To edit or not in Quicktime Pro

Discussion in 'Mac Help/Tips' started by nixd2001, Nov 21, 2002.

  1. nixd2001 macrumors regular

    Joined:
    Aug 21, 2002
    Location:
    UK
    #1
    I've recently shelled out the fee to enable the Pro part of Quicktime. And now I've a question.

    Select/cut/paste are available in AVI files (Divx5 codec I think it was) but the options are all greyed out for an MPEG1. I've seen nothing in the documentation that suggests this difference should exist.

    Does anyone know what gives here - can QTP not edit MPEG1 or is something stranger happening?
     
  2. King Cobra macrumors 603

    Joined:
    Mar 2, 2002
    #2
    I brought this issue up about a month back.

    Decoding MPEG-1 files is, above all else, a pain in the ass.

    You'll need a decoder file, called "bbDEMUX". Follow the below link to download and install. (It's free, so don't worry about any shareware windows.)

    http://www.versiontracker.com/moreinfo.fcgi?id=14618&db=mac

    Second, read over the accompanying directions with the program, and drag the Quicktime file into the program. You should get two files:
    A: one .m1v file, which is the editable video file, and
    B: a .m1a file, which is really .mp3. Rename the extension to .mp3 so iTunes can recognize it.

    Third, edit the decoded video file and export from Quicktime Pro.

    [credit goes to Ms. V for providing me with the link for bbDEMUX]
     
  3. nixd2001 thread starter macrumors regular

    Joined:
    Aug 21, 2002
    Location:
    UK
    #3
    The instructions looked similar - I've tried a thing called mpgtx which will demux an MPG file. I tried the program you pointed me at just in case. But I get the same thing. QTP can load and play (import rather than open makes no difference here), but the Edit menu still won't let me select. I know I could SaveAs in a different format, but this is going to be a lossy operation.

    How does this tie up with your experiences?
     
  4. nixd2001 thread starter macrumors regular

    Joined:
    Aug 21, 2002
    Location:
    UK
    #4
  5. e-coli macrumors 68000

    e-coli

    Joined:
    Jul 27, 2002
    #5
    MPEG files rely on specific packets of grouped information. Each "packet" is initiated by a header of information that includes information about the packet. Then each packet has a trailing footer that tells the file the packet has ended. Each MPEG may contain hundreds of packets.

    To answer your question, no you can't efficiently edit an MPEG with QT Pro, because cutting and pasting will not rewrite packet headers and footers. You may end up with "headless" or "footless" packets which will cause the MPEG to malfunction.

    As a general rule, once an MPEG is an MPEG, it's pretty much unedtiable, and set in stone. You usually have to go back to the original media file to make any efficient changes.

    So, it's not a problem with QT Pro, it's just a format limitation. Hope this helps.
     
  6. King Cobra macrumors 603

    Joined:
    Mar 2, 2002
    #6
    >(nixd2001) The instructions looked similar - I've tried a thing called mpgtx which will demux an MPG file. I tried the program you pointed me at just in case. But I get the same thing. QTP can load and play (import rather than open makes no difference here), but the Edit menu still won't let me select.

    That's strange. I just tried dragging a short 504KB file to DEMUX (my bad for the caps, but this is to distinguish the name of the program from the actual demuxing), and I got a video and an audio soundtrack. If you want to copy a video stream of frames from an MPEG-1 video file, you have to use DEMUX for that file, the same way I previously described for any MPEG-1 video file. If you want to copy MPEG-1 content to MPEG-1 content, you have to use DEMUX for both MPEG-1 files.

    Neither MPEG-4, nor .mov files do the same thing, for whatever reason. I've only experienced this with MPEG-1 video.
     

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