Need help understanding iMovie 11 media managment and rendering options

iMovie uses its own Apple Intermediate Codec in order to give you a smooth editing experience, but that Apple Intermediate Codec saves every single frame of a video in a file, which highly compressed .mp4 files do not (they store keyframes and the frames between those keyframes calculated during playback, in simple terms), thus those .mp4 files are not really meant for editing.
As the Apple Intermediate Codec stores every frame, the resulting .mov file is of course bigger. You have to live with that, if you want to use iMovie. FCP X for example gives you the option to not create those big files and work with the small .mp4 files, but that will put a lot of stress on the CPU and depending on what Mac you have, that might actually slow your process down.

As to the artifacts, what kind of artifacts are we talking about and how did you export the finished sequence from iMovie (be as precise as you can, especially with the settings and maybe even screenshots).
Have you seen these artifacts in iMovie too?

And while the following is not made for iMovie, it explains how editing applications work from time to time.

Video Compression
Why It Matters & How To Make The Most Of It

And the following video should be of interest to get to know the difference between containers and codecs.


And for future reference, these two methods should provide you with better results from the .mts files.
You could try the following two methods involving free applications to get editable or playable video files from .MTS files.

sbroadcast said:

Hi simsaladimbamba - Thank you for your response

Unfortunately the "Transcoding .MTS files (AVCHD footage) to an editable format (.MOV)" process did not produce good results. The transcoded .mov had heavy block artifacts and the resulting file size was 40 gigs from an original 1 gig file. I used the Apple Intermediate Codec and full resolution as suggested on the post. Apple Pro Res is not available on my computer.

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What about the Small tool to convert video containers without reencoding I linked to? And ProRes is only available for FCP.

I know you referenced this before, but is there absolutely no way to speed up the import process?

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Only a faster Mac will do.
Do you have a small sample .mts file you could upload and I could try it?

Now to rendering - What are the best settings to export a Quicktime for both posting on Youtube, DVD creation and a Uncompressed (or high quality) video that can be used by another editor down the road?? As a test I rendered out the video using the compression H.264 at the highest quality and it looked like garbage, taking almost a day to render.

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You should export* a .mov file using the Apple Intermediate Codec, if the bolded part it important to you.
Then use that .mov to create further children for YouTube via HandBrake, for DVD creation via Compressor or whatever DVD authoring software you use.

Btw, what Mac OS X and iMovie version do you run an what Mac model, with specs, if you do not have the Model Identifier handy.

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