It may not happen often, but from time to time you’ll end up with a 25fps sequence in which you need to ingest clips that have been shot at 24fps and at 25fps. In Final Cut Pro X you can mix different clip formats and frame rates voluntarily, but you won’t have control over the end result. Other than just drop clips in a Final Cut Pro X sequence (aka Timeline) and not worry about it, there are five ways to retime a 24fps clip to a 25fps one.
The first retiming trick is using the Retime Editor in Final Cut Pro X. With your 24fps clip loaded in your 25fps Timeline, just select the Retime Editor and drag the slider to 104%. This will speed up your 24fps clip to 25fps, including its audio. Pitch will slightly increase too.
Second method involves selecting “Conform Speed” from the Retime Editor’s drop-down menu with the 24fps clip in the 25fps Timeline. This essentially does the same as adjusting the speed with 104% upwards. In fact, you’ll see the Retime slider appear with 104% filled in.
The third way is to make a side trip to Apple Motion. In Motion, you can select your project to be 25fps. Drag the clip in the project window, save the project, share it to a QuickTime movie or export it to a ProRes format of liking and you’re done. In Project properties you can optionally set Frame Blending to make the clip as smooth playing as the original.
The fourth way is to do the same in Adobe After Effects (CS6 was my version). Just set the frame rate as 25fps and save as a movie. The result may look more stuttering than with Motion. Alternatively, and that’s the fifth method, you can add the Time Warp effect to the clip in After Effects and play with the settings. This allows for control over frame blending, but I personally found the default settings the best.
As far as I could tell with a few 2-minute clips of marbles rolling about randomly in a clear plastic box, the best method was the one in which you sidetrip to Motion with Frame Blending turned on. I did not experience stuttering, nor did the sound went out of sync. The pitch was a little bit higher, but it was hardly noticeable.
Of course, the above only holds when you have Final Cut Pro X (or Premiere Pro) on your system. If you have Avid Media Composer, you get two ways to do this:
- Export your clip to a 24fps QuickTime movie without sound, and use “Same-As-Source”, 601/709 levels. Now create a 25fps project in Media Composer, type “IgnoreQTRate True” into the Console and press Enter. Open a bin and import the 24fps exported clip (601/709 levels). The clip will import frame-by-frame, which will take some time, but you will end up with a 25fps version of it, which you can export again.
- The second method here is to playout your 24fps clip at 25fps from the Digital Cut Tool and record that playout at 25fps.