Root cause of archived video DVD intermittent jerkiness

Discussion in 'Professional Video Production' started by M. T. Arnough, Aug 17, 2005.

  1. Why do archived DVDs sometimes play jerkily like a blockey jigsaw puzzle?

    .. I buy & archive a DVD (using DVD Decrypter, DVD Shrink, & Nero).
    .. Nero has validated the archive data & no warnings ensued
    .. That archived video DVD plays without jerkiness in the pc.

    .. I now play that DVD in my bottom-end DVD player hooked to a TV
    .. Sometimes the video is jerky (but no warnings issues by Nero).
    .. Sometimes that SAME video DVD is not jerky (go figure).

    .. The archived DVD disc is NOT scratched or dirty (it's brand new).
    .. That same archived DVD disc plays without jerkiness in the PC.
    .. If I power cycle the DVD player, often the jerkiness disappears!

    Huh?

    QUESTION:
    What could be causing this intermittently jerky blocky video playback?
     
    M. T. Arnough, Aug 17, 2005
    #1
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  2. M. T. Arnough

    Ron Guest

    Is the DVD free of scratches, clean of dirt and fingerprints?
     
    Ron, Aug 17, 2005
    #2
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  3. Try your archived DVD in a recent machine that supports DVD-R or DVD+R
    explicitly (i.e., says so on the label). I had the same problem but it
    was the player not the DVD. They play fine on my new player.

    -Bill
     
    Captain Slick, Aug 17, 2005
    #3
  4. M. T. Arnough

    Steve Guidry Guest

    I had a similar problem when I recorded material on a stand-alone Panasonic
    DVD recorder. Turns out the problem was that I had the quality set too
    _high_ (on the 1-hour mode). I'm pretty sure that the higher data rate
    overloaded the input buffer of the cheap DVD player.

    When I reduced the quality to the 2-hour mode, everything was OK.

    I'm guessing here, but maybe you're archiving at a too-high bit rate ?

    Steve
     
    Steve Guidry, Aug 17, 2005
    #4
  5. M. T. Arnough

    Ken Maltby Guest

    The usual cause of the "Jerkyness" is dropped frames during
    capture, and how they are handled by your capture software.
    The PC player, and the newer players another responder
    mentioned, make use of buffers and more sophisticated
    algorithms to smoothly play through such dropouts.

    The approach I find easiest, is to use www.VideoReDo.com
    on my .mpg before authoring a DVD. A re-mux in VRD will
    remove the problem altogether.

    Recording at lower settings, or at a smaller image size (if the
    recorder allows such settings) would make dropouts much
    less likely, and so could correct the problem, also.

    (My first instinct would be to blame Nero Express, as it
    wants to use its own codec for every thing, so you might
    try authoring your DVD with a trial of "TMPGEnc DVD
    Author", "DVD Lab Pro", or even "Movie Factory 4".
    Nero is probably not the cause of your "Jerkyness"
    though.)

    Luck;
    Ken
     
    Ken Maltby, Aug 17, 2005
    #5
  6. M. T. Arnough

    Steve Guidry Guest

    Ok, fine. But there was no capture card involved in my scenario, only a
    Panasonic stand-alone recorder.

    I'm sticking with the too-high bit-rate theory.

    Steve
     
    Steve Guidry, Aug 17, 2005
    #6
  7. I've written this a bunch of times before, but it bears repetition.

    A nice DVD Recorder might run you a few hundred bucks. Let's call it
    $300 for the sake of argument.

    Out of that, half probably gets assigned to profit/marketing. So lets
    say you're left with 150.00. Middlemen, shipping, etc probably eat up
    half of that. So you can't economically have more than 75 bucks worth of
    actual parts in the thing. More likely less than $50. So how much does
    that mean the critical internal units like the stepper motors that move
    the laser over the disc surface and the laser itself are really worth?
    Five bucks Three bucks? Fifth cents?

