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sky sync problem - HELP!

Discussion in 'Sky Digital TV Forum' started by shs, Mar 19, 2003.

  1. shs

    shs
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    I have recently bought a Plasma (pana 42pw5b) and am now routing my Sky (grundig digibox - dv3 i think) through my vid as a switching unit (using rgb), with audio going into a sony amp (db780). problem is often the audio is slightly ahead of the pic.

    i have tried pretty much all the permutations of wiring i can think of.... anybody else had this sync problem and anybody got any ideas how to cure it...?!!!

    thanks...........
     
  2. AOD

    AOD
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    What you're most likely experiencing is the dreaded "lip-sync" issue.

    Now this is not as scary as it sounds, but resolving it is another matter.

    When the video signal from your Sky digibox gets fed into your Plasma, the screen does some nifty processing on the signal before it actually gets displayed. Due to the time that this takes, when the image is displayed, it lags behind the audio cos there's basically no processing or very little being done on the audio side of things.

    The way most people resolve this, is by having an amp or processor that allows you to introduce a delay to the audio, this then brings the audio back into sync with the video.

    Note, this is different to the delays you setup on your amp that correspond to how far away from the various speakers you are. This is a "global" or "master" delay that would be applied to *all* channels.

    Do a search on this site for "lip sync" and see what comes up. Short of buying a new amp/processor or perhaps investing in some kind of external audio delay unit (such as used by musicians) there isn't another solution. :(

    FYI, newer amps coming onto the market are including these delay facilities. Denon's latest offering (the 3803) is one such amp.
     
  3. shs

    shs
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    thanks for the info. sounds a bit daunting though...!

    can i bother you with a few more questions...?!

    is this still a problem no matter what digibox i have - thinking about sky +...?
    also, would it make any difference if i went through svideo rather than rgb?
    is this a common problem with sky - i.e. should the shop who sold this plasma / amp package to me have brought it to my attention do you think?
    lastly, what level of processor would be able to do this if i were to buy it additionally...?

    sorry for the list of questions - would be v grateful for your opinion.....

    thanks.
     
  4. kenfowler3966

    kenfowler3966
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    I think this is going to become a bigger issue in the future. I have the same problem with my dvd recorder. If you watch a program through the unit, or even while recording the program the sound can be out of sync with the picture, particularly if the picture is complicated and taking a lot of processing to display.

    The strange thing though is that if you watch the recording it is perfect, as everything has been put right as it records!

    I have also noticed a number of times sky programs on a normal digibox, particularly kids channels, are themselves out of sync, presumably again because of the different time required to process the picture and the sound.

    The real awnser is some sort of delay system which is built into the receiver and can see a reference between the picture and sound coming out of the processor and keep them in sync, with an overide control to sort out timing issues in attached external equipment. However the expense of adding this makes it seem very unlikely
     
  5. AOD

    AOD
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    Taking your points in turn:

    1. Standard Digibox vs Sky+

    Yes this will still be an issue. Remember the delay is being introduced by the processing being applied to the video signal in your Plasma screen. Potentially any source you view (DVD, VCR, PS2 etc) could show the same problem.

    2. S-Video vs RGB

    Unlikely to make any difference. Again, both types of signal would probably undergo similar processing within the Plasma.

    3. Common Sky Problem?

    More accurate to say it's a common issue with Plasma screens. So many have "clever" processing to improve the signals they're being fed that a lot of people are experiencing this issue. I should point out that you can also get lip-sync issues when your video is going through something like an external scaler/de-interlacer which people may use for example with projectors. This is not unique to Plasma screens.

    The shop who sold you this, should have been aware of this kind of issue. If you bought the lot as a package, you could reject it as being "unfit for purpose" or get them to trade up your receiver (should you wish to spend the money of course).

    4. Units with master audio delay.

    Ones that spring to mind are:

    Denon 3803 (newly released AV receiver)
    Denon AVC A1SR (heavyweight THX certified AV receiver)
    Tag AV32R processor (THX certified AV processor)
    Arcam AV8 (THX certified AV processor).

    I'm sure there are a couple more, but they're not exactly thick on the ground. I would audition the Denon 3803 to see what you think of it.
     
  6. StooMonster

    StooMonster
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    Trouble is lip sync doesn't just apply to individual channel, or even programme, it can apply to segments in a programme.

    This can be particulary prevalent with news channels, different segments and live links in particular have differing lip sync issues. For example, what you may see in one bulletin is one item with minor problems, followed by studio discussion where no problems in studio but horrid out of sync with "live" reporter, followed by another item with different sync, etc.

    As well as live links, material converted from NTSC seems to have problems too.

    Therefore, even if you have an audio delay box (such as Vigatec Wave) or an amplifier with audio delay (as above); to get perfect lip-sync you'll have to keep changing it's settings -- sometimes every few minutes/seconds -- or run it so that it's set somewhere between best/worst timing.

    Cause of this is not only the plasma screen, but the broadcasts themselves. However, on smaller screens with no processing it's not as noticeable; plasmas compond the problem, they do not always create it.

    StooMonster
     
  7. shs

    shs
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    yes i've noticed this within segments of programmes, so i guess the upshot it that the problem lies as much with the broadcasters as it does with the user. it does seem to be a 'live' problem more than recorded - although it is odd that when you record a live programme the effect disappears if this is true per the above reply.... can't say i've noticed the sync problem with dvd's / vid - do people find this as frequent?

    in short, looks like we're shafted.....
     

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