Dolby Digital via PCM

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by tvl76, Sep 18, 2007.

  1. tvl76

    tvl76 CUBS WIN !

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    Oct 5, 2005
    Peoria, AZ
    Looked at a lot of threads on this and I'm still confused. I just don't know exactly what PCM is.
    I have my HR10 connected to my TV with HDMI, then coax audio out of TV into my AVR. I also have an optical audio out of the HR10 into my AVR.

    I had to set my HR10 Dolby Digital output via PCM to hear the audio thru the TV connection.
    a) Is this because HDMI cannot transfer DD ?
    b) By doing this via PCM, is the TV processing the DD and sending to my AVR?
    c) Should the sound with the HR10 via PCM to TV to AVR be the same as the HR10 via optical to AVR ?

    Thanks
     
  2. jbernardis

    jbernardis Active Member

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    Oct 21, 2003
    Princeton NJ
    HDMI can indeed handle dolby digital. Can your TV? Perhaps that's why you had to set the output to PCM.

    If you're sending PCM to your TV, I can't imagine that you're getting DD out of your TV into your AVR. Your optical connection from your HR10 to your AVR carries DD, but I don't know how you have your AVR switched when you are listening to/watching TV. Are you listening to the TV input or to the HR10 input?
     
  3. Budget_HT

    Budget_HT Heavy User (of TiVo)

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    Renton, WA
    HDMI can transfer DD5.1, but most HDMI-equipped HDTVs that I have heard about do not support DD5.1 signals sent over HDMI (including my own HDTV). Like you, to hear audio on the TV I had to set the option to PCM, which is simply digital stereo, equivalent to the analog left+right audio.

    I have a separate optical audio connection from my HD DirecTiVo to my A/V Dolby Digital audio system. If the TiVo option is set to PCM, then the optical output is also PCM (like the HDMI). So I have to toggle back and forth between DD5.1 when I want the full audio experience. I would leave it set to DD5.1 except that my wife likes to watch TiVo programs on the TV without using the A/V system.
     
  4. tvl76

    tvl76 CUBS WIN !

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    Oct 5, 2005
    Peoria, AZ
    The reason I want to use my TV output into the AVR, is because I have my HR10 connected to HDMI-1 input, and an HR20 connected to HDMI-2 input on my TV.

    Switching from one HRxx to the other HRxx is as easy as switching the video input. (the audio automatically follows)

    So, is it true then, If I want the best possible audio, from my HRxx's, then I should use the optical connections directly from my HRxx's into my AVR, and send it as DD5.1 ?
    I guess with the dual tuners on the HR10, I really don't have a need to be switching back and forth with the HR20 on a regular basis. I can set up an activity on my remote to use either with just one press of a button.
     
  5. phox_mulder

    phox_mulder I get paid 2watch TV

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    Salt Lake...
    Toslink out of the TV is most likely only connected to the TV's ATSC tuner, not to whatever input the TV is on.

    I know it's that way with my TV.

    You need to run optical from each individual receiver into the surround sound system.

    There are switches out there for those of us with old school DD decoders that only came with one toslink input.


    phox
     
  6. TyroneShoes

    TyroneShoes HD evangelist

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    Sep 6, 2004
    It's not better (quality-wise) than DD 5.1 via HDMI, and the material must be 5.1-formatted to be "better" than 2.0 audio from either optical, HDMI, PCM, or analog. All four protocols are capable of the same quality, so calling one "best" is not really accurate. What is marginally better in a particular application usually depends on that application and the quality of the equipment involved.

    But some of those formats are incapable of 5.1, so would not take advantage of material encoded as such. How good the audio is is not as much related to which format you use to pipe it around your home theatre as it is related to the source material itself and how compatible your components are with one another.

    IOW, there is not simple answer to what is "best". If you want 5.1 capability, it makes sense to avoid the protocols that can't support it, but even analog can match the quality of the others if done right, and in some ways can be better, as it allows you to use volume leveling techniques, equalization (some eq can be done digitally, too) and other features while avoiding certain limitations and kludge-y connection parameters.
     
  7. tvl76

    tvl76 CUBS WIN !

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    Oct 5, 2005
    Peoria, AZ
    I have my HR20 connected to my TV with HDMI and get "audio" on every broadcast, be it SD or HD. I can't tell you right now if my AVR indicates it being DD or not. But I could not get audio from the HD broadcasts from my HR10, until after I switched the output via PCM.

    Is this because the output from my HR10 via PCM cannot be processed back to DD5.1 by any process, or are you assuming that my TV cannot process the output as DD ?

    I have my AVR (Denon 3802), set to auto.

    I am listening to the TV input on my AVR. (Via coax from the TV)
     
  8. jbernardis

    jbernardis Active Member

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    Oct 21, 2003
    Princeton NJ
    I don't know if your TV is capable of passing DD through from it's input to it's output, but AM pretty sure that your TV is not turining PCM input into DD.

    If you are listening to the TV input on your AVR, then the optical connection from the HR10 to the AVR serves no purpose.


    I have a denon 2307 AVR. It switches HDMI. I have the HDMI output from my Tivo connected to my receiver, and I have the receiver set up to extract the audio and play it through its speakers rather than inject it into the HDMI cable going out to the TV. That way I know I'm getting DD into my receiver.
     
  9. stevel

    stevel Dumb Blond TCF Club

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    PCM means CD-style digital stereo, (Literally, it means Pulse Code Modulation) Two channels. No 5.1. This setting would be used for older A/V receivers that have an optical audio input meant for CD players and which do not have Dolby Digital decoders. If a Dolby Digital signal was sent to such a device, you'd get either noise or silence - not proper audio.

    If your audio equipment has a Dolby Digital decoder and you are using the digital audio output, then set the output to Dolby Digital. If you are using HDMI, this always supports Dolby Digital, though many TVs will mix this down to stereo only.
     
  10. tvl76

    tvl76 CUBS WIN !

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    Oct 5, 2005
    Peoria, AZ
    Thanks alot guys, I think I got it.

    Until recently, I have always been listening to my HR10 broadcasts with my optical connection into my AVR, and the HR10 output as DD. Thats works great.

    However, now I also have an HR20 connected to my TV and I just wanted to make the connections simpler by using the TV to switch the audio.

    Appears to me that if I want to hear DD from from HR10, then I will have to change the audio output setting back to DD and use my AVR connection for audio.

    I know this is not the HR20 forum, but since we are are on the subject,
    The only audio output setting, on the HR20, for DD is ON or OFF. With mine set to ON, connected to my TV with HDMI only, I get audio on HD broadcasts (the same broadcsts that the HR10 goes silent with DD on) Is the HR20 outputting PCM ?
     
  11. stevel

    stevel Dumb Blond TCF Club

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    It's possible that the HR20 is detecting what the TV is capable of and sending the appropriate thing - I'm not sure. My A/V receiver doesn't seem to properly handle audio of any kind over HDMI so I use optical/coaxial digital connections as needed.
     

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