6.1/7.1 question

Discussion in 'Archived Threads 2001-2004' started by Brian Schucher, Feb 14, 2002.

  1. Brian Schucher

    Brian Schucher Supporting Actor

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    Hope this hasnt been asked a million times. Im trying to get a full grasp on the discrete vs. matrix aspect of theses configurations. with 6.1 it can either be 6 discrete channles plus LFE or 5 dsicrete channles a matrixed rear center and LFE, right? Also, when their are two rear center speakers, are they indentical signals to both? Can someone just fill me in on ES/EX/Matrix/Logic7 blah blah blah
     
  2. Michael Reuben

    Michael Reuben Studio Mogul

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    In terms of the sound format, yes. But many decoders implement further DSP processing in an effort to differentiate between two center rear speakers.
    Hope this helps.
    M.
     
  3. Brian Schucher

    Brian Schucher Supporting Actor

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    Thank you. Most of it I had a handle on.. It was the dual rear center thing that confused me the most.. Thanx...
     
  4. David John

    David John Stunt Coordinator

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    ok here's a go at it:
    DD-EX has a rear surround channel encoded into the L/R surround channels. So it is recorded as 5.1 separate channels. When it is played back, the rear surround channel is extracted from the L/R surround channel.
    (If you don't have DD-EX, it is played back as normal 5.1)
    DTS-ES Matrix is handled the same as above.
    DTS-ES Discreet is actually recorded as 6.1 separate channels of info. When it is played back, it is played as 6.1 channels.
    (If you don't have DTS-ES, it is played back in normal 5.1, and the surround back info is handled by the L/R surrounds)
    DPL2 is an updated version of Dolby Pro-Logic Surround.
    This takes any stereo source and creates a 5.1 presentation from it, with different info going to each surround speaker.
    (5.1 created from 2.0)
    DPL (the original) has no subwoofer channel, and the both surround speakers get the same info. (4.0 so to speak created from 2.0)
    DTS-Neo:6 is similar to DPL2 however it creates L/R surround and a Rear surround channel from the stereo source. (6.1 if you will, but created from 2.0)
    Logic-7 is a similar to both NEO:6 and DPL2 however it can create 7.1 from the 2.0 source. This is true 7.1 playback, but there is no 7.1 source material.
    As far as 7.1 surround, that is a misnomer.. it is really 6.1 with 2 speakers handling the Rear surround info.
    (7 speakers plus sub, playing back 6 plus sub channel.)
    Although now i see someone beat me to the explanation!
    [​IMG]
    Now I disagree with the above post that there is only one TRUE 6.1...DTS-ES Discreet.
    That is the only 6.1 that is RECORDED as 6.1 separate channels, however, the matrix 6.1 encoded DVD is played back with 6.1 different sources of info going to the speakers.
    There is different info going to all the speakers.
    So I guess it is debatable as to what "TRUE" 6.1 is.
     
  5. Evan S

    Evan S Cinematographer

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    Michael, great post. I consider myself pretty learned in a lot of HT aspects, but these formats even have the experienced people shaking their heads at times. Thanks a lot.[​IMG]
     
  6. Kevin Bracey

    Kevin Bracey Auditioning

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    DD-EX and DTS-ES matrix are definitely NOT 6.1 formats. It has been long-established terminology that X.Y designations denote independent encoded channels. Dolby et al have always been consistent on this. Just as Dolby Surround material has always been 2.0, Dolby Digital Surround EX is and always will be 5.1. By describing it as 6.1 you're abusing the notation, leading to the same sort of confusion as you get when people don't distinguish between LFE and the subwoofer. And 7.1 is even worse - you don't call your local cinema 15.2 just because they've got two subwoofers and several surround speakers per surround channel. The important point is that "X.Y" or "X/Z.Y" notation describes the content, not the presentation.
    I appreciate that people find it convenient to talk about "6.1" and "7.1" but it will just lead to confusion in the long run.
    Dolby themselves talk about this in Marking Dolby Digital Surround EX Soundtracks on DVD. Another explanation can be found at SMR Home Theatre.
    A more accurate way to describe Surround EX is a 5:6.1 system - ie 6 channels matrixed into 5.
     
  7. Kevin P

    Kevin P Screenwriter

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  8. David John

    David John Stunt Coordinator

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    There may only be one 6.1 channel RECORDED surround format out there (DTS-ES discreet). This I most definately agree with.

    However, to say that Dolby Surround (pro-logic) is only a 2 channel format really is inaccurate.

    There is program material that is specifically steered into a certain channel for playback. Even if it is only recorded with 2 channels. There are certainly 4 different channels of information playing back.

    Same with DD-EX, it may be recorded as 5.1, but when played back with the proper decoding, there are 6.1 different channels of info being played back.

    I'm not talking about applying 6.1 decoding to 5.1 material, I'm talking about 6.1 matrix encoded source material. This has been recorded with a 6th channel of info. Be it matrixed into the L/R surrounds or on a discreet track, it is there.

    So as I listen to 6 different sounds come from 6 different speakers, I will NOT agree that it is really only 5 channels. (not including the LFE)

    My point is... although it may be understood that any surround format can only be stated as the number of channels recorded, I feel that it really should be identified by the number of actual channels present during playback. This is a more accurate way of describing the experience of listening to it.

    This is my opinion, I don't mean to call anyone a lier or say that anyone is wrong, I am only stating the mis-logic involved with explaining the surround formats.
     
  9. Michael Reuben

    Michael Reuben Studio Mogul

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  10. AdrianM

    AdrianM Auditioning

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    OK, but does it make sense to spend more money on a system advertised as 7.1? Or even a 6.1 over a 5.1?
     
  11. Michael Reuben

    Michael Reuben Studio Mogul

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