Huge AVIs from camera fine. Small AVIs from dvd cumbersome. Why?

Discussion in 'Amateur Video Production' started by tonyjeffs, Jun 22, 2005.

  1. tonyjeffs

    tonyjeffs Guest

    AVI imported from dv tape using my Handycam and Nero is big at 4000
    megabytes for 15 minutes.
    It is easy to manipulate, plays quickly during edit in forward, reverse
    and fast reverse mode. No problems getting around the project.

    But if I copy vob files from a dvd (which was copied earlier from a vhs
    tape using a dual set-top recorder), and convert them to AVI, the
    files, though half the size and treble the playing time, are really
    sluggish and hard to work with. Drag and drop gives me time for a
    coffee break (almost!). Even if I shrink them to 1/4 of that, they're
    not much better.

    Why are the huge AVI files from the camera much easier to work with
    than small AVI files that are relatively 1/20th the size taken from
    DVD?

    (I'm using Magix Movie Edit Pro., DvdShrink and virtualDub)

    Thanks

    Tony
     
    tonyjeffs, Jun 22, 2005
    #1
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  2. tonyjeffs

    Jukka Aho Guest

    You didn't state which codec you were using for the "small AVI files",
    but obviously it is one that places considerably more stress on the
    processor than the DV codec. Tighter compression algorithms are usually
    more demanding in that way.

    In short, it's not the size of the files but the algorithmical
    complexity of the codec.
     
    Jukka Aho, Jun 22, 2005
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  3. tonyjeffs

    tonyjeffs Guest

    One that I used to make the 'difficult' avi file was Microsoft MPEG-4
    Video Codec V2.


    I dont know how to find what codec Nero used to make the user-friendly
    avi file

    I think I may have solved the problem.
    I de-interlaced the information during conversion from vob to avi &
    that appears to have done the trick. (I think...)


    Tony
     
    tonyjeffs, Jun 22, 2005
    #3
  4. tonyjeffs

    Alex Bird Guest

    This may not be the best MPEG-4 codec, anyone know for sure?
    It would be the DV codec presumably if you've just captured from the
    camera via firewire and the files are huge.
    De-interlacing will work with video material, but not film material
    which is progressive by nature. I can't see why this would cause a
    significant performance gain, so perhaps that is not the only thing you
    have changed ? Have you perhaps changed the interleave and not the
    interlacing ?

    A big difference between the codecs mentioned is their use of key
    frames. A key frame is one that is described completely somewhere in
    your AVI file, like an image file tucked in there. Frames which are
    not key frames are derived partly from the frames before and/or after
    them.

    The DV codec has only key frames - this makes moving through the file,
    clicking on the timeline anywhere, instantaneous. Codecs which use
    high compression can have key frames as infrequently as half a second,
    this means the computer has to crunch through all the frames since the
    last key-frame to seek to a particular frame.

    Try selecting "I-frames only" in your compression codec, it won't
    compress as small but it might fix your problem.

    Hope this helps,
    Alex
     
    Alex Bird, Jun 23, 2005
    #4
  5. tonyjeffs

    Bariloche Guest

    That's the good thing about the Alparysoft codec. That it can compress
    highly and with great quality, even if being a "keyframes only" codec.
     
    Bariloche, Jun 23, 2005
    #5
  6. tonyjeffs

    tonyjeffs Guest

    Hi Alex and all
    I do think the interlace was all I changed. I did this with DVDx by
    selecting deinterlace/interpolate.
    I haven't come accross the term interleave before. I googled it, and
    don't believe I've done that .
    I'll look for l-frames only I didn't notice it before & don't know how
    to select it.

    I have another question re compression:-

    I think dvd vob files are already compressed (?).
    The files on dvd total 2500 mb
    The avi files that I've derived from these vob files are considerably
    smaller, 600mb
    There can't be that much scope for lossless compression, so I
    presumably must've lost quality along the way?

    Thanks for the suggestions.

