Ac-3 = 5.1?

Discussion in 'Archived Threads 2001-2004' started by RaymondK, Mar 23, 2002.

  1. RaymondK

    RaymondK Auditioning

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    I have an older Sony DVD player. It's the DVP-S7000. I'm getting a 5.1 stereo for it. I checked the menu and it only lists PCM or AC-3 Digital. So I'm hoping that the AC3 is for 5.1 sound. Does anyone know more about this or have this player and is getting 5.1 sound?

    Thanks,

    RK
     
  2. Vince Maskeeper

    Vince Maskeeper Producer

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    AC-3 is Dolby Digital.

    -Vince
     
  3. Michael Reuben

    Michael Reuben Studio Mogul

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    To expand on Vince's reply:
    "AC-3" is the same as "Dolby Digital" -- but "Dolby Digital" does not automatically equal "5.1". DD/AC-3 can have anywhere from 1 to 6 separate channels of sound.
    DD/AC-3 is one of the two official sound formats for DVD, and by far the more common (the other is PCM). All DVD players must be capable of passing the DD/AC-3 signal, however many channels it may happen to contain on a given title. The Sony 7000 is no exception; I still have mine, and it's played 5.1 tracks since day 1.
     
  4. Harry Lincoln

    Harry Lincoln Stunt Coordinator

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    I could be wrong, but in the days of laserdisc didn't an ac-3 label on a disc = 5.1 channels, with PCM the preffered format for 2 channel mixes? I have never seen a LD with less than 5.1 channels labelled ac-3.

    Harry.

    Harry.
     
  5. Vince Maskeeper

    Vince Maskeeper Producer

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    Harry,

    You are correct, but this is more a metter of pref than format dictation. As Michael said, AC-3 is a data format that we now know by the trade name DOLBY DIGITAL.

    In the days of laser, it was preferable to use PCM for 2 channel mixes, so AC-3 was exclusively 5.1 on LD... but again this was simply because they had a preferred method for encoding 2 channel material on laser, not because the AC-3 format didn't support it.

    So AC-3 is just the file format for DD, and in earlt DVD players (like the one the original poster asked about) they used AC-3 to denote what we now simply call Dolby Digital.

    -V
     
  6. Michael Reuben

    Michael Reuben Studio Mogul

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    Yes, all of LDs with Dolby Digital tracks had DD 5.1 tracks. That doesn't change anything I said.

    DD and LD were an awkward combination developed by Pioneer and Dolby as a way of getting some sort of DD software into the marketplace for the 20 months or so between the introduction of DD and the appearance of a truly digital medium such as DVD. There would have been no point in including a DD 2.0 mix on an LD since, as you note, LD already featured an excellent format for 2-channel digital sound. On DVD, however, DD 2.0 is quite common, and it's also common on digital cable and satellite. All of that comes under the general label of AC-3.

    M.
     

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