Need help understanding iMovie 11 media managment and rendering options

Discussion in 'Digital Video' started by sbroadcast, Feb 15, 2013.

  1. sbroadcast macrumors newbie

    Feb 15, 2013

    I'm having a hard time understanding how imovie 11 processes and renders videos. Everything I've exported has been a combination of HUGE video files or videos with artifacts.

    I have been importing .mp4 videos that were converted with Handbrake from .mts. I'm using files provided from another person so I do not have the original camera. When I move the files to imovie it looks like it turns these files into huge .mov files in the project folder (for example a 1 gig .mp4 video will be turned into a 20 gig .mov folder)

    I'm trying to produce the best quality video export to be used for youtube, DVD and uncompressed that I can handoff to someone else so they can finish the project. I do not want to directly post to these applications.

    Can somebody walk me through a workaround? I'm using imovie 11 on 10.6.8.
  2. simsaladimbamba

    Nov 28, 2010
    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.
  3. sbroadcast thread starter macrumors newbie

    Feb 15, 2013
    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.

    Going back to the .mp4 that were transcoded from the .mts in Handbrake - these files looked exactly like the original file and had the same file size when transcoded at full quality. When imported into imovie they look and edit fine as well, however getting them imported takes around 3 hours for only an hour of footage. I'm assuming this is because imovie is converting the files over to .mov which they store in the project folder. I know you referenced this before, but is there absolutely no way to speed up the import process?

    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.
  4. simsaladimbamba

    Nov 28, 2010
    What about the Small tool to convert video containers without reencoding I linked to? And ProRes is only available for FCP.

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

    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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