Due to the security gaps identified in Apple QuickTime, the United States Computer Emergency Readiness Team has recommended that users uninstall Apple QuickTime from Windows. Apple has also ended support for Apple QuickTime for Windows.

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Fortunately, modern .mp4 and .mov files can still be read without QuickTime.
If QuickTime is not installed, the software is capable of using H.264/AVC and AAC or PCM audio to read .mp4 and .mov files.
These modern formats are used by many DSLR and action cameras.

However, QuickTime is still necessary to read .mp4 and .mov files with QuickTime-based codecs such as ProRes and CineForm.
When you uninstall QuickTime from Windows, the software is unable to provide support for these formats.

To continue using files with CineForm, we recommend converting the files to AVI.

Catalyst applications (Catalyst Browse, Catalyst Prepare and Catalyst Edit)

The Windows versions of the Catalyst programs do not use QuickTime.
Uninstalling QuickTime will not affect support for file formats in these programs.