5.1 and S/PDIF

Discussion in 'Hardware Discussion & Support' started by dj_stick, Jul 29, 2004.

  1. Lowfat

    Lowfat Xtreme

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    HDA now has a card out that encodes DTS as well as Dolby Digital. I think its called the X-plosive or something like that. ~$130US
     
  2. Timagain

    Timagain New Member

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    Dobly Prologic 2 and KX pass through question

    Where does Prologic 2 fit into this scheme of gaming sound. I know that it can create 5.1 suround sound from 2 channel (encoded?) source. This probley helps older Proloigic sources.
    What about games, does it cost anymore then producing a sound track in DD5.1? can DP2 be
    encoded on the fly with less resorces then DD5.1. I somtimes play games though the spdif
    connector and apply DP2 to stereo PCM channel and its sound pretty dam good. Prolbey not
    as good as DD5.1 but almost as good. :p

    Can KX pass AC3 sources such as softdvd or ffdshow, or does it mess signal up?
    Are the soundblaster drivers a better choice for movies?


    Any one know how to change the spdif in (cd digital in) to spdif out trough KX on SB Live 5.1?
     
  3. sovietdoc

    sovietdoc New Member

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    I dont see a point in "on the fly digital encoding" You cannot make the sound, sound better than its original recording. All u get is a little bit louder and clearer EAX. What a waste. Only cool thing would be a complete shift to 96/24bit
     
  4. ehfr

    ehfr New Member

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    Still looking for a card with digital surround output for PC games to an AV receiver

    http://www.atruereview.com/HDA_X_Plosion/index.php

    Here's the skinny on the X-Plosion card. It has DTS (not just DDL). I'm having a hard time discerning whether it will take the true surround sound of a PC game and output it as 5.1 surround or not. It seems like it may...or it might just start with stereo and interprolate what it thinks surround would be.

    A quote from the review: "Alas, the lack of support for the latest EAX audio engines hampers the card's appeal to gamers. "

    Does anyone have experience with this card?

    BTW, I tried getting the Creative xi-fi and it FAILED at transmitting digital surround sound to my Pioneer AV Receiver. If you are a gamer trying to get digital surround to your AV receiver Creative STILL FAILS to provide that.

    Looking forward to hearing anyone's experience with the x-plosion...
     
  5. ehfr

    ehfr New Member

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    Of course the follow-up thought is....What are your opinions as to whether DTS is significantly better than DDL for gaming?
     
  6. Lowfat

    Lowfat Xtreme

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    Haven't seem too many people with the card howver I know of many people who are happy with the X-Mystique (HDA's DDL card) and the X-Plosion is supposedly quite a bit better.
     
  7. MannieFr3sh

    MannieFr3sh IFinallyGotSomeATiLovin!!

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    I just read through this whole thread and i'm still really confused about this whole S/PDIF thing.
    I have an A/V receiver that has dolby digital 5.1, dolby pro logic II, etc. I mainly use it to play my ps2 and 360 games in dobly digital 5.1 sorround and i use an optical cable for both.

    I just recently got this mobo: http://www.abit-usa.com/products/mb/products.php?categories=1&model=313. The soundcard that came with the mobo (Realtek HD 7.1 Audio) has what they call Dolby Master Studio which i have no clue what it does. But it has a S/PDIF digital out port on it. So lets say that i wanted to play my pc games in 5.1 sorround sound. Would i just have to connect the sound card to my a/v receiver with an optical cable (in other words, S/PDIF Out on sound card>S/PDIF on receiver.)? Would this automatically give me true 5.1 sorround sound in all my games (wether it's dolby digital or pro logic)? Or is there something else i need / need to turn on or enable in order to get 5.1 surround from pc games?

    Here's a screenshot of what it shows in the Realtek HD Audio Manager:
    [​IMG]
    As you can see, right now i have "Dolby Virtual Speaker" enabled because i'm using a regular 2.1 desktop speaker setup. According to the dolby website, dolby virtual speaker gives you "virtual" 5.1 from just 2 speakers: http://www.dolby.com/consumer/technology/virtual_speaker.html.

    But i can also turn on "Dolby Digital Live" and "Dolby ProLogic IIx". So am i capable of playing games in 5.1 surround sound? And if i am, what settings do i need to turn on/enable to get 5.1 from games?
     
  8. Lowfat

    Lowfat Xtreme

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    dolby digital live is true 5.1 over SPDIF/TOSLINK.

    Although you said you have your HT hooked up to your PS2 for Dolby Digital 5.1. I do not believe any game AFAIK has dolby digital 5.1.. I too have a 5.1 setup hooked up to my PS2, but I've never seen it be played in Dolby Digital, just Pro Logic II.
     
  9. MannieFr3sh

    MannieFr3sh IFinallyGotSomeATiLovin!!

