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Not Necessarily Compressed
Authored by: mdwittenberg on Feb 22, '11 08:41:10AM

Excellent hint. I wish that this was the default behavior (or at least an option), though I suppose it does use up a LOT of hard drive space.

NOTE: The "optimized" full size video is not necessarily "compressed" nor suffer from any lost quality. In fact, technically it's less compressed because iMovie converts it to a different format that is simply more easily accessed for scrubbing. Imagine an accordion file folder with many documents stuffed in: the original camera footage keeps the file in the "compressed" state, though normal speed playback is possible by carefully pulling out each page. In contrast, to properly scrub through in iMovie the accordion file must be opened all the way. The footage is (should be) virtually identical, just simply stored in a different way.

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Not Necessarily Compressed
Authored by: Unsoluble on Feb 23, '11 10:19:20AM
Well, with the 960x540 optimization you're clearly losing data. You might be correct that the "Full" optimization is completely lossless, but I've never seen that confirmed.

Edit: Yep, my original assumption was correct — the "Full" optimization is not lossless. Here's a side-by-side comparison of a video frame, with the original HD on the left, and the Full version on the right. Until optimizing doesn't result in that kind of artifacting, I'll be keeping my raw footage.

Edited on Feb 23, '11 10:33:50AM by Unsoluble

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Not Necessarily Compressed
Authored by: mdwittenberg on Feb 23, '11 05:27:26PM

Thank you for running the comparison Unsoluble; I never bothered to check iMovie's conversion quality.
If anyone is interesting in full speed scrubbing AND lossless video, I've used MPEG streamclip in the past at 100% quality. The file size was outrageous, but it worked and appeared to be lossless.

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