Ulead VS7 - Anyway to get Iframes to every frame instead of every 15?

Discussion in 'Amateur Video Production' started by Paul D. Sullivan, Feb 12, 2004.

  1. I want to be able to make an MPEG-2 file that I can use in Ulead
    DVD Movie Factory and select every frame instead of every 15
    frames (I-Frames, I believe).

    When I set chapters in DVD Movie Factory, it only snaps to the
    I-Frames, which is every 15.

    Is there any way to set the MPEG-2 or something in DVD Factory so
    that I can select every frame when choosing chapters?

    Thanks
     
    Paul D. Sullivan, Feb 12, 2004
    #1
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  2. Paul D. Sullivan

    John T Guest

    As I understand it, you are trying to do the impossible, because the
    I-Frames are the only complete frames that exist in an MPEG-2 file.
    The frames in between are either predicted frames (P frames) or
    bidirectional frames ( B frames). B frames are interpolated from
    I-Frames and/or P frames.

    There is an explanation at
    http://www.cisco.com/warp/public/614/20.html
    about half way down the page under the heading of More on MPEG, But
    the whole article is worth a read.

    If you want to select every frame you should work with AVI files and
    only render to MPEG-2 when your are satisfied with your project.

    John
     
    John T, Feb 12, 2004
    #2
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  3. Ok. Thanks

     
    Paul D. Sullivan, Feb 12, 2004
    #3
  4. Paul D. Sullivan

    Ken Maltby Guest

    It is possible but perhaps not too practical. You may be
    able to capture at an I-P distance of 0, or in other words
    I frame only. ( I can.)

    I-P distance 3 = IBBPBBPBBPBB
    2 = IBPBPBPBPBPB
    1 = IPPPPPPPPPPPP
    0 = IIIIIIIIIIIIIII

    As you can see there is only an advantage for editing with
    the I frame only version. In theory, a transcode from MPEG2
    I frame only to I-P distance 3 could be done faster that encoding
    an AVI file; and would entail no more loss than an original
    capture to the I-P distance 3 would have. (perhaps much less
    if a multi-pass transcoder were used, at a cost in time.)

    The only problem is I know of no such transcoder, optimized
    for MPEG2 I frame only to normal MPEG2. I need to do a
    better search, there may be one out there. I've heard that
    TMPGEnc Encoder can work with I frame only MPEG, but I
    don't know if that's as input or not. With all the effort that has
    gone into AVI to MPEG encoding, that may still be the most
    practical approach.
     
    Ken Maltby, Feb 12, 2004
    #4
  5. Thanks for the additional info. :)

     
    Paul D. Sullivan, Feb 12, 2004
    #5
  6. Paul D. Sullivan

    Samuel Paik Guest

    I don't know about Ulead DVD Factory, but other MPEG-2 encoders can
    be configured to create I-frame only MPEG-2 streams. However, such
    a stream will almost certainly be either very low quality or not
    DVD-compliant, as an I-frame only MPEG-2 has about the same
    quality-compression effectiveness as DV or MJPEG, i.e, you'll
    need about three times the bitrate to get the same quality.

    Some (particularly more high-end) MPEG-2 encoders allow you to force
    particular frames to be I-frames.

    Sam
     
    Samuel Paik, Feb 12, 2004
    #6
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