    We're asking this to PRECISELY write data to a disc spining at thousands
    of RPMS, while those stepper motors move the laser over the surface so
    precisely that the data bands and guard bands are in EXCELLENT alignment
    and therefore easily read by any other player.

    Including players with equally cheap components.

    Do we ever drop or jar our players such that it would be reasonable to
    think those critical optical components might get mis-alligned? How
    about age and wear on the belts/pullys/motor windings. Might those ever
    perform less than optimally?

    The more I understand about home DVD burners/players it's a miracle they
    work as well as they do.

    And those are extremely rough guestimates about the economics of a
    "pricy" DVD player.

    How about that unit sitting on your shelf that cost you $49.95 at Costco.

    What did they budget for the stepper motors in THAt beast.

    Sheesh.

    Want better playback? Buy a new machine, and replace it with a newer one
    every six months.

    At $100 bucks a year, it'll save you a thousand bucks in grief. And you
    can regularly pass along your old gear to family and friends and make
    them happy.

    My 2 cents anyway.
     
    William Davis, Aug 17, 2005
    #7
  8. M. T. Arnough

    Ken Maltby Guest

    It is customary for a responder to reply to the OP and
    the subject line, first. As to your approach to the problem
    I would suggest you reread the third paragraph of my reply.
    Sorry, if I didn't hear your cry for help, I thought we were
    both addressing the OP's question.

    You seem to have found a solution to your problem, so
    what's your complaint about my not addressing your
    "scenario"?

    Luck;
    Ken
     
    Ken Maltby, Aug 17, 2005
    #8
  9. M. T. Arnough

    Ken Maltby Guest

    It is surprising how little it costs to mark up a new IC when
    your engineering staff is working to advance the Great Red
    Revolution and bring honor and glory to the PLA General
    appointed over them.

    Luck;
    Ken
     
    Ken Maltby, Aug 17, 2005
    #9
  10. M. T. Arnough

    Bill G Guest

    If it's as bad as you say, passing along the old gear to family and
    friends might not be doing them much of a favor. Fortunately, in my
    experience anyway, it's not nearly as bad as you say.
    And mine. :)
     
    Bill G, Aug 17, 2005
    #10
  11. M. T. Arnough

    Eric Gisin Guest

    That is 10Mb/s, which DVD players MUST support. You have flakey media.
    Read the f*cking post. He shrunk a DVD, so the bit rate has to be LOWER.
     
    Eric Gisin, Aug 18, 2005
    #11
  12. M. T. Arnough

    Jona Vark Guest

    The design makes this accuracy cheap.
    Most use the SAME components.
    No belts or pulleys in a DVD player.
    Not really that complex. It is a combination of a few proven technologies.
    The steppers all come from the same place for the most part. And none of the
    steppers in these devices are THAT high resolution.

    Sheesh and Shong.
     
    Jona Vark, Aug 18, 2005
    #12
  13. M. T. Arnough

    Steve Guidry Guest

    Ok, fine. But there was no capture card involved in my scenario, only
    a
    Ken,

    Life is too short for me to complain about your post. And that wasn't the
    point. Rather, your post seemed to be responding to me, and - - working
    under that assumption - - it seemed that you hadn't bothered to read my
    post, but were rather just expounding on your own position.

    Mrs. Altenburg, my 5th grade English teacher, would give us both deductions
    for "unclear antecedents".

    In my mind, it's over, and I have no beef with you.

    All the best . . .

    Steve
     
    Steve Guidry, Aug 18, 2005
    #13
  14. M. T. Arnough

    Alpha Guest


    Oh no? You do not know anything about it, so stop making up idiocy.
     
    Alpha, Aug 18, 2005
    #14
  15. M. T. Arnough

    Alpha Guest

    Alpha, Aug 18, 2005
    #15
  16. There are no stepping motors in modern CD or DVD
    players/recorders/computer drives.

    The disc is rotated by a small DC motor.
    The "gross" position of the head is done with another cheap
    DC motor.
    Then "voice-coil" technology is used for the dynamic "fine"
    position (in 3 axes) of the optical head.

