Audio Sink Problem

Discussion in 'Professional Video Production' started by Zach Swee, Aug 12, 2004.

  1. Zach Swee

    Zach Swee Guest

    I filmed an even with two cameras, both miniDV, one's a Panasonic and the
    other a JVC. Camera 1 had the house audio going directly into the camera,
    so the audio I want to use for the movie will be
    from Camera 1. I put both camera's footage on my computer, and when I sink
    Camera 2's video to Camera 1's sound, there's a problem. At the point I
    sink them, everything's fine, but as you watch the video, it slowly goes out
    of sink, so that after 30 seconds its not in sink at all. Both indivudaully
    run fine, but for some reason Camera 2 goes out of sink with the audio from
    Camera 1. My only theory on this is that Camera 1 was filmed in LP and
    Camera 2 was filmed in SP. Is this the reason for the problem? If not,
    what is? If so, how can I fix it or get around it?? Any help will be
    greatly appreciated.

    -Zach
     
    Zach Swee, Aug 12, 2004
    #1
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  2. Zach Swee

    MSu1049321 Guest

    Check that both tracks are set for the same bitrate, there's a rate for
    cd-audio, and one for Dv audio, I think it's a 44khz.... cold meds have me
    groggy. look up "sample rate" in your user guide, make sure both tracks are
    properly set, and that both cameras were properly set for the appropriate
    sample rate. this is the cause of this kind of problem 9 times out of 10.
    Soemtimes, one of the video sources will have to be re-sampled. Also, check
    that your video frame rate is the same for both tracks/cameras, in USA NTSC
    that's 29.9, not 30, not 24..... whatever standard you pick, you have to be
    consistent with using it, or these kinds of problems will occur...
     
    MSu1049321, Aug 12, 2004
    #2
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  3. Define "not in sink at all"? Are you talking about seconds
    out of sync (note spelling), or milliseconds?
    Quite possibly. Certainly something to be avoided if you
    have any control over it.
    There could be several reasons. Many of them likely not
    under your control. Best is to experiment beforehand and
    determine which method works best with your particular
    combination of equipment, circumstances, etc.
    Why is it a problem? Presumably the whole reason for
    shooting with two cameras is to be able to switch back
    and forth between them in your editing step. So make
    your video switching decisions, and then drag the Cam
    2 clips back and forth to match the sound track from
    Cam 1. I've done this and it takes longer to explain
    than to just do it.
     
    Richard Crowley, Aug 13, 2004
    #3
  4. Zach Swee

    Zach Swee Guest

    I see your point. the problem though, is that if i link the beginning of
    the clip to the sound, 20 seconds into the clip it's already off by at least
    half a second.
     
    Zach Swee, Aug 13, 2004
    #4
  5. That is the worst case of speed error I have ever heard of.
    And I started working in video back in the days of tube cameras.

    If that is the case one (or both?) of your cameras is dramatically
    broken and you are hip deep in fertilizer. Sorry.
     
    Richard Crowley, Aug 14, 2004
    #5
  6. Zach Swee

    Ryan Boni Guest

    It may not be that bad. First of all what capture card are you using and
    which editing software are you using??

    Secondly, did you capture the footage into the computer using firewire or
    analog (I was going to say recapture them trying each way individually to
    see if there's a problem, but you said each track played fine on its own.)

    Are you locking your audio tracks? If not, lock both tracks so that they
    don't accidently move while you're editing.

    I'm more inclined to think it's a computer hardware (RAM - as in not
    enough - maybe it's processing the audio fine, but having to buffer the
    video when you have the tracks on top of one another) or software (NLE -
    some bizarre setting, or it's having trouble working with either your audio
    or video card) problem, moreso than a video equipment problem if it's that
    drastic of a synch slip, based on the small amount of info we have to go on.

    Ryan


    --
    ---------------------------------------------
    Ryan Boni
    Public Access Director
    Peters Township Community Television
    McMurray, PA
    www.geocities.com/ptct7/
     
    Ryan Boni, Aug 14, 2004
    #6
  7. Zach Swee

    Zach Swee Guest

    Hey. I captured the video using firewire into Adobe Premiere Pro1.5. I'm
    running a 1.3 GHz Pentium 4 with 256 MB of RAM and about 30GB space free on
    my harddrive. The footage is running off my 120GB external Western Digital
    Harddrive. Audio tracks are definitely locked. Any other info might be
    helpful in making a diagnosis?
     
    Zach Swee, Aug 15, 2004
    #7
  8. Zach Swee

    Zach Swee Guest

    Here's some information about the files I'm working with that I'm having the
    problem with.

    The file that I'm getting the audio from was AVI, it's about 7GB big, Avg.
    Video Bitrate: 4002.41 kbit/s, Framerate: 29.9700 fps, Microseconds Per
    Frame: 33366 ms, Wave Type: 1 - Microsoft PCM Format, Avg. Audio Bitrate:
    213.63 kbits/s, Sample Rate: 48000 Hz, Bit Depth: 16 Bits

    The file that I'm using video from is AVI, it's about 7GB big, Avg. Video
    Bitrate: 3278.89 kbits/s, Framerate: 29.9690 fps, Microseconds Per Frame:
    33366 ms, Wave Type: 1 - Microsoft PCM Format, Avg. Audio Bitrate: 116.69
    kbit/s, Sample Rate: 32000 Hz, Bit Depth: 16 Bits.

    Does that give any more clues?
     
    Zach Swee, Aug 15, 2004
    #8
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