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HT Q #2: DTS-ES matrix and discrete

Discussion in 'Archived Threads 2001-2004' started by Kevin C Brown, Jul 24, 2001.

  1. Kevin C Brown

    Kevin C Brown Producer

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    Another stupid question:
    As I understand it, all encoded DTS-ES discrete discs will also have the discrete rear center channel *matrixed* in to the L + R rears a la Dolby Pro Logic (more or less).
    So the question is: because of that matrixing, does the sound at all suffer?
    Dynamic range, channel separation, signal-to-noise ratio, etc?
    In other words, would DTS-ES discrete sound any better if it was truly discrete with no matrixing at all?
    Another, "I always wondered" question...
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  2. Scott L

    Scott L Producer

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    Hmmm, as I understand it, there are 2 types of DTS-ES; matrix and discrete. If you have a DTS-ES discrete receiver (Denon 3801, 5800...) then the center rear speaker is truly a discrete channel. If you have a DTS-ES matrixed recever (Yamaha & Onkyo's available at Best Buy) then the sound is matrixed a la DPL.
    In both cases a DTS-ES disc is being played (Gladiator, The Haunting).
     
  3. Adam Barratt

    Adam Barratt Cinematographer

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    Kevin, you understand the format correctly, and the extraction of the matrixed channel information does affect the channel separation of the discrete channel. However, the effect is minimal and channel separation is still better than that possible if the channel were matrix only.
    Adam
     
  4. Kevin C Brown

    Kevin C Brown Producer

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    Scott and Adam- Oops, wasn't clear enough in my original post. In DTS-ES discrete, the *center* channel is discretely encoded and then decoded.
    But I'm more curious about the L + R rears.
    Even in the discrete format, the rear center channel is matrixed into the L + R rear signals, so that people with *only* DTS-ES matrix can still get the rear center channel somehow.
    So if the rear center *wasn't* matrixed into the L + R rears, how much better (if any) would the rears sound (or measure)?
    I don't know, just curious!
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  5. Adam Barratt

    Adam Barratt Cinematographer

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    Yes, I understood what you were saying. My reference was to the hybrid matrixed/discrete centre-surround channel, not to the front centre channel.
    Adam
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    Adam- OK, I re-re-read your post and I got it! So the answer is, "a little, but probably not noticeable."
    As for me, I'm lucky they did it this way, because I'm using a pseudo (homebrew) THX EX/DTS-ES (matrix) set up to get the center rear channel! Just wondered about any compromises in sound quality because of how they "spec'ed" the format.
    Cheers!
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  7. Kieran Coghlan

    Kieran Coghlan Second Unit

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    Kevin,
    Yes, there is a matrixed surround center (SC) channel in the surround left (SL) and surround right (SR) channels of dts-es-discrete. This is how they acheive backwards compatibility. However, it DOES NOT affect the play back of the SR and SL channels when using a dts-es-discrete capable decoder. The way they acheive this is by using phase cancellation. They extract the matrixed info from the SR and SL channels, then shift the phase 180 degrees and apply this phase shifted signal directly back onto the original SL & SR channels (which still contain the matrixed SC channel.) I *believe* this is done in the digital domain, because the cancellation is supposedly complete and perfect. So, when using a true dts-es-discrete processor, there should be no elements of the matrixed SC channel remaining in the SR & SL channels. This was all explained in wonderful detail in an article on e-town when dts-es-discrete first came out, but was lost when e-town went offline.
    (Note to the editors of The Perfect Vision: Howabout opening a website with all the e-town archives???)
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    -Kieran
    My HT Page
     
  8. Dan Hitchman

    Dan Hitchman Cinematographer

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    Perhaps yes, but they do a pretty darn good job of it now and DTS sure doesn't want to make thousands of regular DTS 5.1 decoders obsolute overnight.
    However, I would L-O-V-E a 7.1 channel discrete (full range, stereo rears instead of mono-- Lexicon's Logic 7 mode was a step towards that goal) DSD or 24 bit/96 kHz PCM track on any future HD-DVD format. If you lossless compress (pack) the uncompressed master, which would somewhat reduce the audio bitrate needed on the disc, it can easily be done.
    FMD is one such high capacity disc format that could do it and probably still have room for low compression 1920x1080p video at up to 30 fps.
    Dan
     
  9. Kevin C Brown

    Kevin C Brown Producer

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    Kieran- That makes sense. (Kind of neat actually.)
    But then I could split hairs, and say that if you didn't have to do all that processing to *remove* the matrixed-in channels from the L + R rears, it could (would) still sound better. [​IMG]
    But I get the point though!
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  10. Kieran Coghlan

    Kieran Coghlan Second Unit

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    Kevin-
    Possibly, but then es-discrete wouldn't be backwards compatible, either... so there's a mild trade off (if you're theory is correct which it may/may not be) and I think that backwards compatibility is worth it.
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    -Kieran
    My HT Page
    [Edited last by Kieran Coghlan on July 25, 2001 at 09:01 PM]
     
  11. Adam Barratt

    Adam Barratt Cinematographer

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    Here's a link to the initial follow-up article.
    In other words, not quite as good as a truly discrete channel, but the next best thing.
    Adam
    [Edited last by Adam Barratt on July 25, 2001 at 11:20 PM]
     
  12. DAN NEIR

    DAN NEIR Guest

    So is it correct to say that thx-ex and dts-es matrix are the same thing? Both using a matrixed rear channel? And dts-es discrete is the only dicrete 6.1 format?
     
  13. Kevin C Brown

    Kevin C Brown Producer

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    Adam- Great link! Great explanation. (WSR...)
    I think I remember 4-5 dB channel separation in original Dolby Surround, and then (yeah) ~30 dB (or so) for Dolby Pro Logic.
    A good turntable can get ~70 dB.
    And then CD is good for 90 or higher.
    I think!
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  14. Kieran Coghlan

    Kieran Coghlan Second Unit

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    Dan Neir:
    DTS-es-matrix and DD-EX are not the same, but they use essentially the same methodology to incorporate the 6th channel (i.e. matrixing).
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    -Kieran
    My HT Page
     
  15. David Judah

    David Judah Screenwriter

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    Wow, talk about semantics and splitting hairs. From the article:
    quote: Yesterday's article speculated that DTS-ES Discrete isn't truly a discrete system -- but in fact, it is.[/quote]
    Obviously, they didn't want to create a whole new format that would be incompatible with existing installations, so they didn't create a whole new channel in the traditional sense as the next sentence mentions:
    quote: True, it doesn't carry 6.1 separate channels in the same way that DTS and Dolby Digital carry five completely discrete, independent channels.[/quote]
    It uses Coherent Acoustics' flexibilty to send discrete rear channel info. directly to the rear center via extension data, so the way it carries it is different, but the result is the same.
    DJ
    [Edited last by David Judah on July 26, 2001 at 01:52 PM]
    [Edited last by David Judah on July 26, 2001 at 01:54 PM]
     

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