Artifacts in iMovie

You can give your feedback directly to Apple at this link:

https://www.apple.com/feedback/imovie.html

You might consider using your Time Machine backup, if you have one, to revert back to Mojave and iMovie 10.1.12, where everything was working.

-- Rich

Oh wow, this bug is getting bigger and bigger!

I’ve got the same problems since Catalina and tried so many things now, but I guess it’s just a really ugly bug in iMovie 😤

https://discussions.apple.com/thread/250814858?answerId=251560101022#251560101022

can I subscribe to one of your reported bugs or should I open another one?!

thx

Doesn't seem to be a problem with the recording device (ie. iPhone). Check this thread:

https://discussions.apple.com/thread/250779422?page=1

I got a great deal for FCPX and have exactly the same problems like with iMovie. One person complained that the problems started since his upgrade to Catalina... 🤷🏻‍♂️

Have all of you guys reported the issues with iMovie to Apple in a formal way?

https://www.apple.com/feedback/imovie.html

I did and I think it’s the only way to raise attention to this bug, this forum is only a self service info portal...

The more bugs we all report the more attention it will get in the priority list.

And I agree: transcoding is not an option, only an ugly workaround 😤

specially when we’re all using Apple’s ecosystem and not some weird third party tools or codecs!

A recent poster found that the artifact was eliminated by splitting the clip just before the artifact, but not actually cutting out the artifact. In other words, just splitting the clip was enough to eliminate the artifact. Just passing it on.

Here’s the thread:

https://discussions.apple.com/thread/251098954

– Rich

My setup:

MBP 15" 2018 with TouchBar, macOS Mojave 10.14.6

iMovie 10.1.14

iPhone 11, iOS 13.3

~90 video clips in HEVC format

I can confirm that not all iPhone videos causing those artifacts. After 22 tries of tweaking, trimming and replacing "damaged" clips with another clips (that also were taken on iPhone) I've managed to conquer those nasty artifacts in my 3min video. This is ridiculous!

I wrote a Bug report to Apple about this and I would recommend to do the same thing for everyone who is facing this issue. Apple will pay more attention if more bug reports will be reported. On other side they pay less attention if reported bug is old. So we should do this as fast and massive as possible.

https://www.apple.com/feedback/imovie.html

Thanks to everyone who has contributed to this post. It have been very helpful to know I am not alone experiencing this issue.

I have a project that is around 25 minutes long, comprised of many clips cut down to 3-5 seconds. Most of the source clips are 4K iPhone, but there are also some HEIC clips pulled from Live Photos, some 1080 clips from a Sony camera, and a few other mics sources.

Exporting the source clips out to another format and recutting is just not practical.

I just tried the suggestion of exporting the entire movie to ProRes 4k file and unfortunately this did not fix the issue for me.

A few other things I have noticed

• I see the clips during playback in iMovie
• tweaking the affected clip by a few frames, making it a bit longer or shorter, will temporarily remove the artifact
• doing the above fix for the entire movie results in a whack a mole situation, where by the time I have fixed the entire project some of the artifacts
• the artifacts tend to come back in the same places
• the artifacts are a few frames from another nearby clip, sometimes rendered upside down and inverted or with mixed transparency over the underlying clip
• splitting the clip containing the artifact into sub clips (as suggested in one of these threads) did not help fix the issue
• setting the view timescale slider to about the middle and then slowly scrubbing the playhead over an artifact area will also temporarily remove the artifact if you go then jump back a minute or so and watch the affected segment in the iMovie preview panel

At this point I am just waiting and hoping that Apple will release an update for iMovie that will fix the issue. It seems to be releted to key frame generation IMHO.

I have the exact same problem. Serious pixel overlay on multiple places in my timeline, both while editing and in the finished file. Have done two separate projects recently, both have the same problem. My clips are shot with iPhone XR. Have also added several GoPro clips in the same project, but these clips are unaffected.

Mmm that's not the same problem I think we have with the artifacs, that is more like

Yours seems to be more related to video quality (it's really good, by the way) and smooth transitions and low-light conditions maybe.

--Alvy

I believe I found a solution that works. I was getting badly pixelated artifacts semi-randomly in my video when I would export to MP4 in any resolution. I was using video clips shot on an iPhone 8.

To resolve it, I rendered my heavily edited project to a 1080 Pro Res (.mov) file, which essentially flattened the timeline to a single video clip and did not have the artifacts created by the MP4 converter (I believe the converter is the issue, going from the raw iPhone format to MP4). I then created a new project and imported the .mov file I just produced. Once I added that to the new timeline, I was able to export it to any MP4 resolution with no artifacts. I've done this about a dozen times now with the same result - no more glitches/pixelated frames or transitions.

(Cross-posting here in case it helps.)

Hi, geniusweb,

I don't think that Air Dropping the project caused this. Possibly a corrupt preference is causing it.

Try opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if the artifacts are gone.

Another thing you can try is to copy your media into a newly created project and see if that cures the problem. To do that, do an Edit/Select All, Edit/Copy, of the media in your project and then Edit/Paste it into the newly created project.

You could also try booting up in Safe Mode and, after everything loads, immediately shut down and reboot in normal mode. Then see if iMovie works properly.

-- Rich

Hmmm. The issue might be related to a quirk with the new updates. I think somebody mentioned that there is a supplemental Catalina update, but not sure. You might check in case there is a supplemental update that addresses this issue.

You might try using a different transition than cross-dissolve and see if that makes a difference. Or try adding the cross-dissolve by doing Edit/Add Cross Dissolve.

As a workaround, you can add a black background to your timeline and adjust its duration to the same duration as your video clips. Then put your video clips into the auxiliary time line above the black background. Then place your cursor on the video clip to reveal the fade handles (blue dot) in the upper corners of the clip. Slide the fade handles toward the middle of the clip to create a fade. Do that to adjacent clips. You then will get a cross fade that looks a little like a cross dissolve. Not perfect, but might suit your needs.

-- Rich

Of course it’s your call as to whether to try a workaround. I understand completely. I just didn’t want to leave you with no place to go.

At the moment it appears that there is nothing to do but wait until the kinks get worked out with the new software updates.

— Rich