File size is huge


macrumors G5
Original poster
Mar 21, 2011
Australia, Perth
Hi all

Regarding HD content 720p 1280x720, i have two files. one goes for about 1 hour 43 minutes: - 2.49Gig, while is other one goes for 2 hours, 11 minutes and is an whopping 10 Gig

Is this correct to anyone ? How can a mere hour or so be an extra 8 Gig ? when there both the same resolution ?

Granted the 10 Gig one was exported from iMovie. The 10 Gig file extension is .mp4, while the other is .m4v (encoded with Handbrake).
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macrumors 68000
Mar 17, 2007
It is all about the bitrate of the video the Handbrake encoded one I would bet if you were to check is somewhere around 1500-2K the larger one I would say somewhere in the 7-8K range. The information stored increases in size the higher the bitrate the video is encoded in, so two copies of same file one at 2K the other at 4K the 4K is double the size.


macrumors 68020
Dec 3, 2001
iMovie isn't uncompressed. The video format it uses to edit is the Intermediate Codec which uses very low video compression and uncompressed audio. Once you export, it's the standard bitrates iMovie exports to based on the chosen output resolution that's causing the large file sizes.

Use the export with Quicktime option in iMovie instead and then choose more approriate settings like this: -

Resolution 1280x720
File Format: mp4
Bitrate 1500-2000 (your choice)
Video: H.254 (2 pass encode)
Audio: AAC 256Kbps (or 320)

You'll get your file sizes smaller. I wouldn't recommend going much below 1500 with 720p video even with 2 pass encode, you'll introduce too many compression artifacts.
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