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What is LPCM - sky DD broadcasts

Discussion in 'Sky Digital TV Forum' started by jaminho, Nov 4, 2003.

  1. jaminho

    jaminho
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    Just set up a new home cinema kit and noticed that sky broadcast DD 5.1 on the newly badged Sky Movies 1, 2 & 3.

    It would seem that these 3 channels are the only ones that output 5.1 and having done a couple of searches of the forum this seems to be confirmed.

    However, all the others broadcast in DS, but this is recognised by my receiver as LPCM.

    The receiver then shows a front left and right channel input only, (no rear surround or centre) and the Dolby PLII comes on.

    The question is then, are the remaining movie channels broadcast in stereo only or am I mistaken

    ie, What is LPCM, (Linear P.... C.... M....)? and does it have any surround channel.

    Sorry if this is a bit confusing or if it's in the wrong forum
    :confused:
     
  2. digitalsafari

    digitalsafari
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    All the other channels are broadcast using MPEG-1 Layer 2 audio compression which your Sky+ decodes to Linear PCM (Pulse Code Modulation) which is sent out of the optical output when there is no Dolby Digital.

    Surround is encoded as Dolby Surround for Pro Logic decoding, however as Sky likes to use Joint Stereo (mono's low frequencies) this can compromise the surround encoding.

    Jonathan
     
  3. jaminho

    jaminho
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    Thanks for that.

    All sounds very technical, but in summary am i correct in saying that there is surround encoded in LPCM signals but it is compromised by the way sky broadcast it.
     
  4. Crocodile JD

    Crocodile JD
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    I believe LPCM is basically stereo. Your Home Cinema Amp is obviously Dolby Pro Logic 2 (DPL II) capable which takes a stereo signal and produces a surround sound from it. Not as good as Dolby Digital or DTS which are true 5.1 systems, but I believe DPL II does a reasonable job, better than standard Dolby Pro Logic at any rate.

    Cheers

    Croc
     

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