iMovie File is enormous

[Spaghet]

I have a 50 min video in iMovie that I need to export. I know I can select different sizes but they all seem far too enormous for what they should be. Don’t want to go under 1080p

under best:
4K: 166 gb
1080: 41.9
720: 21.35
540: 18.42
Under high:
4K: 10.31
1080: 7.09
720: 4.29
540: 2.54

are these normal numbers? I want to keep the best version but 166gb is not possible

 

[Dave Braine]

How do those numbers compare with the size of your original source video?

 

[kohlson]

I recommend Handbrake, which also requires VLC (both free) to slim down a completed movie. The nice thing is that the default settings do an excellent job of dramatically reducing file size without noticeably impacting image quality.

You can also try adjusting the Quality using Custom and playing with the slider.

 

[Spaghet]

I’m not sure Dave... the source material was done in 4K but it’s a film so hundreds of snippets from several clips..
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Kohlson- would handbrake be lossless? The other issue is the physicality of exporting it from iMovie first without crashing my computer or taking 4 days...
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It’s maiming I’m wondering if these sizes sound highly unusual for something just under an hour

 

[bogdanw]

iMovie often overestimates the size, I would say the estimate is at least 30% higher than the final size. Try with 1080p High.

 

[HDFan]

Kohlson- would handbrake be lossless?

the source material was done in 4K

If you are dropping to 1080p it will be lossy. There is always a loss when you re-encode, less at higher or the original bitrate.

Don’t want to go under 1080p

Don't use iMovie, but a 1080p commercial blu-ray (~1.5 hours) in .mkv format is in the 30-40 GB range. A 2:34 4k movie I checked was 83 GB

 

[kohlson]

Kohlson- would handbrake be lossless?

I am always baffled by this question. Loss starts in the camera, and continues, to varying degrees, until the viewers see it. Up to and including YouTube and screens. Editing and transcoding is about knowing when to minimize loss (typically editing) and when to maximize it without impacting image quality. This is a very complex subject in today's world of 4K/wide color gamut/HDR/HLG.

But yes, HB is lossy. That's why it makes file sizes smaller. It does a very good job of removing bits without a noticeable impact on image quality.

One thing which may help is h265, the next-gen h264. Made with 4K in mind, it creates smaller files faster. Needs recent Macs to take advantage of this, but iPhones have had this for a few years. 4K gets unwieldy wrt file size with our h265.

If the source is 4K and you want to keep it 4K, you'll need to have the hardware and software resources to do so. But it will be big. Remember that in relative terms, 4K is the equivalent of 4xHD. Your file sizes at the top reflect this. Try varying the custom slider on a short clip - say 5 minutes - and see how it looks.

 

[Dave Braine]

I’m not sure Dave... the source material was done in 4K but it’s a film so hundreds of snippets from several clips..

"Shooting in 4K is a whole new thing. A single minute of ProRes UHD file (3840 x 2160) is around 5.3 GB (880 Mbits/s). A single hour of 4K footage is a whopping 318 GB."

From here:

How Much Hard Disk Space Do You Need to Shoot in 4K?

Planning your feature film production is essential. In fact, one of the most important aspects that you should take into consideration is the hard drive space you will need for your captured material and backup.

www.4kshooters.net

So maybe your iMovie file sizes are about right.

 

[Erehy Dobon]

It's really difficult to give substantial advice because we don't know the following:

• the quality of original source material
• the type of action (fast like sports, slow like an 80-year-old's birthday celebration)
• the final application of the finished video file (upload to YouTube, copy to an iDevice, burned to optical media)

Since we know none of this I can only give the most generic advice.

Let iMovie render in 4K Best Quality then transcode with Handbrake to 1080p.

I would use H.265 10-bit (x265) at a constant 8000 kbps video bitrate, 2-pass (no turbo first pass). Assuming it is generic 2-channel stereo audio, this should result in a file about 2.8 GB in size. Use passthrough audio if at all possible.

Then it is up to the OP to decide if the quality is "good enough" [sic] for whatever nebulous purposes he/she has.

For some 1080p transcodes, I use a 4000 kbps video bitrate, but this is for very specific low-motion content like a symphony orchestra's concert performance. For these sort of transcodes, I will definitely favor the best audio quality (like DTS-HD MA passthrough).

Again, without knowing what the original material is, it is impossible to make a specific recommendation.