How to fix frame drop issues when editing videos in Final Cut Pro?

The behavior is related to the requirement for "rate conforming" in any NLE, which is magnified by the non-standard 80 fps frame rate. A timeline can only have one fixed frame rate. Clips placed on that timeline must either have the same frame rate, or something must be changed. For an 80 fps clip on a 60 fps timeline, there are three options:

(1) Match the rates frame-for-frame, which means slow-motion playback for the 80 fps clip.

(2) For normal-speed playback, some frames of the original clip must be discarded or duplicated, according to some algorithm. This is called "rate conforming." The default type of rate conforming in FCP is "Floor," which rounds down to the nearest whole frame number. It is efficient but does not produce the smoothest results. The rate-conforming method can be seen and adjusted in the FCP Video Inspector (CMD+4 toggles), under the heading "Rate Conform." This setting only appears if the clip frame rate differs from the timeline frame rate.

The need for rate-conforming predates digital video. When 24.0 fps movies are played on 29.97 fps TV, a type of rate conforming called 3:2 Pulldown (sometimes 2:3 Pulldown).

(3) Synthetically create new frames from image analysis of existing frames which can be smoothly blended to achieve the timeline frame rate while minimizing discarded/duplicate frames. This is normally called "optical flow rate conforming," however there are now more sophisticated methods involving machine learning. These settings are visible in the FCP Video Inspector as described above.

If using Optical Flow or Machine Learning, you click that to apply and just wait until the on-screen message says it is finished. Do not try to export it while that is running.

You may not see the above rate conforming artifacts in Premiere Pro because by default, it will alter the timeline frame rate of a new timeline to match the clip -- even if the clip is highly non-standard. That in turn produces a non-standard output, which if not well understood, will cause problems downstream. FCP does not do that but maintains standard frame rates and warns the editor with a pop-up that they are adding a non-standard clip to the timeline, and it will maintain a standard timeline frame rate.

Normally you don't have to transcode imported videos before editing. In this case, if that seems to work, do that. OBS is often the cause of various downstream problems in video editing. Here is a general explanation:

I would designate as "Tier 1" formats such as ProRes 422 encoded by a licensed product, Sony 10-bit 4:2:2 XAVC-I in the MXF container, etc.

Lacking that, a quality codec from a consumer camera, such as Sony XAVC-S 8-bit 4:2:0 or 10-bit 4:2:2 is generally OK. There are sometimes issues with timecode with that format, and it is less smooth to edit than All-Intra, but most computers and NLEs now support hardware-accelerated decoding, which helps. XAVC from mirrorless cameras uses the MP4 container, for which metadata is not as rich or standardized as MXF, but it still generally works. Formats such as Sony's XAVC family are a restricted subset of the possible H.264/HEVC encoding combinations, so this helps reliability and support. It is similar with Canon's XF-AVC format, which is also a restricted, documented subset of a lower-level encoding stream using H.264 or HEVC. XF-AVC uses only the MP4 container, but it works very well. We rarely see major problems from the above formats, so I would designate those as "Tier 2."

Below Tier 2 are highly compressed formats from devices such as GoPro cameras. Those often are not covered by a vendor-specific application standard such as XAVC, and in general we see more problems from those, but it is usually not disastrous. I would designate those as "Tier 3."

Below Tier 3 are what I call "junk codecs" from things like OBS screen capture, consumer security cameras, automotive dash cameras, oddball frame sizes and resolutions, variable frame rates, and formats resulting from unknown multi-stage transcoding involving unlicensed, untested software. Those I would designate as "Tier 4," and they very frequently cause problems.

Often those problems will manifest as an issue with one particular NLE but not others. To naive consumers, "video is video" and they often report problems from Tier 4 formats as an NLE problem, when in fact it's a problem caused by a "junk codec." It's not really the fault of those users, as the information and tools in this area are scarce. This could be likened to problems caused by "bad gasoline," which may seemingly only affect one type of car. But the solution is not to fix that car, but to realize that standards for gasoline purity must be maintained.

Contributing to these problems is the lack of available technical QA tools. Big places like NetFlix have those, and they can easily fund engineers to design tailor-made QA/QC tools to meet emerging needs. Places like NetFlix have rigid acceptance criteria -- only certain codecs from certain cameras. That's an up-front filter that prevents the junk from getting into their system, and what contaminated video slips through is detected by their sophisticated QA tools.

Smaller content producers cannot be so picky -- they often have to accept video content from many sources. There are also no reliable utilities that perform a thorough inspection for encoding defects, especially for problems commonly encountered with "Tier 4" or "junk" codecs.

Further exacerbating this is the lack of enforcement and regulation of the situation. There is no "codec police" who will give a ticket to producers of problem-ridden junk formats.

If playback is not smooth, it's just because rendering can't keep up. Render the entire timeline with shift+⌘R or control+⌘R.

You should see the white dotted lines at the top of the timeline disappear. When they've all disappeared, rendering is complete and playback will be smooth. Rendering each clip is with control+R.

Tom is probably on the correct track suggesting there may be some corrupt clips in your project.

Even the slowest modern Macs can easily deal with native footage straight from the camera so your Mac Studio should fly through editing without the need for transcoding or rendering . . . unless you are adding really complex effects.

However, even the most powerful machines will be brought to their knees by corrupt clips.

Try a new project with different clips and if that works OK import your original footage again from the SD card and with luck it should be minus any corruption.

No problem on my Mac. Plays ok in QuickTime and FCP.

Where is the file stored when you're playing it back? How much free space do you have on my computer system?

First, dropped frames is a playback issue, has nothing to do with missing frames in your original video. A lot of video drops frames when played back, and 99% of the time you'll never notice. I keep the notices turned off, they don't matter. If I can see serious playback glitches, then I have a problem. But if I can't see it, doesn't matter. FCP is doing much more processing than just simply playing a clip back in QT Player. In Settings, turn off the dropped frame warnings, ignore it. Cause if you can't see the dropped frame, it doesn't matter.

Ian R. Brown wrote:

Another thing I found puzzling was that although the original is 80fps the Custom selection chose 60fps.

I thought the Custom setting was supposed to be based on the original clip's properties ie 80fps.

FCP does not allow editing at 80fps, thus it chose the closest option.

The "Standard 2D" is just regular 2D video.

This does not appear unless you choose "Custom", because it is implicit: e.g. you choose 1080p at 25fps, it is obviously 2D. With "Custom", you can choose not just the frame size and rate, but also whether this is "normal" 2D video, or 360, or "Spatial".

It is better to complete rendering before exporting. If the exported video is choppy, it is probably because the original data is corrupted.

Are you editing off of an external drive? Specs?

Where exactly are these files coming from? What format?