Dolby Pro Logic Software decoder

Discussion in 'Computers' started by Adam Sanchez, May 31, 2005.

  1. Adam Sanchez

    Adam Sanchez Supporting Actor

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    hello all. Coming once again for help.

    I was wondering if there is some kind of free software download or plugin I could get that would decode DVDs in Dolby Prologic?

    What I want to do is watch older TV shows that were only recorded in Dolby Prologic on my computer of course. In my living room, my reciever automatically makes the 2 channel signal into surround sound, but when I play a 2 channel DVD on my computer, it only comes out as 2 channel. I have an Audigy 2 ZS sound card and I'm thinking it must have a simple ability to make a 2 channel mix into surround. I want real Pro Logic if possible, not just the 2 channels upmixed into 5 where all 5 speakers basically have the same sound.

    Thanks!
     
  2. Marko Berg

    Marko Berg Supporting Actor

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    Sounds like the DVD decoding software you are using only supports playback in 2-channel stereo, as is often the case with bundled software that comes preinstalled in some PCs. What is the player (and its version) you use?
     
  3. Adam Sanchez

    Adam Sanchez Supporting Actor

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    I have Power DVD 6 and it's the full version, it plays 5.1 movies just fine. I didn't think this was a player issue, I thought I just needed some kind of pro logic decoder to play 2 channel sources in surround, as my receiver does. I know the Audigy must be able to do something like simple pro logic decoding. [​IMG]
     
  4. Ken Chan

    Ken Chan Producer

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    It might be a little too simple. ProLogic is "just" 4.0; it seems that the marketeers are only interested in 5.1 or 7.1 nowadays.

    PowerDVD 6 Deluxe has ProLogic II decoding. That would be your best bet, since that should accurately read the Dolby Surround encoding, and maybe do a little extra (the II part). You can upgrade from 6 Standard, although I'm not sure that's worth $25.

    Another approach would be to open the Audigy's EAX Console, and on the CMSS 3D page, enable CMSS or CMSS 2 (not Stereo Surround, which is what you said you don't want). CMSS is supposed to work with Dolby Surround encoded material. In that case, you set PowerDVD to output straight stereo, so that the Audigy can do its thing.
     
  5. Adam Sanchez

    Adam Sanchez Supporting Actor

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    I always thought prologic was 2.0 and they decoder just sort of "pulls" the sound from the 2 front channels to give it a center and surrounds. I always noticed the center wasnt pure on PL, like you could put your ear to the front L and R and still hear the dialogue muffled even though it dominately came out of the center.

    Anyway my Power DVD does indeed have the PLII decoding. I turned it on but it doesnt seem to decode right... or maybe it is and I dont know know. I had any other decoders turned off and only had the Power DVD on with the PLII enabled and like all the sound was basically the same. There was no seperation like the center taking the dialogue, etc.

    I'm doing all this on a 2.0 source, which is quantam leap season 3 by the way.
     
  6. Ken Chan

    Ken Chan Producer

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    The output from ProLogic is 4-channel -- left, right, center, and surround -- which is why I called it 4.0. (The earlier non-ProLogic Dolby Surround decoders only did 3 channels -- left, right, and surround -- from the same source.) It is encoded into 2 channels, and the encoding is completely compatible with plain stereo, which is the trick of course. And some DVDs call the Dolby Surround mix 2.0 to indicate it is a stereo signal and/or to clearly differentiate from the 5.1, so yeah, it's confusing [​IMG]

    You can apply ProLogic decoding on any stereo signal. If it is Dolby Surround, then the result will be what the sound mixer intended; as you point out, you may not get perfect channel separation, but that's a known limitation. However, if it's not Dolby Surround, something is still likely to happen, but the results can be "wacky".

    It's possible the PLII is working. The only way to know for sure is to play the same disc somewhere else and compare the two. If they are different, then at least one of them is wrong, although it could be both. Or it could be the disc, or the soundtrack that they used. You might try a more recent show with more surround effects, like a modern Star Trek.
     

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