video / Video 3 / YUV9
- Streambox ACT-L2
- Windows Media Video 7, 8, 9
- Xiph.org’s Theora Video
Convert legacy media files in iMovie
No action is required until you're preparing to update your Mac to the next major version of macOS, after macOS Mojave.
In the first half of 2019, an iMovie update will include a feature to help you identify and convert media that uses the QuickTime 7 framework.
Convert legacy media not contained in an iMovie library
To convert a legacy media file, open it with QuickTime Player (version 10.0 and later), then save a copy with a new name. Versions of macOS after macOS Mojave won't support this method.
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.
Formats compatible with versions of macOS after macOS Mojave
These video, audio, still-image, and container formats don't rely on the QuickTime 7 framework, and will be compatible with iMovie on versions of macOS after macOS Mojave:
- 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
- MOV (QuickTime)