    The spindle- and head-position motors and the three voice
    coil axes are controlled by a long servo "circuit" which began
    back in the digital decoding of the optical data from the pickup
    head. This system of five servos control the voltage to the five
    servo "transducers".
    It is an impressive design/execution, but not THAT impressive.
    "Blank", field-burnable discs are not really blank. They have
    the tracks moulded into the plastic. This is what guides the five
    servos to keep the optical head aligned with the spinning track.

    When writing a disc, we are merely "burning" into the photo-
    sensitive layer behind the moulded tracks. On commercially-
    moulded discs, the data pits are moulded along with the track
    definitions and backed with sputtered aluminum (for reflection).

    Now when they make the optical master for pressing/moulding
    commercial CDs and DVDs, that is a different matter. There,
    the writing head IS truly on its own and its position must be
    precisely controlled by the equipment. But those things are
    many times larger, heavier, more precise (and more expensive)
    than any CD or DVD drives, players, or recorders we deal with.
    Yes, all of those are risks to any system that relies on such
    precision to read/write. Fortunately, the servos are able to
    keep up with most of the nastiness, and when they can't, the
    drive just gives up and spits out the disc.

    The only rubber I've ever seen in any of those kinds of
    drives/mechanisms is the drawer open/close "gear-train"
    on some designs where they use a rubber belt between
    the DC motor and the first gear in the speed-reduction
    train.
    They ARE pretty miraculous. But use of high-speed servos
    (enabled by cheap, high-speed computing resources) has
    made it practical to bring this high-technology to the public.
    The spindle motor may have even cost more than a buck
    because of the bearings, clamping mechanism, etc. But I
    doubt the head-positioning motor is more than a buck.
    The three axes on the optical head may cost more than a
    buck all together if only because of the cost of the rare-earth
    magnets, etc.

    But zero for actual "stepping motors". OTOH I believe that
    modern inkjet printers still use steppers for both axes. But
    then laser printers are back to DC servo IIRC.
     
    Richard Crowley, Aug 18, 2005
    #16
  17. M. T. Arnough

    Alpha Guest

    You are correct.
     
    Alpha, Aug 18, 2005
    #17
  18. QUESTION:
    I too have jerkiness using DVD Shrink and Sonic Record Now.
    Is everyone saying the problem is in the DVD player or the copying
    software?

    If it's in the player, how come only some newly burned DVDs have jerkiness
    and others don't (when using the same equipment on both sides).

    Isn't it the original DVD which is the real culprit in jerky copies?
     
    Avery Goldstein, Aug 18, 2005
    #18
  19. M. T. Arnough

    Eric Gisin Guest

    Why don't you rip a small DVD under 4.5G (no shrinking) and burn it.
    If you still have jerkies, then DVD shrink was not the problem.

    Jerkiness is caused by read error retries. You do not see this on PCs,
    because the drives are 8-16X with large buffers, and retries do have much effect.
    Also, DVD burners are built better than consumer players.
    DVD shrink can put out any bit rate between 3-10 Mb/s.
    Since a player is 1X, or ~12Mb/s, it only has problems with high bitrates.
    I would say the biggest problem is poor media. Try burning at 4X.
    Only with crappy authoring/mastering. Was it in the 88 cent bin at Wal-mart?
     
    Eric Gisin, Aug 18, 2005
    #19
  20. I have read descriptions of CD technology which indicate that the
    submicron accuracy is achieved by small adjustments using voice-coil
    actuators driven by optical feedback. This occurs along and across the
    tracks and also in the vertical (focus) direction, and the submicron
    accuracy comes from these adjustments.

    The same feedback signals are used to keep the coarser motors
    (including the rotation motor) in a more-or-less accurate average
    position, but the voice coils make up for the inaccuracies and the lag
    times.

    I have no reason to think that DVD drives work any differently.

    HTH,
    Gino
     
    Gene E. Bloch, Aug 18, 2005
    #20
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