During the edit of a 60-second spot using RED footage I used QuickTime proxy files. Although this meant continuous rendering of transitions and effects it was painless. Eventually I needed to conform the proxies to their 1080/24p ProRes 422 counterparts. I didn’t bother with Crimson because there were only about 20-30 cuts.
With speed changes and video effects reapplied I prepared for the final render. It wasn’t long before Final Cut Pro generated this error message:
The effect ‘Scrub’ cannot be rendered in a sequence of this size with the current graphics card.
The Scrub filter had been successfully used throughout the entire edit: from proxy files to scrubbing the timeline in ProRes. I tested different video effects and received the same error message.
While I was writing this I found a solution at LAFCPUG. Modify the render depth from 10-bit to 8-bit in the sequence settings.
This solution is also referenced in an Apple Support document. Unfortunately it doesn’t address why late-model Apple video cards generate the error. Lack of 10-bit color support or a bug?