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Imovie files Too big

when I have a a video in my photo's app it is around 2 GB but when i import it to iMovie it becomes close to 14 GB and this is without editing it, Its even going from 2.7k resolution to 1080 resolutions and still growing so big. How do I reduce the file down to its original size without loosing quality?

iMac, OS X 10.11

Posted on Apr 10, 2020 11:51 PM

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Question marked as Top-ranking reply

Posted on Apr 11, 2020 12:44 AM

When you export with Best Qualtiy (pro res) you will get a .mov file about four times larger, or more, than if you export at just Good quality, that renders a Mp4 file. This is because of the much higher bitrate of the pro res format. So what you are doing is exporting at a much higher bitrate than the bitrate of the clip that you originally imported. Therefore much larger file size. Also, iMovie does not support 2.7k resolution, and that's why it got reduced to 1080p.


Additionally, when a movie clip is imported into iMovie, iMovie unpacks it for editing. If the clip were highly compressed it might have been a smaller size initially but will become larger when uncompressed for editing and then exported at with less compression.


Export at Good Quality 1080p instead of Best Quality (pro res) and you should get a movie with the same quality that you imported, with the exception that it won't be 2.7k. It will be a much smaller file size than than the pro res file.


--- Rich



4 replies
Question marked as Top-ranking reply

Apr 11, 2020 12:44 AM in response to Andrewwwwwwww

When you export with Best Qualtiy (pro res) you will get a .mov file about four times larger, or more, than if you export at just Good quality, that renders a Mp4 file. This is because of the much higher bitrate of the pro res format. So what you are doing is exporting at a much higher bitrate than the bitrate of the clip that you originally imported. Therefore much larger file size. Also, iMovie does not support 2.7k resolution, and that's why it got reduced to 1080p.


Additionally, when a movie clip is imported into iMovie, iMovie unpacks it for editing. If the clip were highly compressed it might have been a smaller size initially but will become larger when uncompressed for editing and then exported at with less compression.


Export at Good Quality 1080p instead of Best Quality (pro res) and you should get a movie with the same quality that you imported, with the exception that it won't be 2.7k. It will be a much smaller file size than than the pro res file.


--- Rich



Imovie files Too big

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