    Tony
     
    tonyjeffs, Jun 24, 2005
    #6
  7. tonyjeffs

    Alex Bird Guest

    Okay. I'm not going to explain much of interlace, suffice to say
    there's no perfect way of getting rid of it once something is created
    with it.
    The simplest, and not bad, ways to de-interlace use blending and
    interpolation. These unavoidably smooth out the image. What you've
    selected is a processing option that comes before the compression
    stage, it is also possible to compress in an interlace specific way to
    preserve it, and you should do this if the end result is to be shown on
    a TV. Almost all compression will perform better on smoother video,
    the detail and noise - high frequencys - take more information to
    describe. You just gave the compressor an easier ride. It sounds like
    it's one that doesn't perform well on interlaced material anyway...

    Some software can behave strangely with some interleave settings, which
    was why I thought of it.
    It may not be there, though I would hope it is.
    Yep. Though I suppose if they were really soft pictures with not much
    movement the loss may be quite small.
    s'alright
     
    Alex Bird, Jun 24, 2005
    #7
  8. tonyjeffs

    FLY135 Guest

    Convert your vob files to AVI using the DV codec and they will work the
    same as your camera avis.
     
    FLY135, Jun 24, 2005
    #8
  9. tonyjeffs

    tonyjeffs Guest

    FLY135 ,
    That works!
    I couldn't find a Nero DV codec on my PC, although I presume there must
    be one.
    so I downlaoded the Panasonic DV codec. Huge AVI files, but easy to
    manipulate.
    They're three times the size of the original vob files though.

    Perhaps the reason they're so flexible is because they are not
    compressed, so less calculation is required.

    I tried other codecs:
    Keeping all other settings the same....
    Microsoft Video 1 was awful. Increased file size by x10
    Cinepac was hard work, and filesize twice that of original vob.

    The others were very similar to work with not great
    Microsoft MPEG-4 resulted in a file 1/2 the size of the vob
    Divx resulted in a file 1/4 the size of the vob

    Panasonic dv, using other methods to reduce file size looks like the
    way to go.

    Thanx

    Tony
     
    tonyjeffs, Jun 25, 2005
    #9
  10. tonyjeffs

    Brent Geery Guest

    DV huge? DV uncompressed? DV (DV25 to be exact) *is*
    compressed-- about 5:1 vs real uncompressed video.

    If you want huge AVIs, try real uncompressed video.
     
    Brent Geery, Jun 25, 2005
    #10
  11. tonyjeffs

    tonyjeffs Guest

    OK..maybe I will..

    I'll get a bigger h/d first ;-)
    tony
     
    tonyjeffs, Jun 25, 2005
    #11
  12. tonyjeffs

    Brent Geery Guest

    I had about 600GB over 5 drives, but lost a pair a few weeks
    ago... now I have to limp along on only 300 GB. :(

    Drives are dirt cheap. Check out pricewatch.com. The best deal
    right now on pricewatch is 250GB drives for $97. If you really
    want cheap drives, wait for the weekly sells and "bargain hunter"
    type websites, and you can sometimes find "free after rebate"
    offers on drives.

    A couple of those 250GB drives and you can forget having to
    capture and edit using lossy-compressed formats. Install the
    lossless-compressed (~2.5:1) HuffYUV 2.1.1 codec, and you are on
    your way to 40GB/hour "huge" AVIs splendor without the lossy
    compression artifacts. No file will ever seem huge again. :)
     
    Brent Geery, Jun 26, 2005
    #12
  13. tonyjeffs wrote ...
    Because the bigger the file, the less the data (video) is compressed.
    The less compression, the easier to display, process, etc.

    The smaller the file, the more the data (video) is compressed.
    The more compression, the more CPU time it takes to uncompress
    each frame. In the case of many smaller (MPEG) files, there is
    not only spatial compression, but temporal compression where
    only changes between frames are stored and it takes references
    to several frames worth of data to produce an image of a single
    frame. This is done in sequence, on-the-fly during normal play-
    back, but editing and "scrubbing" the timeline generates HUGE
    demands on your computer.
     
    Richard Crowley, Jun 27, 2005
    #13
  14. tonyjeffs

    tonyjeffs Guest

    Cheers,
    I'm starting to understand about codecs at last.
    I'll find that HuffYUV 2.1.1 codec.

    ....or I might sleep under sun-shade for a few hours first... looks like
    a nice day outside....


    Tony
     
    tonyjeffs, Jun 29, 2005
    #14
  15. tonyjeffs

    Brian Guest

    Some people live a good life. Now where did I put the suntan lotion
    <grin>
     
    Brian, Jun 29, 2005
    #15
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