Dolby 2.0 ?

Discussion in 'Archived Threads 2001-2004' started by Jakob_S, Dec 6, 2001.

  1. Jakob_S

    Jakob_S Stunt Coordinator

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    I have a simple question, that I hope some of you guys can help me with.
    Sometimes on DVD-audio specifications, it's indicated that the audio is Dolby Digital 2.0. But besides this information there is a illustration of 3 channels. Why isn't the track called 3.0 then? And is Dolby Digital 2.0 = Dolby Surround? And is Dolby Surround = Dolby Pro Logic?
    Hope you guys can understand my question and help me [​IMG]
     
  2. Adam Barratt

    Adam Barratt Cinematographer

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    The three speaker symbol you're seeing represents Dolby Surround: the bottom speaker is the surround channel. It's a little confusing, and I'm not sure why it was chosen. Dolby's other symbols are fine, but this one is a little confusing.
    [​IMG]
    Dolby Digital 2.0 just means there are two channels present. They may be Dolby Surround encoded, but they may simply be stereo.
    Dolby Surround is a recording technique used to fold four channels of information into a stereo soundtrack; Pro Logic is the decoder used to extract this information in the home. Dolby Pro Logic isn't Dolby Surround, but the two work in unison.
    Adam
     
  3. Damin J Toell

    Damin J Toell Producer

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    just to build on what Adam said, note that the number following the Dolby Digital designation of a given track (X.X) is the number of discrete channels the track contains. a 2.0 track may contain 4 matrixed channels. or it might just be a plain ol' 2-channel stereo track. so the reason a Dolby Surround track isn't called 3.0 (or 4.0) is because it only contains 2 discrete channels.
    for some light reading on the development of matrixed surround channels and the interplay between Dolby Surround and Dolby Pro Logic, i suggest this PDF document at dolby.com. if you're looking for a more technical view of the principles behind matrixed sound and how the Pro Logic decoder works, try this page. i would note further that Adam is a bit wrong with regard to the Surround/Pro Logic difference. Dolby Surround was originally introduced as a home decoder meant to decode the 4-channel matrixed Dolby Stereo tracks used theatrically. the original Surround decoder, however, could only decode the surround channel; the center channel remained undecoded. Pro Logic decoders were introduced a few years later and are able to decode all 4 matrixed channels, center included. however, the 4-channel matrixed home format is still called Dolby Surround, although Pro Logic is generally (and, at this late date, likely correctly) used interchangably with Surround.
    DJ
     
  4. Adam Barratt

    Adam Barratt Cinematographer

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  5. Damin J Toell

    Damin J Toell Producer

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  6. Jakob_S

    Jakob_S Stunt Coordinator

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    Thank you so much for the help, info and links. I think I understand it a lot better now.

    I have a quick question though: Are "Discrete Surround" and "Quad Surround" both a 4.0-mix, despite that they are different kind of surround mixes?

    I've read some reviews of "Point Break", where they mention that both the Dolby Surround and the DTS-track is encoded as 4.1, because the surrounds works as one channel. This means that Point Break is a "Discrete Surround 4.1"-track right?

    Oh, I just thought of a last question (I promise I won't bother anymore after this...):

    "Dolby Digital 2.0" and "Dolby Surround 2.0" is both mentioned a lot of the back-covers on DVD boxes. But is it right to use the word "digital" in all these cases? If not, when can you use the word "digital"?
     
  7. Brad_W

    Brad_W Screenwriter

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  8. Adam Barratt

    Adam Barratt Cinematographer

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  9. Damin J Toell

    Damin J Toell Producer

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  10. Ken Chan

    Ken Chan Producer

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  11. Roger Dressler

    Roger Dressler Stunt Coordinator

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    It's really cool that y'all really do understand what is often a bit confusing. But I'll add some background, since the little Dolby sound format icons were my idea.

    We hoped to find a way to solve the "what's on the soundtrack?" question, sort of an extension to the FM or TV stereo indicator light, but for the myriad permuations of the 5.1 format. We wanted a way to get the content marking to match the hardware display for best consistency. Many hardware decoders use LEDs, so if an array of 3x2 could be put on the product, with one more tacked between for LFE, we could represent L/C/R in front and Ls/S/Rs in back.

    We recognized also that "2/1" would be a format almost guaranteed never to be used, since there was no content like that made. So when it came time to find a way to distinguish 2/0 programs with 2/0 Surround encoded content, we adopted the "2/1" pattern so as to illuminate the S light, thereby trying to show the 2-ch signal is surround encoded.

    We had internal discussions suggesting we should show phantom C and phantom S equally, but that would have meant using the 3/1 pattern, which does exist in a number of discrete mixes (Out of Africa for ex), so we couldn't do that. It was not considered that we could show the phantom channels differently than the discrete channels, but today the display devices such as LCD, FLD, and on-screen video can of course do that with a hollow box instead of a solid filled box--even though LEDs cannot. So we have now adopted that method for Surround EX content, by adding the "S" position with a hollow box.

    As my grandaddy used to say: "Too soon old but too late smart."
     
  12. Damin J Toell

    Damin J Toell Producer

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  13. Jonathan Burk

    Jonathan Burk Second Unit

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    It was my understanding that the term "Dolby Stereo" referred to a Dolby A, matrix encoded (stereo) soundtrack theatrically presented, and "Dolby Surround" is how they denote the same soundtrack on home video packaging.
    Thus, it could be said Star Wars('77) was presented theatrically in Dolby Stereo, but my Laserdisc of the same soundtrack is presented in Dolby Surround (and says so on the package).
    This is referring to the labeling of the soundtrack itself. The distinction between the hardware decoders as "Dolby Surround" (no center channel, no steering) and "Dolby Pro-Logic" (center channel and steering) still holds true; the software and hardware labels are mutually independent.
     

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