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Why does a video file get bigger after editing it with iMovie? [Resolved]

Input File:

  • Kind: MPEG-4 File
  • Size: 305 MB
  • Dimensions: 640 x 360
  • Codecs: H.264, AAC
  • Duration: 52:07
  • Audio Channels: 2

After using iMovie to trim a bit from the beginning and end of the file, I tried to export the file via File ? Share ? File… with the following settings:

  • Format: Video and Audio
  • Resolution: 720p (iMovie only offers me 540p as alternative)
  • Quality: High (according to an answer to a similar question this means H.264)
  • Compress: Better Quality

The estimation on file size shown by iMovie is 4.35 GB. My questions:

  1. How come the file size increases after I cut something from it, encoded both with H.264?
  2. Why does iMovie not offer me the input resolution as an output resolution?

I'd like to be able to trim a video and save it with roughly the same size/time ratio.

Question Credit: Human
Question Reference
Asked February 2, 2019
Posted Under: Apple
2 Answers

One of the possible solutions I came up with is you upload your video to YouTube and YouTube would help you reduce the size with good quality at the same time. Finally, you just download back the file from YouTube.

credit: Daniil Manokhin
Answered February 2, 2019
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