Dolby Digital EX and DTS-ES - just to be clear

Discussion in 'DVD' started by Lanny_B, Dec 28, 2003.

  1. Lanny_B

    Lanny_B Second Unit

    Nov 24, 2001
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    Let me see if I can sum this up right and get what exactly 6.1 is. There are DVD's encoded with DTS-ES that have a real 6th channel- one that's actually programmed to be it's own unique channel, encoded into the DVD. Then there's Dolby Digital EX and DTS-ES Matrix which are programmed from the DVD creators to take certain parts of the rear speakers in the 5.1 setup, and form a 6th channel. This isn't as fake as your receiver trying to make one, because it's encoded that way right on the DVD. So, it's still a pretty clearly designated 6th channel. Then, lastly, you can use a receiver to fake DD EX or DTS Matrix on any 5.1 which just guesses from the rear two channels and tries to come up with a 6th one.

    So, to restate, there's 3 ways to have 6.1:
    1. DTS-ES - real 6th channel.
    2. Dolby Digital EX or DTS-ES Matrix - an encoded mix of the back two channels, making a semi-real 6th channel.
    3. Dolby Digital 5.1 or DTS with receiver forcing 6.1 - fake 6th channel that's a mixture of the back two.

    That's my understanding of it after my studying into it. Anyone, step in if I'm wrong.

    A few questions to add:
    1. As I said, I can tell the receiver to fake a back channel for any 5.1 DVD. What's you guys' experience with the results? Is that usually a good thing, or do you all find that it is better just to leave it alone?

    2. On DVD's that have Dolby Digital EX and a DTS channel (not DTS-ES), is it better to go with the DD EX, or just go DTS Matrixed? (Pirates of the Carribean, for example)

    3. How beneficial do you think it is to have a 7th speaker? Or, what really is the point? Does it just balance things better?

    4. My receiver has outputs for 6 speakers, but I don't see a seventh. After reading the Primer, I gather that I have to have a specific receiver for 7.l. I know there's only 6 discrete channels though, so I just want to be sure: Does this mean 7.1 is not an option on a 6.1 receiver -- no way to separate the 6th channel externally into two rear speakers?
  2. Michael Osadciw

    Michael Osadciw Screenwriter

    Jun 24, 2003
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    Michael Osadciw
    Hi Lanny

    There is only one 6 channel format: DTS-ES discrete

    Dolby Digital EX and DTS-ES (Matrix) are 5.1 surround formats that have rear-center information recorded (in left and right surround). A flag in the signal lets the matrix decoder put that center information into a rear center speaker. This is not a discrete channel, it is derived, thus cannot be considered a discrete 6th channel.

    You can also apply this (Pro-Logic) processing for films that were recorded without rear-center information in mind. I never advise to do it because:

    -the rear soundstage can collapse to the center rear, thus limiting a rear soundstage

    -adding more processing to a "discrete" 5.1 signal will decrease channel separation, add noise, and limit audio resolution

    -many receivers attenuate surround channel levels by 3dB when adding the processing to force information into a rear center channel. This causes an imbalance to your system's channel levels that you may have taken time to set-up from your listening position.

    Therefore, I'd leave a 5.1 recording alone, but if there is a flag present I will use the decoding.

    "On DVD's that have Dolby Digital EX and a DTS track (not DTS-ES), is it better to go with the DD EX, or just go DTS Matrixed? (Pirates of the Carribean, for example)"

    -I'd still use DTS because I believe it sounds better and a 6th speaker is less important to me than audio resolution.

    "How beneficial do you think it is to have a 7th speaker?"

    -In my opinion it's highly unnecessary unless you have a huge space between your left/right surround speakers (imo, greater than 20ft). The 7th speaker is a replication of the 6th speaker, so why anyone would want 2 speakers putting out a dominant mono sound behind them is beyond me (especially in small rooms).

    Walk away remembering one thing: there is NO 7.1. That is marketing for (at best) 6.1 + one extra speaker putting out the same sound as the "6th".


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