Size-blowup of AVCHD files when importing into iMovie

Discussion in 'Digital Video' started by macbook123, Jan 11, 2011.

  1. macbook123 macrumors 68000

    Joined:
    Feb 11, 2006
    #1
    When I import AVCHD videos into iMovie the original .mts files end up being 3 times large files in the library. Why is that? Can it be changed?
     
  2. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #2
    That is normal, as iMovie can't edit with native AVCHD footage, which uses a highly compressive and lossy MPEG-4 codec. Therefore the footage gets transcoded to a .mov file using the Apple Intermediate Codec (AIC) for video and Uncompressed for audio, as that is a much better format and codec to edit properly and the new .mov files contain every single frame instead of approximation between keyframes in the AVCHD footage, thus the bigger file size.
    HD footage gets "blown up" to 25GB/hour for 720p/30 footage and up to 49GB/hour for 1080i/60 footage.
    http://support.apple.com/kb/HT2704?viewlocale=en_US
     
  3. notjustjay, Jan 11, 2011
    Last edited: Jan 11, 2011

    notjustjay macrumors 603

    notjustjay

    Joined:
    Sep 19, 2003
    Location:
    Canada, eh?
    #3
    Yes, unfortunately, this is a fact of life when editing AVCHD video on a Mac using iMovie and Final Cut.

    You get to wait longer for the additional transcode process from AVCHD to AIC (a little longer than real-time), plus deal with the huge increase in disk space required. Further, since iMovie didn't suck in the original .mts file, how do you plan to back up your footage? You can't just copy the .mts file to a backup drive somewhere and hope to re-import it at a later date: they only recognize the clips as part of a fully formatted memory card. So you either save the AIC file (which already has one generation of compression loss and take up huge disk space) or you need to resort to tricks to archive entire memory card volumes.

    (Edit: oops, I forgot that I'm using a slightly older version of iMovie. The latest version has an archiving utility which helps you copy/archive the original footage.)

    I've been told that Premiere can handle native AVCHD video just fine. Hopefully this is true, I haven't had a chance to try it yet. There are also third party utilities that can partially alleviate some of these issues.

    This is the one issue that is starting to make me want to either buy a Windows 7 machine or at least dual-boot Windows on my MacBook Pro. I know how AVCHD video works and I know it is highly compressed, long-GOP encoding, CPU intensive, and so on. If every platform or editing suite required an intermediate codec for editing, I would not be complaining. But the fact is that on modern hardware, pretty much every non-Apple editing suite (including everything on Windows) seems to be able to handle native AVCHD just fine. Apple needs to get with the program here.
     
  4. aarond12 macrumors 65816

    aarond12

    Joined:
    May 20, 2002
    Location:
    Dallas, TX USA
    #4
    You are comparing a consumer-level application (iMovie) to a professional-level application (Premiere). Yes, Premiere can handle AVCHD files natively, but the CPU usage is WAY higher than an I-frame only CODEC like Apple Lossless. Yes, the files are larger, but the performance on consumer-level hardware is significantly better than what Premiere can do on the same computer.

    You CAN back up the AVCHD files to another device -- it doesn't have to be a memory card. Just use your favorite DVD burning software and burn the files from your memory card directly to the DVD (in the same directory structure) and, when you need to reimport the footage, it's there for you.

    Remember, AVCHD files are just MPEG-encapsulated H.264 video files. There's nothing really magical about them.
     
  5. simsaladimbamba

    Joined:
    Nov 28, 2010
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    #5
    I once edited XDCam footage (1920 x 1080, 25p, 50Mbit/s) on a Mac Pro 3,3 and used Avid Media Composer and AMA to edit the MPEG-2 footage without further transcoding (DNxHD 185 for example) and even though we only used a two camera multi-cam-group, the MP was crawling and the CPUs spiked all the time and the delay in playing a group with two cameras was very noticeable and and it took the second camera stream up to two seconds to play along the first camera stream.

    Once I transcoded the footage to DNxHD for colour correction, it was buttery smooth.

    Even though the ability to edit AVCHD or other highly compressive formats natively seems fine on paper, why give your computer and yourself a hard time (waiting) every now and then instead of transcoding it at night, even though ingestion of 1 hour of non-tape HD material takes longer than an hour if one uses a good codec like DNxHD or ProRes/AIC.
     
  6. notjustjay, Jan 11, 2011
    Last edited: Jan 11, 2011

    notjustjay macrumors 603

    notjustjay

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    Canada, eh?
    #6
    Fair enough. So let's not pick on iMovie, let's compare apples to apples. Final Cut Pro perhaps? Nope: according to Apple, "AVCHD footage is transcoded to the Apple ProRes 422 codec or the Apple Intermediate Codec". Same with Final Cut Express.

    That's what I was referring to. The backup needs to be an exact copy of the original memory card or the import won't work. (By the way, I have three 16GB memory cards... If I fill a card beyond 4.7 gigs, I can't use a DVD to back them up.) The best way I've seen to do this is to use Disk Utility to make a complete .DMG image of the memory card (equivalent to burning a DVD), then storing the .DMG file on a hard drive or whatever backup medium you choose. Then to restore the clips, you mount the .DMG file, open iMovie and it shows you the Import window just as it did with the original memory card.

