Use Final Cut Pro to transcode Quicktime movie files that contain PNG frames
If you are using Quicktime movie files that contain PNG frames that include an alpha channel, use Final Cut Pro 10.4.9 to transcode them instead of Compressor.
Open your project with the QuickTime movie files that have PNG frames with an alpha channel Final Cut Pro 10.4.9. Choose File > Share, select Master File, then click Settings. Choose an Apple ProRes option from the Video Codec pop-up menu:
To preserve the alpha channel, choose ProRes 4444 or ProRes 4444XQ.
If you don’t need to preserve the alpha channel you can choose any of the other ProRes options.