Optimize Video, Full (Original Size) - What Does It Do?

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Level 2

290 points

Optimize Video, Full (Original Size) - What Does It Do?

I've recently noticed that some of the video I've imported into iMovie '09 is "optimized" and some isn't. What's the difference?

Specifically, what does the action "Optimize Video - Full (Original Size)" actually do? If the video can already play in iMovie, and is clearly compatible with it, why does it need optimizing?

Once you optimize a video, you can't de-optimize it, right? It's a one-way street.

iMac (21.5-inch, Late 2009, Week 47), 3.06GHz, 4GB RAM, Mac OS X (10.6.3), iPhone 3GS (16GB), Apple TV (160GB)

Posted on Jun 26, 2010 1:57 PM

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Answer 1

Jun 26, 2010 2:47 PM in response to Reuben Feffer

Optimize converts, say, h.264 into Apple Intermediate Codec.
H.264 is a highly compressed codec, with a full frame of video about every 24 frames, and partial information for the remainder of the frames, containing info like what has changed since the last frame, the direction of motion, etc. Apple Intermediate Codec resolves these into full frames.

This is important when doing operations like image stabilization or speed changes where iMovie needs access to every frame.

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Answer 2

Reuben Feffer Author

Level 2

290 points

Jul 1, 2010 7:21 AM in response to AppleMan1958

Thanks for the reply.

I did some tests with a 42 second clip recorded in HD with an iPhone 4.

• The original .MOV file was 56.1 MB
• When I imported it into iMovie '09, ticking Optimize Video (Full - Original Size), it became 349.4 MB
• When I imported it into iMovie '09, ticking Optimize Video (Large - 960x540), it became 236.9 MB

So personally I'd rather NOT have iMovie '09 optimize my videos, because the optimized files (converted to use the Apple Intermediate Codec) are ridiculously huge!

• Straight off the iPhone 4, the .mov files use the H.264 codec and have a bit rate of 10,720 kbps
• But "optimized" with iMovie '09 they use the AIC codec and have a bit rate of 66,837 kbps!

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Answer 3

Jul 6, 2010 8:08 PM in response to Reuben Feffer

There is an advantage to having the optimized video: At least on my computer, it plays significantly more smoothly, and it scrubs better, too. Here's what I found for an 8.1 s clip from my iPhone 4:

Original file: 10.5 MB, 95% CPU when playing.
Optimized Large: 37.6 MB, 51% CPU
Optimized Full: 56.9 MB, 47% CPU

With the original file, the viewer is jerky when it's playing, and the red scrub bar has trouble keeping up with the mouse. With the two optimized, the viewer is smoother (but not perfect), and the scrub bar keeps up with the mouse pretty well.

I don't understand why the original is so jerky in iMovie when it plays perfectly in QuickTime. I've always had problems with jerky video in iMovie.

I will also mention another point of interest: I have compared video from my iPhone 4 with video from my Sony HDR-HC5 HDV video camera, a pretty decent HD camera that records on mini-DV tapes. I was surprised to find that the iPhone video is markedly sharper. It really looks significantly better. I will probably be taking more video using my phone now, instead of always lugging around the video camera.

Downsides to the iPhone video: Not as good in low light. Terrible orange hue in incandescent light (some posters have claimed this might be a defect, as not all phones seem to have this). "Rolling shutter" artifacts. Hard to hold steady, and worries about dropping it since it has to be held in an awkward way.

Still, it'll be great to always have a high-quality (in outdoor light, at least) video camera close at hand.

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