How the DC10Plus handles dropped frames...

Discussion in 'Amateur Video Production' started by jeremy ross, Jul 14, 2003.

  1. jeremy ross

    jeremy ross Guest

    I'm attempting to use Virtual VCR with my DC10Plus and I've noticed
    that a/v sync sucks unless there are almost no dropped frames. So I
    ask myself, how does the DC10Plus handle dropped frames? Ideally, it
    would insert a "blank" frame, which results in a repitition of the
    previous frame. This would keep a/v sync. However, I did a "next
    dropped frame" in VirtualDub, and it could find no dropped frames.
    This leads me to think that the DC10Plus does not insert blank frames.
    Rather, it relies on the capture program (Studio, for example) to
    adjust the frame rate to compensate for missed frames. Frame rate
    adjustment doesn't work if you're going to SVCD or DVD. The prog I'm
    currently using, Virtual VCR, doesn't mess with the video frame rate.
    It expects the DC10Plus to insert blank frames.

    So, if the above is correct, how does one capture with a DC10Plus and
    maintain a perfect 29.97 frame rate? Virtual VCR's a/v sync features
    are very nice, but they assume the blank frame insertion for dropped

    Any suggestions?


    jeremy ross, Jul 14, 2003
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  2. jeremy ross

    erratic Guest

    I guess Virtual VCR doesn't work well with the DC10+ card.

    It works just great with my ATI Radeon card though. Dropped frames are
    reported correctly and I can always find their location with VirtualDub.
    VirtualDub shows the previous frame twice in that case.
    erratic, Jul 14, 2003
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  3. jeremy ross

    jeremy ross Guest

    well at least I know that the "next dropped/duplicate frame" in
    VirtualDub actually works. I just did a capture last night, with
    about 30 dropped frames. The resulting .avi progressively loses sync
    and VDub didn't report any dropped frames. So, for whatever reason,
    my caps with the DC10 are not replacing dropped frames with duplicate
    or "blank" frames. Makes for a useless capture.

    jeremy ross, Jul 17, 2003
  4. jeremy ross

    erratic Guest

    A while ago someone mentioned the same problem with the DC10+ card in a
    Dutch newsgroup. When frames are dropped with Virtual VCR they can't be
    located with VirtualDub and the AV sync is lost. There seems to be no
    solution. I have no idea why this is happening either.
    erratic, Jul 17, 2003
  5. jeremy ross

    Markus Zingg Guest

    Ok, Jeremy, trip is over :)
    No, not the only thing. You should take into acount that the speed of
    the video stream (the frame rate) is controlled by the video source
    (i.e. the VCR) and as such is using a completely different base clock
    than the PC. That said, the 44100Hz audio sampling rate of the sound
    card may very well does not match a "second" as it's seen by the VCR.
    So, although the driver does not see a drop (cause there is none) the
    streams still can get out of sync.
    Obviousely not. The onle two software solutions known to me that let
    you capture in sync with the DC10+ when it's using the WDM drivers
    (read under W2k and up) is Studio itself and alternatively a propperly
    setup capture filter graph when using Graphedit.

    Markus Zingg, Jul 19, 2003
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