FCP inserting black frames in video for no reason

Another day, another frustrating FCP issue. What is this, Adobe Premiere?

When I import certain HEVC files into Final Cut Pro (FCP version doesn't seem to matter), it will insert black frames that are not there. I have attached an example file for people to download. Play it in Quicktime. No issues at all. Now import that file into Final Cut Pro. You don't even have to put it in a timeline, just play it in the Browser. The video will drop out for about a half second every so often. Seriously, what the hell? Another Mac Studio issue? If so, this computer is starting to become a liability.

DOWNLOAD:
drive.google.com/file/d/1Glv5x_wUm4JdCNR...1Yq/view?usp=sharing

I see artifacts when playing in Quicktime. Granted the machine I'm on at the moment is an old iMac running 10.13. ffprobe reports it as 59.63 fps.Stream #0:1(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, smpte170m/smpte170m/bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 50098 kb/s, 59.63 fps, 60 tbr, 60k tbn, 60k tbc (default)

It's consistent in three different places in the file. MediaInfo shows this

Frame rate mode                          : VariableFrame rate                               : 59.633 FPSMinimum frame rate                       : 30.000 FPSMaximum frame rate                       : 60.000 FPS

The only thing I can really add at this point was the HEVC file was made with Compressor, the same preset I've used dozens of times.

Is the frame rate set to automatic? You’ll get whatever the original file is.

Redifer wrote:

When I import certain HEVC files into Final Cut Pro (FCP version doesn't seem to matter), it will insert black frames that are not there...

I see it on 10.6.1 and 10.6.3 on my M1 Ultra and M1 Max. It also happens with Resolve Studio 17.4.6 on M1 Ultra. It's some kind of HEVC decoding problem -- it doesn't happen if you transcode to optimized media. VLC 3.0.17.3 on M1 Ultra shows similar problems. It doesn't happen on FCP 10.5.2 on Intel or VLC 3.0.7.1 on Intel. We need someone to test it on M1 and M1 Pro to determine if it's another Ultra/Max problem or if it's FCP/VLC/Resolve on any Apple Silicon machine.

The metadata looks a little odd -- Invisor shows one frame rate field as 59.633 fps. Another field in the video header says 60.0 fps. How was the video produced, was it captured by some utility or what?

I see three spots where image glitches appear, in both the Browser and in a test timeline. One near the beginning, one near the end, and a third one around the middle of the clip.

In QT Player I only see the first and the last glitch. I believe that QT Player will drop/skip frames during playback as its normal behavior (and won't "say" anything).

From looking at the file metadata, the clip was transcoded to HEVC with its original variable frame rate intact. I know that this alone is a no-no. Variable frame rates are not kosher for editing. If you transcode the source into a new HEVC file with a fixed frame rate, you may eliminate the glitches (unless those were in the original file). Screen recording and (usually cheaper) capture devices are notorious for capturing in variable frame rates.

Also, when I select the clip in a timeline, the Rate Conform effect shows in the inspector, which suggests that FCP is applying a temporal conform to get the clip to a constant frame rate.

2019 (Intel) Mac Pro, FCP 10.6.3, macOS 12.4

Redifer wrote:

The only thing I can really add at this point was the HEVC file was made with Compressor, the same preset I've used dozens of times.

If the input file was ProRes 422 recorded by Quicktime through that Magewell card, it would be interesting to see the video header for that file. If you have MediaInfo or Invisor you can use those.

It might be some grey area in the encoding spec that is triggering a bug in FCP on Max/Ultra. However VLC is totally stand alone, and that also shows problems on Max/Ultra.

It was indeed recorded in ProRes with the Magewell. All of the recordings I made that day are doing this so now I must spend hours re-recording the games as I tossed the ProRes originals away. I have since re-recorded and re-encoded Montezuma's Revenge with the same Compressor preset and the issue is not there. The Magewell is set to record at 60.01 frames per second which is what the RetroTink 5X outputs. I could put the RetroTink on Frame Lock mode, but then each console has its own frame rate, Nintendo consoles for example run at 60.1Hz and Sega consoles run at 59.92 and the Magewell doesn't adapt automatically to that, sadly. The frame rate in the file itself should not be variable. I believe that's being misreported or perhaps mis-encoded by Compressor.

Here is the new recording I made 20 minutes ago, compressed with the same Compressor preset, but it works fine now.
drive.google.com/file/d/11KUH3r5mgb-4GXh...Wit/view?usp=sharing

The Compressor setting is indeed on Automatic, I'd have it no other way. I don't want it changing anything.

I don't see artifacts on this one but ffprobe reports 59.55 FPS. Invisor says it's variable so I'd expect there to be problems at some point in the workflow.

Stream #0:1(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, smpte170m/smpte170m/bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 58769 kb/s, 59.55 fps, 60 tbr, 60k tbn, 60k tbc (default)

Invisor must be misreporting. It says 60 solid in VLC and Quicktime. Or Quicktime is screwed up and is somehow recording variable framerate videos out of streams that are not variable frame rate. Or Compressor is screwed up and encoding variable frame rate videos out of clips that are not variable frame rate.

Here's the ProRes version before encoding. What does Invisor report?
drive.google.com/file/d/1o7CmdBYI4P6NOnA...Agd/view?usp=sharing

Invisor says Constant. Both ffprobe and Invisor report it as 60 fps.

So that means the issue is happening in Compressor.

Why not test Compressor with explicit 60 fps output rather than automatic?

QT Player and VLC probably round the frame rate. Invisor or MediaInfo both report fractional/variable frame rates.

"NewTry.mov" shows as variable frame rate In MeidaInfo or Invisor.
Frame rate mode: Variable
Frame rate: 59.551 FPS
Minimum frame rate: 30.000 FPS
Maximum frame rate: 60.000 FPS
Frame count: 391

"ProRes.move" shows as 60.000 fps in MediaInfo or Invisor.
Frame rate mode: Constant
Frame rate: 60.000 FPS
Frame count: 467

I will later, am recording now. Why would it change anything in the first place though?

Some oddity in the captured ProRes file that's throwing Compressor off? I don't know. Simple enough test to run. I don't have Compressor on this iMac or I'd run the test.

OK this is HEVC with Compressor locked at 60. Is that what Invisor reports?


drive.google.com/file/d/1942sVf7Y9rS3hSZ...acT/view?usp=sharing

Yes, Invisor reports Constant. Both Invisor and ffprobe report 60 fps.

I ran ProRes.mov through Compressor and my result is 60.000 fps (I left the frame rate encoder setting on Automatic).

Of course, without using the same preset it's a crap shoot. I just picked the Apple Devices 4K 8-bit HEVC preset...

In MediaInfo/Invisor, NewTry.mov shows 391 frames, whereas NewTry-HEVC.mov shows 394 frames. NewTry.mov has a variable frame rate, whereas NewTry-HEVC.mov has a frame rate of 60.000.

Intel, FCP 10.6.3, macOS 12.4