FCP X: Render Files, Exporting and Image Quality

Recently, I was ready to export a project from Final Cut Pro X only to discover that the project render files did not match the format that I wanted to export. This started me wondering how FCP X handles sharing (exporting) when render files and export settings don’t match.

BACKGROUND

I tend to record in two formats:

• ProRes 422 HQ for camera-based recording
• ProRes 4444 for screen-captures and Motion or After Effects projects

To see or change the render settings, choose Window > Project Properties (type: Cmd+J), then click Modify Settings.

By default, Final Cut sets ProRes 422 as the render format. Use the Render Format menu to change the render settings.

Keep in mind that FCP X makes use of all the processing resources in the system simultaneously (GPU + CPU). In other words, Final Cut has the GPU doing effects and image processing, which offloads work from the CPU so it can focus on encoding. So with both GPU and CPU working together in parallel, Apple has made huge improvements in the export speed compared to FCP 7, or other applications that are not so tightly integrated into the Apple hardware.

HOW FINAL CUT PRO X HANDLES RENDER FILES

When the time comes to share (export) a file, there are three ways Final Cut will handle render files:

1. If the render files exactly match your export destination codec (for example, a project with ProRes 422 HQ render files exporting to a ProRes 422 HQ master file), then the render files will be used. That is, the frames are simply copied to the final file.
2. If your export destination codec is one of the 6 ProRes codecs, or one of the two uncompressed 4:2:2 codecs, and the render files don’t match, Final Cut treats the timeline as if it was unrendered. In other words, it goes back to the original/optimized/proxy files rather than use your render files. This is similar to the way Export Movie worked in FCP 7.
3. If the final delivery codec is of a lower quality than the render files, then Final Cut transcodes directly from the render files during share. This preserves original quality (one of the main purposes of ProRes) and insures that the final output is finished as quickly as possible.

SUMMARY

I really like how Apple’s engineers have solved this problem. It means that if my render files don’t match my final output, Apple will use the highest quality when creating a master file or the fastest option when compressing a file for the web.

Cool.

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