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    You're right. My mistake. I've only seen up to PLII on ps2. But Xbox360 is always dolby digital. I'm not even sure if ps2 supports DD. But anyways, back to my question. So since DDL is true 5.1, all i have to do is enable DDL through the realtek soundcard software (after i've connected the sound card to the A/V receiver with an optical cable of course)? Then i will always get true 5.1 for all games? Or do i have to change some kind of setting in-game also?
     
  10. Lowfat

    Lowfat Xtreme

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    Yes, all you need to do is select Dolby Digital Live, and you will get true 5.1 over SPDIF/TOSLINK.

    The PS2 supports Dolby Digital Passthrough for DVD movies for sure, just dont think so with games.
     
  11. lambition

    lambition New Member

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    Not true.

    Your point it not entirely true.

    S/PDIF (Sony/Philips Digital Interface) is not 2 channel. SPDIF is just an way to transmit digital audio data. It has notthing to do with channels.

    When S/PDIF was first introduced, it carried PCM (Pulse Code Modulation) signals, which are 2 channel. It is the same data used on the Audio CD.

    When AC3/DTS signals are sent out through S/PDIF, sound card does not encode anything, but it might decode signal if you have decode option on. If sound card is set to pass through, then SPDIF will just carry pure AC3 or DTS signal and they are decoded by decoder on the receiver. They are not compressed to 2ch data like you said.
    If you are playing wave or mp3, then the sound card's DSP (Digital Sound Processor) is sampling wave data back to PCM. However, that is not true in the case of AC3 or DTS. They are just pass through. And this also means, when you are playing AC3 or DTS sound through SPDIF to be decoded by receiver, it doesn't matter how good is your sound card cause it doesn't do anything but to just pass the signal out.
     
  12. dj_stick

    dj_stick Apple Fanboy?

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    i agree with your points about the soundcard not doing anything if it's in passthrough mode, but some soundcards (soundstorm and others) do actually encode ac3

    However the original spdif standard was (and still is) for 2 channel uncompressed audio, that's all that the bandwidth of the standard allows. AC3 and DTS are compressed formats, allowing a larger number of audio channels to fit through the SPDIF bandwidth, which is then decoded/uncompressed by the receiver.

    Think of it like rar-ing a file to send over a dial up connection, and then un-raring the file to use on the receiving computer (however unlike .rar, AC3 and DTS are not lossless formats)
     
  13. lambition

    lambition New Member

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    True about compression, but that doesn't mean its compressed to 2 ch. Its just carrying different data stream.
    Guess I miss understood the way you explained.

    I don't think its losing that much data anyway. Even regular PCM looses some data when digitizing.

    Anyway, because S/PDIF is just an interface, I don't think it can be said that its problem with S/PDIF. It can carry many different data. (Like Internet)

    Maximum bandwidth of SPDIF I believe is 6MHz (from Google research).
    http://www.epanorama.net/documents/audio/spdif.html
     
  14. Lowfat

    Lowfat Xtreme

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    I never said it was compressed to 2 channels. There is are just no sources besides DVDs that use AC3/DTS over SPDIF. So generally if your soundcard doesn't encode DTS/DDL then it will only have 2 channels of sound unless its a DVD,etc.
     
  15. dj_stick

    dj_stick Apple Fanboy?

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    Lowfat - i think lambitions post was in regards to my post at the start of the thread, rather than your own
     
  16. sm007h

    sm007h New Member

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    I had to register and dig this old thread up because I'm confused about something I'd like to know before I try an ac3 encoder or sound card to send my processor 5.1 DD.

    First, if there are differences between decoders, are there quality differences between encoders?

    Second, if our processors are Pro Logic II(x) capable, how different is allowing the processor to produce 5.1 or 7.1 on the fly from a stereo stream then feeding it on the fly software or soundcard produced DD 5.1?

    Would that question depend on the quality of the processor (receiver)?


    EDIT: After thinking about it some more, I wrote this on a different forum and figured I repeat my thoughts here:

    First of all, AFAIK, sound cards don't pass raw EAX or 3D positioning to a reciever or speakers.
    They don't create discreet channels, either. EAX and 3D positioning were designed to give ambiance to the listener and, in the begining at least, they were primarily aimed at 2 channel listeners (earphones in particular).
    EAX (all the way up to 4.0 HD) produces effects in the audio stream, not channels.

    In any case, the only dolby digital that is "true" would be that which is recorded at the source in multi-channel.
    Unless a game is producing multi-channel audio, in which case it'd simply be passed through to the reciever, either software, the soundcard, or the processor (receiver) have to extract sounds from the audio stream and send them down their appropriate channels.

