What does Dolby 5.1 mean?

Discussion in 'Archived Threads 2001-2004' started by Jae_P, Dec 4, 2001.

  1. Jae_P

    Jae_P Extra

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    Ok, can somebody please explain to me what all these different Dolbys mean? Before i watch a DVD i can choose from like 3 different Dolby options from the audio category. Dolby 5.1, Dolby 2.0 and Dolby Digital Surround. What does each one mean? Which one am i suppose to use? Which one is the best? Thanks.
     
  2. Henry Carmona

    Henry Carmona Screenwriter

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    Hi Jae,
    Hope this helps some.
    CLICK
    If you have any further questions, plz ask.
    Basically,
    The goal is to listen to a movie as it was played in the movie theaters, which is now 5.1, 5 channels of sound(Front Left, Center, Front Right, Rear Right, and Rear Left speakers), and .1 means the subwoofer, or low frequencies.
    You need a DVD player that can decode Dolby Digital and a Dolby Digital receiver to play it.
    Hope this helps.
     
  3. Gordon C Jr

    Gordon C Jr Stunt Coordinator

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    Not so sure that Henry is completely correct.

    I believe you need EITHER a DVD player connected to a receiver that contains Dolby Digital decoder (Receiver decodes the DD5.1)

    OR

    have a DVD with an onboard decoder connected to a receiver with six inputs (DVD player decodes the DD5.1)

    Both DVD player with DD5.1 decoder and Dolby Digital receiver are not required. Just one or the other needs decoding capability, but the connections (wiring) will be different for both.
     
  4. Rob Peloski

    Rob Peloski Agent

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    Dolby Prologic (aka Dolby Surround) is 4 channels (left, right, center, rear) encoded into a 2 channel (stereo)signal. The center and rear channel are not discrete (i.e. the rear channel isn't full frequency) but usually Prologic is an improvement over a straight stereo soundtrack. HiFI VCR's and the majority of television shows use this format (although sometimes satellite and digital cable shows can be dolby digital if you have the hardware). Some DVD's also have a Dolby Prologic soundtrack.

    There is also a new format out called Dolby Prologic 2 which improves on the original Dolby Prologic (i.e. it has a stereo rear channel and there is better seperation between the channels...although not as great as Dolby Digital). I haven't heard it myself but it is supposed to be a nice improvement over Dolby Prologic. I believe existing Prologic material is supposed to sound better when played back on a Receiver that supports Prologic 2.

    Dolby Digital is a digital format designed to have up to 6 seperate and discrete channels (although some encoding "tricks" can be used to get a center rear channel as well). Dolby Digital 5.1 is the most common. The "5" in 5.1 is referring to the Front Left, Front Right, Center, Rear Left and Rear Right speaker channels. The ".1" is referring to the LFE (Low Frequency Effects) channel (it's denoted .1 as it doesn't need as much bandwidth as the other 5). The purpose of the LFE channel is to help strengthen the bass during certain sections of the movie.

    It's not uncommon for a Dolby Digital signal to have fewer then the 6 channels above. One common example is Dolby Digital 2/0 which refers to a stereo signal (the "2" refers to the number of front channels, the "0" refers to the number of rear channels, A 5.1 mix would usually be displayed as 3/2). Quite often a Prologic signal is encoded into these two channels. A movie with a mono soundtrack would be 1/0. There are also movies that don't have an LFE track (or only have it in spots). In such cases, the LFE indicator on your receiver wouldn't come on or would only come on in certain spots.

    Which one is the best? It depends on the movie. If the movie originally had a 5.1 sound track then Dolby Digital 5.1 would be the best. If it only has a stereo or prologic track then Dolby 2.0 is appropriate. Some people insist that all movies without a 5.1 soundtrack should be remixed to have one. However a lot (if not the majority) of people on this forum perfer to have the original soundtrack even if it's only a mono track. It's very similar to the original aspect ratio (widescreen vs full frame/pan and scan) debate...we want what the director intended.

    While on this topic I'm also going to mention another format called DTS. DTS is an alternative to Dolby Digital (and is not made by Dolby). Although it uses a different encoding method, for the most part it works the same way as Dolby Digital (i.e. has all descrete channels, not all of them have to be used, etc). I believe that at the moment DTS supports more descrete channels then Dolby Digital (I know it does 7 for sure, I believe in theory it can have up to 8). Some people argue that DTS sounds better then Dolby Digital because it uses less compession but really isn't an answer as to which is better (usually any differences are due to one company getting a higher quality master to create the soundtrack with). I highly suggest you don't ever start a thread that debates which one is better but you can always do a search for older threads to see what people have said on the topic.

    As for your question as to which one to choose on your DVD. If you have a Dolby Digital system (either a Receiver that can decode Dolby Digital thats hooked digitally to your DVD player, or a DVD Player with a Dolby Digital decoder in it hooked to the 5.1 inputs on a Dolby Digital "Ready" receiver) then choose Dolby Digital 5.1. If you do not have a Dolby Digital system (i.e. you are using the red and white analog jacks hooked either to your television or an older Prologic only receiver) select Dolby Prologic/Surround/2.0
     
  5. Jae_P

    Jae_P Extra

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    What would happen if i chose the Dolby 5.1 without a receiver? I use my TV speakers. Wouldnt it sound better than the Dolby 2.0? I think most DVDs are already set on Dolby 5.0 so i should probably not even bother with it huh? Until i get some kind of a receiver that decodes Dolby 5.1 or DTS i shouldnt worry about which one to choose and just start the movie right?
     
  6. Sean Conklin

    Sean Conklin Screenwriter

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    With no receiver, just choose DD surround or DD 2.0
     
  7. Michael Reuben

    Michael Reuben Studio Mogul

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    Don't choose DTS until and unless you have a receiver that decodes it. Most DVD players aren't equipped to decode DTS internally. Selecting it in your current setup may get you nothing but silence. In theory, the player should automatically switch back to DD, but you never know . . .
    M.
     
  8. Vince Maskeeper

    Vince Maskeeper Producer

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    As the others have said, if you have have you player connected analong to your TV (which you say you do), you should select the 2.0 (or sometimes called "dolby surround" track).

    To be clear, when you select the 5.1 mix, it doesn't do anything "bad", the player simply internally "downmixes" the signal automatically from 5.1 to 2.0 for you.

    However, the player's ability to do this "downmix" is not as good as a dedicated 2.0 mix would be, and that is why 2.0 mixes are included.

    On some discs, 5.1 is the only option- and this shouldn't be a major problem, as the player will downmix. But, when given the option to chose, just select the specifically prepared dolby 2.0 mix.

    -Vince
     
  9. Henry Carmona

    Henry Carmona Screenwriter

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    Thanks Gordon,
    Sometimes i just type too fast [​IMG]
     
  10. Gordon C Jr

    Gordon C Jr Stunt Coordinator

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    “The only way to get DD 5.1 is through a digital connection to a receiver or processor that decodes DD.”

    Michael,

    Is it not true that you can also obtain DD 5.1 through an analog connection, if your DVD has an onboard decoder and is connected to 6 channel inputs on your receiver?

    That is if the receiver is “AC3 ready” or even a Dolby Digital receiver (though not recommended) through the 6 inputs, similar to a DVD-A or SACD connection
     
  11. Michael Reuben

    Michael Reuben Studio Mogul

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    Of course it's true, Gordon, but my comments were directed to Jae_P's situation. They weren't intended to exhaust the subject. When trying to help someone who's obviously new to HT, there's such a thing as too much information.

    M.
     

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