Why is iMovie export to using so little

Question

Why is iMovie export to using so little

I'm using iMovie 10.1.11 to export 25 minutes of 720p H.264 to a 720p file,

running on a 2018 MacMini 3.2 GHz Intel Core i7, with 32GB RAM, with Mojave 10.14.5,

and a Thunderbolt 3 connected Radeon RX 580 8GB eGPU.

iMovie is only using 3% of the CPU, 64 threads,

and the ProTrranscoderTool_sp is using 0.5% with 33 threads.

The GPU History shows the AMD Radeon RX 580 processing the video but only one dot high.

The export takes about 24 hours.

There are no transitions, no mixing of audio, for the first 20 minutes of the video it should be a straight container copy, and then the last 5 minutes have a closing titles.

Mac mini, macOS 10.14

Posted on Jun 4, 2019 5:37 PM

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Answer 1

Best reply

Rich839

Level 8

47,280 points

Jun 5, 2019 8:50 AM in response to Alan McDonley

Hi, Alan,

I don't know the answer to your question. You might want to read the following Apple article on eGPU set up on a Mac, to see if anything in there raises an eyebrow about your set up:

https://support.apple.com/en-us/HT208544

Possibly it is just a matter of plugging into a different port or configuring iMovie to prefer an eGPU.

-- Rich

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Answer 2

Jun 6, 2019 9:17 AM in response to Rich839

Thanks for replying.

I was familiar with that article, and do have "Prefer external GPU" set on the iMovie.app and indeed it seems to be using the eGPU.

Looking back at past questions, I see other folks, that do not have an external GPU, complained about iMovie not using much of the processing resources.

Not that I'm in such a hurry, but it does not speak well for iMovie against alternatives.

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Answer 3

Rich839

Level 8

47,280 points

Jun 6, 2019 9:32 AM in response to Alan McDonley

There are a couple of old standby procedures that you can try.

The first is to delete preferences by opening iMovie while holding down the Option and Command keys, and deleting preferences from the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects.

Now see if you can share out at a faster rate.

Secondly, sometimes some projects inexplicably act differently than others. You might try doing an Edit/Select All, Edit/Copy, of the media in your project and then Edit/Paste it into a newly created project. See if your export time is reduced.

Two things that can increase export times are exporting in Best Quality (pro res) that will give you a .mov file that is 4x larger; and exporting simultaneously to Theater. High frame rates also increase export time.

-- Rich

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Why is iMovie export to using so little

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