    The latest pro logic decoding schemes can rival multi-channel audio. Music mode adds ambiance to the source in order to give the listener a more enveloping soundstage than 2 channel. It "expands" the music, as one person posted earlier. But PLII movie mode matrixes out positional channels; it "separates" the channels, just like DD 5.1. The difference is that DD 5.1 is recorded in 6 separate channels at the source. Encoding a stereo stream from a video game is not the same as recording it at the source, in my opinion.

    http://www.axiomaudio.com/dolbyprologicII.html
    http://www.wildwestelectronics.net/lisguidtodol1.html


    The only significance would be in the case of mono sources, since PLII(x) upmixes only 2 channel or multi-channel sources. But with PLII matrix mode, which upmixes from a mono source, this doesn't even need to be a concern.

    There are two ways to test this that I can think of:
    1) AB between a 2 channel source and an identical 5.1 channel source.
    This would test how closely PLII can approximate true multi-channel sound.

    2) AB between PLII and DDL.
    This would test whether PLII can meet or exceed the quality and sound positioning of DD 5.1.

    I'm going to test #2 as soon as possible. I have a problem with BF2 and PLII and sounds directly behind me. They come out of the front speaker. Side positioning is great, but as soon as a line is crossed behind my ear, the sounds shift to the center speaker. So I think having someone stand behind me and shoot a gun would be a good, objective test of whether DDL can produce more stable positioning than PLII. Note: I'm not referring to which one sounds better. That decision is going to have to be made by the listener, if one can tell the difference at all (you'll have to test #1 yourselves).

    I also don't think dolby encoding is lossless. That means you might actually degrade the signal when you encode to 5.1 and then decode to analog. Assuming PLII does as good a job of seperation as DDL, then the signal's quality should be preserved better by not encoding and decoding it.
     
    Last edited: Nov 10, 2006
  17. dj_stick

    dj_stick Apple Fanboy?

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    dolby encoding is far from lossless, it's a lossy codec (has to be to fit into the stereo bandwidth of SPDIF)

    the soundquality of any sound system is mostly dependent on the Digital To Analogue converters. Using analogue connections, these converters are on the soundcard, using a digital connection, they are on the receiver/decoder

    EAX really has nothing to do with producing multi-channel sound, so it's best to leave it out of the equation to save confusion

    however Soundcards can and will produce seperate channels if the host application requires it (and the soundcard supports it)

    if a game has multi-channel support, it means that where the sound comes from (speaker wise) is calculated on-the-fly based on the in-game source's position in relation to the player

    some games do this well, others not so well, and is often driver dependent (hardware mixing)

    imo this method will be more accurate than any upmixing algorythm if the game's 3D audio engine is up to scratch
     
  18. sm007h

    sm007h New Member

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    hmm, I can see your point if games start outputting multi-channel sound. I was under the impression that pc games weren't doing that yet. If they aren't, then the soundcard is simply extracting multi-channel audio in leiu of the receiver. If so, then I'd rather leave it to the higher end compoenent (whichever one may be).


    But after reading up more on DD compression, PCM bandwidth limitations, I've come to a new realization that might give further support for the idea of on the fly DD before receiver: even two channel sound has the potential to saturate the spdif channel. So DDL can funnel more sound information down the pipe than PCM, if I'm understanding this.
     
  19. dj_stick

    dj_stick Apple Fanboy?

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    two channel PCM sound will saturate the spdif channel if the level of the signal is over 0.0dB FS, clipping the signal

    what Dolby Digital a.k.a. AC-3 does is compresses the sound of each channel from 768kbps (this is the bitrate of a single channel of uncompressed PCM at 16bit, 48khz - the standard for DVD-Video Audio channels) down to maybe a third of that, two fit 6 channels down the space that normally only fits 2 channels. It's like using winrar to compress a file to send over the net.

    Like MP3, AC-3 was not designed purely with audio in mind, it was designed to be an "acceptable" audio codec that would allow a DVD-Video to have multi-channel sound, with out taking up too much space (space that was needed for the video part). So it's far from the ideal audio transfer if you're interested in audio quality.

    Although the quality loss in an AC-3 signal is not as noticeable as that in an MP3 file, a decent soundcard with high quality DAC chips using analogue connections could easily beat the quality of an AC-3 signal, when paired with a high quality speakers/amp
     
  20. skinnie

    skinnie New Member

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    hi,I am with some doubts,I have a nforce soundstorm board,and I am very tempted to see it's capabilities buying some digital speakers,but is it worth against my fortissimo 3 in analog with the x-530?I am asking this because I mostly listen to mp3,and some games.
    And for the speakers,are there any digital 2.1 speaker set?are the promedia's 2.1 or the 5.1 digital?I am asking this,because I am an overclocking fna,and the fortissimo 3 is limiting me I think..(sorry for my bad spell)
     

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