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Plasma screens and sync issues

Discussion in 'Plasma TVs' started by Tonmeistermat, May 24, 2004.

  1. Tonmeistermat

    Tonmeistermat
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    Hi All, we are thinking of getting a plasma for our studio and we do a lot of sound to picture work. I've heard rumours that plasma screens play out of sync (ie the picture is behind the sound), but can't find anything about it on this forum! Aparently Panasonic admit (after some persuading) that there is a delay in some of their screens, but won't say why. Does anyone on here have sync problems, particularly if you are going via an external scaler or something, and if you do, has anyone found a way round it?

    Ta,

    Mat
     
  2. macdaddy

    macdaddy
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    I found a slight sync problem on some Sky channels. The only way round it is to buy a medium/high end amp which has a sound delay feature.
     
  3. Joe Fernand

    Joe Fernand
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    Tonmeistermat

    Using a Plasma Display or PlasmaTV to Preview your work will in the main not cause you any problems - assuming you are sending the Display or TV 'In-Sync' Interlaced or Progressive Video + Stereo Audio and using the on-board or detachable loudspeakers as your Audio monitors.

    The 'problem' you allude to is only really relevant* if you separate Audio from Video and have your Audio going direct to an AV or Stereo Amp which has no delay to compensate for the Video processing time within the Plasma.

    *Some folk will see Audio delay with any Display or TV and will certainly notice a small delay in most Display or TV even when using the on-board loudspeakers.

    Having to compensate for Video Processing time through the Plasma when you have the Audio on a separate signal path wouldn't seem to me to be that unusual in a Studio environment.

    Best regards

    Joe
     
  4. Tonmeistermat

    Tonmeistermat
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    Thanks guys! As youy suggest, we will be separating the sound and the picture (ie not sending the sound through the plasma's internal speakers). Is the delay a known value, or is it slightly different for different machines or different screen content? ie can I set the system up, insert a 2 frame (or whatever) delay in the monitor path and leave it, or will I have to change the value depending on what the source material is? I know for instance that some 24P and HD projectors require a fixed 3 frame delay whatever you feed them, and the machine works it out such that this delay never changes.

    Mat
     
  5. Joe Fernand

    Joe Fernand
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    Tonmeistermat

    You should find the delay pretty constant - it will vary if your sending Interlaced and letting the Plasma do the Deinterlacing as opposed to you sending our Progressive; you may just need two settings in your output profile.

    Some of the Home Theatre set-up DVD's you can get have pretty good test sequences for setting up Audio delays on video systems.

    Best regards

    Joe
     
  6. Tonmeistermat

    Tonmeistermat
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    Thanks Joe,

    That makes sense! These test DVDs... I've read in some other threads people refering to AVIA... is it this one you mean, or are there others that are specific to sound alignment?

    Thanks for taking the time to answer my stream of questions!

    Mat
     
  7. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Digital Video Essentials has a audio/video sync test pattern on it. You can get PAL and NTSC varients of the disc

    Gordon
     

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