Audio/Visual sync

Discussion in 'Home Theater Projects' started by mike.yirga, Aug 22, 2005.

  1. mike.yirga

    mike.yirga Auditioning

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    Recently purchased a projector (Sharp dt400), a new dvd player (LG up-conversion), and all new cables (all monster THX except for the hdmi to dvi cable). The problem I am having is that the audio doesn't seem to be matching up to the video. I don't really notice it until there is a long sentence and the video keeps talking after the audio stops.
    Where should I start checking for problems? Should there be a way to correct this on the receiver (on older Kenwood THX)? I'm pretty new to this, so any help will be greatly appreciated.
     
  2. Phil A

    Phil A Producer

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    If there's no provision in the DVD player you may want to look at the delay for your speakers in milliseconds in the set-up feature of the rec'r.
     
  3. Ted Lee

    Ted Lee Lead Actor

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    yep, this is a more and more common occurance. the problem is the gear (maybe the dvd player, maybe the receiver, maybe the display device) can't keep up with the audio (it takes longer to process video then audio, that'w why you get the video delay.).

    you'll see more and more components offer some sort of audio delay (my receiver does it). i know *for sure* the sony upconverting dvd player does it as well. i also know that your lg does not. :b

    bottom line, you may have to find some component that has that feature, then go from there.
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    Almost all good de-interlacing (converting interlaced video to progressive) introduces a non-trivial time delay in the video signal path. Three to four frames is typical. Scaling may also introduce a delay but this delay is less, usually less than one frame.

    (A three frame delay is 1/20'th of a second.)

    The A/V receiver probably does not introduce a perceptible delay even if it does S-video input to interlaced component video output, involving upconversion.

    In order for DVD to be played on an HDTV (or SVGA/XGA/HDTV projector), de-interlacing and then scaling must occur somewhere.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  5. Phil A

    Phil A Producer

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    Interesting discussion, a new video scaler being introduced at CEDIA has some interesting reading in a press release related to the above - http://www.calibreuk.com/downloads/vantage-pr.pdf

    "Lip-Sync errors significantly degrade the home theater viewing experience Vantage-HD automatically adjusts the audio time-line to suit its internal video processing delay. Audio time-line correction operates on all audio channels—digital coaxial, digital fiber-optic, analog and HDMI audio channels. It’s easy to see that Vantage-HD is far more than just another scaler."
     
  6. aaron campbell

    aaron campbell Second Unit

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