DVD Studio Pro import MPEG-2 IBP problems

Discussion in 'Amateur Video Production' started by Curtis Rempel, Nov 2, 2003.

  1. I've recently made the switch to a dual G5 with Final Cut Pro and DVD
    Studio Pro.

    I have a fair number of MPEG-2 IBP projects that were made using the
    Premiere export feature using the Matrox RT2500 preset for MPEG-2 IBP.
    I've burned those files using DVDit on Windows and they all worked fine.

    DVD Studio Pro does not seem to recognize them by default, unless there
    is some sort of configuration that I've overlooked. I have been able to
    convert a small number of projects using QuickTime Pro 6 by first
    renaming the .AVI file (in MPEG-2 IBP format) and then using the Movie
    to MPEG2 preset and importing the resulting .m2v file with DVD Studio Pro.

    I came across Compressor in my G5 travels (not exactly sure at this
    point whether it is part of Final Cut or DVD Studio Pro) and it seems to
    be a great way to batch convert from one format to another. Using the
    exact same preset values (2 pass VBR, 7.0 Mbit rate, Best Motion, etc.)
    as I did with QuickTime Pro does not produce the same results however.
    The difference seems to be that files converted with Compressor result
    in flickering bluish bands on the lower third of the resulting output
    file when previewed in DVD Studio Pro.

    I think I've seen this before or heard of it but can't seem to recall
    what is going on here.

    Is there something else I need to do when using Compressor for these
    conversions? It sure would be nice rather than have to do each one
    manually with QuickTime Pro. Or conversely, is there a way to import
    the files I have directly into DVD Studio Pro without converting them?
    I don't have a problem converting them, but it would nice to be able to
    do it in batch rather than individually.

    Thanks in advance for any tips.

    Curtis
     
    Curtis Rempel, Nov 2, 2003
    #1
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  2. Curtis Rempel

    Dan Maas Guest

    DVD Studio Pro does not seem to recognize them by default, unless there
    DVD Studio Pro only understands raw MPEG-2 Elementary Streams. If your
    streams are wrapped in some kind of AVI container, or they are Program
    Streams (audio + video), then DVD Studio Pro will not recognize them.
    This *probably* means you are re-compressing the video, which is
    something you should try to avoid.
    Compressor comes with DVD Studio Pro version 2.
    I have no idea about the reliability of Compressor because I haven't
    worked with it yet. However, I do know that the "preview" feature of
    DVD Studio Pro is very unreliable (e.g. don't trust it to judge A/V
    sync). The only way to be sure is to burn a real DVD and watch it on a
    set-top player.

    One thing to keep in mind is that the DVD spec has some restrictions
    on the MPEG-2 encoding parameters. You can't just take any old MPEG-2
    video stream and throw it on a DVD; it may not meet the spec. You have
    to watch for bitrate (9mbit/sec max, though 7-8mbit/sec is the
    practical limit), GOP length (18 frames max in NTSC), 4:2:0 chroma,
    etc.

    Here's a reference -
    http://graphics.lcs.mit.edu/~tbuehler/video/MPEG-2.html

    Regards,
    Dan
     
    Dan Maas, Nov 3, 2003
    #2
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  3. Even though they received a .AVI extension during export from Premiere,
    they are in fact MPEG-2 IBP. From scouring the spec sheet for DVD
    Studio Pro, I gather than this particular flavor of MPEG-2 is not
    importable.
    Agreed. Although, when viewing the resulting burn, I cannot tell the
    difference between the original DVD burned with Windows/Premiere and the
    one with DVD Studio Pro after converting the MPEG-2 IBP to MPEG-2 only
    with QuickTime Pro. So, it would seem that there is really no
    re-compressing happening at all. The way I understand MPEG-2 IBP is
    that it is a slimmed down version of straight MPEG-2 which only tracks
    the changes in the frames whereas full MPEG-2 would be the same data
    even if no changes took place. So, if anything, my understanding is
    that the file is simply "expanded" with duplicate data. Please tell me
    if my assumption is incorrect, but as far as I can tell, there is no
    perceptible difference in the resulting quality.
    I will have to try that suggestion.
    Agreed. And I don't think I have anything out of spec as all of these
    archived MPEG-2 IBP files burned quite happily using Windows.
    Thanks!
     
    Curtis Rempel, Nov 4, 2003
    #3
  4. Curtis Rempel

    Dan Maas Guest

    and then using the Movie
    Just to update my earlier statement: the DVD Studio Pro 2 manual
    implies (but does not state explicitly) that "Export to MPEG2" with
    Quicktime will not re-encode an existing MPEG-2 stream. Supposedly it
    can de-multiplex a Program Stream into Elementary Streams (which is
    handy since DVD Studio Pro only accepts Elementary Streams). I'm not
    sure under what circumstances it will re-encode vs. not re-encode.
    See above; I think Quicktime may actually not be re-encoding in this
    case. (one way to be sure is to export to MPEG-2 at a *really* low
    bitrate, and see if it looks like crap :).
    It's tough to evaluate MPEG-2 streams since most modern DVD players
    have liberal MPEG-2 decoders that will accept slightly out-of-spec
    streams. The real test is whether the resulting DVD plays on *all* DVD
    players. (it's a surprisingly difficult challenge to make this work,
    as I've learned from experience :).

    I have a Samsung DVD player that will play almost anything you throw
    at it - streams that exceed the bitrate spec, streams with errors,
    etc. My "test" machine is a Sony Playstation 2, which appears to have
    a much stricter MPEG-2 decoder. The Playstation very quickly chokes on
    out-of-spec streams.

    A lot of this is only a concern for mass-produced, mass-market DVDs.
    (Hollywood film DVDs go through very extensive, and expensive,
    compatiblity testing). If it's just a home movie to send grandma, then
    you can mostly ignore these issues :)

    Regards,
    Dan
     
    Dan Maas, Nov 5, 2003
    #4
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