    Apparently the newer version of iMovie helps you out with this step so you don't need to play with Disk Utility.

    But why should I have to import/backup entire memory cards at once? Why can't I work on a clip by clip basis? If you dig into the memory card you'll see the individual video files with a .MTS extension. I can copy a .MTS file onto my Mac, and I can play it using VLC. I can even convert it using third-party utilities. But can I drag the .MTS file onto an iMovie or Final Cut timeline and expect it to import (like many other video formats would)? Even if it still needs to convert it to AIC? No, that doesn't work. Why not? There's no reason it shouldn't.

    It works on Windows. Copy a .MTS file onto a Windows machine. Windows Media Player can play it. So can VLC of course. You can drop it right onto a Premiere timeline and it works just as you'd expect. Naturally you need a fast machine to avoid frame stuttering. But it works.

    What I want is to be able to copy a pile of .MTS files off the memory card and onto my computer. Then sort them how I like. These first few clips are from my vacation, so put them in the Vacation archive. These next few clips are junk, so delete them. These last few clips are from a concert, so they go in a different archive (or clip bin for editing, or whatever). As it stands, if I forget to archive the memory card in between my vacation and the concert, then I'm stuck with that forever: my backup archive will have to be the "Vacation Plus Concert" volume.

    I can do this, no problem. But then once I've got my pile of .MTS files, I can't edit them! I can't bring them into iMovie or Final Cut because it only wants to import from the original memory card (or reasonable facsimile).

    It doesn't work like that for digital cameras. You can import the pictures or video clips (non-AVCHD files) and sort them however you like on your hard drive. Drag the images or video clips into whatever app you want to use them.

    It doesn't work like that for miniDV footage (using the previous iMovie HD). It would cut up the imported footage into individual Quicktime-wrapped DV files. Sort them however you want on your hard drive. Drag and drop the clips you want into a timeline in iMovie or Final Cut. If it needs to convert the clip, it will do so at this time.

    Luckily, there are third-party utilities that can take an individual .MTS file and transcode it into an AIC clip. Then I can drag and drop into iMovie or Final Cut. So why can't I do that with Apple's built in tools?

    Exactly. Someone needs to tell that to Apple.
     
  7. FroColin macrumors regular

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    Jun 4, 2008
    #7
    Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

    I had an avchd camera a couple years ago an I used to HATE the importing thing. I really wanted premiere because it has native avc editing. Well I used it... It was awful. I have premiere and fcs and when I use that camera (which I really don't do much but anyway) I use fcp for transcoding even though I have premeire. Avc is not a format that was designed to be used in post there are many complex reasons for this but in the end it's just a pain. It's similar to the H.264 that the DSLRs output you don't edit in that even though you CAN. You transcode it to pro res or some other codec
     
  8. dmnelson macrumors newbie

    Joined:
    Jan 13, 2011
    #8
    Suggestions for video converter?

    I don't want to open a can of worms, but I just realized this issue for the first time last night after opening my new 27" i7 iMAC. I had imported AVCHD into my parent’s iMAC from my camcorder and then edited it with no issues. I didn't realize the computer was converting it to AIC. Now I have about 150GB of AVCHD on an external drive that I need to convert to AIC so that I can edit / play it. Normally I wouldn't hijack a thread, but you guys seem knowledgeable. Any suggestions for which program is the best for a large "batch" conversion of this nature?
     
  9. notjustjay macrumors 603

    notjustjay

    Joined:
    Sep 19, 2003
    Location:
    Canada, eh?
    #10
    There are probably lots of options.

    The MacWorld review of Final Cut Express mentioned Voltaic as a small utility that can do a lot of conversion work. I haven't tried it, but I'm going to - it looks pretty good from the website.
     
  10. Menneisyys2 macrumors 603

    Joined:
    Jun 7, 2011
    #11
    I don't recommend it. Both iVI and ClipWrap are better.

    ----------

    I've just published a tutorial on creating FCPX / iMovie-compliant Camera archives of individual MTS files. See http://forums.macrumors.com/showpost.php?p=15856443&postcount=23
     
  11. rjphoto macrumors 6502a

    rjphoto

    Joined:
    Mar 7, 2005
    #12
    New Camera vS. Software

    Just found this on Nikon's D600:

    Movie File Format: MOV
    Movie Video Compression: H.264/MPEG-4 Advanced Video Coding

    Would this be ok and not need transcoding?
     
  12. Menneisyys2 macrumors 603

    Joined:
    Jun 7, 2011
    #13
    Just tested it with the video footage at http://img.photographyblog.com/reviews/nikon_d600/photos/nikon_d600_01.mov , linked from http://www.photographyblog.com/previews/nikon_d600_photos/

    Yup, you can import it directly via File > Import > Movies... Just make sure you uncheck the "Optimize Video" checkbox to avoid any conversion upon importing.
     

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