What is PCM?

Discussion in 'AV Receivers' started by dan-0, Sep 10, 2003.

  1. dan-0

    dan-0 Stunt Coordinator

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    I just got my first digital receiver, a Denon AVR2803. After conecting my old Sony DVD player via the coax (outlaw silver) I had to go into the DVD's menu to select digital out. My opions were analog, pcm, or DTS. I of course selected DTS.

    Then I noticed whilst going through the menues on the Denon that you oculd toggle between analog (i think), DTS, and PCM (again).

    Just curious as to what PCM is, and is there any reason why I would ever select it.

    Thanks heaps
    dan
     
  2. Lew Crippen

    Lew Crippen Executive Producer

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    Pulse Code Modulation. Unlike DTS and DD, there is no compression. CDs are recorded in PCM format, as are some DVDs.
     
  3. John Royster

    John Royster Screenwriter

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    Dan,

    PCM is the digital encoding of CDs. your receiver would use PCM when decoding a CD.
     
  4. John Royster

    John Royster Screenwriter

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    Dang Lew, you stalking me?

    [​IMG]
    [​IMG]
     
  5. Lew Crippen

    Lew Crippen Executive Producer

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    [​IMG]
     
  6. Aaron Garman

    Aaron Garman Second Unit

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    Don't forget, most laserdiscs have a PCM track as well. I think DSS recievers and PS2's when connected with a digital output are also PCM.

    AJG
     
  7. Chuck Kent

    Chuck Kent Supporting Actor

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    dan: FWIW, set the input mode on the 2803 to AUTO. In a very very very very short amount of time it decides which mode it needs to use (PCM, DD, DD-EX, DTS, DTS-ES, DTS-ES Discrete, DTS 96/24 or analog.) It always gives priority to digital over analog...
     
  8. BrianWoerndle

    BrianWoerndle Supporting Actor

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    PCM is only stereo. Your DVD player should be set to DTS, or bitstream for 5.1.
     
  9. FeisalK

    FeisalK Screenwriter

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  10. dan-0

    dan-0 Stunt Coordinator

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    Thanks for all the helpfull repsonses so far.

    I was happily plodding along for the last ten years with my 'ol Denon AV700, pro logic surround sound receiver.

    Since upgrading receiver and speakers (NHT) I've been a bit overwhelmed with all the terminology and digital formats. It's starting to come together little by little.

    This forum and in particular, all the knowledgeable people on the forum, have been a real god-send for me.

    Edit: I've found for CD playback, I enjoy the best sound played in stereo, with tone controls turned off. Supposedly, this routes the sound to the speakers with a minimal amount of circitry being involved in the process.

    Thanks a bunch
    dan
     
  11. Marty Neudel

    Marty Neudel Stunt Coordinator

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    >PCM - some (older) recievers do not handle high bandwidth signals so the audio soundtrack on the DVD (DD/DTS is usually 88kHz or 96hHz) must be downconverted to 48kHz or 44.1kHz PCM. It's still digital, and you still get 5.1 channels<

    Feisal,

    while the studios record the 5.1 (or 6.1)channels in PCM, they are not passed on this way to consumer media. DVD-A compresses the 5.1 pcm track using mlp, sacd uses dsd encoding, and DD and DTS use their own compression schemes.

    The PCM tracks on DVDs and CDs are currently 2-channel stereo.

    Marty
     
  12. FeisalK

    FeisalK Screenwriter

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  13. Marty Neudel

    Marty Neudel Stunt Coordinator

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    Feisal,

    DVD Video disks are required to have either a DD or a PCM digital track for region 1. DTS is an optional format for this region.

    Downconversion is applied only to PCM tracks. DD and DTS are passed on as is. Even the earliest DD and DTS decoders could handle 20/96. 24 bit DTS is an recent feature with the extra 4 bits stored in a metadata form. Since the bandwidth is not increased for DTS 96/24 many people consider this enhancement to be of questionable value.

    Marty
     
  14. LanceJ

    LanceJ Producer

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    For music videos, from the disc's menu I would pick the PCM track. Because unless the multichannel track is TRULY multichannel and not some barely-audible ambience mix, the PCM track almost always sounds better 99.9% of the time. Just because there are more channels in DTS/Dolby does not mean it sounds better--crap is crap (the sound, not the DTS or Dolby format itself[​IMG]). And being the old fart like I am, I'm always a little suspicious of any format that uses any lossy compression system--are they sure LanceJ couldn't hear those supposedly inaudible parts the encoder throws out?

    LJ
     
  15. FeisalK

    FeisalK Screenwriter

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    Marty

    I get what you're saying but I distinctly remember setting up my Panasonic and Philips DVD players and the setup has options for DTS - output either Bitstream or PCM, and I think thats what Dan's original question was about.
     
  16. Marty Neudel

    Marty Neudel Stunt Coordinator

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    Feisal,

    Dan's original post referred to:

    >you oculd toggle between analog (i think), DTS, and PCM (again)<

    This refers to the ability to select which output the player transmits. This is pretty much the same set of options available on the Panasonic 210 DVD player I have in my bedroom. If you choose DTS (for bitstream), the DTS track will be sent to your receiver. If you choose PCM, your receiver will get the PCM or DD alternative track.

    Marty
     
  17. FeisalK

    FeisalK Screenwriter

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    Marty,

    when you put on a DVD, how do you access the PCM track - I only see options for DD or DTS (if available) on most discs? I think LPCM tracks are only available on DVD-A

    you might want to see this thread - Aaron had his player converting DD to PCM
     
  18. LanceJ

    LanceJ Producer

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    I own some video dvd's that include LPCM tracks--a Sade concert & two Supreme Beings of Leisure (pop/lounge group) dvds for example. And I've seen other discs that include them too.

    And an FYI for the heck of it [​IMG]: "LPCM" stands for "Linear Pulse Code Modulation", meaning no compression is going on.

    LJ
     

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