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WizOSX · Feb 17, 2009, 02:09 AM

I recently read that iMovie "drops" every other line of an HD event in order to make editing quicker. Does anyone know for sure if this is true? When I first import a HiDef movie into iMovie from my HDV camera it creates the .mov events in the Movies folder. Do these have 100% of the original information? I'd like to know whether I can safely overwrite a DV tape assuming I have a 100% backup on my Mac's hard drive. Related question: my Sony HD camera saves to the DV tapes in MPEG4. I've read that .mov files are MPEG4 (with, I assume, a little Quicktime info added). Is this true?

mduell · Feb 17, 2009, 08:26 PM

iMovie can't edit HDV natively so it converts to Apple Intermediate Codec (which is about 4x the size) with a lossy conversion (reduces quality).

Are you sure your camera is putting MPEG4 on DV tape? The HDV standard is derived from MPEG2, not MPEG4; the hard drive and flash based HD cameras generally used AVCHD, which is derived from MPEG4.

Veltliner · Feb 19, 2009, 08:19 PM

Originally Posted by WizOSX

I recently read that iMovie "drops" every other line of an HD event in order to make editing quicker. Does anyone know for sure if this is true? When I first import a HiDef movie into iMovie from my HDV camera it creates the .mov events in the Movies folder. Do these have 100% of the original information? I'd like to know whether I can safely overwrite a DV tape assuming I have a 100% backup on my Mac's hard drive. Related question: my Sony HD camera saves to the DV tapes in MPEG4. I've read that .mov files are MPEG4 (with, I assume, a little Quicktime info added). Is this true?

It's true.

There's this feature called "skimming" (or something like that). It's one of the reason why data has to be overcompressed. It's like the MP3 for video.

You can download iMovie HD for free from apple, which doesn't have any of that kind of quality reduction. Its interface is closer to "real" editing software like Final Cut Pro/Final Cut Express. It was the last iMovie before the switch and is still pretty good, even though 2 or more years old.

WizOSX · Mar 3, 2009, 01:43 AM

Thanks Veltliner and mduell.

Yes, the files are actually a variant of MPEG2.

I guess what I'm mainly wondering is whether the file that iMovie imports from the camera is exactly the same as what Quicktime, iMovieHD and FCP would initially import (the .mov file). IMovie calls Quicktime to import the file from the camera, asks you if you want it to be HD (i.e. 1080, etc.) and then puts the file in the Movies folder. Is this file the same as what FCP would import before editing?