does duping a tape cause a loss of frame accuracy?

Discussion in 'Professional Video Production' started by bjanko, Apr 5, 2005.

  1. bjanko

    bjanko Guest

    I'm working on a documentary that was shot on miniDV. (I think it was
    shot on miniDV, although I was told there might be some DVCam as
    well... if the casettes look the same, how can I tell the difference?)

    Anyway, the real question is that I took these tapes to be duplicated.
    There is already timecode on the tape, though I did not ask for a
    burn-in since the dupes are only a safety measure in case anything
    happens to the camera original tapes.

    A tech at the posthouse told me that the timecode on the dupe would not
    be frame accurate. He said if he did a timecode burn-in, that it WOULD
    be frame accurate.

    I had never heard this before and would like to hear from any of you
    who might be able to provide an explanation or might have run into a
    similar situation. (The dubhouse tech said it had something to do with
    the inability to start the play and record decks -- original to dub --
    at precisely the same moment... but I thought that was what black
    encoding a tape was supposed to do!)

    Any help or even theories about what the tech meant would be greatly

    -- Brian
    bjanko, Apr 5, 2005
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  2. The most obvious way is that a 60-minute DV tape will run
    only 40 minutes with DVCAM because the DVCAM tape
    speed is faster.
    It depends on what equipment and connection and method
    they are using to copy the tapes. Clearly if they are making
    an analog connection between the player and the recorder,
    you will lose the original timecode. There are likely even
    digital methods that don't preserve timecode. Only two
    machines that are intended for making bit-perfect clones
    are likely to preserve everything including the timecode.
    Something sounds significantly screwy. I'd look for a different
    posthouse (or at least someone there that knew what they were
    talking about). Making clones of digital tapes should have
    nothing to do with "starting the play and record deks at the
    same moment".
    My theory is that the tech doesn't know what he's talking about.
    If you can't find someone at the posthouse who knows better
    than that, take your valuable tapes to somebody who knows
    what they are doing.
    Richard Crowley, Apr 6, 2005
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  3. bjanko

    Bob A Guest

    Several Sony DV and DVCam decks have the "Duplicate with Time Code" or
    "Duplicate entire tape" options on the front panel that will produce a
    dub with the exact time code of the original.
    Not sure what you mean by "Frame accuracy" of the dub, though?? Some
    decks will give a display of what format the tape is recorded in. But
    the easiest way is to look at the "Time Remaining" display at the
    beginning of the tape in 'play' and you will know instantly whether it
    was recorded in DVCam, DV or DV-LP. For instance a DV 60 minute (or
    DVCam 40 minute) cassette will have approximately 40 min for DVCam, 60
    Minutes for DV and 1 hr 30 min for DV-LP. A time code "burn-in" would
    make the tape useless as the TC could not be removed ever again. Find a
    new tech.....
    Bob A, Apr 6, 2005
  4. bjanko

    nap Guest

    Many DV decks have a DUB feature which will pass time code from one to the
    other as you make the dupe. A lot of post houses do not know about this. I
    recenly had a director make dubs of her raw footage and I had to show the
    post house how to do it.

    Sony's have a DUB feature which will allow one deck to control another and
    the dub is automatic.
    nap, Apr 6, 2005
  5. bjanko

    bjanko Guest

    All you who have posted:

    MANY THANKS for your great answers! They've clarified a lot of issues
    and will really help me proceed with the film I'm doing!

    - Brian
    bjanko, Apr 6, 2005
  6. If I'm not mistaken the DVX100A has the ability to control one cam from
    another as well.

    Tom P.
    Henry Padilla, Apr 7, 2005
  7. You can't. They are the same tape. (At the PA where I live we use the same
    tape in both cameras. Shh, don't tell anybody.)

    "Start the record and Play at the same time"? That sounds like an analog
    copy over RCA/S-Video cables.

    On most high-end cameras you can plug the Firewire from one into the other
    and make a "frame-accurate" copy. Meaning you can get the frames to be what
    they were in the original, the TC may not even come close.

    Some high-end cameras have a dub on them and that will make "perfect"
    copies. TC and everything.
    Tom P.
    Henry Padilla, Apr 7, 2005
  8. bjanko

    nap Guest

    did not know that.. I'll look again at mine. .
    nap, Apr 7, 2005
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