The following is taken from the Adobe website and lists the codecs that Premiere Pro will now load as they have stopped using QuickTime for Windows. You can see the original page here: https://helpx.adobe.com/uk/x-productkb/multi/quicktime7-support-dropped.html
Adobe continuously aims to keep up with the most modern workflows, support formats, and codecs broadly used across the professional film and video industry. As a result, Adobe will no longer support legacy QuickTime 7 era formats and codecs starting from the following product versions:
- April 2018 release of Premiere Pro CC (version 12.1)
- April 2018 release of After Effects CC (version 15.1)
- April 2018 release of Adobe Media Encoder (version 12.1)
- April 2018 release of Adobe Audition (version 11.1.0)
Older codecs such as Cinepak, Graphics or Sorenson Video are affected by this change. Media using such legacy codecs should be converted to a modern codec, so that use with these products can be continued.
Professional codecs typically found in QuickTime movie files, such as ProRes, DNxHD, and Animation, are not affected by this change.
Codecs supported by After Effects, Media Encoder, and Premiere Pro
If you run into issues because of this change, use any of the following workarounds:
- For export formats, use the currently available newer codecs.
- For import formats, transcode legacy footage to a newer codec.
Older versions of the software will continue to support 32-bit QuickTime media on currently released operating systems.