Avi compression

Discussion in 'Amateur Video Production' started by themire, Mar 2, 2006.

  1. themire

    themire Guest


    Simple question about compressing AVI files.

    I have an AVI file that is ~730 MB and therefore won't fit on a CD.

    How do I compress it a small bit so that it will?

    themire, Mar 2, 2006
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  2. Is it just for your own storage, or is it for distribution?

    If it is for your own storage, you could use a file compression
    utility like Zip or FLAC, (and others). But then you will
    need to un-compress the file to use it again.

    You could also use 800MB CDR discs (assuming your
    CDR drive will read/write them)

    You could use DVDR discs with a capacity of 4700 Mb.
    DVDR drives in my neighborhood start ~$25 which is
    cheaper than a spindle of CDR discs.

    If it is for distribution to others, you could encode in
    some other format (besides AVI). My favorite is WMV.
    Richard Crowley, Mar 2, 2006
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  3. themire

    themire Guest

    It's for my own storage.
    I have VirtualDub but can't figure out how to compress it.
    Do you know if it is possible using VirtualDub to compress avi's like
    themire, Mar 2, 2006
  4. No, I am talking about a separate step. Generic compression
    as you would do for any kind of file. Note that some kinds of
    AVI files may not compress very much.

    Google returned 1,760,000 hits for: avi compression
    Richard Crowley, Mar 2, 2006
  5. themire

    themire Guest

    That's 1,760,000 jargon-filled pages too many.
    What I need to do is too elementary.
    Anyway, I think Nero might have some compression thingy in it.
    themire, Mar 2, 2006
  6. themire

    JimK Guest

    GSpot will analyze your avi, you need to know what codecs was used to
    encode the avi

    avi to divx guide (or cloose another avi codec for compression)
    JimK, Mar 2, 2006
  7. themire

    Scubajam Guest

    Many think that avi is a standard, but it isn't. Just as mpg can be
    encoded to several quality standards, aspect ratios, and bit rates, so
    can avi. Avi is just a file extension.

    My first suggestion is to zip the file. That should get you down where
    you want. There are many free zip programs, and it's a standard so
    that you will be able to unzip for years.

    Second, change the avi codec. If that's too technical sounding for
    you, encode (make video file) to something else. If you encode to mpg
    you'll get it down to less than half the avi file, and are ready to
    burn to DVD later. But, some quality will be lost IF you ever want to
    go back to edit in avi. Can just edit in mpg. Or burn to wmv, but
    just as with avi and mpg, there are many settings (quality standards,
    frame size, bit rates), but wmv uses subjective quality terms instead
    of objective numerical terms.

    Third, edit out a couple minutes.

    Fourth, burn a DVD. Presuming you have a DVD burner.

    Fifth, get a program that will let you burn the file across two discs.
    There are many such programs.

    and the list goes on.

    Jim McGauhey
    Washington State
    Scubajam, Mar 3, 2006
  8. themire

    Ritz Guest

    Are you going to only play the file on this computer or do you want to
    play it on a DVD player too? Are you going to play it at all? Is this
    just for physical storage?

    Is the file compressed now? If yes, what codec is used and what
    bitrate? Virtualdub can easily be used to compress the file.

    Ritz, Mar 3, 2006
  9. If you want to keep the full DV-AVI quality the answer is, "no, there is no
    way to compress it further and therefore make the file size smaller". If you
    are just wanting a playable CD version of the file then the answer is, "yes,
    you may use any number of software based codecs for this purpose".

    Software based codecs include: Cinepak, Quicktime, Indeo, DivX and many
    more. You may choose a target data rate with most of them to reduce file
    sizes. You may also use other techniques as well. Most software based codecs
    use square pixels, and if I am assuming correctly that your video file is
    DV- it uses non-square pixels.

    So, if you original video is DV and you compress it using square pixel the
    result is a squished looking picture. To avoid this you could use your NLE
    program to crop 40 pixels on both left and right sides of the original video
    turning it into a square pixel ready resolution of 640x480. Otherwise the
    square pixel equivalent would be 720x540, which stretches the video
    vertically to accomodate this resolution.

    Other ways of reducing file size can be reducing the frame rate to 15fps, or
    14.98fps -half fps for non-interlaced and interlaced video respectively. You
    can also reduce the audio sampling rate from 48kHz or 44kHz 16bit stereo to
    22kHz to 8bit stereo. Actually there are many choices of 16bit and 8bit
    stereo and mono audio combintaions.

    Then again, you could encode this file to MPEG-2 and make a playable DVD out
    of it. No matter what you do to reduce the file size to fit it on a CD you
    will have to give up the notion of ever using it again within an editing
    environment. Even if you use MPEG-2, somewhere down the line the compression
    will reach up and bite you on the ass sooner or later.
    Larry Johnson, Mar 4, 2006
  10. themire

    Ken Maltby Guest

    Why do you assume that the OP has DV-AVI? My
    guess would be that he downloaded a DivX or Xvid

    Ken Maltby, Mar 4, 2006
  11. themire

    dave xnet Guest

    regardless of the source, the recompression is simple.
    Install Divx if it's not already installed.

    Open the original AVI.
    Look at file/file information/video stream data rate
    and make a note of it.

    Open the original avi. Select video/fast recompress
    Audio/direct stream copy.

    Select video/compression.
    Choose Divx/configure/restore defaults
    and select the bit rate accordingly.
    For example, if the original is 1000kbps
    and you want it 5% smaller, choose 950kbps.
    Select OK,OK, File/save avi - give it name
    and wait for it to encode.

    These are just the bare skills you need to use virtualdub.
    It's a great program.


    dave xnet, Mar 5, 2006
  12. The process is the same no matter what assumptions of resolution and frame
    rate are made. All video begins as either NTSC, PAL or SECAM, so why not
    just start from native resolutions? Why does the assumption of frame
    resolution bother you so much? Is it somehow politically incorrect?
    Larry Johnson, Mar 5, 2006
  13. themire

    Pete Guest

    virtualdub and xvid
    Pete, Mar 8, 2006
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